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Exotic Animal Medicine Veterinary TechnicianSecond EditionExotic Animal Medicine Veterinary TechnicianSecond EditionEdited byBonnie Ballard, dvm and Ryan Cheek, RVTg vts (ecc)WILEY-BLACKWELLA John Wiley & Sons, Inc., PublicationFirst edition first published 2003 Second edition first published...  
Exotic Animal Medicine Veterinary TechnicianSecond EditionExotic Animal Medicine Veterinary TechnicianSecond EditionEdited byBonnie Ballard, dvm and Ryan Cheek, RVTg vts (ecc)WILEY-BLACKWELLA John Wiley & Sons, Inc., PublicationFirst edition first published 2003 Second edition first published 2010©2010 Blackwell PublishingBlackwell Publishing was acquired by John Wiley & Sons in February2007. Blackwells publishing program has been merged with Wileys globalScientific, Technical, and Medical business to form Wiley-Blackwell.Editorial Office2121 State Avenue, Ames, Iowa 50014-8300, USAFor details of our global editorial offices, for customer services, andfor information about how to apply for permission to reuse the copyrightmaterial in this book, please see our website at www.wiley.com/wiley-blackwell.Authorization to photocopy items for internal or personal use, or theinternal or personal use of specific clients, is granted by BlackwellPublishing, provided that the base fee is paid directly to the CopyrightClearance Center, 222 Rosewood Drive, Danvers, MA 01923. For those organizationsthat have been granted a photocopy license by CCC, a separate system of pay­mentshas been arranged. The fee codes for users of the Transactional ReportingService are ISBN-13: 978-0-8138-2206-8/2010.Designations used by companies to distinguish their products are oftenclaimed as trademarks. All brand names and product names used in this book aretrade names, service marks, trade­marks or registered trademarks of theirrespective owners. The publisher is not associated with any product or vendormen­tioned in this book. This publication is designed to provide accurate andauthoritative information in regard to the subject matter covered. It is soldon the understanding that the publisher is not engaged in renderingprofessional services. If professional advice or other expert assistance isrequired, the services of a competent professional should be sought.Library of Congress Cataloging-in-Publication DataExotic animal medicine for the veterinary technician / edited by BonnieBallard and Ryan Cheek. - 2nd ed. p. ; cm.Includes bibliographical references and index. ISBN-13:978-0-8138-2206-8 (alk. paper)1. Exotic animals-Diseases.  2. Wildlifediseases.  3. Pet medicine.  4. Veterinarynursing.  I. Ballard, Bonnie M.  II. Cheek, Ryan.[DNLM:  1. Animal Diseases.  2. Animals,Wild.  3. Animal Technicians.  4. VeterinaryMedicine-methods.  SF 997.5.E95 E96 2010]SF997.5.E95C44 2010636.089073-dc22 2009035848A catalog record for this book is available from the U.S. Library ofCongress.Set in 10 on 12 pt Sabon by Toppan Best-set Premedia Limited Printed andbound in Malaysia by Vivar Printing Sdn BhdDisclaimerThe contents of this work are intended to further general scien­tificresearch, understanding, and discussion only and are not intended and shouldnot be relied upon as recommending or promoting a specific method, diagnosis,or treatment by practi­tioners for any particular patient. The publisher andthe author make no representations or warranties with respect to the accuracy orcompleteness of the contents of this work and spe­cifically disclaim allwarranties, including without limitation any implied warranties of fitness fora particular purpose. In view of ongoing research, equipment modifications,changes in gov­ernmental regulations, and the constant flow of informationrelating to the use of medicines, equipment, and devices, the reader is urgedto review and evaluate the information provided in the package insert orinstructions for each medicine, equip­ment, or device for, among other things,any changes in the instructions or indication of usage and for added warningsand precautions. Readers should consult with a specialist where appropriate.The fact that an organization or Website is referred to in this work as a citationand/or a potential source of further information does not mean that the authoror the publisher endorses the information the organization or Website mayprovide or recommendations it may make. Further, readers should be aware thatInternet Websites listed in this work may have changed or disappeared betweenwhen this work was written and when it is read. No warranty may be created orextended by any promotional statements for this work. Neither the publisher northe author shall be liable for any damages arising herefrom.2  2010Table of ContentsPreface xiiiAcknowledgements xvContributors xviiDisclaimer xxiSection 1 Introduction3Chapter 1  The Role of the Veterinary Technician inExotic Animal Medicine 5Bonnie BallardSection 2 Avian 9Chapter 2  Psittacines and Passerines11Cheryl B. Greenacre and Lillian GerhardtIntroduction 11Anatomy and Physiology 12Comparative Clinical Pathology 16Nutrition 17History, Restraint, and Physical Examination18Common Diseases 24Radiology 30Anesthesia and Analgesia 30Surgery 32Parasitology 33Gender Determination 33Grooming 34Emergency and Critical Care 35Techniques 37Administration of Medications 38Diagnostic Sampling 42Wound Care and Bandaging 42Euthanasia 43References 43Chapter 3  Psittacine Behavior, Husbandry, and Enrichment45Tarah HadleyIntroduction 45Behavior of Common Pet Psittacine Species45Husbandry 49Normal Behavior of Psittacine Bird Species51Abnormal Behavior 52Additional Reading 54See the supporting companion Web site for this book: www.wiley.com/go/ballard, Vvi ContentsChapter 4  Aviary Design and Management 55April RomagnanoIntroduction 55Aviculture 55Quarantine 55 Examinations andDiagnostic Testing: Neonates, Juveniles, Breeders, andNew Acquisitions 56Disinfection and Disease Prevention57Pediatrics for the Aviculturist 58Conclusion 59Additional Reading 60Chapter 5  Sex Differentiation and Reproduction 61April Romagnano and Tarah HadleyIntroduction 61Sex Differentiation 61Reproduction 62Reproductive Medicine and Surgery 63Additional Reading 65Section 3 Reptiles 67Chapter 6  Lizards 69Brad WilsonIntroduction 69Anatomy and Physiology 69Husbandry 78Quarantine 83Nutrition 83Common Disorders 87Behavior 93Toxicity and Miscellaneous Nutritional Disorders94Zoonoses 94History, Restraint, and Physical Exam96Radiology 100Anesthesia and Surgery 101Parasitology 103Emergencies 106Techniques 110Euthanasia 116References 116Chapter 7  Snakes 119Ryan Cheek, Shannon Richards, and Maria CraneIntroduction 119Captive-Bred Versus Wild-Caught 119Behavior 119Anatomy and Physiology 120Reproductive Biology and Husbandry126Egg Anatomy 128Egg Incubation and Management 128Housing 130See the supporting companion Web site for this book: www.wiley.com/go/ballard,Contents viiSee the supporting companion Web site for this book: www.wiley.com/go/ballard.Quarantine 137Nutrition 138Transportation 140Diseases and Clinical Conditions 140Taking a History^ 145Preparing For the Physical Exam 146Restraint 146The Physical Exam 148Radiology 150Anesthesia 150Surgery 153Parasitology 154Common Parasites of Snakes 154Emergency and Critical Care 155Emergency Conditions 156Critical Care Monitoring 157Sex Determinination 158Clinical Techniques 159Venomous Snakes 163Euthanasia 164Being a Responsible Snake Owner 164References 165Chapter 8  Chelonians 167Samuel RiveraIntroduction 167Anatomy and Physiology 168Husbandry and Nutrition 169Common Diseases 171Zoonoses 174Obtaining a History and Performing a Physical Examination174Restraint 175Radiology 175Anesthesia 175Parasitology 176Emergency and Critical Care 176Clinical Techniques 177Administration of Medications 179Euthanasia 180References 181Chapter 9  Herpetoculture and Reproduction 183David Martinez-JimenezIntroduction 183Captive-Bred Versus Wild-Caught 183Quarantine 183Managing Large Collections 184Managing Large Collections Of Dangerous Species188Methods Of Sex Determination 188Reproductive Behavior 191Follicle and Egg Development 193Clutch Dynamics 193Oviparous, Ovoviviparous, Or Viviparous194viii ContentsEgg Incubation Versus Maternal Incubation194Egg Incubation Methods 194Diagnosing Egg Problems 198Caring For The Newborn 199References 200Section 4 Amphibians 203Chapter 10 Amphibians 205Brad WilsonIntroduction, Taxonomy, and Natural History205Anatomy and Physiology 209Husbandry 214Enclosure Design 218Amphibian-Environment Interaction 219Amphibian-Amphibian Interaction 219Quarantine 220Nutrition 221Food Items 222Common Disorders 224Larval Amphibians 228History and Physical Exam 229Radiology 232Anesthesia and Surgery 232Techniques 233Euthanasia 236References 237Section 5 Mammals 239Chapter 11 Ferrets 241James R. McClearen, Julie Mays, and Tarah HadleyIntroduction 241Anatomy 241Behavior 243Husbandry 244Nutrition 244Common and Zoonotic Diseases 245History and Physical Examination 246Preventive Medicine 247Restraint 247Radiology and Ultrasound 247Anesthesia and Surgery 248Parasitology 248Urinalysis 248Emergency and Critical Care 249Sex Determination 250Techniques 250References 253See the supporting companion Web site for this book: www.wiley.com/go/ballard.ContentsIXChapter 12 Rabbits 255Douglas K. Taylor, Vanessa Lee, Deborah Mook, and Michael J. HuerkampIntroduction 255Behavior 255Anatomy and Physiology 256Biologic and Reproductive Data 259Husbandry 259Nutrition 261Common and Zoonotic Diseases 262Taking a History 269Physical Examination and Preventive Medicine271Restraint 273Radiology 274Anesthesia 275Common Surgical Procedures 280Parasitology 281Urinalysis 282Clinical Techniques 282Sex Determination 287Emergency and Critical Care 287Euthanasia 289References 289Chapter 13 Mice, Rats, Gerbils, and Hamsters293Anne Hudson and April RomagnanoIntroduction 293Anatomy and Physiology 293Biologic and Reproductive Data 295Husbandry 295Nutrition 296Common Parasites, Diseases, and Zoonoses296Behavior 300History and Physical Examination 301Restraint and Handling 301Radiology 302Surgery and Anesthesia 302Bandaging and Wound Care 303Emergency and Critical Care 303Sex Determination 303Techniques 303Euthanasia 308Additional Reading 309Chapter 14 Chinchillas 311Trevor Lyon and Bonnie BallardTaxonomy/Common Species Seen in Practice311Anatomy and Physiology 311Reproduction 313Husbandry 313Nutrition 313Common and Zoonotic Diseases 313Behavior 315Taking the History and Performing the Physical Exam315See the supporting companion Web site for this book: www.wiley.com/go/ballard,x ContentsHandling and Restraint 315Radiology 316Anesthesia and Surgery 316Parasitology 316Urinalysis 316Emergency and Critical Care 317Sex Determination 317Techniques 317Euthanasia 318References 318Chapter 15 Guinea Pigs 319Anne Hudson and Maria CraneCommon Types 319Behavior 319Anatomy and Physiology 319Biologic and Reproductive Data 319Husbandry 320Nutrition 320Common and Zoonotic Diseases 321History and Physical Examination 321Restraint 322Radiology 322Anesthesia and Surgery 322Parasitology 322Urinalysis 323Emergency and Critical Care 323Sex Determination 323Techniques 323Euthanasia 325References 325Chapter 16 Hedgehogs 327Michael Duffy JonesTaxomony, Anatomy, and Physiology 327Biologic and Reproductive Data 329Behavior 329Husbandry 329Nutrition 330Common Diseases 330Obtaining a History and Physical Examination331Radiology 331Anesthesia and Surgery 331Urinalysis 332Parasitology 332Emergency and Critical Care 332Sex Determination 332Techniques 332References 334Chapter 17 Skunks 335Samuel RiveraIntroduction 335Anatomy and Physiology 335See the supporting companion Web site for this book: wvyw.wiley.com/go/ballard,Contents xiSection 6 Wildlife Rehabilitation 349Chapter 20 The Role of the Veterinary Technician in WildlifeRehabilitation 351Melanie HaireIntroduction 351Getting Started 351Rehabilitating Wildlife in a Small Animal Veterinary Hospital352Clinic Protocols 352Intake Procedures 355Ethical Considerations and Reducing Stress in Captive Wildlife356Initial Exam 356Choosing Treatment Routes 357See the supporting companion Web site for this book: vyrww.wiley.com/go/ballard,Husbandry and Nutrition 335Common Health Problems 335Amyloidosis 336Zoonotic Diseases 336Physical Examination 337Vaccinations 337Restraint 337Radiology 337Anesthesia 337Parasitology 337Clinical Techniques 337Administration of Medications 339References 339Chapter 18 Sugar Gliders341Samuel RiveraIntroduction 341Anatomy 341Husbandry and Nutrition 341Common Diseases 342Physical Examination 342Restraint 342Radiology 343Anesthesia 343Parasitology 343Clinical Techniques 343References 344Chapter 19 Prairie Dogs345Samuel RiveraIntroduction 345Anatomy and Physiology 345Husbandry and Nutrition 345Common and Zoonotic Diseases 345Restraint 347Radiology 347Anesthesia 347Clinical Techniques 347References 348xii ContentsRelease Criteria Versus Euthanasia358Imprinting and Taming 359Transporting Wildlife 360Raptor Care 362Altricial Orphan Songbirds 368Caring for Adult Passerine (Song) Birds373Precocial Bird Basic Care 376Adult Precocial Birds (Including Waterfowl and Wading Birds)377General Orphan Mammal Care 378Species Care Sheets 382Acknowledgments 382References 383Section 7 Hematology 385Chapter 21 Avian and Reptile Hematology387Denise I. BounousIntroduction 387Blood Collection 387Blood Smear and Assessment 388Leukocytes 388Erythrocytes 391Thrombocytes 392References 392Appendices  1. State/Federal Wildlife Permit Offices3952. WildlifeAdmission/Exam/Care Forms 3993. Handling andRestraint of Wildlife Species 4034. Tail Wrapping4095. Guide toIdentification of Hatchling and Nestling Songbirds4116. Average BodyWeights of Selected North American Songbirds4177. Species Care Sheets4198. Biological Data ofSelected North American Wild Mammals 4279. Glossary of MedicalConditions and Treatments 42910. Wildlife ProductSources 43311. AdditionalResources 43712. Supplies Necessaryfor an Exotic Practice 441Index 443See the supporting companion Web site for this book: wvyw.wiley.com/go/ballard.PrefaceThe second edition was written to provide the veterinary technician withimportant information about a variety of species commonly seen in exoticpractice, reflecting changes in this branch of medicine that have occurredsince the first edition. This text is beneficial to the technician who wouldlike to work with these animals but may have graduated years ago, before thisarea of medicine was popular. This text is also helpful to the techni­cian whoworks for a veterinarian who would like to add exotic species to his/herpractice. While it was not written for veterinarians, they may find itbeneficial as well.With the help of this book, the technician will know what questions toask to obtain an adequate history, be able to educate the client abouthusbandry and nutrition, be able to safely handle and restrain common species,and be able to perform necessary procedures when needed. Because the field ofexotic animal medicine is a dynamic one, new knowledge is constantly emergingabout many of the species kept as pets, and new informa­tion can, in somecases, contradict what was thought to be true before. For many species, exoticanimal medicine can be said to be in its infancy. We realize that for some ofthe species featured in this book, the information presented may need to bemodified in the future. Further, because what we know about exotic animalmedicine is forever changing and much has not been scientifically proven, it iscommon to find contradicting information from one reputable source to the next.This can create frustration but also provide the challenge of working in acutting edge area of medicine. This is the major reason why it is paramount toattend continuing education in this area of medicine. Veterinary techniciansworking in exotic medicine must engage in lifelong learning to be up to date onthe latest information.New contributors as well as new chapters have been added to thisedition. Although some of the contributors have provided drug dosages andformularies, we do not take responsibility for what this information. We alsorealize that while technicians do not make decisions about what drugs to use inany animal, they are required to be familiar with different pharmaceuticals,know where to find a dosage, and know how to calculate it.This book was written with the assumption that the technician already iseducated in topics such as anatomy, physiology, medical terminology, pathology,and pharmacology. We present only what is unique to the species featured here.We hope this book proves to be beneficial to all technicians interestedin exotic animal medicine.XlllAcknowledgementsI would like to thank all of our new contributors who gave their time toprovide additional information to enhance this edition. Appreciation also goesto the original contributors who took time to update their original chapters. Iwould like to thank my husband Brian Kershaw for continually being supportiveand understanding when I had to take my precious little free time to work onthe book!Bonnie BallardThis second edition has seen many changes. I would like to thank myfamily and friends for the support they have given me throughout this entireprocess. I would also like to acknowledge the many technicians working in thefield of exotic animal medicine. This is an ever-changing and evolving fieldthat requires dedication and patience. Your commitment to this field is trulyinspiring.Ryan CheekxvContributorsBonnie Ballard, DVM, has worked in veterinary medicine since 1974,starting as a veterinary assistant, becoming a technician in 1979, and earninga DVM in 1994. In 1997, she started the veterinary technology program atGwinnett Technical College. The program has been AVMA accredited since 2000.Dr. Ballard currently is the programs director and one of two full timefaculty members. She has won numerous teaching awards and has received manyaccolades for the program. She also practices small animal and exotic medicineat Winder Animal Hospital in Winder, Georgia.Denise I. Bounous, DVM, PhD, Diplomate ACVP, was a professor of clinicalpathology at the University of Georgia College of Veterinary Medicine beforeher move into the pharmaceutical industry. Her academic interests includedavian and reptilian clinical pathology, and her research was in avianimmunomodulation.Ryan Cheek graduated from Gwinnett Technical College in 1999 with anAssociates Degree in Applied Technology in veterinary technology, where hefocused his studies on exotic animal medicine. He worked at Zoo Atlanta andthen at a small animal/exotic animal practice for four years. He has worked inemergency and critical care for the past eleven years. He completed hisVeterinary Technician Specialist in Emergency and Critical Care in 2005 and hisBachelors of Applied Science Degree in veterinary technology from St.Petersburg College in 2007. He has taught full time at Gwinnett TechnicalCollege since 2007; he teaches many subjects including exotic, wildlife, zoo,and laboratory animal medicine.Maria M. Crane, DVM, received her MS in exercise science from GeorgiaState University and her DVM from the University of Georgia in 1994. She workedas a veterinarian at Zoo Atlanta, providing clinical and surgi­cal care, andlater as vice president of animal health, managing veterinary and nutritionalservices. She has also practiced small and exotic animal medicine.Lillian Gerhardt, LVT, graduated from the State University of New York.She has been a technician at the University of Tennessee College of VeterinaryMedicine in the Avian and Zoological Medicine Service for eighteen years. Shehas presented seminars at the Avian Veterinarian Annual Conferences severaltimes. She has always had a special interest in birds and has shared the lasttwenty-three years of her life with a sulphur crested cockatoo named Sugar.Cheryl B. Greenacre, DVM, Diplomate ABVP-Avian, graduated from theUniversity of Georgia College of Veterinary Medicine in 1991 and taught avianand exotic animal medicine at UGA for ten years and at the University ofTennessee College of Veterinary Medicine for nine years. Dr. Greenacre is theimmediate past chair for the UT Institutional Animal Care and Use Committee,and is currently a professor at the University of Tennessee. She divides herwork time between teaching veterinary students and residents, providing clientsand referring veterinarians with service, and studying thyroid testing in birdsand pain relief in reptiles.Tarah Hadley, DVM, Diplomate ABVP-Avian, is a graduate of DartmouthCollege and Tufts University, where she received her DVM. She completed aninternship in small animal medicine and surgery at Rowley Memorial AnimalHospital in Massachusetts and a residency in avian medicine and surgery at theUniversity of Tennessee. During her residency, Dr. Hadley was also trained inexotic animal and zoological medicine. She currently serves as director of theAtlanta Hospital for Birds and Exotics and is a member of the veterinary staffat Zoo Atlanta.Melanie Haire, VMT, received an AS degree in veterinary technology fromWilson College in 1987 and worked for six years in an Atlanta small animalclinic following graduation. She has spent the last fifteen years on theveterinary staff at Zoo Atlanta, where she is the senior veterinary technicianand hospital manager. She isxvnxviii  Contributorsfederally licensed to rehabilitate migratory bird species and raptorsand has a state permit to rehabilitate wild mammals, including rabies vectorspecies. She volunteers at the local wildlife rehabilitation center, AtlantaWild Animal Rescue Effort (AWARE), where she is also a board member.Anne E. Hudson, LVT, LAT, graduated from Blue Ridge Community Collegewith an AAS in veterinary technol­ogy and received AALAS certification. She hasworked as a biological laboratory technician for the Department of DefensesClinical Investigation and Research Department. She teaches veterinaryassisting to high school students interested in pursuing careers in theveterinary field.Michael J. Huerkamp, DVM, Diplomate ACLAM, earned his DVM from The OhioState University and did postdoctoral training in the specialty area oflaboratory animal medicine at the University of Michigan. He is a professor ofpathology and laboratory medicine in the Emory University School of Medicine,where he also serves as director of the Division of Animal Resources. Dr.Huerkamp has twenty-two years of experience in the medical care and managementof laboratory animals, including rabbits.Michael Duffy Jones, DVM, received a BS from Notre Dame and DVM fromTufts University. He completed an internship at Georgia Veterinary Specialists.He worked for five years at Bells Ferry Animal Hospital before opening his ownpractice, Peachtree Hills Animal Hospital, in Atlanta in 2005. He has aparticular interest in the use of ultrasound as a diagnostic tool, which he usesregularly in his practice and which he teaches to other veterinarians.Vanessa Lee, DVM, obtained her veterinary degree from the University ofGeorgia in 2005. She was an associate veterinarian in a small animal and exoticcompanion animal private practice for two years and is currently in alaboratory animal medicine residency at Emory University in Atlanta, Georgia.Trevor Lyon, RVT, graduated from Maple Woods Community College with anAA in veterinary technology. Focusing on internal medicine, he has lectured atseveral veterinary conferences around the country. He is a techniciansupervisor and co-owner of Bells Ferry Veterinary Hospital. He has worked withwildlife rehabilita­tion programs and participated in programs to educate thepublic about wildlife.David Martinez-Jimenez, DVM, was born in Spain, where he completed hisveterinary degree in 2002. After graduation, he performed several externshipsin exotic pet, zoo, and wildlife medicine. In 2004, he completed a MastersDegree in Wild Animal Health at the Royal Veterinary College and Institute ofZoology of London. He then moved to the USA, where he completed an internshipin exotic, zoo, and wildlife medicine at the University of Georgia College ofVeterinary Medicine. Dr. Martinez-Jimenez is currently practicing in zoo,wildlife, and exotic medicineJulie Mays, LVT, graduated from Snead State Community College with an AAin veterinary technology. She has long had an interest in exotic animalmedicine and surgery.James R. McClearen, DVM, graduated from the University of Georgia with aBS in agriculture. He received his DVM from the University of Georgia Collegeof Veterinary Medicine, where he worked for several years in raptorrehabilitation. He sold Bells Ferry Veterinary Hospital, his small animal andexotic pet practice, in 2007, although he still works there. He is active inthe Georgia Veterinary Medical Association and served as its president in 2008.Deborah Mook, DVM, Diplomate ACLAM, received her DVM from the Universityof Wisconsin-Madison in 1998 and became board-certified in laboratory animalmedicine in 2004. She worked with pet rabbits in the clinical setting andrabbits as research models in the medical school setting. Her primary expertiselies in the field of laboratory animal medicine, with a focus on murineinfectious disease.Shannon Goldsmith, CAT, operates a reptile and amphibian rescue programand is active in the community, providing educational programs related to thesewonderful creatures.Contributors  xixSamuel Rivera, DVM, Diplomate ABVP-Avian, graduated from Kansas StateUniversity College of Veterinary Medicine. He later received a Masters ofScience in veterinary pathobiology. After practicing in an avian and exoticpractice for several years, he now serves as an associate veterinarian at ZooAtlanta.April Romagnano, PhD, DVM, Diplomate ABVP, obtained her PhD from theUniversitae de Montrajal in 1987, and a DVM from the University of Florida in1992. She completed an internship in wildlife/small animal medicine at theUniversity of Florida in 1993, a residency in non-domestic avian medicine atNorth Carolina State University in 1995, and a post doctoral appointment inBCL2 transgenic mice at the Howard Hughes Medical Institute Research Lab at WashingtonUniversity in St. Louis, Missouri, in 1988. In 2001 she opened an animal clinicand serves as the avian specialist there. She also serves as the full-timedirector of animal resources at Scripps Florida, a consultant veterinarian forLion Country Safari in Loxahatchee, Florida, and a courtesy clinical assistantprofessor at the College of Veterinary Medicine at the University of Florida.Douglas K. Taylor, DVM, MS, Diplomate ACLAM, received his VeterinaryDegree from Michigan State University in 1995 and practiced small animalmedicine for five years afterward. He received his specialty training inlaboratory animal medicine at the University of Michigan, where he also earnedhis MS. He is currently the director of surgery and anesthesia services and theassistant director of the residency training program at Emory University inAtlanta, Georgia.Brad Wilson, DVM, is a veterinarian and partner in two private practiceveterinary clinics in north Atlanta. He received his BS in zoology and his DVMfrom the University of Georgia. He is the consulting veterinarian for thelargest wholesale importer and distributor of fish, reptiles, amphibians,pocket pets, ferrets, and birds in north Georgia as well as for the AtlantaBotanical Garden, which has an extensive collection of dendrobatid and Centraland South American hylid frogs. He has personally maintained and captively bredmany species of snakes and frogs.DisclaimerBecause exotic animal dosages are based largely on empirical data andnot researched facts, the editors and contributors make no guarantees regardingthe results obtained from dosages used in this textbook.xxiExotic Animal MedicineVeterinary TechnicianSecond EditionSection 1 IntroductionCHAPTER ONEThe Role of the Veterinary Technician in Exotic Animal MedicineBonnie BallardWelcome to the world of exotic animal medicine! For those who practiceit, it is the variety that provides the spice to veterihary life. In a practicethat sees exotics, it is not uncommon to see a dog for vaccines, a diabeticcat, an iguana with metabolic bone disease, a ferret for a physicalexamination, a rabbit with hair loss, and a feather-picking cockatoo all in oneday. The challenge for those in this field lies in the vast differences in thespecies seen (Figure 1.1).In the world of veterinary medicine, an exotic animal is any animal thatisnt a dog, cat, horse, or cow. Exotic animals include wildlife species,animals commonly used in research that are kept as pets, and animals native tovarious regions of the world such as South America, Australia, and Africa.Owners of "pocket pets" such as mice, rats, gerbils, and hamsterscommonly seek veterinary care for their pets.There are several scenarios in which a technician faced with exotics mayfind this book helpful. For instance, a technician might take a job in apractice that sees exotics but she knows little about them because shegraduated before exotics became popular pets. Another technician may work for aveterinarian who wants to add exotics to the practice but doesnt have hands-onexperience with them. Alternatively, a technician who finds employment at azoological park or works with a wildlife rehabilitator may want to brush up oncurrent ideas about exotics. While this book does not cover zoo speciesspecifically, knowl­edge of exotic animals, their treatment, and their care isdesirable in the zoo environment.It is essential that a technician who works for a veterinarian who wouldlike to add exotics to the practice help the veterinarian understand how thepractice will need to change to accommodate these species. One must accept thefact that a fifteen- or twenty-minute appointment will not suffice. In manycases appointments of thirty minutes or longer are required. Because husbandryand nutrition are typically the two most common causes of illness in exotics, athorough history in these areas is essential. Furthermore, more time may berequired to perform a physical examination due to the delicate nature of someof the species. In many cases it is necessary to allow adequate time to educatethe owner about how to keep his/her pet healthy.The front office staff must be knowledgeable and interested in exoticpets because they will be the first people the pet owner sees in the office.The worst thing that can happen for a snake owner, for example, is to step upto the front desk and see the receptionist recoil in horror. Not only is thisbehavior unprofessional, but it also calls into question the knowledge of thedoctors. Likewise, if a receptionist does not know the difference between a macawand a cockatoo, it may give the impression that the clinic doesnt see manybirds.Housing is another consideration in the decision to treat exotic pets.Because many pocket pets are preyFigure 1.1. A technician drawing blood from a skunk. (Photo courtesy of Ryan Cheek.)56 Chapter 1animals, their housing in relation to that of dogs and cats must beconsidered. For example, a rabbit should not be caged where a cat patient canwatch it. This alone can create undue added stress for a rabbit patient, whichis already stressed by being in the hos­pital environment. An exotic pet shouldnot have to add the fear of being eaten to its worries during a hospital stay.While the average animal hospital has most of the necessary equipmentneeded to treat exotics, some items will need to be purchased. For example, agram scale is required to weigh many of the very small patients. Microtainerblood collection tubes are also essential. A list of equipment that is usefulin exotic practices appears in Appendix 12.The technicians role in exotic animal medicine is the same as it is insmall or large animal medicine. One of the most important roles is that of ameticulous history taker. As each chapter illustrates, a simple history willnot do. Detailed questions must be asked about how and where the pet wasacquired. Wild-caught species can have different health problems than thoseraised in captivity. How the pet is housed is vitally important, and this meansnot only asking what it is housed in but the cage size, construction, substrateused, and where it is kept in the house. If the animal is not brought in thecage it is housed in, the techni­cian, after gathering the history, should beable to create a mental picture of what the cage at home looks like.The same is true for gathering adequate information about the petsdiet. It is not good enough to ask what is fed, because that may not be what isconsumed. For example, an owner may report that his Amazon par­rots daily dietis made up of fruits, vegetables, and seeds. When asked how much of each isconsumed each day, the answer may be mostly seeds, which is an inadequate diet.In many cases, owners of exotics may have been misinformed about theirpets care by the pet shops where the pets were purchased. Although some petshop employees are knowledgeable, many simply do not know the correctinformation about the species they sell. In addition, an owner may have readinfor­mation from a less than reputable source. The veteri­nary technicianshould be able to give owners the correct information about husbandry andnutrition without chastising them for their mistakes. Many owners honestly maynot know that what they were doing was wrong. They may have obtained books thatare not written by reputable sources or found informa­tion on the Internet thatis inaccurate. Clients value information about how to keep their pets healthy,and their veterinary clinic should be the source of that information.The technician can also provide valuable informa­tion about what type ofexotic pet a client should buy. For example, an iguana is considered to be adifficult reptile to keep because its housing and nutrition requirements aredemanding. A bearded dragon may be a better choice. A parakeet may be a betterchoice than a macaw for a first-time bird owner, because macaws can be noisyand messy. The topic of conser­vation of species is important here as well. Newexotic pet owners should be encouraged to acquire captive-raised species ratherthan wild-caught if possible. In many exotic species, the numbers in the wild arediminishing. This is especially true of many avian species. Most exotic speciesthat are desirable as pets can be obtained from captive-raised sources.One should never underestimate the strength of the human-animal bondthat exists between owners and their exotic pets. An owner can be as bonded toa mouse or a snake as another owner is to a dog or horse. Just as one shouldnever assume what an owner is willing to spend for medical care on dogs, cats,and horses, one should never assume what exotic pet owners will spend for theirpets. It is not uncommon to see a devoted owner spend hundreds of dollars for asurgical procedure for a pet rat.Some veterinary practices see primates and venom­ous species. Because ofthe dangers to humans, these veterinarians typically set "rules ofengagement" regarding the care and treatment of these animals. Forexample, the veterinarian may only see a primate or venomous snake after hours,when all employees and clients are gone. Likewise, a veterinarian may requirethat an owner of a venomous snake provide in-date antivenin along with thesnake.Some veterinarians will not see large exotic cats due to safetyconcerns. And yes, there are people who have permits to keep them. Others willsee these animals on the owners premises as long as handling equipment, suchas squeeze cages, is provided. It is important that all employees know theclinics protocol for seeing primates, venomous species, and large cats.Every state has different laws regarding which species are legal to keepas pets and which are not. It is up to the veterinarian to decide whether shewill see animals that may in fact be illegal pets, and to com­municate thisinformation to the technicians and other staff.Continuing education is an important part of a graduate techniciansprofessional enhancement, and its importance in exotic medicine cannot beoverem­phasized. What is known about the care and treatmentRole of the Veterinary Technician in Exotic Animal Medicine7of exotic animals is forever changing as more and more is learned. Whatwas described as the proper diet for a particular lizard one year may besomething different the next. More and more drugs are being tried in exotics.This type of cutting-edge information is often presented at conferences and inprofessional publica­tions. This presents an added challenge to practices thatsee exotic animals because information is forever changing.In response to this challenge, we have assembled here for the veterinarytechnician a survey of the most recent practices in the area of exotic animalcare. Exotic animal medicine provides a veterinary techni­cian with theopportunity to use all of his skills and knowledge in a way that has a directbenefit to the practice and to the patients. Enjoy!AvianCHAPTER TWOPsittacines and PasserinesCheryl B. Greenacre and Lillian GerhardtINTRODUCTIONThe Class Aves consists of more than 8,500 species of birds and 29orders of birds. Two orders commonly kept as pets in the United States are thePsittaciformes (parrots) (Table 2.1) and the Passeriformes (canaries andfinches) (Figures 2.1, 2.2). Anatomically and phys­iologically there is nogeneric bird, meaning that each species is different in its anatomy, hematology(lym­phocytes may predominate in some species), and drug metabolism. Avianmedicine has many similarities to canine and feline medicine, as well as somedefinite differences. The similarities include use of similar, albeit smaller,equipment, similar drugs, and similar techniques. Most differences encounteredin caring for birds relate to the drastically different anatomy and physiology,especially respiratory physiology, and this in turn dictates a differentapproach to restraint, pro-Table 2.1. Examples of commonspecies of birds encountered inpractice.Common nameScientific nameColor plate numberCommon nameScientific nameColor plate numberCockatooMoluccan Umbrella* Sulfur-crestedMacawBlue and gold*ScarletHyacinthMilitary Green-wingedAmazon parrotYellow-naped* Red-lored Orange-winged Doubleyellow-headed Blue-fronted Mexicanred-headed Lory, RainbowCacutua moluccensis Cacatua alba 3.1Cacatua sulphureaAra ararauna 3.6Ara macaoAnodorbynchus 3.7byacinthinus Ara militaris 3.8Ara chloropteraAmazona ochrocephala  3.10 Amazona autumnalisAmazona amazonica Amazona ochrocephalaAmazona aestiva 3.11Amazona viridigenalisTrichoglossus haematodusConureBlue-crowned SunHalf-moon Maroon(Red)-bellied Nanday Green-cheeked Mitred Lovebird,Peach-faced Cockatiel* Parakeet Standardbudgie* Grey-cheekedQuaker (Monk)FinchZebraLady Gouldian ParrotAfrican grey* EclectusAratinga acuticaudata Aratinga solstitialis Aratinga canicularisPyrrhura frontalisNandayus nenday Pyrrhura molinae Aratinga mitrata Agapornis rosicollisNymphicus hollandicusMelopsittacusundulates Brotogerispyrrhopterus Myiopsitta monachusPoephila castanotis Poephila gouldiaePsittacus erithacus Eclectus roratus3.4 3.2Source: Forshaw and Cooper (1989). *Most commonly encounteredspecies.1112 Chapter 2Figure 2.1. Two scarlet macaws (Ara macaoj in an outdooraviary. This is an example of apsittacine bird, or parrot.viding air to the lungs, and supportive care. Once these differences arerecognized, avian medicine is quite straightforward and rewarding.ANATOMY AND PHYSIOLOGYThe anatomy and physiology of birds is drastically different frommammalian anatomy and physiology. These differences are usually due to anadaptation that helps enable flight or relates to development within an egg-Integumentary SystemFeathers are made of keratin and are used for flight, insulation, andattracting a mate. There are various types of feathers including primaries,also known as wing remiges and tail rectrices (very large feathers thatoriginate from the carpus and metacarpus, and pygo-style, respectively), secondaries(large feathers that originate from the radius and ulna), contour (over thebody), and down feathers (produce powder down). Feathers lay in featheredtracts called pterylae, and the non-feathered tracts are called apterylae. Themain shaft of the feather is called the rachis; barbs are attached to therachis, and barbules are attached to theFigure 2.2. A female fawn-colored zebra finch (Toephilacastanotisj. This is an example ofa passerine, or soft billed, bird.barbs at a 45-degree angle that hook with nearby barbules at a 90-degreeangle (Figure 2.3).The very thin skin (two to four cell layers thick in feathered areas) isdifficult to suture, usually requiring 4-0 or 5-0 suture. There is very little,if any, subcutane­ous tissue. The feet are an exception in that they usuallyhave thick, prominent scales in the non-feathered regions to protect them fromtrauma. The wing web of a bird is called a patagium. There are only two properglands in birds, the bi-lobed uropygial (preen) gland that helps waterproof thefeathers, which are absent in some birds (such as in Amazon parrots), and theear gland, which is absent in most birds. Birds have no external ear pinna andno sweat glands. Birds bruise green because they lack biliverdin reductase,which converts biliverdin to bilirubin. Do not confuse a bright green bruise ona bird for gangrene.Musculoskeletal SystemUnlike mammals, birds can have a variable number of cervical vertebrae;they have eight to twenty-five instead of seven (King 1984) (Figure 2.4). Birdsuse their long, flexible necks to gain access to food and to reach theuropygial (preen) gland to preen their feath­ers. The remainder of the spine isfused in many areas to provide a stable body part for flight. A keel along thesternum provides for attachment of the large pec­toral (flight) muscles. Thenotarium is a fusion of the first thoracic vertebrae. The synsacrum is a fusionof the caudal thoracic, lumbar, sacral, and caudal verte­brae. The pygostyle isa distal fusion of the caudal vertebrae for tail muscle attachment. The sternumhas a prominent keel for pectoral muscle attachment. ThePsittacines and Passerines 13Figure 2.3. The central main shaft ofthe feather is called the rachis. Barbs extend from each side of the rachis at a 45-degree angle.Microscopically, barbules extend from each side of the barb a 45 degree angle. Barbules on the leading edge of a barb hook onto the barbules of the trailing edge. When birds preentheir feathers, they are realigning these barbules.pectoral girdle consists of the unique coracoid bone, that acts as astrut enabling flight, the clavicle, and the scapula. Bones of the wing fromproximal to distal include humerus; radius; ulna; ulnar and radial carpalbones; and major and minor metacarpals, phalanges, and alula (remnants of athumb). Bones of the hind limb from proximal to distal include femur,tibiotar-sus, tarsometatarsus, and phalanges.Most important clinically is that the femur, humerus, and some vertebraeare pneumatic bones—bones filled with air—which connect directly to therespiratory tract to lighten the bones for flight. Intraosseous cath­etersshould not be placed in pneumatic bones because any fluid administered could godirectly to the lungs and drown the bird.Cardiovascular SystemBirds, like mammals, possess a four-chambered heart, but unlike mammals,birds lack a diaphragm, therefore the apex of the heart is directly surroundedby liver (Figure 2.5). The avian heart is comparatively one and a half to twotimes larger than a mammalian heart. Unlike mammals, the mean electrical axisof birds isCORACOID -FURCULA-STERNAL RIB -CARPOMETACARPUS POLLEXI RADIAL^ ULNA-RADIUS-.ULNARE VERTEBRAL RIBSYNSACRUM ILIUM  / PYGOSTYLE-FEMUR-PUBISTIBIOTARSUS-Figure 2.4. Avian skeletal anatomy.Figure 2.5. Birds, like mammals, possess a four-chambered heart, butbecause birds lack a diaphragm, the apex ofthe heart is directly surrounded by liver.14 Chapter 2Table 2.2. Representative heart and respiratory rates for variousspecies of birds. > Species Weight (grams) HR (rest) HR (restraint) RR (rest) RR (restraint) Cockatiel 100 200 500-600 40-52 60-80 Amazon 400 150 200-350 25-30 40-60 Macaw 1000 125 150-350 15-20 25-40 Source: Ritchie, Harrison, and Harrison (1994). Note: HR = heart rate, RR= respiratory rate.negative 90 degrees (in dogs it is positive 90 degrees). Birds do notpossess lymph nodes, but they do have lymph vessels. Phlebotomy sites in birdsinclude the right jugular vein (the right one is two-thirds larger than theleft), basilic (or cutaneous ulnar) vein, and medial metatarsal vein. Thecutaneous ulnar vein, as it crosses the proximal ulna, is an excellent vein fordetermining vein refill time; if the vein can be seen to refill this isconsidered slow and suggestive of dehydra­tion or shock. Through a renal-portalsystem, birds can choose to shunt blood from the caudal half of the bodythrough the kidneys first before going through the heart. Therefore, it is betterto give parenteral medications in the front half of the body (i.e. give IMinjections in the pectoral muscles rather than the in the leg) (Table 2.2).Renal SystemBirds possess a renal portal system in which blood from the caudal halfof the body may pass through the kidneys first before reaching the heart. Thismeans that any drug administered in the caudal half of the body may goundiluted directly to the kidneys before going to the heart. Parrots have threedivisions to their kidneys (cranial, middle, and caudal) and the kidneys arelocated dorsally in a concavity of the sacrum. Avian kidneys produce both urine(from their mammalian-type nephrons) and urates (from their reptilian-typenephrons that lack a loop of Henle). Urates consist of uric acid. Therefore,uric acid concentrations and not BUN are evaluated to determine renal functionin birds.Neurology and OphthalmologyBirds possess a large optic nerve compared to mammals. In fact, the twooptic nerves together are larger than the birds spinal cord. Olfactory lobesare small in most birds because sense of smell is not an important sense inmost birds. The eyes of a bird constitute approximately 15% of their bodyweight, whereas in humans they constitute 1%. The avian iris consists ofvoluntary, striated muscle, rather than smooth muscle as in mammals; therefore,atropine is ineffective at dilating the pupils. Birds have a well-developedthird eyelid that closes over the eye in a craniodorsal toFigure 2.6. Birds have a well developed third eyelid that closes overthe eye in a craniodorsal to caudal ventral direction.caudal ventral direction (Figure 2.6). A unique pig­mented structurecalled the pecten, which is attached to the retina, supplies nutrients to thevitreous. Birds have no tapetum, but they have an avascular retina.Respiratory SystemThe cere is an area at the base of the upper beak that surrounds thenostrils (nares) (Figure 2.7). Just inside the nares in parrots is akeratinized flap of tissue called the operculum. Birds possess an extensiveinfraorbital sinus; in fact, most of their head is sinus. Compared to mammals,birds have a very large trachea, allowing birds to inhale more air than domammals. The opening to the trachea is called a glottis (Figure 2.8). Birdshave complete tracheal rings; therefore uncuffed endotra­cheal tubes must beused to avoid pressure necrosis inside the trachea. Again, birds lack adiaphragm; therefore, they must be allowed to move their sternum up and down orthey will suffocate. Old stories of birds dying right after being restrainedwere probably due to accidental sternal compression and secondary suffocation.The syrinx is responsible for sound generation in the bird, not thelarynx, as in mammals. Because the syrinx is just past the trachealbifurcation, birds can still vocalize even when intubated. The path of airPsittacines and Passerines 15Figure 2.7. The cere is an area at the base of the upper beak that surrounds the nostrils (nares). In adultmale budgerigars, such as this one, the cere is blue. In adult femalebudgerigars the cere is a brownish pink.Figure 2.8. The opening to the trachea in birds is called a glottis. Theglottis is usually located directly caudal to the base of the tongue in most birds. This is the glottis of a barn owl. Also note the V-shapedopening on the roof of the mouth called the choana.through the lungs goes from the trachea or air sacs to the primarybronchus to the secondary bronchus to the parabronchi to the air capillaries.Birds have air capil­laries that are 3 microns in diameter, whereas mammalshave alveoli that are approximately 10 microns in diameter. Therefore, birdshave a comparatively greater lung surface area than mammals. Birds also haveair sacs, usually nine of them, that store and warm air (Figure 2.9). Becauseair can go from the air sacs to the lungs, as well as from the trachea to the lungs,oxygen exchange occurs on both inspiration andFigure 2.9. Necropsy of aparrot demonstrating clear, normal air sacs. Air sacs warm and store air.Because air from the caudal air sacs shown here go directly to the lungs, air,oxygen, or anesthesia can be delivered through a tube (air sac tube) placedinto one of these air sacs.expiration, increasing oxygen use in birds compared to mammals.Digestive SystemBirds lack a diaphragm, so they possess a coelomic cavity, not anabdominal cavity. Birds do not have teeth; instead, they have a beak that isvariable between species. Parrots are sometimes called hookbills because oftheir strong, hooked beak. The tongue is quite vari­able among bird species;parrots have a muscular tongue. The esophagus in birds is divided into twosections (cervical esophagus and thoracic esophagus) by an out-pouching of theesophagus called the crop (ingluvies). The ingluvies stores food and has wavesof peristalsis that occur at a rate of at least one per minute. Birds possess aproventriculus (true glandular stomach) and a ventriculus (the gizzard) (Figure2.10). Some birds possess a cecum (chickens) while others lack one (parrots). Somebirds possess a gall bladder, while others lack one (parrots).The feces of parrots contains mainly (90% or more) Gram-positiveorganisms (purple); waterfowl, raptors, and poultry can have mostlyGram-negative organisms16 Chapter 2TRACHEA ESOPHAGUSHEART-CROP— SYRINX -LUNGS-LIVER -GIZZARDSUPRADUODENAL LOOPPANCREASVENTFigure 2.10. Avian viscera.(pink). Typically, passerine birds have very little bacte­ria in theirfeces, and it is Gram-positive. Clostridium spp. should not be seen in parrotfeces and is character­ized by a septic tank smell to the feces and the charac­teristicsafety-pin or racket shape seen on a Gram stain (Color Plate 2.1). The cloacais the end point for three systems: gastrointestinal, reproductive, and urinary.The cloaca is divided into three parts: the copradeum receives feces from therectum, the urodeum receives urine and urates from the ureter and sperm or eggsfrom the vas deferens and uterus/vagina, respectively, and the proctodeum isthe area just before the opening (vent).Reproductive SystemThe male bird possesses two intra-abdominal testis and a phallus (arudimentary fold of tissue that is either intromittant or non-intromittant).The female bird usually possesses only one left ovary (the right ovary usuallyfails to develop). The female reproduc­tive tract consists of an infundibulum,magnum, isthmus, uterus (shell gland), and a very short vagina. Parrots are notusually sexually dimorphic; therefore, surgical sexing or blood sexing must beperformed to determine the gender of a bird. Surgical sexing involvesvisualizing the gonads and reproductive tract via a rigid endoscope placed inthe abdominal air sac. Blood sexing involves evaluating 0.2 ml of blood via anELISA test for a heterogamete (female is ZW) or homogamete (male is ZZ).Plate 2.1. Clostridial overgrowth is apparent in this fecal Gram stainfrom a parrot. Clostridium shown here is a large Gram-positive rod with nospore, a clear central spore (safety pin shape), or clear end spore (racketshape). (See also color plates)■1Plate 2.2. A Diff-Quick stained blood smear from a parrot. Note thatbirds have nucleated red blood cells. The cell at the twelve oclock positionis a lymphocyte, the two oclock position is a monocyte, the six oclockposition is a heterophil (like a neutrophil), and the nine oclock position isa normally occurring nucleated thrombocyte. (See also color plates)COMPARATIVE CLINICAL PATHOLOGYThe blood glucose of birds is twice that of mammals. Birds possessheterophils instead of neutrophils; they are called heterophils due to thedifferent, eosinophilic staining of the rod-shaped cytoplasmic granules. Birds,like reptiles, have nucleated RBCs and thrombocytes (not platelets). Someparrots are lymphocytic speciesPsittacines and Passerines 17like cows (Amazon parrots, cockatiels, budgies, eclec­tus, etc.) Birdscan show up to 8% polychromasia since their RBC lifespan is so short(thirty-eight days com­pared to the 120 days of most mammals) (Color Plate2.2).NUTRITIONSpecies of birds kept as pets come from all over the world. Their dietsare as varied as they are and the environments they come from. The specificdietary requirements for all these species are not well known.Historically, psittacines (hookbilled birds or parrots) and passerines(canaries and finches) kept in captivity readily accepted seed diets, whichthen became the basis of diets available for pet birds. Seed-based dietsprovide poor nutrition—they are low in calcium, vita­mins, and protein, andthey are high in fat (Color Plate 2.3). Consequently, rather long-lived birdson all seed diets, such as Amazon parrots (possibly 50+ years) are seen dyingfrom effects associated with chronic mal­nutrition as young as ten to fifteenyears of age. Most nutritional research is still based on the dietary require­mentsof chickens (Brue 1994).The introduction of pelleted foods for avian species has made itpossible to dramatically improve the overall health of companion and cagedbirds (Color Plate 2.4). Balanced nutrition can be provided by pellets with thesame ease of feeding as a seed diet.Plate 2.3. Examples of seedsfound in seed diets. The left column, from top to bottom, is oat groats, smallblack sunflower seed, and large white striped sunflower seed. The right column,from top to bottom, is safflower seeds, red millet, white millet, and rapeseeds. (See also color plates)Two methods are used to manufacture pelleted diets. "Bound"pellets are not usually cooked and are finely ground. The ingredients are mixedunder pressure with a substance that, when pressed, forms the pellets. Much ofthe color and smell of the food used is retained in bound pellets."Extruded" pellets are made of food ingredients that have been cookedand mixed together. The mixture moves through a processing machine that pressesthe food into various shapes. Color and vita­mins are added afterward to theshapes and many have a sweet smell.The current recommendation is to feed parrots a quality pelleted foodthat makes up 80% of their total intake. Fresh dark green and dark yellowvegetables (leafy greens, carrots, sweet potatoes) should make up the other20%. Fruits and seeds are to be offered as treats. Some quality nuts(preferably in their shells) such as almonds, brazil nuts, or pine nuts can alsobe offered. Avoid peanuts because they may contain ana­toxins, which over timeaffect the liver. Budgerigars and cockatiels are the exception and require seedas part of their daily diet (up to 50%). Pellets alone may provide proteinlevels that are too high for these species.Passerine birds (songbirds, i.e. canary and finches) require seed aspart of their basic diet (up to 50%). Canary/ finch diets contain millet, rape,hemp, sesame, and linseed among other types of seed. These seedPlate 2.4. The introduction ofpelleted foods for avian species has made it possible to dramatically improvethe overall health of companion andcaged birds. Various brands ofnatural and artificially colored pelleted food marketed for birds are shownhere. Finely ground formulas are available to mix with water for hand or tubefeeding. (See also color plates)18 Chapter 2mixes, along with pellets and fresh vegetables, form a complete diet.Many of the rarer species of finches not commonly kept as pets also requireinsects or fruit as part of their regular diet.Special need diets have been created for some species. Lories andlorikeets from Australia and the South Pacific Islands eat mainly nectar,fruits, and pollen. Fresh fruits and powdered diets commercially available forlories should be the basic diet for these species. Toucans, mynah birds, andsome lories are predisposed to iron storage disease of the liver (hemo­chromatosis).Diets with low iron composition have been specially formulated for these species.Care must be taken with the choice of vegetables and fruit added for thesespecies. For example, grapes are high in iron and should not be fed to mynahbirds or toucans and others susceptible to iron storage disease (Tully 2009).Food high in vitamin C also should be avoided because vitamin C enhancesabsorption of iron.Some foods can be toxic to birds. Do not feed chocolate (toxictheobromine) or avocados. Foods high in salt, sugar, or caffeine should also beavoided. Peanuts should be avoided for the anatoxins that are invariablypresent.Birds in the wild spend long hours foraging for food. They eat a widevariety of foods that change with each season and have many colors, textures,and tastes, creating a diverse diet that stimulates a bird psycho­logically andprovides a lifetime of health. In the hos­pital setting a variety of dietsshould be kept on hand, such as the commonly used pelleted foods, as well asseed diets appropriate for various species. During hos­pitalization is not thetime to change diets. During illness and the stress associated with a hospitalstay it is often difficult to keep a bird eating enough to maintain weight.Having familiar diets available can encourage the avian patient to eat. Thisincludes fresh vegetables and fruits.Should a birds appetite decrease or stop during hospitalization it isnecessary to supplement nutrition via gavage feeding. Gavage tubes come in anumber of sizes. There are various critical care diets available to readilypass through a gavage tube (see the techniques section). Hand feeding formulasdesigned for neonates also work well. Weighing the bird becomes a critical partof care to ensure that enough nutrition and calo­ries are provided to maintainbody weight. Ideally the patient should be weighed every morning before food ortreatments are given.Fresh clean water should be provided daily. Birds are able to toleratemunicipal tap water. Well water may be clean coming out of the ground, but maybe easily contaminated by bacteria colonizing the pipes leading to the faucet.Some owners choose bottled water. Spring or drinking water can be used, but donot use distilled water, because this lacks necessary salts and minerals.HISTORY, RESTRAINT, AND PHYSICAL EXAMINATIONOften a birds illness has been developing much longer than the ownerrealized and by the time signs are noticed the problem may be advanced. As withall species of animals, acquiring a through history is the first step.Obtaining an adequate avian history may involve more time than that of a dog ora cat patient. Birds should always be enclosed in a carrier or travel cage whenarriving for their appointments (Figure 2.11). There are too many opportunitiesfor harm toFigure 2.11. Birds should always be enclosed in a carrier or travel cagewhen arriving for their appointments. A towel can be used to cover a cage,especially a clear one such as this, to provide visual security for the bird.Psittacines and Passerines 19come to the bird in an unfamiliar environment. Be sure the owner is madeaware of this when the appointment is made.HistoryThe following questions should be asked during the history taking:How old is the bird?How long has it been owned and where was it acquired(breeder/pet store/ bird fair)? Have there been any previous problems?Has the bird been tested for chlamydiosis or psittacinebeak and feather disease? Has it been vaccinated against polyomavirus?Have there been any changes in the bird such as voicechange, attitude or weight change, or a change inthe droppings (increase or decrease, color changes,more or less urine or urates) (Color Plates 2.5, 2.6,2.7, 2.8, 2.9). When was the last molt and has the bird been givenany medications or herbal supplements? What is the problem today? Howlong has the illness been occurring? When, if at all, has the bird been to aveterinarian?Next, move to questions about the animals environment:What is the bird fed and what does it actually eat outof what is offered? What is the cage like: size, perching? Whatmaterials are used to make the cage (lead/zinc)? What type of substrate isused, how often is it cleaned,and with what?Plate 2.5. Polyuria (See also color plates)Plate 2.6. Normal feces. (See also color plates)Plate 2.7. Normal feces. (See also color plates)Plate 2.8. Hematuria and melena (See also color plates)20 Chapter 2Plate 2.9. Undigested seeds. (See also color plates)Does the bird spend time outdoors?What is the temperature where the cage is kept andare there any drafts? Is the bird let out of the cage and is itsupervised duringthat time?What type of enrichment is used (toys)?How much sleep does the bird get? Sleep is very impor­tant to a bird andapproximately twelve hours of sleep each night is required for good health.This should not be in a covered cage in a room where the television is on orfamily members are still talking, but somewhere quiet.With these questions you can also develop an idea of the generalknowledge that the owner has regarding bird care.When a complete history has been attained move to the physical exam.Begin by observing the bird from afar. Birds are prey animals and they work atlooking normal, especially in an unfamiliar environment. A bird in the hospitalshould never be sitting fluffed or with closed eyes. This indicates a very sickanimal. Observe the birds behavior, attitude, posture, breath­ing, skin andfeather quality, and neurological status. Look for symmetry. Look at thedroppings in the cage bottom or for regurgitated food. Dyspnea in a birdusually manifests as a "tail bob" movement of the tail up and downwith each breath. After observing the bird from a distance, a physical exam canbe per­formed with the bird restrained in a towel.RestraintAfter the bird has been observed and deemed able to withstand a hands-onexamination it can be restrained in a towel. Restraint is needed to perform athoroughFigure 2.12. Capturing a bird while in its cage.examination. Capture and restraint are perhaps the most traumatic eventsfor the avian patient. If the bird will step up on to a perch it can be removedfrom the cage or carrier, set on the floor in a corner, and then caught using atowel. Setting the bird on the floor should only be done if the bird hasclipped wing feath­ers and cannot become airborne. If the bird will not comeout of its enclosure, the towel can be used to reach in and secure the animal.The towel is used to help protect the hands and to have the bird associatebeing restrained with the towel, not the hands. Never attempt to capture a birdwhen it is being held by the owner. The owner could be bitten and it ispossible that this could affect the bond between the owner and bird.Approach the parrot with a towel-covered hand and attempt to quicklywrap the fingers around the birds neck. An ideal opportunity to grasp the neckis when the bird is attempting to move away from the towel, using its beak tohold onto the cage or carrier (Figure 2.12). Coming from behind, wrap thefingers around the neck, forming a collar. When the head is secured, bring thetowel around the body with the other hand42547576Psittacines and Passerines 21meeting the two ends of the towel across the front of the bird (Figure2.13 A and B). This controls flapping of the wings. Remember, birds use themuscle around the sternum to move air through the respiratory system (they lacka diaphragm), and therefore care must be taken not to put pressure on the sternumbecause suf­focation can occur (Figure 2.14). Proper hand place­ment is shownin Figure 2.15. The towel can be moved to expose sections of the bird as theexamination pro­gresses. When dealing with small cage birds (canaries,budgerigars), it is helpful to have one person at the light switch whileanother puts his hand into the cage. Make note of where the bird is just beforethe lights are turned off and then grab the bird quickly before it has time toadjust to the darkness.Restraint time should be kept to a minimum (prefer­ably less than two tofour minutes). Before the bird is caught up, all of the material needed fordiagnostic sample collection, examination, and grooming should be anticipatedand in place. During restraint it is com­monly the responsibility of the holderto monitor the well being of the bird. When signs of excessive stress includingpanting, eye closing, weakness, and generally any change from when the bird wasinitially restrained appear, the bird should be released and given theopportunity to recover. Speaking to the bird in a soothing voice can helpreduce the stress during handling.Physical ExaminationOnce the bird has been restrained the physical exami­nation of the avianpatient is no different from that of another animal. The examination begins atthe head and ends at the vent. Look straight on at the head and beak. Examinefor symmetry and normal alignment of the beak and check for swelling orbruising, pitting on surface of beak, or fractures (Harrison 1994). Look at thenares (nostrils) to check for symmetry and anyFigure 2.13. (A) A bird that is properly restrained within a towel. Theneck and wings are under control. (B) The towel can be manipulated to gainaccess to various areas while still restraining the bird.22 Chapter 2Figure 2.14. Restrain I uf asmall bird.Figure 2.15. Restraint of abird.discharge, debris, or blood. Because most birds have feathers near thenares, matting of the feathers above the nares will occur with a discharge.Note: It is normal for a structure to be present just inside the nares;this is called the operculum (Figure 2.16). Disturbing this structure can causebleeding. The eyes are also checked for discharge (again the matting offeathers will be present), lens opacity, blood, or disruption of normalanatomy. Hydration can be assessed using ocular parameters, such as mois­tureof the cornea (dull appearance when dehydrated) and the position of the globe(recessed when dehydrated).While there is seldom disease in the ears of birds, the ears shouldstill be examined. There is no external pinna and the ears are located caudaland ventral to the lateral canthus of the eye. The ears may be observed bymoving the feathers (Figure 2.17).The oral cavity and choanal slit can be viewed with the help of an avianspeculum. The cloacal slit is theFigure 2.16. Just inside the nares (nostril) is a fleshy part called theoperculum that warms and regulates air. Most birds, including this red-tailedhawk, have an operculum and it should not be mistaken for something that needsto be removed because disturbing this structure causes bleeding.Figure 2.17. Birds do not have an external ear pinna. The ears arelocated caudal and ventral to the lateral canthus of the eye. The ears may be observed by moving the featherscranially, as is shown on this white Carneaux pigeon.V-shaped opening on the roof of the mouth. Care must be taken when usinga speculum to prevent iatrogenic trauma to the beak (Figures 2.18 A and B). Anormal choanal slit is lined with papillae (pointed projections). Lack ofvitamin A can cause the papillae to become blunted or disappear completely insevere cases. The tongue is a prominent feature in the oral cavity. The glottisis at the base of the tongue. The tissue in the oral cavity should be dry andsmooth. Abnormal findings can include abscesses, fungal plaques, and excessivemoisture.Psittacines and Passerines 23Figure 2.18. (A) A variety ofspeculums are available. (B) Care must be taken when using any speculum in abird because beak damage can occur.Next, palpate the thoracic inlet. Check the crop for foreign objects,crop burns (in young birds being handfed), distention, or crop stasis. Cropstasis can be noted by parting feathers and watching for movementFigure 2.19. A Coopers hawk restrained with gloves in dorsal recumbancyshowing normal pectoral muscle mass on either side of the bony keel, forming a slight V-shape. This view is from thehead of the bird looking caudally.Less pectoral muscle mass and a more prominent keel would have suggested a thinbird.(regular contractions occur in the crop). There should be at least onewave of movement across the crop per minute.Palpating the pectoral muscles can determine the body condition of theavian patient (Figure 2.19). A score of one to five is used; one signifies avery emaci­ated animal and five is considered to be overweight. Normally, theedge of the keel can be palpated between the rounded pectoral muscles thatslope slightly on either side. The feathers should be examined over the body.Feathers should have a bright iridescent appear­ance. Wings and legs should begently flexed, and extended to evaluate joint function. Check the plantarsurface of the feet. Erosion of the bottom of the feet may be associated with adiet deficient in vitamin A and/or improper perches. Erosions can lead to ulcer­ativedermatitis, commonly known as bumblefoot (Figure 2.20). Also look for necroticareas, swelling, abscesses, or gout (an accumulation of white uric acid underthe skin). Examine the cloaca (vent), looking for masses, irritation(hyperemic), prolapse of the tissue, and the presence of matted fecal material(the feathers around the vent should be clean).The caudal coelomic cavity can be palpated. Organs cannot be easilypalpated due to the sternum extending over most of the coelomic cavity,although a large liver or the presence of an egg can be palpated and should beconsidered as abnormal findings. Normally the liver24 Chapter 2Figure 2.20. Plantar surface ofa raptor foot demonstrating ulcerative pododermatitis, as known as bumblefoot.This lesion can start as a smooth, pink, erosive, or flattened area on theplantar surface of the foot. Inpsittacine birds this can be due to poor quality perches or vitamin Adeficiency.does not extend past the level of the sternum. The uropygial gland(preen gland) can be found at the extreme caudal dorsal surface and should beexamined for symmetry and overall appearance. Remember, not all birds kept aspets have a uropygial gland.The bird should be ausculated to access heart health and respiratorycondition. Placing a pediatric stetho­scope over the lateral body wall allowsauscultation of the heart. Listening over the craniodorsal body wall is best toassess the respiratory condition. Hydration can be assessed with a "veinrefill time" using the basilic (cutaneous ulnar) vein. In a normallyhydrated bird this vein should instantaneously refill; by the time a finger isoff the vein to see it, it should have refilled. If the basilic vein can beseen refilling, it is estimated that the bird is about 5% dehydrated. If thevein requires one second to refill, the bird is severely dehydrated (10%) or isin shock (low blood pressure) (Figure 2.21).Obtain the birds weight at the end of the exam, before it is placedback into the carrier. Use a digital gram scale that has a maximum weight of 4to 5 kilo­grams and weigh in 1-gram increments (Figure 2.22).COMMON DISEASES Infectious Diseases Avian ChlamydiosisAvian chlamydiosis is one name given the disease in birds caused by theorganism Chlamydophila psittaci;Figure 2.21. Elbow area of abird showing the cutaneous ulnar (basilic) vein crossing superficial to theproximal ulna. This vein is used to determine hydration status in a bird, forphlebotomy, and IV injections.Figure 2.22. A digital gram scale should be used to accurately determinethe weight of birds. The scale shouldbe able to weigh in 1-gram increments.other names include ornithosis, chlamydiosis, and chlamydophilosis. Theterm "psittacosis" refers to the disease in people originating from aparrot (a psitta­cine bird), whereas the term ornithosis refers to the diseasein people originating from any species of bird. Note that Chlamydophilapsittaci should not be con­fused with a related organism inpeople, Chlamydia trachomatis, which causes asexually transmitted disease, or another related organism, Chlamydophilapneumoniae, a common mild respiratory pathogen ofPsittacines and Passerines 25people. Changes in nomenclature in 1999 reflected recent advances in DNAtesting that revealed differ­ences between organisms that were previouslythought to be the same. What used to be just one genus, Chlamydia, is now described astwo, Chlamydia and Chlamydophila. A word of caution,therefore, when reading any literature on chlamydial organisms prior to1999—the reader may not be 100% certain as to which of the newly categorizedorganisms was being referred to in the document. The term Chlamydophilapsittaci is used throughout this docu­ment to refer to theorganism formerly known as Chlamydia psittaci.The organism has been found in more than 130 species of birds worldwideand a variety of mammals, including humans, and is therefore a zoonoticdisease. Numerous potential avian species may act as a source of infection forpeople. The most common source of infection (70% of all cases in the 1980s) isexposure to a recently acquired psittacine bird. Other birds can be a potentialsource of infection, such as domestic or wild pigeons, passerines (soft-billedbirds), or poultry. People at occupational risk include pet store employ­ees,veterinarians, veterinary technicians, laboratory workers, workers in avianquarantine stations, farmers, wildlife rehabilitators, zoo workers, andemployees of poultry (usually turkey) slaughtering and processing plants.Occasionally exposure to wild pigeon roosts is a source of infection to thegeneral public.The Chlamydophila psittaci organism istransmitted by inhalation or ingestion of the spore-like elementary body phaseof the organism. Shedding in birds can be activated by stress, such asshipping, crowding, chill­ing, and breeding. Person-to-person transmission hasbeen suggested, but never proven. Those individuals that are immunosuppressedare more susceptible to the disease and its effects. The organism Chlamydophilapsittaci is relatively resistant, surviving in the soil forthree months or within a bird dropping for up to one month.Clinical signs can differ based on species of bird. Some birds presentquite ill, whereas others exhibit very subtle signs of disease. Generally, aparrot with psittacosis presents with depression, lethargy, anorexia, dyspnea,nasal or ocular discharge, conjunctivitis, and biliverdinuria (green urates).Rarely, birds present comatose, which has been observed in sensitive speciessuch as macaws. Commonly both the spleen and liver are enlarged. Pigeons andpasserines seem to exhibit little if any clinical signs of disease whileinfected with the Chlamydophila psittaci organism andtherefore are sometimes referred to as asymptomatic carriers of the disease.A suggestive diagnosis can be made by radiographs showing splenomegaly,+ hepatomegaly. A CBC showing a heterophilic, monocytic leukocytosis and a mildnon-regenerative anemia are also suggestive. A plasma electrophoresis may besuggestive of either acute or chronic disease.Diagnostic testing is varied. There are tests to detect antibodies inthe serum (elementary body assay [EBA] and irnmunofluorescent antibody [IFA])and tests to detect antigen in the feces or blood (enzyme linkedirnmunofluorescent antibody assay [ELISA] and poly­merase chain reaction[PCR]). It is best to perform a panel of three tests including PCR of blood,PCR of feces, and IFA of serum. In addition, a fluorescent antibody (FA) testcan be performed on tissue such as liver tissue from a biopsy or necropsy. Forlegal pur­poses, cell culture from the feces is the best test, but the organismdoes not consistently grow, and shedding of the organism in the feces isintermittent. There is also risk to laboratory personnel when the organism isgrown in the laboratory.The Texas Medical Diagnostic Laboratory is cur­rently the only laboratorycommercially offering culture. Addresses and phone numbers of laboratories thattest for Chlamydophila and definitions that have been accepted bythe American Veterinary Medical Association (AVMA) and the Association of AvianVeterinarians can be found in the Compendium of Measures to Control Chlamydophilapsittaci (formerly Chlamydia psittaci) Infection AmongHumans (Psittacosis) and Pet Birds (Avian Chlamydiosis), 2004, by the NationalAssociation of State Public Health Veterinarians (NASPHV) http:// www.avma.org/pubhlth/psittacosis.asp.Treatment of birds, which should be supervised by a licensedveterinarian, consists of doxycycline for forty-five days. A lower dose is usedin macaws to prevent regurgitation. Avian chlamydiosis is usually a reportabledisease, but it depends on the state. Most states require that veterinariansreport any diagnoses of psittacosis in a bird to the state veterinarian orpublic health department.Other Bacterial InfectionsBacterial infections in birds can be localized or sys­temic and caninvolve any system, but commonly involve the liver or GI or respiratorysystems. Usually Gram-negative organisms, such as E. coli,Klebsiella, Enterobacter, or Pseudomonas, are involved, butinfections involving Gram-positive organisms or anaerobes can occur as well.Treatment is based on culture and sensitivity and cytological findings (such asan in-house Gram stain), but usually involves the26 Chapter 2use of broad-spectrum, bacteriocidal antibiotics such as enrofloxacin,trimethoprim-sulfa, and cephaolspo-rins. Macaws commonly regurgitate aftertrimethoprim-sulfa or doxycycline administration.Canary PoxPoxviruses are the largest of viruses and the genus Avipoxviruses arefound worldwide in more than twenty families of birds. There are many speciesof Avipoxvirus, such as psittacine pox, canary pox, pigeon pox, falcon pox, andfowl pox. Each species of pox has varied host specificity, but typically themost severe clinical signs are seen in its natural host. Pox used to be commonin recently imported Amazon parrots, especially blue-fronted Amazon parrots,macaws and pionus, but is rarely seen today. Occasionally an older importedbird presents with old pox scars on the eyelids, nostrils, and face.Today canary pox is the most commonly seen pox. The virus is transmittedvia mosquito or mechanical means through broken skin. Birds can show blephari­tis,ocular discharge, rhinitis, and conjunctivitis associ­ated with raised papulesten to fourteen days post infection. Clinical signs can be divided into"dry" pox, which consists of cutaneous papular lesions, and"wet" pox, which consists of mucosal papular lesions of theoropharynx. Occasionally birds may display neuro­logical signs.Diagnosis is based on typical clinical signs and his­tological findingof Bollinger bodies, which are intra-cytoplasmic inclusion bodies, of skin ormucosal cells, and is considered pathognomonic. Treatment consists of providingsupportive care. Leave scabs to heal natu­rally to lessen scarring. Vaccineshave been created for chickens, pigeons, turkeys, canaries (Poximmune, Biomune,Lenexa, KS), quail, waterfowl, falcons, and Amazon parrots. It is recommendedto vaccinate before the breeding and/or mosquito season. Maximum protectionoccurs three to four months after vaccina­tion. Some canary breeders vaccinateevery six months.PolyomavirusPolyomaviruses are rather host specific and cause sub­clinical diseasein mammals, but in psittacine birds they cause severe clinical disease in awide variety of psittacine and other species of birds. Immature psitta­cinebirds commonly present with acute disease with an approximate mortality rate of27% to 41%. The disease is characterized by twelve to forty-eight hours ofdepression, anorexia, delayed crop emptying, regurgitation, diarrhea,dehydration, SQ hemorrhage, dyspnea, and polyuria. The SQ hemorrhages are mosteasily seen over the crop, carpi, or cranium.Transmission of polyomavirus is through exposure to excretions andsecretions, especially urine.Polyomavirus is a non-enveloped virus and there­fore very stable in theenvironment and difficult to destroy. A DNA probe (PCR) test is available todetect viral DNA in tissue or feces. Antibody tests are avail­able and apositive result denotes exposure has occurred and that the bird probably shedsvirus intermittently. Many birds in aviaries are subclinically affected and area constant source of infection for all birds in the aviary and are a particulardanger for young birds. Therefore, all birds should be vaccinated. Psittamune(Biomune, Lenexa, KS) is a commercially available, licensed vaccine for use inpsittacine birds. The vaccine is administered SQ and has been proven to be safeand effective. It is an inactivated vaccine; therefore, optimum protectionoccurs two weeks after the second vaccine. There is no treatment for thedisease. The prognosis is grave if clinical signs are present in a young bird.Proventricular Dilation DiseaseThe causative organism of this disease has been identi­fied as an 89 nmvirus, but of unknown type. The route of transmission is via fecal-oral andappears to affect birds of many orders, including psittacine birds. Clinicalsigns include severe, chronic weight loss, regurgitation, delayed cropemptying, ravenous appe­tite, undigested food in stool, and neurological signs(i.e. falling off perch) in an adult bird. The virus para­lyzes the nerves inthe proventriculus and the bird essentially starves to death, despite a goodappetite, due to the inability to process its food. Suggestive diagnostictesting includes radiographs demonstrating proventricular dilation and wholeundigested food particles or seeds in the feces.Note that many diseases can cause proventricular dilation, includingdisease from parasites, yeast, mega-bacterium, mycobacterium, foreign bodies,neoplasia, and lead and zinc toxicosis. Definitive diagnostic testing includesa crop biopsy demonstrating lympho-plasmocytic ganglioneuritis. Birds usuallydie within two years of developing clinical signs, but recently treatment withthe NSAID celecoxib (Celebrex®, a COX-2 inhibitor) or any other COX-2 inhibitorhas been described; however, the mechanism against the virus is unknown.Prevention currently consists of avoiding exposure to known infected birds.Psittacine Beak and Feather Disease (PBFD)This disease of parrots is caused by a circovirus. These non-envelopedviruses are among of the smallest yet described, at 14 to 16 nm. PBFD virus isshed in feces,Psittacines and Passerines 27feather dander, and various excretions and secretions. Asymptomaticbirds can shed the virus for years before exhibiting any clinical signs.Because the virus is non-enveloped, it is very stable and can survive years inthe environment and is resistant to destruction by common disinfectants.Generally the progression of the disease is dictated by the age of thebird when clinical signs first appear. Younger birds have a faster progressionof the disease. Most birds present with chronic PBFD, which is char­acterizedby symmetrical, slowly progressive dystrophy of developing feathers thatworsens with each succes­sive molt. The feather dystrophy includes retainedfeather sheaths, hemorrhage within the pulp, curled feathers, andcircumferential constrictions of the feather shaft. Usually the down andcontour feathers are affected first, and then the primaries. Birds can go on todevelop complete alopecia and sometimes beak abnor­malities consisting ofprogressive elongation of the beak and necrosis of the palate rostrally, nearthe upper beak. These birds are often immunocompromised and die of secondarybacterial or fungal infections.The PBFD DNA probe tests are performed on whole blood and detect viralDNA; therefore, a positive result means there was PBFD viral DNA in the blood.In a bird with no clinical signs, it is recommended to retest the bird inninety days to see if the viral DNA is still present. If so, then the bird isinfected, but if not, then the bird was transiently infected and overcame theinfection. Any bird displaying feather abnormalities should have a featherfollicle biopsy and DNA in situ hybridization performed in addition to the DNAprobe blood test, since some clinical birds are so viremic that they will havea negative blood test.This can also occur if a bird is extremely leukope­nic. A DNA probe testcan be used to detect viral DNA on a swab of the environment to assist indetermining the effectiveness of disinfection efforts. Treatment con­sists ofsupportive care and antimicrobials for second­ary infections. Once clinicalsigns develop the disease is always fatal (Color Plate 2.10).Papillomatosis Caused by HerpesvirusPapillomatosis, or wart-like GI lesions caused by a herpesvirus, shouldnot be confused with facial warts caused by papillomavirus. Species mostcommonly affected include the Amazon parrots and macaws. Amazon parrots areprone to developing concomitant bile duct or GI tract carcinoma that hasrecently been associated with PHV-1, genotype 3.Clinical signs of papillomatosis include wart-like masses observedanywhere along the GI tract, but most commonly in the cloaca and oropharynx(Figure 2.23).Plate 2.10. Bird with PBFD. (See also color plates)Figure 2.23. Clinical signs ofpapillomatosis (caused by a herpesvirus) include wart-like masses observedanywhere along the GI tract, but most commonly in the cloaca, as seen in thisAmazon parrot, and oropharynx.Birds may exhibit weight loss, signs of straining to defecate, soiledvent, or blood in the stool. Some cases have GI obstruction with associatedclinical signs. Because the virus is latent, birds that have been previ­ouslytreated may have a recurrence of lesions and signs with stress. Amazon parrotswith bile duct car­cinoma may exhibit biliverdinuria and lethargy, and bileacid levels may be high. Diagnosis is suggestive based on gross appearance andlocation. Definitive diagnosis is based on histology. Treatment involvesremoving the wart-like growth. In the authors experi­ence it is best to applysilver nitrate to the lesion, or half of the lesion if it is circumferentiallyinvolving the cloaca, every week under anesthesia until gone.28 Chapter 2Butorphanol is also administered at 1 to 2mg/kg IM once before theprocedure.West Nile VirusWest Nile virus is caused by a flavivirus. West Nile virus is endemic inother countries, but in the late 1990s it was found within the eastern U.S. andhas since spread across the country. Crows, jays, and raptors, as well ashorses, are susceptible species, whereas poultry are considered resistant. TheWNV virus is spread by mosquitoes. If people or dogs are affected they areusually older or immunosuppressed. Clinical signs range from none in resistantspecies such as poultry to neurologic signs (ataxia, circling, head tilt, andseizuring) and death in susceptible species. A CBC is usually normal or alymphocytosis is present. A serum antibody test is available. Treatmentconsists of supportive care. Recently the use of alpha interferon has seemed toresult in better success in people. This disease has already spread throughoutthe U.S. so it is too late to prevent the disease in this country. A con­ditionallylicensed vaccine is available for use in horses that is currently being usedintramuscularly in birds at the same or a reduced dose.AspergillosisThe two most common etiological agents associated with aspergillosis inbirds are Aspergillus flavus or fumigatus. Predisposingfactors associated with the disease are immunosuppression, including hypovita-minosisA, and being exposed to massive quantities of fungal spores which can easilyoccur when corn cob or wheat or pine straw is used as bedding. Aspergillosis ismore common in African Grey parrots, macaws, and raptors. The location of theinfection is most commonly in the bifurcation of the trachea near the syrinx orin the caudal thoracic air sac, and occa­sionally in the sinuses. A suggestivediagnosis is based on a very elevated CBC (usually above 40,000), with aheterophilic leukocytosis and monocytosis. Serum antigen and antibody tests areavailable, but are just suggestive of the disease. A definitive diagnosis isusually obtained by direct visualization and sampling via endoscopy of eitherthe trachea or the air sac, and cytology or culture of those samples. Treatmentconsists of antifungals such as the conazoles, including ketaconazole,itraconazole, and fluconazole. Itraconazole is the best, but should not be usedin African Grey parrots (or used at very low doses). Also amphotericin-B isgood, but can only be given IV or through nebulization and it is quicklyrenal-toxic. Months of treatment are necessary, so early and proper diagnosisis imperative. Any underlying cause of immunosupression or overexposure shouldalso be corrected.CandidiasisCandidiasis is caused by the yeast organism Candida albicans. Clinical signsinclude regurgitation, delayed crop emptying, and white plaques in oral cavity.The crop is the most common organ affected and the crop contents have a yeasty,sweet smell. Young birds/neo-nates are the most severely affected. If adultshave clinical signs of candidiasis, look for some cause of immunosuppression.Diagnosis is easily done by iden­tifying the organism on a Gram stain of cropor fecal material. Treatment of mild cases consists of antifun­gal therapy withoral nystatin, which acts topically in the GI tract. If the candidiasis issevere and invading the mucosa, then in addition to nystatain, a systemicantifungal such as one of the conazoles is necessary to attack the infectionfrom the vascular system as well as topically.Non-infectious Diseases Heavy Metal ToxicosisHeavy metal toxicosis is usually caused by ingestion of lead or zinc.Sources of lead include fishing weights, curtain weights, bullets, paint, andcostume jewelry. Sources of zinc include pennies minted after 1986, Monopoly®game pieces, powder coating, paint, and costume jewelry. The ventriculus(gizzard) of birds retains heavy particles for grinding food, but in the caseof heavy metal particles, they are retained and slowly digested, allowingconstant absorption of the toxins. Clinical signs include depres­sion,weakness, regurgitation, and sometimes neuro­logical signs.Diagnosis is usually made by visualizing the metal-dense particles onradiographs, but a definitive diag­nosis can be made on only 0.2 ml of bloodfor lead or 0.2 ml of serum for zinc at the Louisiana Veterinary MedicalDiagnostic Laboratory (Figures 2.24 A and B). Toxic levels of lead in the bloodare greater than 0.2 ppm, and greater than 2ppm for serum zinc. Treatmentconsists of a chelating agent such as CaEDTA or dimercaptosuccinic acid ord-penicilla-mine to bind with the heavy metal, rendering it harm­less; it thencan be urinated out of the body. Stressful procedures such as surgery orendoscopy to remove a large particle should be done after some chelationtherapy, because stress can cause lead to move sud­denly from the bone where itis stored to the blood and worsen clinical signs. Other products such as lact­uloseto assist the liver with toxicosis, lubricants suchPsittacines and Passerines 29BFigure 2.24. (A) Lateral standing radiograph in a duck showing heavymetal in the ventriculus. Later, 97 cents worth of various coins were removed endoscopically. (B) Ventrodorsalview of the same duck.as corn oil or peanut butter, or bulking agents such as psyillium canalso be given.Hypovitaminosis AA diet deficient in vitamin A, such as an all seed diet, can lead tohypovitaminosis A. Clinical signs include choanal papillae in the oral cavitythat are blunted, plantar ero­sions on the feet, and poor quality skin andfeathers (darkened areas on the feathers of the wings). A diagno­sis is madebased on history and clinical signs. Secondary bacterial or fungal infectionsinvolving the respiratory tract are common. Sometimes a Gram stain of a choanalswab shows increased epithelial cells and basophilic staining. Treatmentincludes an increase in dietary vitamin A by providing the bird with darkyellow vege­tables (sweet potato, carrot, commercial bird pellets). One couldalso give one injection of vitamin A. Avoid giving too much vitamin A becauseit is a fat-soluble vitamin that can result in hypervitaminosis A.Hypocalcemia of African Grey ParrotsAdult African grey parrots, especially those on a low calcium seed dietrather than a healthy pelleted diet, can present with seizures due tohypocalcemia. A total calcium level, and even better, an ionized calcium aswell, diagnoses the disease. Treatment consists of calcium gluconate IM. Oralcalcium can be adminis­tered later in the form of calcium glubionate. Of coursetreatment also includes improving the diet by supple­menting with calcium andslowly changing to a pel­leted diet.Non-stick Cookware ToxicosisNon-stick cookware, such as Teflon®, is made of polytetrafluoroethylene(PTFE). If burned and heated to above 540°F, the PTFE fumes are released,causing immediate pulmonary hemorrhage and death in birds anywhere in thehousehold. Rarely, immediately supplied fresh air and steroids prevent death.Egg BindingSome birds, such as cockatiels, chronically lay eggs, and especiallythose on an all seed diet that is low calcium can present with egg binding. Theegg is stuck in the uterus because the uterine muscles lack enough calcium tocontract and push the egg out. The egg puts pressure on the kidneys, causingthe bird to go into shock, and it can die within hours to days without removalof the egg. Other birds may have egg binding due to an abnormally large egg. Ifthe egg is normal size and there are no obstructions such as scarring of theuterus, then hormones, such as oxytocin or prostaglandin F2 alpha, can be givento stimulate contractions, but only after calcium has been absorbed IM so theuterine muscles have enough calcium to contract. In the case of an egg thatshould not be forced out, it can be imploded by creating negative pressurewithin the egg by suctioning out the contents with a needle and syringe placedthrough the egg exposed at the cloaca or through the celomic wall and uterus onthe ventral abdomen. This is an emergency procedure performed under anesthesiaand is not without risk of hemorrhage or infection. If these procedures areunsuccessful, surgery to perform a salpingohysterectomy (removal of uterus) canbe per­formed. Supportive care with fluids, antibiotics, etc. are alsonecessary.30 Chapter 2Crop BurnsJuvenile birds that are hand fed by humans may some­times be offeredgruel that is too hot (above 105°F), usually heated in a microwave, that causesa burn of the thin crop and overlying skin. It is usually not until ten dayslater that the effects of the burn are noticed by visualizing the suddenappearance of gruel pouring out of a hole in the crop and running down thebreast of the bird. It is only at this ten-day point, after a scab has formedand the body has determined dead from healthy tissue, that surgery should beperformed to close the hole. Supportive care, including antibiotics or the mildantifungal nystatin and fluids, etc., are usually needed.RADIOLOGYRadiographs can be taken awake or under anesthesia depending on thegoals. Usually the bird is under anes­thesia so that it is absolutely still andin the proper position for accurate evaluation. This also produces the leastamount of stress. A bird can be placed in a cardboard box awake to determine ifan egg or metal is present, or in the case of a barium series, see the locationand speed of barium travel. Most radiogaphs are taken at 500 mAs and 50 Kvp for1/120 of a second, but each machine is different. Two views are taken: theventrodorsal, with the keel of the sternum perfectly aligned with the spine,and the lateral, with the coxo-femoral joints and shoulder joints superimposed(McMillan 1994). This positioning allows evaluation of the radiographs (Figures2.25 A, B, and C and 2.26 A and B).ANESTHESIA AND ANALGESIAIsoflurane is the safest gas anesthetic choice in birds (Curro 1994).Sevoflurane has been shown to be just as effective and recovery is slightlyfaster (Quandt 1999). Birds are usually restrained in a towel and mask induced,usually starting at 2% in healthy birds at 21/ minute oxygen flow rate. Forshort procedures, such as immobilization for radiographs that require less thanfifteen minutes, most birds are not intubated. For longer procedures, birds canbe intubated with an uncuffed endotracheal tube. Once intubated, the oxygen flowrate must be reduced to 11/minute so as not to damage the delicate air sacs.The best method to secure an endotracheal tube in a bird is to tape itto the bottom beak so the mouth can be opened to wipe out excess moisture ifnecessary.cFigure 2.25. (A) A red tailed hawk properly positioned for aventrodorsal radiograph. (B and C) Positioning of an avian patient for radiographs.Always keep the head and glottis above the level of the crop, becauseliquid from the crop can trickle into the trachea and drown the bird in aninstant. Birds have complete tracheal rings, so an inflated cuffed tube canPsittacines and Passerines 31Figure 2.26. (A) An example ofa parrot well positioned for a lateral radiograph. Note how the shoulder andhip joints are aligned. (B) An example ofa parrot well positioned for a ventrodorsal radiograph. Note how the keel andspine are aligned (superimposed).exert too much pressure on the lumen of the trachea that cannot expandand thus cause pressure necrosis and a subsequent diphtheritic membrane. It isimpor­tant to realize that birds, especially cockatoos, have tracheas thatnarrow a few centimeters past the glottis, causing an endotracheal tube toinitially seem the appropriate size but then after passing it a quarter of theway down the trachea it becomes lodged, causing pressure necrosis. Therefore,pick an appropriate size tube and re-intubate if it feels as if it is lodged.It isFigure 2.27. A _____..irkey intubated and underanesthesia, showing the placement ofa Doppler probe on the roof of the mouth over the palatine artery tomonitor heart rate. This can be performed in any species of bird.very easy to intubate a parrot because the glottis is very forward atthe base of the tongue.Birds tend to not do well after one hour under anesthesia due tohypothermia, hypoventilation, and respiratory acidosis. The use of forcedheated air blan­kets has greatly improved the attempted maintenance of normalbody temperature in birds under anesthesia (Rembert 2001). It is imperativethat adequate lubrica­tion is applied to the eyes to prevent dry eye withforced heated air blankets. In addition, the laterally placed eyes of birdsshould not be allowed to rest on any surface or they can collapse. Althoughthis is usually temporary, it may be a permanent condition. Common monitoringequipment includes a pulse oximeter on the leg, Doppler probe over the radialartery or palatine artery, and ECG (Figure 2.27). Simply listening with astethoscope and CONSTANT watch of the respiratory rate and depth are absoluteminimums in monitoring birds under anesthesia.When assessing an avian patient for signs of pain, selecting a painreliever, or determining a dose and the frequency of administration, it must beremembered that there is NO GENERIC PARROT. One must be familiar with the verylimited scientific research that has been conducted regarding pain managementin psittacine birds. Furthermore, each patient must be evaluated andre-evaluated individually and constantly. Unlike mammals, birds have more kappathan mu opiate receptors; therefore, a partial agonist/antagonist such asbutorphanol has been shown to provide pain32 Chapter 2relief, but at much higher than mammalian doses at 1 to 2mg/Kg IM(Paul-Murphy 1999). Buprenorphine has not been shown to work as well(Paul-Murphy 2004).Pollack (2005) recommends the following analgesic doses:Lidocaine: lmg/kg at site, dilute 1:10; 4mg/kg orhigher is toxic Butorphanol: 0.5-2 mg/kg IM (1 to 2mg/kg IM every2 to 4 hours as needed) Carprofen:  1 to  10 mg/kg  IM/PO  (most  use2 mg/kg)Celecoxib: 10 mg/kg PO (used for proventricular dila­tation disease)Meloxicam: 0.1 to 1 mg/kg IM/PO (0.5 mg/kg) (Wilson 2004)It is very difficult to assess pain in birds and there are no standardmethods or assessments available. Therefore, one must rely on past experience,observa­tion, and anthropomorphism (If I had a fractured bone I would want anopiate). Birds are very stoic and do not cry out in pain despite the fact thatthey can be very loud when they want to be. Birds have a flock mentality,meaning they are a prey species and if they make their illness conspicuous tothe rest of the flock they risk being ostracized (so as not to attract theattention of a predator). It is best to observe your patient before it is awarethat you are observing it. When it realizes you are there, you will probablyobserve it straightening up, opening its eyelids more, and it may even turn topartially face you in an attempt to look alert.Birds do not seem to become profoundly depressed on analgesics,therefore I tend to give analgesics at any hint of pain in a bird. In mostcases I tend to give an opiate at surgery, then both an opiate (butorphanol)and an anti-inflammatory (meloxicam) for the first six to forty-eight hours,followed by only the anti­inflammatory for about three to five days.SURGERYIt is best to remember to use analgesics before pain occurs to prevent"wind up." Butorphanol is best in birds.Preparation of the skin is similar as for mammals, with threeapplications in succession of chlorhexidine scrub, but there are somedifferences, including the use of sterile saline or very sparing amounts ofalcohol, patting the skin rather than rubbing so as not to cause subcutaneouspetechial hemorrhaging, and plucking of feathers under anesthesia beforepreparing the skin. Plucking feathers is very painful and usually requires asurgical plane of anesthesia and should be done one feather at a time, pullingin the direction in which it grows. Clear, see-through drapes are a necessityfor the anesthetist to be able to assess breathing in the patient. Stickysurgi-drapes or sterile clear plastic wrap can be used.A radiosurgical unit is preferable to an electrosurgi-cal unit in birds.It can be used in monopolar or bipolar modes. A special "Harrisontip" is a bipolar tip used in birds (Figure 2.28). Birds should be underanesthesia for less than one hour, so having everything possible prepared andready for use to shorten surgery time is essential in avian surgery. If thecelomic cavity is to be breeched, remember that birds do not have a diaphragmand that anesthetic gases will escape the surgery site, causing the birdsanesthetic depth to lighten.Also be aware that it is easier to "bag" or IPPV (intermittentpartial pressure ventilation) a bird once the air sac is incised. If at anytime the birds breathing cannot be assessed it is the anesthetistsresponsibility to stop the surgeon to assess breathing. Fluids, such as LRS orNormosol-R, are usually administered atFigure 2.28. A radiosurgical or electrocautery tip used in birds, calleda "Harrison tip," is specifically designed for birds with one benttip for better access. Do not straighten.Psittacines and Passerines 33lOml/Kg/hour for the first hour and then at 5 ml/Kg/ hour thereafter. Abolus of fluids may need to be given if blood loss is greater than 10% of theblood volume. The suture used is typically 4-0 to 5-0 PDS.Common surgeries include accessing the crop for a biopsy to definitivelydiagnose proventricular dilation disease (PDD), repairing a crop burn in aneonate, or removing a foreign body or accessing the proventricu-lus with anendoscope through the crop. Common surgeries requiring celomic cavity accessinclude salpingohysterectomy (removing the uterus, not the ovary, in a bird),liver biopsy (either directly or endo-scopically), proventriculotomy to removea foreign body, or exploratory laparatomy.Strictly follow manufacturers directions on clean­ing, maintaining, andhandling endoscopes to ensure the long life of this expensive equipment.PARASITOLOGYAlthough ascaridosis is now uncommon, the clinical signs are none ordiarrhea; rarely a GI impaction can occur. A diagnosis is easily made on fecalflotation. The treatment can be with ivermectin, fenbendazole, or piperazine.Giardiaisis is caused by the protozoal organism in the Giardia spp. Clinical signs canbe none or diarrhea and weight loss. A diagnosis can be made on a fecal Gramstain in severe cases, but the motile protozoa are easier to visualize on adirect saline smear, especially with the addition of iodine. An ELISA forgiardia Ag is the best current test. Treatment is with metronidazole.Trichomoniasis is caused by the Trichomonas spp. of protozoaand is called "canker" in pigeons and "frounce" in raptorseating pigeons. It is associated with white plaques in the oral cavity.Diagnosis is based on demonstration of the protozoal organisms on direct salinesmear of the oral cavity. Treatment is metronidazole. Syngamus is also known as"gape worm" because affected birds gape their mouths open trying tobreathe around the physical presence of the large worm in their trachea. Theworms are thick bodied and dark red, and the male and female join to form apermanent "Y" shape. It is common in water­fowl and robins, and it istreatable with antiparasiti-cides. Some have even used endoscopy to retrievethe worms.Knemidokoptes pilae, or the scaly leg and face mite, causespitting and scaling of the keratin of the skin and beak of parakeets and otherbirds, but causes scaling on the legs and feet of canaries and finches (Figure2.29 A and B). Although the diagnosis can be made by theFigure 2.29. (A) Knemidokoptes infestation in a canary, manifesting asflaking of skin on feet. (B) Deformedbeak from Knemidokoptes. (Courtesy ofCheryl Greenacre.)typical appearance of the skin and beak, a scraping of the affected areaonto a slide with mineral oil reveals the round-shaped mites. The treatment istopical Ivermectin, or similar product, given twice ten to four­teen daysapart. Do NOT give ivermectin IM in birds, especially small birds, because theycommonly die from an anaphylactic reaction, presumably from the propyleneglycol in the product.GENDER DETERMINATIONMost parrots do not exhibit obvious signs of sexual dimorphism. Thegonads in both males and females are internal. If a client wishes to know thegender of34 Chapter 2her pet bird, a blood test should be recommended. This involves taking asmall amount (0.2ml) of blood or pulling a feather, which are DNA checked forchro­mosomes. Several companies offer this test. Surgical sexing should only beoffered to owners who plan on breeding their birds. The gonads are visualizedwith a sterile rigid endoscope. Any abnormalities of the gonads or otherstructures can then be identified. This, of course, carries the low risk ofanesthetic complica­tions, hemorrhage, and infection.GROOMING NailsOften when a bird presents for a nail trim, the nail is not overgrownbut the points have begun to trauma­tize the skin of the owners arm. A stonetip on a roto-tool or an emory board can be used to quickly round and dull thepoints. If nails are overgrown, human nail clippers or guillotine-type nailtrimmers can be used to take the length back. This should then be followed withthe roto-tool or emory board to round off any sharp edges created duringclipping. If the nail extends in an arc that is more than half a circle it isprobably too long (Figure 2.30). The quick differs in length betweenindividuals. Always have silver nitrate sticks or ferric subsulfate powderavailable to stop hemorrhage if it occurs.Figure 2.30. A clipped and undipped nail.BeakKnowing the normal beak shape and length for various species is a mustbefore any trimming takes place. Some species of parrots possess a longer beak thanothers (i.e. compare a macaw to an Amazon parrot). Beak trims can be performedwhen the bird is awake. A roto-tool (larger parrot) or nail file (birds smallerthan a cockatiel) can be used. The tip can be blunted. If the bill tip organbecomes visible (as a row of white dots on the occlusal surface of the beak) donot trim further or hemorrhage and pain will occur. The flaking on the externalsurface of the beak can be removed with the roto-tool/nail file. When using thepower tool be sure to never stop moving, using long, gentle strokes to avoidgoing too deep and cutting into bone. The beak is a bony structure covered withkeratin. Some individual parrots maintain their beak length and never need atrim. A bird with a maloccluded beak needs corrective trimming on a regularschedule. A bird with a fast growing beak that is constantly in need oftrimming may have underlying liver disease that needs to be addressed (Figure2.31).WingWing trims are performed to prevent the bird from flying freely. Indoors,free flying birds have encounters with ceiling fans, windows, being squeezedinto doors, and flying out through an open door or window. An ideal wing trimis symmetrical and allows the bird to gently glide to the floor. Too severe awing trim canFigure 2.31. Most birds do not need to have their beaks trimmed. Thesevere macaw on the right has a normal beak, while its clutch mate on the lefthas an abnormal, thickened beak.Psittacines and Passerines 35Figure 2.32. Wing trim.cause trauma, most commonly resulting in damage to the keel.A correct wing trim depends on the weight (i.e. obese compared to anormal weight bird), body type (i.e. heavy bodied bird compared to anelongated, long tailed bird), and the number of pin (blood) feathers that aregrowing in at the time of the trim. Only primary feathers (consisting of thefirst ten wing feath­ers counting from the tip) should be trimmed. Therefore,depending on the body shape of the bird, a wing trim consists of cutting fourto ten primary feath­ers on each side (Figure 2.32). If, for example, one weretrimming an Amazon parrot, which is a heavy bodied, short tailed bird,approximately four or five feathers would be trimmed on both wings. Acockatiel, built very differently than an Amazon, most likely would need allten primary feathers removed.To clip the feathers, the wing must be gently extended, and a firm gripshould be used, incorporat­ing the carpus and patagial ligament in the hold.This will support the wing if the bird should struggle and help to avoid injuryto the wing. Before cutting, check for pin feathers—those that have notfinished growing and still have a blood source. If pin feathers are presentleave a mature feather on either side of the pin feather to protect the growingfeather. If several blood feathers are present it is best to reschedule thetrim when they have finished maturing. The feathers are trimmed just behind thetips of the lateral coverts. Care should be taken not to clip the covertfeathers because this will leave an unsightly cut line. Always use sharpscissors and be sure not to cut toes straying into the field of the scissors.Birds with properly trimmed wings live safer lives indoors. Owners must be madeaware that even a bird with properly trimmed wings can fly away.EMERGENCY AND CRITICAL CAREThe causes for a bird to have an emergency visit to the veterinarian aresimilar to those for mammals, but may vary slightly. Examples of emergencycases include trauma (hit by ceiling fan, toe closed in door, big bird/ littlebird incidents, dog/cat attack, burns), toxins (lead, zinc, PTFE fumes fromTeflon®), metabolic dis­orders (chronic hypovitaminosis A, hypocalcemia inAfrican grey parrots), or infection (due to bacteria, virus, fungus, orChlamydophila usually involving the liver or GI or respiratory tract). Eggbinding (dystocia) due to low total body calcium from a long-term cal­cium-deficientdiet (such as a seed diet) is a common avian emergency.Unlike mammals, birds usually present with a ter­minal manifestation ofchronic disease that has just recently showed overt acute signs. Subtle cluesof disease often go unrecognized by the owner because birds hide signs ofdisease to avoid being ostracized by the flock (i.e. the flock doesnt want to bearound a bird that is attracting a predator). The first approach to anemergency should include, if possible, obtaining a history over the phone so asto be as prepared as possible when the bird arrives. Be familiar with commonspecies problems (i.e. hypocalcemia should be at the top of the rule-out listfor a seizuring African grey parrot). Evaluate the history, cage and husbandry,and droppings, and observe the bird for clues about the etiology beforepursuing stressful restraint.Perform a rapid but thorough physical exam and diagnostic collection(+CBC, profile, radiographs, fecal Gram stain). Sometimes the bird may be sostressed that the examination may need to be performed in less than one minuteor in stages. Obtain an accurate weight with a gram scale so drugs can be dosedand administered accurately. Provide therapy to stabilize the patient: warmth(85° to 90°F), a stress-free envi­ronment (no barking dogs), and ±02(Figure 2.33). Offer familiar/favorite foods and water at an elevated levelright in front of the bird, provide ten hours of daylight and fourteen hours ofdark, and provide a low perch or none at all (birds insist on perching on thehighest available perch, even when severely debilitated.During the examination for an emergent bird, first check to see that thepatient has a patent airway. Is the airway patent or is there a mass or foreignbody in the trachea? Examples of a mass include an aspergil-lus granuloma,neoplasia, or diptheritic membrane. A millet seed in a cockatiel trachea (thiscan be directly visualized in the trachea with a rigid 1-mm endoscope) is anexample of a foreign body.Second, check to see if the animal is breathing; if not, intubate withan uncuffed endotracheal tube and provide intermittent partial pressure ventilation(IPPV) in birds at one breath/five seconds. Due to the unique respiratorysystem in birds an air sac tube can be36 Chapter 2Figure 2.33. Hospitalized owl in warmed cage. The owl is receivingsupplemental oxygen and fluids through an intraosseous catheter.placed in the caudal thoracic or abdominal air sac and oxygenated airwill flow through the lung. An air sac tube can be connected to 02or anesthesia and left in place for five days.Third, check to see if there is a heartbeat. If a bird experiencescardiac arrest, the prognosis for reversing this situation is poor/grave due toa birds high meta­bolic rate and oxygen demands. The following treat­ments canbe attempted to reinitiate heart beat: rapid heart massage and ventilation (100beats/minute and one breath/five seconds), epinephrine IV or IT(intratracheally), atropine (usually used to prevent bradycardia, though),doxapram IV or IT (stimulates respirations), or bolus IV fluids ±2.5% to 5%dextrose.Blood LossThe average blood volume of a bird is approximately 10% of its bodyweight (BW). For example, a 1-kg blue and gold macaw has an average bloodvolume of about 100 ml. A healthy bird can lose up to 10% of its blood volume(or 1% of BW) without any adverse side effects. Therefore, a healthy 1-kg blueand gold macaw could lose up to 10 ml without any adverse side effects. Unlikemammals, a healthy bird can usually lose up to 30% of its blood volume withoutdying due to compensatory mechanisms. Because of these com­pensatorymechanisms, it is important to realize that the packed cell volume (PCV) in abird is not accurate (i.e. not equilibrated) for twenty-four hours after ahemorrhagic incident because birds can shunt blood from large skeletal musclecapillary beds and away from the kidneys via the renal portal system toincrease blood flow to central areas. Therefore, an equilibrated PCV or an immediate PCV blood transfu­sion. Fluids, hetastarch, oxyglobin, or a blood transfu­sion (5%of BW) help a bird with severe blood loss. The anemic patient may requirevitamin B complex, iron dextran, and vitamin Ki.DehydrationMost sick birds are 5% to 10% dehydrated. Severe dehydration is usually> 10%. Clinical signs of dehy­dration include depression, reduced skinelasticity over digits, sunken eyes, cool digits, and decreased refill time ofthe basilic (cutaneous ulnar) vein. A general rule of thumb is that a normallyhydrated bird has a basilic vein refill time that is instantaneous, such thatyou cannot see the vein refill after applying digital pressure to it. If youcan see the vein refill, the bird is at least 5% dehydrated, and if the veintakes one second or more to refill, the bird is more than 5% dehydrated.Maintenance fluids are the same for birds as they are for mammals: 50ml/kg/day. For example, mainte­nance fluid calculations for a 500-gram Amazonparrot are 0.5 kg x 50 ml/kg/day = 25 ml/day. The dehydration fluid replacementneeded for a 500-gram Amazon parrot that is 6% dehydrated is as follows:dehydration replacement in liters is BW (in kg) x % dehydration (expressed as adecimal amount), 0.5 kg x 0.06 = 0.030 liters = 30 ml. The calculated dose fordehydration replacement (30ml) should be administered over forty-eight hours.The schedule for administration of maintenance and dehydration fluidsgiven to the above bird in forty-eight hours is as follows: Day 1: 25 ml formainte­nance + 15 ml for half the dehydration replacement = 40 ml; Day 2: 25 mlfor mainte­nance + 15 ml for the second half of dehydration replacement = 40ml.Fluid therapy is a critical component of emergency therapy. The mostcommonly used fluids are lactated Ringers solution or Normosol-R because theymost closely resemble the fluid lost. Warm fluids (about 100°F) are imperative.Keep in mind that the body temperature of most birds is 104° to 109°F.Sometimes 2.5% dextrose is added to the SQ or IV fluids.Mild dehydration may only require conservative management such as oralor SQ fluids. SQ fluids are generally administered into the inguinal area inbirds. Severe dehydration or shock requires rapid circulatory expansion with IVor intraosseous (IO) fluids; oral or SQ fluids are inadequate in these casesdue to lackPsittacines and Passerines 37of absorption at the administration site. Peripheral indwellingcatheters have been avoided in birds because birds have small, fragile veinsthat easily form hema­tomas, their dermis is highly mobile (causing difficul­tiesin stabilizing the catheter), and they have refractory temperaments and apowerful beak. Repeated IV bolusing can be attempted, but it is stressful tothe birds to be repeatedly restrained and it is damaging to the veins.Switching to oral fluids should be done as soon as possible.TECHNIQUESCatheter Placement Intraosseous CathetersIO catheters allow continuous access to peripheral cir­culation, andthey provide the ability to administer drugs, fluids, or total parenteralnutrition (TPN). Their use is safe, rapid, and practical. IO catheters are mostcommonly placed in the distal ulna or proximal tibio-tarsus. They should not beplaced in a pneumatic bone because pneumatic bones communicate with the respi­ratorysystem; therefore, this may drown the bird when fluids are administered.Likewise, intracoelomic fluids should not be administered because this may alsodrown the bird if fluids get into an air sac. To place the IO catheter, pluckand aseptically prepare the carpus. Position the needle in the center of distalulna. Support the ulna and rotate the catheter. Once past the cortex, thecatheter passes easily. Aspiration should produce a small amount of blood.Anchor the catheter to the soft tissue of the carpus and apply a figure-8bandage (Figure 2.34 A and B).Air Sac TubeTo place an air sac tube, make a skin incisionover the sternal notch area (borders are the last rib, the femur, and thelateral processes of the vertebrae) and use a pair of hemostats to penetratebody wall, and then insert an ET tube.Blood CollectionThe blood volume of birds is approximately 10% of their body weight. Theamount of blood that can be collected safely from a healthy bird isapproximately 1 % of the body weight (1 ml/100 grams of body weight in ahealthy bird). This amount should be reduced with a sick patient. For example,a maximum of 1.2 ml of blood can be removed from a healthy 120-gram (0.12 Kg)sun conure without adverse effects. For a 1,000 gram (lKg) healthy macaw amaximum of 10 ml can be removed. For example:BFigure 2.34. (A and B) Intraosseous catheter placement into the distalulna of a Coopers hawk. A 22-gaugeneedle or spinal needle can be used. A catheter cap fits on the end. Steriletechnique should be used to place a catheter.cockatiel: 0.120 Kg x 0.01 = 0.001 liters = 1ml macaw: 1 Kg x 0.01 =0.010 liters = 10 mlThere are a variety of sites from which blood can be collected in theavian patient. These include the right jugular vein, basilic vein (also calledthe cutane­ous ulnar vein), and the medial metatarsal vein. The size of thebird influences the site chosen.Jugular VeinThe right jugular vein is the vein of choice for parrots kept as pets.The right jugular vein is chosen over the38 Chapter 2left because it is two-thirds larger. Tocollect from the jugular vein the bird must be restrained in right lateralrecumbency with the head and neck gently extended. The vein should be visiblewhen collecting blood. The jugular vein is found in a featherless tract oraptera (featherless area) on the ventrolateral aspect of the cervical area. Thevein can be seen by lightly wetting the feathers with alcohol. Bird veins aremobile under the skin and have very elastic vessel walls, which can make needlepunctures a challenge. Light digital pres­sure at the level of the thoracicinlet should be used when holding off the vein. A 1-ml or 3-ml syringe with a22- to 25-gauge needle is commonly used.Basilic VeinThe basilic vein (cutaneous ulnar vein) is also a choice for bloodcollection on medium to large birds and courses over the medial surface of theproximal ulna. This vein is superficial, lacking support tissue to dis­perse ahematoma, and often small, making it prone to collapse. To collect from this vein the bird should be restrained on itsback. The wing should carefully be extended, and it should be supported bygrasping the carpus and patagium.Medial Metatarsal VeinThe medial metatarsal vein is another venipuncture choice. The largerthe bird, the more developed the vein is. This vein lies in a groove on themedial side of the tibiotarsus, near the tiobtarsal-tarsaometatarsal joint(hock joint). This vein is a good choice for small amounts of blood, an IVinjection, or IV catheter placement. The bird can be restrained in a towel,held upright, and the leg gently extended. Poultry and water fowl have a largemetatarsal vein, making it an excel­lent choice for blood collection in thesebirds. Small blood tubes, including serum separator tubes, are available for usein small patients (Figures 2.35, 2.36).ADMINISTRATION OF MEDICATIONSMost infections in parrots are due to Gram-negative organisms. Mostdrugs are used empirically, since very few if any pharmacodynamic andpharmacokinetic studies have been performed in any species of bird, or in justa few species of birds. Remember that there is no generic bird; differentparrot species react differ­ently to different drugs so, research on eachspecies would take forever.The goal is to achieve antimicrobial tissue levels at the site ofinfection that are greater than the MIC, but one must realize that tissuepenetrations vary. One must also realize that drug excretion is rapid in birdscompared to mammals. Antibiotics can cause immu­nosuppression and change normalflora, producing a secondary fungal infection. Therefore, antibiotics shouldonly be used when indicated to avoid upsetting the delicate balance of normalflora in birds. Choose bacteriocidal instead of bacteriostatic antibiotics.Water AdditivesThe advantages of adding medication to the drinking water are ease ofadministration, the bird medicates itself, restraint isnt required, andspecific water borne diseases may be reduced. The disadvantages, which far outweigh the advantages, include inexact dosing, poor palatability that reduceswater and drug intake, insta­bility of some medications in water, the likelypossibil­ity of under-dosing, increasing organism resistance, and medicationbeing poorly or slowly absorbed.Food AdditivesThe advantages of adding medication to the food include ease ofadministration, food consumption may be fairly consistent, and ease of treatinghand-fed nest­lings. The disadvantages again outweigh the advan­tages andinclude the same reasons discussed above for adding medication to water. Onemust also realize that sick birds are often anorectic.Direct Oral MedicationThe advantages of giving medications orally include the fact that aprecise dose is given (unless the bird spits the drug out or doesnt swallow),many pediatric suspensions are available, and these medications can be givensimultaneously when a bird is gavaged or tube fed. The disadvantages includethe stress of capture and restraint, the risk of aspiration of the drug, thedrug may be poorly or slowly absorbed through the gastrointestinal tract ofvery ill birds, or malabsorption (if, for example, the bird is in shock or hasa GI dis­order) (Figure 2.37).Intramuscular Injection ofMedicationThe advantages of giving medication via an intramus­cular injection intothe pectoral muscle of a bird include the knowledge that the bird will receivean exact dose, it is quick and easy to administer (meaning less stress ofhandling), and it is quickly absorbed. Among the disadvantages, not all drugsare available for IM use, and pain and necrosis may occur at the injectionsite. In critically ill birds that cannot initially absorb oral medications,the bird can be started on IM medications and then switched to oral forms later(Figure 2.38).The jugular veinLThe medialmetatarsal. Figure 2.35. Venipuncture sites.Figure 2.36. Small blood collection tubes are available for smallpatients.The ulnar veincrosses the ventral surface of the elbow.Figure 2.37. Oral medications being given to a Quaker parakeet. One dropat a time should be given under the tongue to avoid aspiration.3940 Chapter 2Figure 2.38. Intramuscular injection given into the left pectoral muscleof a bird. The pectoral muscles arefound to either side of the bonykeel. Use a 25-to 26-gauge needle.Intravenous MedicationsThe advantages of intravenous medications via the jugular or medialmetatarsal or basilic vein are that an exact dose is given, it is rapidlyabsorbed, and it rapidly reaches therapeutic levels. The disadvantages of IVmedications are the stress of prolonged restraint while giving a bolus, therisk of the bird chewing the IV line if it is on an IV drip, and the fragileveins of birds.Intraosseous MedicationThe advantages of giving medications via an intraos­seous catheter inthe distal ulna or proximal tibiotarsus include the fact that a precise dose isgiven (and like IV administration it is rapidly absorbed) and the cath­eter canbe left in place up to five days. The disadvan­tages of IO administrationinclude discomfort or, if not bolus treating, the bird chewing the IV line.Subcutaneous MedicationThe advantages of giving medications via the subcuta­neous route in theinguinal region include the fact that a precise dose can be given and it isquick and easy to administer. The disadvantages include the fact that somedrugs are irritating when given SQ and someFigure 2.39. Subcutaneous fluids being given to a bird with a 22-gaugeneedle into the left inguinal area. The left leg is gently pulled caudally.Care should be taken to not abduct (pull laterally on) the leg because birdlegs do not abduct much.severely debilitated birds may not absorb SQ fluids or drugs. If fluidspool in the SQ space and are not absorbed within one to two hours then IV or IOfluids are necessary (Figure 2.39).TopicalIn birds, greasy topical compounds should be avoided because thisreduces the insulation of the feathers. If ointments must be used, then theyshould be used spar­ingly. It is better to use water soluble creams.NebulizationNebulization is used to deliver medications for respira­tory infections.Nebulization is a process in which atomization of a liquid into small (microns) drop­lets occurs so that it can be inhaled. Usually nebuliza­tion isperformed for ten to thirty minutes by forcing oxygen through a solutioncontaining antibiotics or antifungals, etc.Sinus/Nasal FlushingSinus flushing can be diagnostic (cytology, culture) and/or therapeutic.Warm saline should be used. It is imperative to hold the bird completelyvertically upside down to avoid aspiration of fluid into the trachea.Psittacines and Passerines 41Flushing can be performed in an awake bird or an anesthetized, intubatedbird (Figure 2.40).Tube FeedingTube feeding is controversial in critically ill patients (will theyprocess it?). The bird must be hydrated first. Usually one should start with athin carbohydrate supplement (such as Emeraid) and later use a juvenile parrothand feeding formula or specially made avian critical care diet (high calorie,easy to digest).Birds have a high basal metabolic rate with very little in reserve;therefore, if a bird is losing weight, it needs to be tube fed. Whilehospitalized, a bird is weighed daily in the morning on a gram scale. Tubefeeding is necessary if a bird is not maintaining or gaining weight in thehospital. Generally birds are tube fed one to four times/day. The techniqueconsists of restraining the bird in a normal upright position to avoidregurgitation and aspiration. Some prefer a stainless steel feeding needle withball tip; others use a red-rubber catheter and a speculum to prevent the birdfrom biting the tube in two (Figure 2.41).The tube is aimed from the left commissure to the right crop area (Figure2.42). Care must be taken to avoid the large trachea and excessive force mustbe avoided to prevent puncturing the esophagus and depositing food into theneck of the bird. Confirm placement of the tube by palpating/visualizing thetube in the crop before administering the formula. If the bird regurgitates atany time, then set it down and let go immediately to allow the bird toconcentrate on not aspirating.Figure 2.41. A variety ofsizes of stainless steel ball tippedfeeding needles used to gavage food directly into a birds crop.Figure 2.42. A metal ball tipped feeding or gavage tube is held externalto the bird to show the proper placement ofthe tube internally. The tube should gently enter from the birds leftcommissure and aim for the right shoulder area. The crop of a bird is on the right side of the neck and is very thin and subject topuncture.Figure 2.40. Nasal flush. (Courtesy ofCheryl Greenacre.)42 Chapter 2Approximate Feeding Quantities (Start with Small Amounts, Then Increaseto Amount Below)Budgie: 1ml Cockatiel: 3 to 5 ml Amazon parrot: 15 to 30 ml Cockatoo: 20to 40 ml Macaw: 30 to 60 mlDIAGNOSTIC SAMPLINGBlood is drawn from the right jugular vein because it is two-thirdslarger than the left. No more than 10% of the blood volume, or 1 % of the bodyweight, can be removed from a healthy bird without adverse effects. If a birdis sick or debilitated in any way, less must be taken. Generally, whole bloodis placed in a lithium heparin tube for a CBC, but a CaEDTA tube can be used.Plasma from a lithium heparin separator tube is ideal, but other tubesproducing plasma or serum can be used. Microtainer tubes that hold less than 1ml are ideal for small bird patients. Nasal flush and other techniques arecovered in the techniques section.WOUND CARE AND BANDAGINGWound care is very similar to that of mammals, except that birds arevery sensitive to steroids; thus, topical or parenteral steroids should beavoided. Bandaging is also similar except for those below pertaining to thespecial anatomy of birds. Typical bandage materials simply need to be cutsmaller.Ball or snowshoe bandages are used to protect the plantar surface of thefoot and evenly distribute the birds weight in cases of ulcerativepododermatitis, or bumblefoot. The interdigitating bandage is wrapped aroundthe entire foot between the toes (Figure 2.43). The ball bandage is more ballshaped, and the snow-shoe bandage is flatter.Figure 2.43. Ball foot bandage.Figure-8 bandages are used to immobilize the wing distal to andincluding the radius and ulna. They are not used for humeral fractures unless awrap about the body is included. This bandage is usually for tempo­rary usebecause the propatagial ligament that extends from the shoulder to the carpusbecomes severely con­tracted after five to seven days (Figure 2.44).Figure 2.44. Figure-eight bandage.Figure 2.45. Examples ofElizabethan and tube collars used in birds. Generally they are not recommendedfor use in birds because they are invariably heavy, make eating and preeningdifficult, and they stress the bird. Exceptions are made for collar use when abird self traumatizes, i.e. bites its own flesh and bleeds.Psittacines and Passerines 43Elizabethan or tube collars about the neck are not recommended in birdsbecause they are invariably heavy, make eating and preening difficult, andstress the bird. Exceptions are made for collar use when a bird selftraumatizes, i.e. bites its own flesh and bleeds (Figure 2.45).EUTHANASIAAny animal should be rendered unconscious prior to euthanasia,regardless of the species. Birds are easily masked under anesthesia withisoflurane and then once unconscious, the euthanasia solution can be given viathe intravenous or intracardiac route or in the cisterna magna. AVMA EuthanasiaGuidelines 2007 include birds and can be found at http://www.avma.org/issues/animal_welfare/euthanasia.pdf.REFERENCESBrue RN. 1994. Nutrition. In: Avian Medicine: Principles andApplication, edited by Ritchie BW, Harrison GJ, Harrison LR. Lake Worth:Wingers Publications.Curro TG, Brunson DB, Paul-Murphy J. 1994. Determination of the ED ;o of isoflurane andevaluation of the isoflurane-sparing effect of butorphanol in cockatoos (Cacatua spp.). Vet Surg, 23: 429-433.Forshaw JM, Cooper WT. 1989. Parrots of the World. 3rd ed. Willoughby,Australia: Landsdown Press.Harrison GJ, Ritchie BW. 1994. Making distinctions on the physicalexamination. In: Avian Medicine: Principles and Application,edited by Ritchie BW, Harrison GJ, Harrison LR, Lake Worth:Wingers Publications. King AS, McLelland J. 1984. Birds, TheirStructure and Function.2nd edition. Eastbourne, England: Bailliere Tindall. McMillan MC. 1994.Imaging Techniques. In: Avian Medicine:Principles and Application, edited by Ritchie BW, Harrison GJ,Harrison LR, Lake Worth: Wingers Publications. Paul-Murphy JR, BrunsonDB, Miletic V. 1999. Analgesic effects ofbutorphanol and buprenorphine in conscious African greyparrots (Psittacus erithacus erithacus and P. erithacustimneh).Amer ] Vet Res, 60(10): 1218-1221. Paul-Murphy J, Hess JC, FialkowskiJP. 2004. Pharmacokineticproperties of a single intramuscular dose of buprenorphine inAfrican grey parrots (Psittacus erithacus erithacus). J Avian MedSurg, 18(4): 224-228. Pollack C, Carpenter JW, Antinoff N.Birds. 2005. In: ExoticAnimal Formulary, 3rd edition, edited by Carpenter JW. St.Louis: Elsevier, pp. 135-346. Quandt JE,  Greenacre CB.  1999.  Sevoflurane  anesthesia  inpsittacines. Journal of Zoo and Wildlife Medicine 30 (2): 308-309.Rembert MS, Smith JA, Hosgood G, Marks SL, Tully TN. 2001. Comparison oftraditional thermal support with the forced air warmer system in HispaniolanAmazon parrots (Amazona ven-tralis). Assoc. of AvianVets Annual Conf, 215-217.Ritchie B, Harrison GJ, Harrison LR. 1994. Avian Medicine: Principlesand Application. Lake Warde: Wingers Publishing.Tully TN. Birds. In: Mitchell MA, Tully TN. 2009. Manual of Exotic PetPractice, St. Louis: Elsevier, pp. 250-298.Wilson GH, Hernandez-Divers S, Budsberg SC. 2004. Pharmaco­kinetics anduse of meloxicam in psittacine birds. Proc Annu Conf Assoc Avian Vet, 7-9.CHAPTER THREEPsittacine Behavior, Husbandry, and EnrichmentTarab HadleyINTRODUCTIONPsittacine bird species account for approximately 330 of the 9,700 knownavian species. These birds, which are primarily found in tropical regions ofthe world, are classified into three families: the Loriidae (includes loriesand lorikeets), the Cacatuidae (cockatoos), and the Psittacidae (includesparakeets and parrots). Birds in each of these families demonstrate distinctphysical and behavioral characteristics. Keep in mind that what constitutesnormal and abnormal behavior may be heavily influenced by the species, theindividual bird, and the environment. In many situations, behavior in captivebirds does not always equate with the behavior of those in the wild.BEHAVIOR OF COMMON PET PSITTACINE SPECIESLories and LorikeetsThese birds are extremely energetic and intelligent. They are not goodtalkers but when excited or stressed they may emit an ear-piercing,high-pitched screech. In the home environment these birds tend to be verycurious and may get into trouble going into places they shouldnt. Many ofthese birds do well in a group of at least two. As individual pets, they canattach them­selves to one favorite owner and be very nippy toward anyone else.In general, due to their wet diet of fruit, nectar, and pollen, thesebirds are also very messy eaters and it is not unusual to see food splashedaround the cage or on floors and walls. Species from this family com­monly seenin the pet trade include the black lory, red lory, rainbow lory, and chatteringLory. The brilliance and beauty of their plumage have made these birdsattractive as pets. However, they may also be extremely territorial, which maycontribute to unwanted biting behavior.CockatoosLike all birds, cockatoos are very intelligent (Color Plate 3.1). Mostcockatoos, especially the larger variet­ies, also tend to be verysweet-natured. This behavioral tendency may encourage some owners to treat themlike babies or small children instead of birds. Likewise, many of these samebirds become very attached to their owners, contributing to the development ofabnormal behavior, such as feather picking.Smaller cockatoos tend to bite even their owners but some may besweet-natured. Cockatoos are decent talkers. They are also prone to screamingloudly at certain times of the day, such as dusk or dawn, when they are tiredand ready for sleep, or when they become excited. If left unattended orsometimes in plain view, their curiosity may get the best of them and lead todamaged baseboards or other broken items.Cockatoos cannot distinguish between safe and unsafe items so it isessential to bird-proof the home environment from electrical cords or metallicitems such as jewelry. The cockatoo species most com­monly kept as pets includethe umbrella cockatoo, salmon-crested cockatoo (also known as the moluccancockatoo), galah (also known as the rose-breasted cockatoo), sulphur-crestedcockatoo (including the lesser variety), Goffins cockatoo, and Ducorpscockatoo.In general, the temperament of these pet birds may quickly change fromvery quiet and observant to very noisy and active. These birds also produce alarge amount of dander which coats the beak with a visible layer of fine whitepowder. In addition, a large amount of feces is produced daily by these birds.4546 Chapter 3Plate 3.1. Umbrella cockatoo. (Photo courtesy of Dr. Tarah Hadley.) (See also color plates)BudgerigarThese small birds are very active and social, especially when groupedwith other birds. It is not unusual to see preening or food sharing behaviorbetween birds. As with other birds, they may be trained to step up and obeyother commands. If they are not trained they tend to be very flighty whenapproached and can some­times be a challenge to capture. These birds may alsobecome nippy during restraint. In most other areas, the behavior of budgerigarsis similar to that of other birds. Therefore, it is important to avoidpromotion of these birds as "starter birds" for new enthusiastsbecause their intelligence requires enrichment equal to that of other birds.EclectusThese birds are one of the few sexually dimorphic species (males aregreen and females are red) (Plate 3.2). The male eclectus tends to have asweeter and calmer disposition compared to the female eclectus, whose behaviorseems more cautious and suspicious, espe­cially toward people she does notknow. The females also have a reputation for being more aggressive in somesituations and more likely to bite than the males.In general, eclectus birds are quieter and less active than other birds.Like most birds, however, they are very intelligent and curious about theirsurroundings. As pets, these birds thrive with owners that have a patient hand.With time and practice, they may become adequate talkers. Like the cockatoos,these birds may also develop feather destructive behaviors.CockatielCockatiels are sweet, feisty birds with very active social lives (ColorPlate 3.3). They may also be veryPlate 3.2. Pair of eclectusparrots, one of several sexuallydimorphic psittacine species. (Photo courtesy ofDr. April Romagnano.) (See also color plates)Plate 3.3. Bright orange cheek patches are often more prevalent in malecockatiels, such as the one pictured here. (Photo courtesy of Dr. Tarah Hadley.) (See also colorplates)vocal at times and can be good talkers and singers. They are verytrainable to the hand and make good avian pets for first-time bird owners. Theyenjoy inter­acting with other cockatiels or people. Female birds kept in a groupor alone may be prone to chronic egg-laying, which can be detrimental to theiroverall health.African GreyThese birds are extremely intelligent and also very good talkers. (ColorPlate 3.4) They tend to be friendly but also may be somewhat cautious dependingon the environment. African grey parrots are also one of a few species thatcommonly present for feather destruc­tive behaviors. Respiratory diseases suchas sinusitis and aspergillosis also seem to be prevalent in thisPsittacine Behavior, Husbandry, and Enrichment47way partly out one side of acardboard box. (Photo Plate 3.4. Congo African grey parrot. (Photocourtesyof Dr. Tarah Hadley.) (See also colorcourtesy of Cherie Fox.) (Seealso color plates) plates)Plate 3.5. Congo African grey parrot with an enlarged left nare, mostlikely caused by chronic upper respiratory infections and sinusitis. (Photocourtesy of Dr. Tarah Hadley.) (Seealso color plates)species (Color Plate 3.5). Hence, many of these birds may be moresensitive to aerosolized toxins and other agents. Like other birds, interactionwith the owner and environmental enrichment are just some of the ways thesebirds may be kept stimulated. These birds normally produce a small amount offeather dander that lightly coats their beaks with a fine white powder.SenegalThese smaller parrots make good pets and seem to thrive in anenvironment supported by interaction with the owner. They are fairly goodspeakers and may also be trained to perform small tricks.LovebirdOwners may form close and friendly relationships with these birds on anindividual basis. The birds may learn to vocalize some and tend to be fairlyactive singers. When paired with one or more other lovebirds, these birds maysometimes become less friendly with the owner to the point of biting and maybecome overly protective of their cage mates.MacawsThese birds make up some of the largest members of the Psittacidaefamily. They are very active and vocal and may be adequate to fairly goodtalkers with encouragement. Sometimes their vocalizations can be ear-piercing.Behavior of these birds may range from friendly to cautious or unfriendly,depending on the background of the bird. (Color Plates 3.6, 3.7, 3.8) Onoccasion, macaws in stressful environments may exhibit feather destructivebehaviors. Due to their large size and particularly long feathers, large cagesthat permit activity are required to house these birds. Owners should also beaware that they produce large amounts of feces on a daily basis. Their largebeaks, another common characteristic of these birds, are used to crack opennuts with the largest and hardest of shells. Many species exist in the petpopulation, including the hyacinth macaw, blue and gold macaw, scarlet macaw, green-wingedmacaw, and military macaw.48 Chapter 3Plate 3.7. Hyacinth macaws. (Photo courtesy of Cherie Fox.) (See also color plates)Plate 3.8. Military macaw. (Photo courtesy of Cherie Fox.) (See also color plates)ConureThese species of birds comprise some of the small to medium-sizedparrots. They are extremely active birds and very active singers or talkers.They may sing or screech for several minutes at a time or longer. Hence,Plate 3.9. Cuban Amazon in outside aviary on a natural wood perch.(Photo courtesy of Dr. AprilRomagnano.) (See also color plates)the best households are those that can tolerate the loud vocalizations.They may form close relationships with owners and they can also be nippy orbite in certain situations. Common species seen in the pet industry include themitred conure, sun conure, maroon-bellied conure, and green-cheeked conure.ParrotletParrotlets include some of the smallest species in the Psittacidaefamily. They are also extremely intelligent birds with a feisty temperamentthat belies their body size. They have been known to challenge or defend theirterritory from birds that are many times larger, which can sometimes get theminto trouble. They are not considered very good talkers but will vocalize withencouragement. Parrotlets lead very active lives and tend to be very goodfliers. Owners should always be aware of the location of non-caged birdsbecause they can sometimes get underfoot.AmazonAmazon bird species are big-bodied birds that are medium in size (ColorPlates 3.9, 3.10, 3.11). They may be trained to become very good talkers andmay be friendly pets, depending on the individual bird and the environment.They enjoy the interaction with owners as well as playing on their own withtoys in their environment.Psittacine Behavior, Husbandry, and Enrichment49Plate 3.10. Yellow-naped Amazon. (Photo courtesy of Dr. Sam Rivera.) (See also color plates)Plate 3.11. Blue-fronted Amazon. (Photo courtesy of Dr. Sam Rivera.) (See also color plates)HUSBANDRYThe Cage EnvironmentAfter—and sometimes before—the acquisition of a pet bird, many ownersconsider the habitat that the bird will live in when it is inside the cage. Oneof the most important considerations will be the size of the cage. The sizeshould be appropriately matched to the size of the bird. If the cage is for alarge parrot species, such as a macaw, the cage should at least be as wide asthe wingspan of the bird. An even wider cage pro­vides plenty of room for playand other antics. The height of the cage must also be evaluated such that thelong feathers of perched birds have adequate space to prevent damage when thebird moves around. Likewise, smaller birds require cages that are proportional totheir wingspans and sizes.Other considerations include the thickness of the bars and the widthbetween bars. Whereas larger birds may be safely enclosed in cages with widespaces between bars, owners of small birds need to be careful that the width isnot so great that the bird may be able to easily slip through. Precautionsshould also be taken to ensure that the cages are properly manufactured and donot contain materials such as lead that may harm birds.Cages should have the ability to separate birds from fecal droppings sothat birds that like to go to the bottom of their cages may do so without riskof step­ping in their feces. Ideally, the grate above the bottom of the cage isremovable for ease of cleaning.Placement of food bowls within cages should also be considered. Somecages have built-in brackets that hold food and water bowls. Others areflexible and allow the owners to decide where they should be located. Keep inmind that many smaller birds do a better job of leaving the food bowls aloneand not trying to remove them from their holders. However, many larger birdscontinually attempt to dislodge bowls from their holders. For these birds, asystem in which the bowl sits in a permanent bracket and cannot be removed whenthe bowl is inside the cage is a good solution. This also prevents birds fromcreating more cage mess by wasting food or water on the floor.There are a tremendous variety of cage styles and designs to choosefrom. The actual style chosen may depend on multiple factors. Owners shouldconsider the space available for the cage. The shape is also a majorconsideration because some birds prefer dome-shaped cages over flat-toppedcages. The shape of the cage also affects the inside space available to thebird. Owners should wisely choose the preferred height of the cage so thatbirds on top of cages are not unreachable by the owner. Owners may choose froma variety of cage designs that may include external play and perching areas.PerchesThe appropriate choice of perches is often poorly understood by manyowners. There are also many opinions about the best type and size of perch.Many owners forget that birds stand on their feet all day while they are awakeand all night while they sleep. Hence, what the bird stands on may have a seriousimpact on its overall well being in addition to its health. That said, ownersmay choose from a variety of perch sizes and types. A few considerations forchoosing the best perch:50 Chapter 3As a general rule, the best perch allows the birds toes to wrap aroundabout three-fourths of the diam­eter of the perch. The best perches are alsotypically made out of natural wood. Owners often ask whether wooden dowels orconcrete perches are acceptable types of perches. The answer is likely thatmost birds will do fine with them as long as they are not the only perches inthe cage.Although they are made out of wood, the downside of wood dowels is thatthey are flat, sometimes slip­pery, and lack good texture for gripping. Theyare a reliable form of transport for birds that travel between water and foodbowls at mealtimes. They are not comfortable for long-term perching. Pet storesalso sell plastic dowels which fit nicely inside pre-fabricated cages; however,they tend to be more slippery than wood dowels. Smaller and lighter-weightbirds do better on plastic dowels but also likely encounter the same problemswith discomfort after a period of time.Concrete perches are often touted as a good alterna­tive to nailtrimming in birds of any size. Based upon experience, these perches dull thenails of a select few birds; many more still need to be trimmed regularly. Formany birds, particularly those with foot or ankle prob­lems and heavier birds,the concrete may wear away the normal skin layer on some parts of the foot. Inits place the skin may become calloused, worn, and unnaturally smooth. This mayalso lead to extreme discomfort.Natural wood perches, such as manzanita, may provide the best source ofcomfort to a birds feet. These perches come in varying diameters. As long aspart of the perch length is an appropriate diameter for the foot size of thebird, changes in the diameter within the same perch provide the bestopportunity for a bird to exercise its feet. Foot problems may lead to poorhealth and increased risk for systemic disease. Healthy feet lead to healthyskin, allow for increased activity and movement, and permit the bird to getbetter quality rest in the evenings. The number of perches provided is affectedby the size of the cage. Avoid having too many perches because that crowds thecage and decreases the available space.The Cage BottomBird owners far and wide have all received a similar warning: when yourbird goes to the bottom of the cage, it is extremely sick. While that is truein some cases, it is not always true. In fact, the cage bottom is just anotherplace where birds may play. Many birds routinely go to the bottom of the cageto play with toys or shred newspaper, and this is completely normal.Not all birds do this. Some birds are completely terri­fied of thebottom of the cage. Do not force them to go to the cage bottom.It is important to provide birds that do play on the cage bottom withappropriate toys or enrichment. If a bird likes to shred newspaper, place alayer of news­paper on top of the grate so the bird has access to it. Do notscold birds that like to play with newspaper for making a mess. That is justpart of being an active bird. Some birds may also enjoy paper balls or card­boardboxes. Birds that were previously scolded for shredding newspaper may enjoyaccidental access to newspaper. In this scenario, owners may make it a littleeasier for birds to grab newspaper through the grate while the birds still seeit as a challenging and forbidden activity.Upkeep of the cage bottom is especially important to the overallcleanliness of the cage. Substrate options include newspaper, butcher paper,recycled cardboard, wood shavings, and corn cob bedding. Ideally, the substrateon the cage bottom should be changed daily. This is easier to do when newspaperor butcher paper are used as the substrates. Daily cleaning limits growth ofbacteria or fungus and formation of maggots.Daily cleaning is not so easy or cost efficient when shavings or corncob bedding are used. Many owners that use these substrates prefer to scoopaway fecal piles on a daily basis rather than replace the substrate. Thelikelihood that bacteria or fungus will grow in these scenarios is higher. Woodshavings with added treatments, such as cedar wood shavings, can be harmful tobirds. Young birds that dont know any better or older birds that have atendency to eat things they shouldnt have been known to ingest the sub­strate,so it is essential that it be relatively safe.Toys and Non-toy Enrichment ItemsBirds are extremely intelligent animals that need an active, fulfillingenvironment to match their intensity. Toys tend to be the most common way ofproviding fulfillment to the inner and outer environment of birds cages. Toyscome in a variety of shapes, sizes, colors, and noise options.The best toy for a bird depends on its size and per­sonality andavailable space. Many birds are afraid of new additions to their cages and mayneed time to get used to new toys. Owners should also avoid the temp­tation tocrowd the cage with several toys. Crowded cages do not allow enough room forbirds to stretch or play with toys and may pose an environmental hazard. Toysshould be individually assessed for prac­ticality and safeness.Psittacine Behavior, Husbandry, and Enrichment51Toys may also be created from safe household items, such as cardboardboxes, cereal boxes, rope, and paper towel rolls. These items are usually cheapto create and are easily replaced. They may also be tailor-made to suit theactivity level of the bird. Toys that encourage curiosity on the part of thebird, particularly those that encourage foraging or searching for food, mayprovide great stimulation to the birds environment. Other items of enrichmentthat birds may enjoy include music, television, or videos.Cage LocationThe location of the cage is also important. Owners should choose alocation for their bird that will allow daily interaction with owners andprovide quiet in the evening for rest. It is not simply enough to cover abirds cage in the evening and expect that complete rest will occur. As long asactivity, noise, and bright light occurs in the environment, birds may alsocontinue to stay awake and not sleep. For this reason many owners have aseparate cage in a quiet place to put their bird at night.As a general rule, birds usually need between ten and twelve hours ofsleep each night to be well rested the following day. Birds that dont getenough sleep may become anxious or nippy or may resort to feather destructivebehaviors. Safety should also be a consid­eration. For instance, a kitchenlocation for a cage may expose birds to undesirable fumes.NORMAL BEHAVIOR OF PSITTACINE BIRD SPECIESWhat constitutes normal behavior tends to be similar across manypsittacine bird species, with some minor differences. Many of these behaviorsare particular to birds in captivity, although some may be exhibited by birdsin the wild that have not had the influence of a captive experience. Birdowners also come to learn that differences in behavior, activity level, and tem­peramentoccur among their individual pet birds. Environment and husbandry likely havestrong influ­ences on the development of certain behaviors.BathingSome birds enjoy bathing themselves in their water bowl. Bathing may betriggered by loud noises, such as music or a vacuum, or the appearance ofnatural sunlight on certain portions of the cage, or it may just occur at sometime known only to the bird. When a bird is self-bathing it is not uncommon forit to dunk its head, beak, feet and legs, or parts of its tail in the waterbowl. After dunking parts of its body, the bird usually shakes off the waterand then the behavior is repeated. A bird that is allowed more free flight inthe home may fly to the sound of running water and immerse itself underneaththe running spout or sprayer.Playing on the Cage BottomSome birds actually enjoy spending time on the cage bottom as much asthey do on perches near the top of the cage. The cage bottom is where"illegal" access to newspaper or other substrate may be obtained,which seems to be thrilling for many birds.Owners are encouraged to place toys, newspaper, or other items on thebottom grate so birds have activi­ties. The healthy bird that plays on the cagebottom may still vocalize and will continue to be very active— all normalbehaviors for birds.Preening and MoltingPreening is a normal grooming activity that birds perform on a dailybasis. Birds use their beaks to smooth down erratic-looking feathers all overtheir body. Often, owners may see birds reaching to the hidden preen gland atthe lower back near the base of the tail. The material taken from this area isused by the birds to get their feathers back in shape. As part of the normalpreening behavior, it is not usual to see a few old or loose feathers drop fromthe body.Molting is another behavior that occurs in birds. As new feathers comein, old feathers are pushed out. Newer feathers may come in singly, as in thecase of large wing and tail feathers, or in groups, such as is the case withhead feathers. Newer feathers may be surrounded by an opaque sheath that thebird removes during the preening process. When a large tail or wing feathermolts on one side of the body, the same feather on the opposite side of thebody usually molts at the same time. In general, it is normal for largefeathers to molt twice yearly and small feathers such as those covering thechest and head to molt several times yearly.SleepingMany birds sleep through the evening for about nine to twelve hours,depending on the environment and lighting conditions. Birds also take napsperiodically during the day. Most birds that are sleeping for an extendedperiod of time usually sleep on their52 Chapter 3most comfortable perch with one foot clenched and held up near theirabdominal area. Their heads are often turned backward a full 180 degrees andtheir beaks are tucked into the feathers of their back near their wings. Anyloud noise or other distur­bance may disrupt a bird from this position. Somebirds, such as cockatoos, may get upset about disrup­tions to their sleep timeand may vocalize loudly until their environment quiets down. Many birds respondwell to having a cover placed around their cages at sleep time.RegurgitationParents that raise chicks in the nest provide nutrition to them in theform of regurgitated food. However, juvenile and adult birds have been known toregurgitate to their owners. Often no food material is expelled but the birdsgo through the motion of regur­gitating food into their mouths andre-swallowing it. This may simply be a sign of a birds close attachment withan owner and not necessarily mean that the bird is sick.Eye MovementsOwners often marvel at how quickly and easily birds are able to changethe way their eyes look. In most other animals, the size of the colored iris isaffected by the amount of light coming into the eye. Hence, these animals haveinvoluntary control of their iris muscles. Birds are uniquely able to directlycontrol the move­ment of their irises due to the presence of voluntary muscles.Birds that are excited or angry often make the openings of their irisessmaller. This is often referred to as "flashing" their eyes.Body ShiveringMany birds give the appearance of being cold when their bodies start toquiver or shake. Although this is a possibility for birds exposed to coldweather, birds usually quiver or shake when they are nervous or exposed to newenvironments or people. Some birds appear to do this for no reason inenvironments where they have been completely comfortable.VocalizationsThe time of day or situation during which a bird vocal­izes depends uponmany factors. The species of bird and the personality of the individual birdusually play a role. Stimuli that cause vocalizations by birds may be naturalor artificial in origin. Common stimuli for vocalization by birds includebathing time, loud noises such as music or the vacuum cleaner, feeding time, orduring dawn and dusk.ABNORMAL BEHAVIORVeterinary staff may pick up on some very obvious signs to determinewhether a bird is not feeling well. More subtle clues are usually detected bythe owner. That is why it is so important to get a thorough and completehistory, which should include asking the same background questions of everyavian owner.Feather Destructive BehaviorsFeather destructive behaviors include medical and non­medical causes ofinjury to the feathers and surrounding tissue. Birds may destroy parts or allof a feather. They also may directly cause trauma to the underlying skin andmuscle. Some birds just pull out feathers. Behaviors that involve feather andtissue destruction are not normal and potential causes should be investigatedas early as possible to try to minimize trauma. Any trauma that causesexcessive bleeding and/or tissue damage needs immediate attention (Color Plate3.12).Sitting on the Cage BottomBirds that are extremely ill are often too tired or weak to perch and goto the bottom of the cage. These birds may be distinguished from their healthycounterparts by their dull attitude and overall depression. Sometimes they leanagainst the side of the cage and keep their eyes closed for extended periods oftime, even when attempts are made to stimulate them. This is consid­ered amedical emergency and requires immediate attention by a veterinarian.Fluffed Feathers and ShiveringOften one of the first signs of illness that owners notice is when theirbirds feathers become fluffed and theyPlate 3.12. A feather picker. (Photo courtesy of Dr. Sam Rivera.) (See also color plates)Psittacine Behavior, Husbandry, and Enrichment53Plate 3.13. Yellow-beaded Amazon that presented lethargic with eyesclosed and fluffed feathers. (Photo courtesy ofDr. Tarah Hadley.) (See also color plates)look puffy (Color Plate 3.13). Many birds often shiver. These are signsthat the bird is unable to properly regulate its body temperature and the birdis doing everything it can to trap heat for warmth. Birds in this conditionshould be evaluated as soon as possible by a veterinarian.Regurgitation and VomitingRegurgitation can be a sign of illness in a bird. Birds often makebobbing motions with their heads as food is moved from the lowergastrointestinal tract to the beak. If the food material is unable to beswallowed, the bird will vomit the contents. A sick bird makes these motionsrepetitively. Causes of regurgitation and vomiting include an obstruction inthe gastrointestinal tract, inflammation, infection, heavy metal toxicosis, andcancer.Mean Bird Turned FriendlyThis is a classic sign observed by owners who notice that their bird isnot acting like it usually does. Owners who inquire further will interact witha usually mean bird and are surprised to see that the bird will come out of itscage and onto the owners hand easily. These birds are likely sick and tend tobe more quiet and docile than usual. In addition, some previously unap­proachablebirds may permit you to touch them.Decreased or No Fecal ProductionStool production is one of the best indicators of how well or how poorlya bird is eating. That is why it isPlate 3.14. Cockatiel with fecal staining of vent area secondary to egg binding. (Photo courtesy of Dr. Tarah Hadley.) (See also colorplates)a good idea for owners to change the substrate at the bottom of cagefrequently so that the amount of fecal production may be regularly evaluated. Abird that is anorexic or has decreased appetite will have scant or no feces inits droppings. Some birds may also have multiple droppings stuck to theunderside of their tails, which is usually caused by general weakness and aninability to properly release feces away from the body (Color Plate 3.14).Open-mouth Breathing and Tail BobbingA bird that is breathing abnormally breathes with its mouth open andoften its tongue moves in and out of the mouth as it inhales and exhales. Manybirds having difficulty breathing also bob their tails up and down as theystruggle to bring air into their bodies. These signs should also be treated asmedical emergencies and oxygen supplementation may be required as part of theinitial treatment.Falling Off PerchIt is not unusual for most birds to fall of their perches at some pointwhile they are sleeping. However, birds that do this consistently while asleepor awake are not normal. This may actually be a sign of neurologic disease, anutritional abnormality, or some other illness. Causes of falling off the perchmay need further investigation. Until then, it may be safer to lower theperches in these birds cages or use a smaller cage in which the perches arecloser to the bottom.54 Chapter 3Inappropriate MoltingMost birds should molt their large wing and tail feath­ers at leasttwice yearly while their small covert or covering feathers usually molt morefrequently. Birds that fail to molt these feathers on a regular basis may haveissues with their nutrition or some other illness affecting their metabolism.Long-standing feathers may become tattered, broken, or dull. Regular bathsshould be part of the hygiene for all birds to assist them in maintaining theirfeathers.ADDITIONAL READINGBays TB, Lightfoot T, Mayer J. 2006. Exotic PetBehavior.Philadelphia: Saunders. Forshaw JM. 1977. Parrots of theWorld. Neptune: Doubleday andCompany.Manual of Parrot Behavior, edited by Andrew U. Luescher, 2006.Australia: Wiley-Blackwell.CHAPTER FOURAviary Design and ManagementApril RomagnanoINTRODUCTIONThe avicultural veterinary team, consisting of the avian technician andavian veterinarian, must know the avian collection, including its size andculture, and be aware of the importance of avicultural management and pediatriccare. Good hygiene and impeccable sani­tation are important for successfulpediatrics and breeding of adult birds, but sound avicultural manage­ment mustprecede it.This primarily includes good sanitation, effective nutritional protocolsfor birds of all ages, and preven­tive avicultural and pediatric medicine. Thisis a greater challenge in larger aviaries. Second, proper quarantine for newacquisitions is imperative, as are necropsy and histopathology of those lost tothe collection. The latter procedures, necropsy and histopathology, areimportant because a complete preventive medicine program incorporates athorough pre- and post­mortem evaluation.AVICULTUREThe avicultural veterinary team must first be aware of the importance ofcleanliness, husbandry, avicultural and pediatric medicine, and common sense inaviary management to ensure a successful avicultural collec­tion. The best wayto achieve the above is to follow a strict set of rules in the aviary toprotect the entire avicultural collection as a whole.• Consider in advancethe number of birds to be acquired.• Consider in advancethe species of birds to be acquired.• Acquire birds froma reputable source.• Follow strictquarantine at all times.• Require extensivetesting at pre- and post-purchase examination, as well as yearly for the healthof the collection.• Implement proper  management  and  nutrition (Figures 4.1 and4.2).• Routinely practicegood hygiene and impeccable sanitation (Figure 4.3).Infectious disease prevention is best achieved by following theprinciples mentioned above. Hence, the avicultural veterinary team must firstmake sure that good medicine, management, husbandry, and hygiene practices arein place. The team must then implement proper quarantine, vaccination,disinfection, necropsy, and histopathology procedures. The latter two proce­duresare important because a complete preventive medicine program incorporatesthorough post-mortem evaluation.QUARANTINENewly introduced birds should undergo strict quaran­tine in a separatedesignated quarantine building whereFigure 4.1. High-quality pelleted brands of feed are commonly part ofthe nutrition for birds in an aviary. (Photo courtesy of Dr. April Romagnano.)5556 Chapter 4Figure 4.2. Aviary watering system that constantly provides fresh waterfrom a central system into individual cages. Aviary birds learn to operate anddrink water from the nozzle, which minimizes bacteria buildup. (Photo courtesy of Dr. April Romagnano.)extensive testing and a minimum quarantine period of forty-five days arerequired. Although testing can be cost prohibitive to some, an outbreak wouldbe dev­astating to all. Management must decide if new acqui­sitions are worththe risk.Quarantine is indeed one of the best methods of infectious diseasecontrol. When a separate building is unavailable an alternative plan must beinstituted. Hence, regardless of the collection size, location, or value, aseparate quarantine facility, even if it is a friends bird-free home, isimperative.Collections vary and may include large or small psittacines, soft bills,and passerines. All collections warrant constant consistent flock management. Acomplete health history of all breeding birds in a col­lection, including baselineblood work and endoscopy, is imperative for ensuring proper reproductivemanagement and optimal reproductive performance. Consideration for maintainingan open or closed aviary is important in the health of the collection. Openaviaries are defined as those in which new birds (thus new potential diseases)can be introduced into the collection.The "closed aviary concept," in which strict quar­antineprocedures are practiced, is a must in an effec­tive preventive medicineprogram. A closed aviary means no new introductions, with birds only leavingthe collection. Traffic within the aviary should be managed and controlled, andnew introductions must immediately be put into the separate quarantine build­ing.Only dedicated staff that has no contact withFigure 4.3. Longitudinal aviary cage design permits quick visualization of multiple cages. The cage design providesbarriers between individual cages to minimize contact. Mesh cage bottoms permitrelease of unwanted food, water, andfeces away from the cage and onto the ground where appropriate removal may takeplace. Wooden nest boxes, located for easy access by the veterinary team, maybe easily replaced as needed. (Photo courtesy ofDr. April Romagnano.)other birds or general staff who are at the end of their day and aboutto leave the property should enter this building.Further, before entering, employees must gown and put on booties, masks,and gloves. The building should be self-sufficient with its own caging, nets,towels, protective clothing, water source, bowls, and washing facilities.Nothing should ever leave the quar­antine building to be re-introduced into themain col­lection because it may act as a fomite. The only exception should begarbage going directly off the property.EXAMINATIONS AND DIAGNOSTIC TESTING: NEONATES, JUVENILES, BREEDERS, ANDNEW ACQUISITIONSNeonates and juveniles are examined daily and tested on a case-by-casebasis (Figure 4.4). A crop and cloacal culture and fecal Gram stain areconsidered routine tests in young and very young birds. Yearly examina­tion andtesting of breeders and immediate testing of new acquisitions should include aCBC, serum chem­istries, fecal float, fecal direct exam, fecal Gram stain andcytology, cloacal culture, polyoma virus swab DNA probe test, PBFD whole bloodDNA probe test,Aviary Design and Management 57Figure 4.4. Young hyacinth macaw during examination by the veterinaryteam. (Photo courtesy Dr. April Romagnano.)chlamydophila serology, and indirect and direct screen­ing for PDD.Additional or alternative testing may be performed and is determined on acase-by-case basis. Again, although testing can be cost prohibitive to some, anoutbreak would be devastating to all.Vaccination protocols are limited in avian medicine, because very fewvaccines are available, safe, and effective in psittacine birds. Presently onlythe polyoma vaccine (Avian Polyoma Virus vaccine, Biomune) is recommended forroutine use and is USDA-registered.DISINFECTION AND DISEASE PREVENTIONDisinfection and infectious disease prevention are very important in aneffective preventive medicine protocol because organic matter inactivates mostdisinfectants. A disinfectant is defined as an agent that destroys manydisease-causing microorganisms present on the surface of inanimate objects.Hence, first clean the area by removing all organic debris prior todisinfectant application. The easier an object is to clean the more likely itcan be adequately disinfected.Wood is the perfect example of a difficult-to-clean object; therefore,all wooden perches, nest boxes, and toys should be destroyed and replacedyearly, or imme­Figure 4.5. Metal traps and hot-wire fencing are just some of the methods used to minimize theintroduction of disease into anaviary via indigenous vectors such as opossums and raccoons. (Photo courtesy of Dr. April Romagnano.)diately if an infectious disease is suspected (Figure 4.3). Envelopedviruses are the most easily inactivated and are susceptible to quaternary ammoniaproducts. Note that chlorhexidine has limited activity against some bacteria,especially Pseudomonas spp. and certainGram-negative bacteria, and although it can kill some enveloped viruses, itcannot be considered a reliable viricide. Non-enveloped viruses require pheno­liccompounds and sodium hypochlorite (bleach) or stabilized chlorine dioxide forinactivation.Glutaraldehydes inactivate most bacteria, including mycobacteria, manyviruses, and chlamydophila, even in the presence of organic debris. As aresult, this product is particularly useful for endoscopy disin­fection andsterilization. Overall, the most widely recommended and economical disinfectantin avian establishments is bleach (at the dilution of one part bleach to twentyparts of water). Bleach, in any strength, should never be sprayed around birds,because it can be fatal. However, bleach is often used to disinfect floors andbowls in aviculture, once they have been pre-washed with hot water and soap.The geographic location and whether the birds are housed in or out ofdoors reflect disease potential and susceptibility. For example, sarcocystosisand eastern equine encephalitis pox are diseases that are introduced byindigenous vectors such as rats, mosquitoes, opossums, raccoons, cockroaches,and snakes in southern states such as Florida. An effective pest-preventionprogram is required in any aviary (Figure 4.5).58 Chapter 4PEDIATRICS FOR THE AVICULTURISTPediatric History EvaluationNote that a chicks health depends on many historical factors, such asits parents health and breeding history, the condition of its siblings, andany problems the chick may have had during its incubation and hatch­ing. Thepediatric diet, its preparation, and the amount and frequency of feedingsdelivered are also part of the history. Whether the chicks crop is empty foreach feeding, especially the first feeding of the day, is also part of thehistory. It is important to know whether the chicks environment, housing, andsubstrate were and are clean, safe, and warm choices. A chicks behavior,especially its feeding response, and the colors, consistency, and volume of itsfeces, urine, and urates are all important historical factors.Frequent Examination of YoungBirdsPhysical examination of the chick entails evaluation of available weightcharts for daily gain, assessing overall appearance, proportions, and behavior.In neonates, this examination should be performed in a warm room withpre-warmed hands. Knowledge of different species growth rates, development, andbehavioral characteristics is helpful.Psittacine neonates are altricial (hatched with eyes closed, downminimal to absent, and limited mobility), hence nourishment, warmth (93° to98°F), and a safe place must be provided (Figure 4.6). Neonates nor­mally havea visible liver, duodenal loop, yolk sac, ventriculus, and occasionally lungthrough their body skin. The lungs and heart should be ausculted. AssessFigure 4.6. Psittacine neonate. (Photo courtesy of Dr. April Romagnano.)body mass by palpation of elbows, toes, and hips, because keel musclemass is an unreliable indicator of weight in the very young.Crops should be examined visually for size and color, and carefullypalpated for thickness, tone, burns, punctures, or the presence of foreignbodies. Skin should be evaluated for color, texture, hydration, and thepresence of SQ fat. Normally, psittacine chicks should have beige-pink, warm,and supple skin. Dehydration causes a chicks skin to become dry, hyperemic,and tacky. In juveniles, feathers should be examined for stress marks, colorbars, hemorrhage, or deformities of shafts and emerging feathers.The musculoskeletal system should be palpated and assessed for skeletaldefects or trauma in chicks of all ages. Until weaning, cockatoo chicks sitback on their hocks and are balanced forward on their large abdo­mens; macawsprefer to lie down. Chicks normally have prominent abdomens due to afood-filled proven-triculus, ventriculus, and small intestine. Beaks should beexamined for malformations at rest. Examine the beaks pump pads for wounds.Eyes should be examined for swelling, discharge, crusting, orblepharospasm. Normally a clear discharge is noted in the eyes when they arefirst opening, which typically occurs unilaterally. Nares and ears should beexamined for discharge and aperture size. The oral cavity should be examinedfor plaques, inflammation, or injuries. Generally, a healthy chick or baby birdshould elicit a vigorous feeding response when stimu­lated at the beakslateral commissures or pump pads.Pediatric DiagnosticsClinical pathology:PCV, TP = lowerWBC = higherAlbumin, uric acids = lowerALP, CPK = higherMicrobiologyGram-positive bacteria normal:Cloacal cultures Crop cultures Gram stainRadiologyGastrointestinal tract enlarged—endoscopy:Foreign body retrieval Syrinx examination Surgical sexingAviary Design and Management 59Common Pediatric ProblemsUnretracted yolk sac StuntingLeg and toe deformities Constricted toe syndrome Beak malformationsRegurgitationEsophageal or pharyngeal punctures Crop stasis Crop burnsForeign body ingestion or impactionLess Common Pediatric ProblemsIntestinal intussusception Hepatic hematomas GoutWine-colored urine Hepatic lipidosisDiseases in the NurseryViral diseases:PolyomavirusPsittacine beak and feather disease Proventricular dilatation diseasePachecos disease PoxvirusMicrobial Diseases—Microbial Alimentary and Respiratory InfectionsGram-negative or yeast infections are abnormalMicrobial Diseases—ChlamydophilaZoonotic diseaseCONCLUSIONThe aviculture care of breeders and pediatric patients are tightlyassociated disciplines. A neonate that gets off to a good start has the bestchance of becoming a thriving juvenile, and eventually a reproductively suc­cessfuladult (Figure 4.7). The majority of pediatric problems are associated withavicultural husbandry and hand feeding. Nursery management and veteri­narypreventive medicine are equally important in the production of healthy babybirds.Crop stasis is the most common pediatric problem seen, and if managedcorrectly, it need not be a fatalFigure 4.7. Healthy Congo African grey chick (right) and parent in nestbox. (Photo courtesy of Dr. AprilRomagnano.)Figure 4.8. Psittacine embryo deceased in egg. Necropsy often includesassessment of the embryos positionin the egg, evaluation of anatomy,and culture when infection is suspected. (Photo courtesy of Dr. April Romagnano.)condition. Immediate intervention should include a thorough history,physical examination, medical and mechanical therapy, and blood work to helpreverse this condition. Fluids (± whole blood) are critical in this reversalprocess, and lactobacillus and acetic acid may be helpful.Antibiotic and antifungal medications, although important, should beused cautiously in baby birds. When used correctly, antimicrobials can haltinfection60 Chapter 4and decrease the chance of sepsis. Along with dehydra­tion, sepsis isthe most common killer of pediatric patients.Preventive avicultural medicine and pediatrics are ongoing interactiveprocesses that incorporates thor­ough routine avicultural team visits as amethod of data collection. The aviculturist and the avian veteri­narian andtechnician must know the pet bird and/or the collection (large or small)intricately, and be aware of the importance of psittacine husbandry and man­agement.The team must evaluate, diagnose, and treat the individual pet bird, as well asthe entire collection. The necessity of diagnostic testing and therapeutic pro­tocolsare established based on the patients history, the veterinarians overallobservations of the collec­tion, and the physical examination of the individualpatient.Thus, pre-mortem tests are chosen on a case-by-case basis, butpost-mortem examination is imperative and should be performed in all cases.Hence, necropsy and histopathology are also necessary for infectious diseaseprevention, as are quarantine, vaccination, and disin­fection (Figure 4.8).ADDITIONAL READINGRomagnano A. 2006. Mate Trauma. In: Manual of Parrot Behavior, edited byAU. Luescher, Australia: Wiley-Blackwell.Romagnano A, Wolf S, Garner MM. 2000. Management of diseases andsyndromes in a closed psittacine nursery. Proceedings of the 21 st AnnualConference of the Association of Avian Veterinarians, Portland, Oregon.Schubot RM, Clubb KJ, Clubb SL. 1992. Psittacine Aviculture.Loxahatchee: Avicultural Breeding and Research Center.CHAPTER FIVESex Differentiation and ReproductionApril Romagnano and Tarah HadleyINTRODUCTIONVeterinary clinics that see birds as patients are likely to have ownerswho want to know if their pet is male or female, if it isnt visually obvious.Veterinary techni­cians must be educated in the methods of sexing a bird andable to discuss these options with owners. Veterinary technicians also must beknowledgeable about normal reproductive anatomy and problems that can arise.These topics are addressed in this chapter.SEX DIFFERENTIATIONMost psittacines are sexually monomorphic—the male and female arevisually indistinguishable from each other. Although a few generalcharacteristics may help the aviculturist guess a birds sex, they are onlyindica­tors that are incapable of accurate sexual determina­tion. Suchindicators include the size of the head and beak, overall size of the bird,feather color, and aggres­sive behavior.Sexual differentiation is paramount for successful psittacine aviculturebecause the first requirement for successful captive breeding is a heterosexualor true pair. Sexual differentiation is also important for the client who isstruggling with his pet birds identity— should "it" be named Jack orJill? Whatever the reason, accurate sexual differentiation is important becausethe clinician is making a diagnosis when pro­viding the veterinary service ofsexing. Various options for sexing are now available, so the avian veterinariancan choose the method most suitable to the patient, the client^ and herpractice.Visual SexingA handful of psittacine species are sexually dimorphic and can bedefinitively sexed by visual examination. Among these species:Eclectus parrot: Male is green and female is vibrant red and purple.White-fronted Amazon parrot: Male has red versus green feathers on theupper wing coverts, the edge of the carpus, and the alula.Pileated parrot: Males have red feathers on head; females have green.Red-tailed black cockatoos: Females have spots on head, body, and wingfeathers, and tail is barred with yellow-orange feathers. Males lack spots andthe tail has red bars.White-tailed black cockatoos: Females have white ear coverts and lighthorn-colored beak. Males have gray ear coverts and dark gray beaks.Gang gang cockatoos: Males have red head and crest feathers; females aretotally gray and barred with grayish white (Color Plate 5.1).White cockatoos: In some of the white cockatoo species iris color is redat maturity in females and dark brown to black in males.Pesquets parrot: Males have red feathers behind the eye, which areabsent in females.Australian king parrot: Males have scarlet red feathers on the head,neck, and under parts. Female has green feathers on the head and chest and redfeathers on the lower abdomen. The beak is red-orange and black tipped in themale and black in the female.Vent SexingVent sexing is an accurate sexing method for some avian species, such asthe vasa parrot, poultry, water­fowl, ratites, and canaries during the breedingseason.Surgical SexingSurgical sexing was first performed in the 1970s. The fasted bird ismasked down with isoflurane. The endo­scope is inserted through an incision inthe left flank between the ribs and the femur. Typically the caudal thoracicair sac is entered first; the lungs are straight6162 Chapter 5Plate 5.1. Pair of gang gangcockatoos. Note the distinction between the male (left) and the female. (Photocourtesy of Dr. April Romagnano.)(See also color plates)ahead, the abdominal air sac is to the right, and the cranial thoracicair sac is to the left. The abdominal air sac is entered next, and the gonadsare visualized and evaluated, sexing the bird immediately.The standard protocol is to tattoo the ventral wing web of the sexedbird; males are tattooed on the right, females on the left. In the abdominalair sac, the kidneys, adrenals, spleen, and gastrointestinal (GI) tract shouldalso be examined. Organs visible through the caudal thoracic and cranialthoracic air sacs, including the proventriculus and liver, and the heart andgreat vessels should be assessed respectively. The main disadvantage ofsurgical sexing is the inherent, though minimal, surgical risk.Feather SexingFeather sexing was first performed in the 1980s as a non-surgicalalternative for sexing birds. Blood feath­ers are plucked and placed in mediafor overnight mailing to a cytogenetic laboratory. Chromosomal analysis isperformed on cells cultured from the growing blood feathers.Advantages of cytogenetics include complete karyo­type evaluation andidentification of chromosomal defects. Cytogenetic defects identified inpsittacines include chromosomal inversions, chromosome trans­locations,triploidy, and ZZ ZW chimerism. These defects significantly reduce fertility.Disadvantages of feather sexing include a two-week turn-around time and theremote possibility of culture failure.DNA or Blood SexingDNA and blood sexing tests, the newest means of non­surgical sexdetermination in avian medicine, became commercially available in the 1990s.This technique involves acquiring and submitting a very small amount of wholeblood preserved in saline and EDTA or blotted on paper to a sexing laboratory.The DNA is run on an electrophoretic gel (southern blot) and the resultingbands are probed and compared with male and female controls. The maindisadvantages of blood or DNA sexing are the one-week turn-around time and therequirement of species-specific probes in some cases.REPRODUCTION FemaleIn most species, the female reproductive tract consists of a left ovaryand oviduct because the right side regresses before hatch. Exceptions includesome raptors and the brown kiwi. In raptors the right ovary and oviduct may bepresent and even active post-hatch. In the kiwi, both ovaries are active, butonly the left oviduct receives the ovum by spanning the width of the coelomiccavity with its fimbria.The avian ovary is located at the cranial pole of the kidney, and isflat and small in young birds and bumpy and large in mature birds. Normally itcontains numerous follicles when active and it may be melanis-tic depending onthe species. During lay, the left oviduct enlarges and occupies most of theleft abdomen; in the non-breeding season it shrinks considerably in size.The oviduct consists of five microscopically distin­guishable regions:infundibulum, magnum, isthmus, uterus (shell gland), and vagina. Peristalticactivity moves the ovum down and the sperm up. The infun­dibulum has a funnelshape near the top. Fertilization occurs in the lower tubular part of theinfundibulum as does the production of the chalaziferous layer of the albumenand the paired chalazae, which suspends the yolk at both ends of the egg.In the magnum, the largest part of the oviduct, the egg takes onalbumen, sodium, magnesium, and calcium. In the isthmus, it acquires the innerand outer shell membranes. The uterus, or shell gland, produces the eggs shelland its pigment. It also gives the egg salts and water. The vagina is thethickest portion of the oviduct and terminates in the cloaca.Sex Differentiation and Reproduction63MaleThe male reproductive tract consists of paired "tic tac"shaped internal testes located ventral to and near the cranial border of thekidney and the abdominal air sac. Both testes are functional, although one maybe larger than the other. Like the ovaries, the testes may be melanisticdepending on the species. During the breed­ing season yellow testes may turnwhite and black-gray testes turn gray-white. Some species of birds have aphallus or phallus-like protrusion. These include the vasa parrots, variouswaterfowl, and ratites.REPRODUCTIVE MEDICINE AND SURGERYNormal OvipositionOviposition includes the processes that occur when the egg is expelled fromthe body. The muscular uterus pushes the formed egg into the vagina. Thebearing down reflex is started when the vagina "senses" the presenceof the egg, forcing the egg into the cloaca and then out of the body.The length of time for oviposition and the time of day when ovipositionoccurs is different between bird species. However, in most birds the egg layinginterval ranges from twenty-four hours to five days. The brown kiwi lies at theopposite end of the spectrum with a laying interval up to forty-four days.Post Incubation and HatchingAt the end of incubation, the beak of the embryo breaks through theinner shell membrane into the air cell. The lungs start to work at this time.After several hours, the beak "pips" or cracks the outer shell mem­braneand shell to begin the active part of hatching.Abnormal Oviposition or DystociaSome birds experience difficulty laying eggs. Many of these birds arefirst-time layers. Others may be chronic egg layers. Avian speciesoverrepresented as problem layers include parakeets, cockatiels, cockatoos, andeclectus. Amazon species may lay their first egg well into their prime andexperience multiple problems as a result. Of key importance is that thepresence of a male bird is often not required to stimulate egg laying behaviorin a female bird.Improper diets have been partly blamed as a cause for dystocia. Femalebirds that have been on mostly seed diets may be predisposed to vitamin andmineral deficiencies and have a greater risk of egg-laying dif­ficulties. Thesediets tend to be low in calcium and other needed nutrients. Inappropriatehusbandry may also play a role, including the lack of a proper nesting area andproper temperature and humidity. The requirements vary between avian species.Some, such as cockatoos, may experience heightened repro­ductive behavior dueto an inappropriate relationship with the human caretaker.Signs of dystocia in a bird may include decreased or absent fecalproduction, watery or bloody drop­pings, anorexia, regurgitation, difficultybreathing, tail bobbing, fluffed feathers, swollen coelomic (abdomi­nal) area,abdominal straining, leg lameness, and sitting on the cage bottom. These signsoccur for many reasons. The egg may put pressure on the gastrointes­tinaltract, preventing the passage of ingesta. This blockage may lead toregurgitation. Other times only liquid products may pass through, resulting inwatery droppings.A large egg may also put pressure on the air sacs, making it difficultfor the bird to breathe. Likewise, pressure from the egg on the sciatic nerveunilaterally or bilaterally can cause lameness. Similar pressure on the kidneysmay lead to life-threatening renal compro­mise. Abdominal straining may lead toprolapsed tissues, such as a prolapsed cloaca or prolapsed oviduct (Color Plate5.2). Other signs seen in these patients may be due to general illness. A basicblood panel can provide the first step in determining the underlying healthstatus of the patient.Palpation of the abdominal area often reveals skin that is stretched andedematous. A firm egg-shaped swelling can usually be felt beneath. Care must betaken not to stress the patient and to avoid cracking what may be a fragileegg. Radiographs of the bird usually show the outline of an egg in thfe area ofthe pelvic canal. The egg may also be just cranial to the pelvis and unable topass through the canal because it is over large. Sometimes the egg issoft-shelled and difficult to detect radiographically (Figure 5.1).A bird in dystocia is considered a medical emer­gency due to the riskthat the patient may die while attempting to pass the egg. These patientsusually require humidity and a warm incubator heated to 87°F to 90°F. Thepatient in respiratory distress also requires supplemental oxygen. Other medicaltreat­ments include nutritional supplementation, calcium supplementation,antibiotic medication, anti-inflam­matory medication, reproductive musclestimulants, and fluid therapy.A patient that is early in the dystocia process may successfully pass theegg with this minimal supportive care. An egg that is close to passing may alsobe lubri­cated with a water-based lubricant. Sometimes gentle massage of thearea may assist with passage of the egg.64 Chapter 5Plate 5.2. Parrot with prolapse ofthe oviduct. (Photo courtesy of Dr.April Romagnano.) (See also color plates)Figure 5.1. Radiograph showing dystocia in a bird. (Photo courtesy of Ryan Cheek.)Plate 5.3. Egg yolk peritonitis in a parrot. Note the yellow-tingedcoelomic cavity contents caused by a ruptured egg. (Photo courtesy of Dr. April Romagnano.) (See also colorplates)More critical patients require faster intervention and possibly moreinvasive therapy. Over large eggs that will not pass on their own may becollapsed by having their contents expelled with a needle attached to a syringeinserted into the egg. The collapsed egg may be gently removed or allowed topass on its own.Other patients, particularly those suspected of having severely infectedreproductive tracts, may require surgery to remove egg contents. One of themost challenging circumstances is a patient with soft-shelled eggs. Sometimesthe back-up of soft-shelled eggs behind a calcified egg causes parts of therepro­ductive system to become necrotic. The breakdown of egg components and/orassociated soft tissue often leads to peritonitis, a severe inflammation of thecoe­lomic cavity (Color Plate 5.3). The risk of sepsis, or a systemicinfection, is increased in these patients.Many of these procedures require anesthesia, a risk that may need to betaken to save the life of the patient who is already in dire straits.Anesthesia should only be used if there is no other alternative to save thelife of the patient and if all possible attempts to stabilize the patient havebeen taken. The anesthetic risk increases in patients with suspected renalcompromise.Care of the patient after treatment for dystocia is just as important.These birds may need additionalSex Differentiation and Reproduction65supportive care to help them feel better prior to dis­charge from thehospital. In particular, a plan of action must be formulated for chronic egglayers to break the reproductive cycle. Some birds have experienced successfultreatment with human reproductive hor­mones used to create a negative feedbackmechanism. Modifications in diet, light cycle, and relationship with the humancaretaker may also go a long way toward improving the birds reproductivefunction.ADDITIONAL READINGClubb K, Clubb S, Phillips A, Wolf S. 1992. Intraspecific Aggression inCockatoos. In Psittacine Aviculture: Perspectives, Techniques, and Research,edited by Schubot RM, Clubb KJ, and Clubb SL,Chapter 8. Loxahatchee: Avicultural and Breeding Research Center.Clubb SL. 1986. Sex Determination Techniques. In Clinical AvianMedicine and Surgery, edited by Harrison GJ and Harrison LR.Philadelphia: WB Saunders. Harrison GJ. 1986. Reproductive Medicine. InClinical AvianMedicine and Surgery, edited by Harrison GJ and Harrison LR.Philadelphia: WB Saunders. Joyner KL. 1994. Theriogenology. In AvianMedicine Principles andApplication, edited by Ritchie BW, Harrison GJ, and HarrisonLR. Lake Worth: Wingers Publishing. King AS, McLelland J. 1984. FemaleReproductive System. In Birds:Their Structure and Function, Philadelphia: Bailliere Tindall. AbramsonJ, Speer BL, Thomsen JB, eds. 1995. The Large Macaws:Their Care, Breeding, and Conservation. Fort Bragg: RairitreePublications. Chapters 3 and 17. Orosz S, Dorrestein GM, Speer BL. 1997.Urogenital Disorders. InAvian Medicine and Surgery. Philadelphia: WB Saunders.Section 3 ReptilesCHAPTER SIXLizardsBrad WilsonINTRODUCTIONFrom the seemingly impenetrable spines of Moloch horridus, the glidingpseudo-wings of Draco spp., the color-changing chromatophores of Chamaeleo spp., the crypticcutaneous fimbriations of Uroplatus spp., the venomousbite of Heloderma spp., to the bipedal water-walking Basiliscus spp., the adhesiveglass-climbing Gekkonidae, and the legless snake-like Anguinidae, lizards, ofthe order Squamata in the class Reptilia, exhibit tremendous anatomic,physiologic, nutritional, and behavioral variation that make them the hallmarkof diversity among all modern reptiles. When distributed among 3,800 knownspecies (Barten 1996a, de Vosjoli 1992), it becomes obvious that the diagnosticchallenge presented to the veterinary clini­cian and technician can beoverwhelming (Color Plates 6.1-6.6).Though the details may be overwhelming, the basic categories ofdifferentiating lizards based on natural history leads to a basic understandingof husbandry requirements. Technicians familiar with reptile medi­cine soonlearn that many health disorders arise from improper husbandry; therefore,recognizing and cor­recting improper husbandry techniques may hasten therecovery from disease and prevent unnecessary medi­cating of debilitatedpatients.Representatives of many families of lizards are com­monly seen in thepet trade (Table 6.1). The green iguana (Iguana iguana) is one of the mostpopular of all reptile pets and historically has been the first reptile pet ofmany people new to the hobby of herpetocul-ture, the care and maintenance ofcaptive reptiles and amphibians. In the past fifteen years the reptile petindustry has exponentially increased in popularity and in recent years theauthor has observed the popularity of lizards approach, if not exceed, that ofsnakes as reptile pets. This leads to the question: why keep rep­tiles as pets?To the dedicated pet owner, the answer is the same as if the question wereabout keeping a spider, fish, bird, cat, dog, goat, or horse as a pet. For avidreptile pet owners, however, a quote from de Vosjoli (1997) is mostappropriate: "the current philosophy in herpetoculture strives towardsestablish­ing viable self-sustaining captive-breeding populations throughmanaged field culture and/or through more controlled systems of indoor andoutdoor vivaria."ANATOMY AND PHYSIOLOGY IntegumentLizard scales commonly overlap and are created by a many-layeredepidermis that is shed at regular inter­vals during the life of the lizard. Theshedding of skin, ecdysis, occurs in multiple pieces in lizards, as opposed tosnakes, in which the skin is usually shed in one piece. Many lizard species eatthe shed skin. Factors that influence ecdysis are age, growth rate, tempera­ture,humidity, and nutrition (Barten 1996a, Goin et al. 1978). Dysecdysis iscommonly associated with low humidity and poor nutrition among other healthabnormalities.Reptilian epidermis does not have a respiratory function and containsvery few glands (Goin et al. 1978). The skin and scales are relativelyimpermeable in normal health. The mucous membranes (oral cavity, cloaca, conjunctiva)are quite permeable, however. This consideration is important when consideringpotential absorption of topical medications applied to these regions (Mader2000a, Klingenberg 1996). Some reptile vitamin supplements are marketed assprays to be applied to the skin. These products, though not likely harmful,have little to no systemic physiologic value to reptiles.Chamaeleo spp. and Anolis spp. have chromato­phoresin the skin that allow change in the reflectivity of visible light, resultingin color change. These changes are influenced by light, heat, and socialinfluences, but not by surrounding environmental color (Barten 1996a, Goin etal. 1978). Many herpetoculturists who raise chameleons can predict colorchanges of69Plate 6.1. Bearded dragon. (Photo courtesy of Ryan Cheek.) (See also color plates)Plate 6.2. Mali uromastyx. (Photo courtesy of Ryan Cheek.) (See also color plates)Plate 6.3. Jackson chameleon. (Photo courtesy of Dr. Sam Rivera.) (See also color plates)Plate 6.4. Chameleon. (Photo courtesy ofRyan Cheek.) (See also color plates)Plate 6.5. Mangrove monitor. (Photo courtesy of Ryan Cheek.) (See also color plates)Plate 6.6. Savannah monitor. (Photo courtesy of Dr. Sam Rivera.) (See also color plates)70Table 6.1. Lizards Commonly Seen in Captivity. > Common name/species name Origin Habitat Size (cm)1 Temp (d/n)2 Repro3 Feed4 Rest5 Handling concerns6 Agamidae                 Agamas, Agama spp.10 Africa Arid, desert, 30-40 30C/20C oviparous O/a yes, Occas. aggressive,     terrestrial         no sturdy Bearded Dragon, Pogona „„_ 10,16 Australia Arid, terrestrial to 50 30C/20C oviparous O/a yes Docile, sturdy spp. Frilled lizard, Australia Dry, forest, to 100 30C/20C oviparous C/a,v yes Occas. aggressive, Chlamydosaurus kingi1016   terrestrial           sturdy Water dragon, Physignathus SE Asia Humid, rain 100 26C/20C oviparous 0/a,v,n no Occas. aggressive, coccinus10   forest, arboreal           sturdy Uromastyx, Uromastyx spp.12 NW Africa, Arid, desert, 30-50 37C/22C oviparous H,0/a yes Docile, sturdy   SW Asia terrestrial             Anguidae                 Glass lizards, Opbisaurus Worldwide Dry, rocky forest, to 140 26C/20C oviparous C/a,g yes Docile, fragile, tail spp.10   terrestrial           autotomy* Chamaeleontidae                 Veiled chameleon, Chamaeleo E Africa Montane forest, 50 30C/20C oviparous I no Docile, fragile to calyptratus13   arboreal           sturdy Flapneck chameleon, Africa Tropical savanna, 30 30C/20C oviparous I no Docile, fragile to Chamaeleo dilepis1014   arboreal           sturdy Three-horned chameleon, Ch. E Africa Montane forest, 30 25C/20C viviparous I no Docile, fragile to jacksoniP   arboreal           sturdy Panther chameleon, Madagascar Coastal forest, 60 30C/20C oviparous I no Occas. aggressive, Chamaeleo pardalis13   arboreal           sturdy Gekkonidae                 Day geckos, Phelsuma spp.8 Indian Ocean Tropical rain to 25 30C/25C oviparous 0/a,n no Docile, tail autotomy,   Islands forest, arboreal           skin slough Leaf-tailed geckos, Uroplatus Madagascar Tropical rain to 25 28C/22C oviparous I no Docile, fragile, tail spp.61014   forest, arboreal           autotomy* Leopard gecko, Eublepharis Asia Desert, terrestrial to 20 30C/25C oviparous I yes Occas. aggressive, tail macularius9               autotomy* Tokay gecko, Gekko gecko10 SE Asia Tropical rain to 30 27C/20C oviparous C/a,v no Aggressive, sturdy forest, arboreal\1Table 6.1. Continued >       Size Temp (d/n)2         Common name/species name Origin Habitat (cm)1   Repro3 Feed4 Rest5 Handling concerns6 Iguanidae                 Green anole, Anolis N America Temperate forest, 20 26C/20C oviparous I yes Docile, tail autotomy carolinensis10   arboreal             Green iguana, Iguana iguana7 Central, S America Tropical rain forest, arboreal 200 31C/22C oviparous H yes Very aggressive, tail autotomy Horned lizards, Phrynosoma Central, N Arid, desert, to 20 35C/20C vivi-,ovi- I/t yes Docile, sturdy spp.10 America savanna, terrestrial             Spiny lizards, Sceloporus N, S, Central Dry, rocky, forest, to 30 26C/20C vivi-,ovi- I yes Docile, sturdy spp.10-14 America arb/terrestrial             Lacertidae                 Jeweled lizard, Lacerta spp.10 Europe, Africa Dry, forest, arboreal/ terrestrial to 40 25C/15C vivi-,ovi- 0/a,n yes Occas. aggressive, sturdy Scincidae                 Skinks, Eumeces spp.10 Worldwide Forest, terrestrial, to 30 26C/20C vivi-,ovi- I yes Docile, tail autotomy     occas. arboreal             Blue-tongued skinks, Tiliqua Australia Forest, desert, to 50 30C/20C viviparous 0/a,g yes Docile, sturdy spp.10-14   terrestrial             Prehensile-tailed skink, Solomon Tropical forest, to 60 30C/24C viviparous H yes Occas. aggressive, Corucia zebrata15 Islands arboreal           sturdy Teiidae                 Ameivas, Ameiva spp.10 Central, S America Forest, fields, terrestrial to 50 26C/20C oviparous 0/a,n yes Docile, sturdy Tegus, Tupinambis spp.1011 S America Forests, terrestrial to 140 30C/20C oviparous C/a,v,e yes Occas. aggressive, sturdyVaranidaeNile monitor, Varanus niloticus11Savannah monitor, V. exanth ematicus11AfricaAfricaStream, to200  30C/20C oviparous C/e,g,v yes Very aggressive, riverbank, sturdyterrestrialDesert, dry to100  30C/20C oviparous C/a,g,e,v yes Occas. aggressive, grassland, sturdyterrestrialAverage maximum adult size.2 Average day and night temperatures foradults of species or typical of genus.Oviparous (ovi-) = egg laying; viviparous (vivi-) = live birth;parthenogenic (partheno) = produces offspring without mating.4Diet of the adult lizard in nature: O = omnivore, I =exclusive insectivore, C = primary carnivore, H = exclusive herbivore,H,0 = some spp. exclusively herbivorous, some spp. omnivorous. Specializationsor primary food consumed listed in order of importance for each sp.: a =arthropods, e = eggs, g = gastropods, n = nectar or ripe fruit, t = termitesand ants, v = vertebrates.5Does lizard seasonally hibernate or brumate?Yes = successful captive breeding may require cooling/rest period. No =successful breeding does not require cooling/rest period.Typical response of patient to handling:Docile: lizards will allow handling with minimal resistance.Occasionally aggressive: lizards may attempt to bite or claw whenhandled and can inflict injury upon handler.Aggressive: lizards will routinely bite, claw, or struggle duringor before handling. The Tokay gecko is not particularly dangerous to handle, butis aggressive.Very aggressive: lizards may bite, scratch, or whip tail prior to handling. Largemonitors and iguanas should be considered dangerous at all times and handledonly byexperienced staff.Sturdy: little to no stress or trauma results from routinehandling when healthy.Fragile: may stress easily when handled for routine examination.Bodily injury to lizard may result from routine restraint or handling.Tail autotomy: lizards may lose tail when handled (not all spp.capable of autotomy are marked). *Tail autotomy in some species may occur evenif lizard is not handled, but merely stressed.Skin slough: lizards with skin that tears easily when minimallyrestrained or touched.7de Vosjoli, 1992.8McKeown 1993.9de Vosjoli et al. 1997.10Obst et al. 1988."Balsai 1997.12de Vosjoli 1995.13de Vosjoli & Ferguson 1995.14de Vosjoli 1997.I5de Vosjoli 1993.16de Vosjoli 2001.74 Chapter 6particular species or individuals based on a variety of environmental orbehavioral influences.Some gecko species can autotomize, tear, or release, the entire skin inresponse to capture by a predator. These species include the fish-scale geckos (Geckolepis spp.) and the daygeckos (Phelsuma spp.) (Glaw and Vences 1994, McKeown 1993).Skin regeneration occurs in these species but may result in unsightly scars andsecondary bacterial or fungal infections.Foot and toe adaptations are diverse. Integument specialization is quitenotable in the fan-like adhesive discs of Gekkonidae. These species are capableof climbing glass and inverted smooth surfaces. Large arboreal and terrestriallizards usually possess sharp sturdy claws. Lizard claws are similar to thoseof birds; they have a pulp containing a blood vessel and nerve that issensitive to short trimming.Skeletal SystemThe general lizard skeletal system is quadruped con­sisting of anossified skull, vertebral column, ribs, and pelvic and pectoral girdles (Figure6.1). The ribs of lizards connect ventrally to a cartilaginous sternum that isabsent in snakes and turtles (Goin et al. 1978). Lizard teeth are eitheracrodont or pleurodont. Acrodont teeth attach to the masticating surface of themandible or maxilla and have no socket. These teeth are not replaced when lostand are characteristic of true chameleons. Pleurodont teeth are attached to theinner or lingual surface of the mandible or maxilla and have no socket. Theseteeth are replaced through the life of the lizard and are characteristic ofiguanas and monitors.Locomotion for lizards is apodal, bipedal, or quadrupedal. Most lizardshave four legs and five toes, though there are species that are snake-like withno functional legs {Anguis spp., Anniela spp., Lialis spp., Ophisaurus spp.) and otherswith greatly reduced limbs (Chalcides chalcides, Neoseps reynoldsi,Chamaesaura spp.). Bipedal locomotion is observed in basilisks (Basiliscus spp.) and frilleddragons (Chlamydosaurus kingii) when excited orduring escape behavior. This behavior is rarely observed in small enclosures.Old world chameleons (Chamaeleo spp.) are zygodactylous, having two toes andthree toes fused into a claw-like foot, creating a strong gripping foot forclimbing on limbs and branches (Goin et al. 1978).Tail autotomy, the loss or release of the tail, occurs in many species(Iguanidae, Gekkonidae, some Scincidae). This adaptation (coupled with certainbehaviors) creates distraction and allows the tailless lizard to escape as apotential predator investigates the released yet still moving tail. Transversecleavage plates are present in each caudal vertebrae of these species, allowingrelease of the tail at multiple loca­tions (Barten 1996a, Goin et al. 1978).Hemorrhage is minimal with tail loss because vertebral vessels are quick toconstrict. If the tail stump is undamaged, species capable of autotomy canregenerate tails that are usually smaller with irregular scalation and darkercolor than the original tail. If species that are notFigure 6.1. Lizard skeletal anatomy.Lizards 75capable of autotomy (Chamaeleontidae, Varanidae) suffer traumatic tailloss, the tail usually cannot regen­erate completely. Some lizards (someChamaeleontidae and Corucia zebrata) use a prehensiletail for stabiliza­tion or movement between branches.It is important to note that touching or manipulat­ing the tail is notnecessary to cause its release in some species. The leaf-tailed geckos, Uroplatus spp., can onlyautotomize the entire tail from the first one or two caudal vertebrae so theentire tail is always lost (Glaw and Vences 1994). A common escape behavior inthese species is to wave the tail to distract the potential predator and thenrelease it from the body without the lizard being touched or manipulated.Similar behavior can occur in the terrestrial leopard and African fat-tailedgeckos (Eublepbaris macularius, Hemitheconyx caudicinctus) (de Vosjoli 1997).Cardiovascular SystemThe heart has three chambers consisting of two atria and one ventricle.Despite the absence of an interven­tricular septum, the majority ofdeoxygenated blood is directed to the lungs via the pulmonary aorta andoxygenated blood is directed to the right and left aortic arches to perfuse thebody tissues (Goin et al. 1978).Lizards, like amphibians, possess a large ventral abdominal vein that isintracoelomic along the ventral midline several millimeters dorsal to the bodywall. This vein is secured by a thin mesovasorum and travels adjacent to theventral midline from one-fourth the distance from the cranial aspect of thepubis cranially to the umbilicus and then courses dorsally to join the hepaticvein. Venous collateral circulation parallels the ventral abdominal vein viathe caudal vena cava. The ventral abdominal vein is routinely avoided duringcoelomic surgery, though accidental or intentional transection and ligation ofthis vessel is compensated by collateral circulation (Mader 2002b).The caudal tail vein is the optimal site for blood collection fromlizards. It is located along the ventral midline of the tail and is accessedapproximately one-third (or less) the distance from the cloaca to the tail tip.Respiratory SystemThe respiratory system of lizards consists of external nares, internalnares, glottis, trachea, and lungs. The internal nares are located rostrally inthe dorsal oral cavity and are contiguous with the external nares. The glottis,located at the base of the tongue, fits into the common opening of the internalnares when the mouth is closed to enable nasal respiration.The trachea of most lizards bifurcates into the lungs that in somelizards may more resemble air sacs of birds than the familiar mammalian lung.Lizards do not have a diaphragm and therefore have a common coelomic cavityrather than separate thoracic and abdominal cavities. Ventilation in lizards isaccom­plished with rib expansion by contraction of intercos­tal muscles.The lungs of lizards are not as highly derived as those of mammals. Thecranial portions of the lungs are more vascular and serve for most respiratoryfunc­tions and the caudal lungs are more sac-like and may extend to the pelvis(Murray 1996). Unlike birds, lizards do not have pneumatic bones.Digestive SystemThe digestive system of most lizards is quite basic and, with the exceptionof the teeth, follows the design of higher vertebrates. The oral cavitycontains several glands that aid in the lubrication of food items forswallowing. The Gila monster and Mexican beaded lizard (Helodermasuspectum, H. horridum) have modified bilateral sublingual glandsthat produce poi­sonous saliva that is chewed into the prey item rather thanhypodermically injected as with venomous snakes (Barten 1996a, Goin et al.1978).The tongue of some lizards serves both in scent col­lection and swallowing.The tongue of anguimorph (legless) lizards serves almost exclusively a sensoryfunction and the tongue of some Chamaeleontidae serves an exclusive foodprehension and swallowing function (Goin et al. 1978). Most carnivorous lizards(Varanidae) have snake-like tongues to track prey items and the majority ofherbivorous lizards have thick fleshy tongues to aid in swallowing. The sensorytongue retracts into a lingual sheath that lies ventral to the glottis.The alimentary tract consists of an esophagus, stomach, small and largeintestine, and cloaca. The alimentary, respiratory, reproductive,cardiovascular, and reproductive tracts are not separated by a dia­phragm andare contained within a pleuroperitoneum or coelomic cavity (coelom). Theproximal portion of the esophagus is the only opening to the back of the oralcavity. Thus, by visualizing and avoiding the opening to the glottis on thefloor of the mouth, feeding or sampling tubes may be safely passed into thediges­tive tract with no risk of accidental respiratory intuba­tion. Thestomach in most lizards is quite large and does not serve as a gizzard orgrinding organ (Barten 1996a, Goin et al. 1978). The small intestine has his­tologicallydiscrete duodenum, jejunum, and ileum (Frye 1991). A cecum-like sacculation ofthe colon is76 Chapter 6present in herbivorous lizards (Corucia zebrata, Iguana spp., Uromastyx spp., and others).The cloaca is the common collecting chamber of the digestive and geni­tourinarytracts. These openings are the coprodeum and urodeum, respectively. Theproctodeum is the common chamber opening to the vent. (Figures 6.2, 6.3).The liver and gall bladder are present in lizards and located cranial tothe stomach in the cranio-ventral abdomen. The gall bladder in anguimorphlizards is observed in a more caudal position, and is usually found in closeproximity to the pancreas, as seen in snakes. The pancreas in lizards has bothendocrine and exocrine glandular functions.Large paired fat bodies in the left and right caudal coelomic cavity arenot digestive structures, but may be commonly confused with pathologic lesions.These are particularly palpable in bearded dragons and are commonly observed indorsoventral radiographs.Excretory SystemPaired kidneys are located in the caudo-dorsal coelom and the caudalpoles commonly extend into the pelvic canal. Lizards are uricotelic; themajority of nitroge­nous waste from purine digestion is excreted from mostlizards as insoluble uric acid (Frye 1991). A mesonephric duct collects andtransports nitrogenous wastes from each kidney to a urinary bladder. Theurinary bladder empties into the cranio-ventral urodeum. In larger lizards theurinary bladder may be catheterized from the cloaca via this opening.The renal portal system in reptiles is well docu­mented (Barten 1996a,Frye 1991, Innis 2000). The system allows blood to flow from the caudal portionof the body directly to the kidneys prior to returning to the heart.Historically, this physiology has led to the conclusion that the reptile kidneymay reduce the con­centration of chemotherapeutics injected into the caudalbody prior to their entry into the general circu­lation, thus leading to adecreased concentration in the blood and tissues. Also, suspicion was raisedthat injections of potentially nephrotoxic drugs should be avoided in theregion. Several pharmacologic studies in turtles have revealed that thepresence of this system does not necessarily indicate that all blood flowfollows this theorized pathway and there may be no impact on drug metabolismwhen injected into the caudal body of tortoises (Innis 2000).Reproductive SystemLizards have intracoelomic paired testes or ovaries, and oviducts.Female lizards have no true uterus, but in live-bearing (ovoviviparous orviviparous) lizards,Figure 6.2. Lizard visceral anatomy.Lizards 77Figure 6.3. Lizard cloaca.the oviduct may serve a similar function to the non-placental uterus ofmammals by providing nutrients for the developing non-shelled embryo (DeNardo1996). DeNardo (1996) refers to all ovoviviparous reptiles as viviparous. Theeggshell is secreted in the oviduct of oviparous lizards and is occasionallyreferred to as the "shell gland." The eggshell of many lizards(except Gekkonidae) is somewhat pliable, as seen in snakes, rather than rigid,as seen in tortoises and birds.Male lizards have paired hemipenes that are invagi-nated into theproximal ventral tail slightly lateral and caudal to the vent. During matingone hemipenis is everted by relaxation of the retractor muscle and the fillingof vascular spaces of the hemipenes with blood. Following mating fertilizationis internal and occurs within the oviduct. No urinary structures are presentwithin the hemipenes of lizards.Sexual dimorphism occurs in some species of lizards, while in othersdetermining sex may be difficult. For most juvenile lizards of all speciesthere is no reliable method to determine sex. For adult lizards, the tech­niqueof sex determination is determined by species (Table 6.2).External sex characteristics may be applied to many lizards. Thesecharacteristics include the presence of obvious sexual dimorphism such as thehorns of Chamaeleo jacksonii, precloacal pores ofmany Gekkonidae, femoral pores of many Iguanidae, and post-cloacal tail bulgingof the hemipenes in many species. Researching the anatomy of the species inquestion is the best method to determine if external sex characteristics areapplicable.Cloacal probing, the primary technique used in sex determination ofsnakes, may be applied to monitors (Varanidae), but is not 100% accurate in allspecies. A blunt or ball-tipped smooth metal sexing probe designed exclusivelyfor this purpose is used. The only other acceptable instrument may be asovereign red rubber urinary catheter or feeding tube. This proce­dure carriesthe risk of causing trauma to the patient; therefore, proper restraint andproficiency are required. The probe is inserted into the vent and directedcau-dally just lateral to the ventral midline in a position parallel to thesurface of the tail. In males, the probe enters the inverted sheath of thehemipenis and travel a distance into the tail. This distance is subjective andvariable by species. In some female monitors the dis­tance the probe travels isshorter when compared to the male.Radiographic sex determination is possible in some monitors. Thistechnique is based on the presence of calcifications in the hemipenes of somespecies. These mineralizations are absent in males of both Nile and savannahmonitors.Surgical or endoscopic sex determination is obvi­ously definitive.Surgical scar tissue formation, difficult visualization, and availability ofequipment are poten­tial complications. Sedation is required for eitherprocedure.Manual eversion of the hemipenes is advocated for some species (Pogona spp., Corucia zebrata) (de Vosjoli 1993,de Vosjoli et al. 2001). This method is commonly used in juvenile snakes. Theprocedure involves bending the tail slightly dorsally distal to the cloacawhile simultaneously applying light pressure with the thumb in a rolling motionproximally toward the cloaca. This process will evert the hemipenes in somemale lizards. Whereas this method definitively identifies males by the presenceof the hemipenes, it only identifies females by exclusion. Males that do notevert a hemipene may be mistaken for females.Hydrostatic eversion of the hemipenes is a definitive method for sexingmonitors, but carries moderate to great risk of injury to the lizard. Properrestraint and mastery of technique are paramount. The principle is thatinjection of sterile saline caudal to the retracted hemipenis everts the organthrough its cloacal opening. In female lizards, with proper technique, nohemipenis will evert and the oviductal papillae of the female may bevisualized. This technique should be performed in sedated patients andrestricted only to those animals in which no other method of sex determinationis available.78 Chapter 6Table 6.2. Sex Determination in Selected Captive Lizards. > Species Anatomic Probe Manual eversion Hydrostatic eversion Bearded dragon, Pogona spp. A   J   Frilled lizard, Chlamydosaurus kingi A       Uromastyx, Uromastyx spp. A       Veiled chameleon, Chamaeleo calyptratus A       Three-horned chameleon, Ch. jacksonii AJ       Day geckos, Phelsuma spp. A,j       Leopard gecko, Eublepharis macularius A,j       Green iguana, Iguana iguana A,j       Blue-tongued skinks, Tiliqua spp. a   ) A Prehensile-tailed skink, Corucia zebrata a   A,j   Tegus, Tupinambis spp. a A     Nile monitor, Varanus niloticus   a   A Savannah monitor, V. exanthematicus   a   A Note: A = preferred method, adult; a = inconsistent method,adult; J = preferred method, juvenile; j = inconsistent method, juvenile.Nervous SystemThe central nervous system consists of a cerebrum, cerebellum,brainstem, and spinal cord. The spinal cord extends to the tip of the tail asopposed to mammals, in which the cord terminates proximal to the sacralvertebrae. The peripheral nervous system consists of twelve cranial nerves andnumerous periph­eral nerves to the viscera, trunk, and limbs.Pain receptors and pain responses in reptiles are still poorlyunderstood (Bennett 1996a). It is apparent that lizards have a withdrawalresponse or reflex from trau­matic wounds such as punctures, lacerations, orsurgi­cal incisions; however, expected withdrawal reflexes and responses frompotentially traumatic heat are not observed (Mader 2000b). Captive managementof lizards must take into account these apparent behavioral and/or neurologicreflex differences from mammals with regard to cage heating (see Husbandry).Sense OrgansThe majority of lizards have movable eyelids and a nictitating membrane.Those without movable lids (some Gekkonidae, and Ablepharus spp.) have a clearspectacle as seen in snakes. The spectacle is a scale-like structure formed bythe fusion of the upper and lower eyelids. As with snakes, the spectacle isimpermeable to topical medications. True chameleons possess tur­ret-likeeyelids and eyes that are capable of indepen­dent movement. Glands are presentin the eyelids of lizards and may become swollen in cases of hypovita­minosisA.The muscles of the iris are striated and under con­scious control; thus,pupillary light reflexes are not predictable and the use of standard mammalianmyd­riatics is not possible (Williams 1996). The pupil may be circular orelliptical.The parietal eye or "third eye" is apparent in some species(Iguanidae; Tuatara, Sphenodon punctatus). This structure is locatedon the dorsal head and is connected via the parietal nerve to the pineal bodyin the brain. The parietal eye is a photoreceptor that is integral in hormonalproduction and thermoregulatory behavior (Goin et al. 1978).The lizard ear consists of an external acoustic meatus, tympanicmembrane, middle ear cavity, and inner ear cavity. Within the middle ear cavityis the columella bone that receives vibrations from the tympanic membrane viathe extracolumella cartilage (Rossi 1998b). The tympanic membrane of somelizard species is clear and in others it is covered with scales and notvisible.The vomeronasal organ or Jacobsons organ is present in many lizards andlocated in the dorsal oral cavity ventral to the nasal cavity but notcontinuous with the nasal cavity (Goin et al. 1978). Scent particles collectedon the tongue are transferred to sensory cells when the tongue is retractedinto the mouth. This organ is primarily used by lizards to track prey items andpossibly to detect mates or enemies by detecting pheromones.HUSBANDRYUnderstanding the natural history (anatomy, physiol­ogy, habitatrequirements, reproductive habits, behav­Lizards 79ior, longevity) of the patient in question is the greatest diagnostictool in differentiating between normal health and disease. Combining thisknowledge with the presenting complaint, medical history, physical examination,and laboratory data is necessary for the treatment and rehabilitation of thediseased patient. For instance, understanding the differences in dietary andhabitat requirements of two common similarly sized lizard pets, the greeniguana (Iguana iguana) and savannah monitor (Varanus exanthematicus),isessen­tial even to obtain an appropriate history. It is not possible for eventhe most educated zookeeper to know every aspect of natural history of everylizard, nor is it expected that the veterinary technician can become educatedin the feeding habits of every species of lizard kept in captivity. There are,however, several fundamental aspects of knowledge regarding lizards with whichto simplify the approach to understanding natural history.The following are general categories and associated specific questionswith which the technician and prac­titioner should be familiar regarding everylizard patient:Native habitat and microhabitat: Does the patient inhabit tropical rainforest, desert, mountain slope, estuary, beach, etc.? Is the patient arboreal,terrestrial, aquatic, or subterranean?Anatomy and physiology: What is normal color­ation and can the patientchange coloration in response to environmental, seasonal, health, reproductive,or behavioral influences? Are there size or other physical differences based onsex? What is the normal mucous membrane color? Does the patient normally havefour limbs and a certain number of digits? Does the patient normally havesecretions from the eyes or nostrils? What are the characteristics of normal fecesand urates? How long does the patient normally live?Diet: Is the patient insectivorous, carnivorous, her­bivorous, oromnivorous, and does the diet change with respect to life stage or seasonality?If insectivo­rous, does the patient have a preferred food item or size of fooditem (i.e. ants, centipedes, spiders, etc.)? How does the patient prehend foodand at what time of day does it normally feed? How does the patient normallyobtain water?Behavior: Is the patient diurnal, nocturnal, or cre­puscular? Is thepatient solitary or communal? Does the patient experience climatic seasonality?Does the patient hibernate or aestivate? Does the patient use dif­ferentmicrohabitats during different seasons or life stages? How does the patientreproduce and how often?These natural history parameters for all species of lizards wouldrequire volumes to list and these are questions to which the technician orveterinarian may not always know the answer. There are many similari­ties amonggenera, but even within the same genus there are marked differences betweenspecies in hus­bandry requirements.Looking again at the green iguana and the savannah monitor: the greeniguana is a tropical, arboreal, diurnal, somewhat communal (though not incaptivity), generally non-seasonal, and non-hibernating lizard (de Vosjoli1992, Obst et al. 1988), whereas the savannah monitor is a temperate,semi-arid, terrestrial (and bur­rowing), crepuscular (to diurnal), solitary,somewhat seasonal, and occasionally hibernating lizard (Obst et al. 1988,Balsai 1997). The diet of green iguanas is generally herbivorous, though aswith other species, in their native habitat they may be opportunistically insec­tivorous.For the savannah monitor the diet is carnivo­rous or insectivorous (dependingon the life stage and food availability). Remember, however, that one can onlyspeak of living systems in generalities; adaptation is the key to survival andmany captive lizards "adapt" to the captive environment. Thus,behavior observed in nature may not occur in captivity.Reptile hobbyists who pride themselves on main­taining and breedingcommon and rare lizards in captivity have learned that recreating the nativeenvi­ronment in almost every aspect is the key to success. These achievementsare accomplished by observing the animals in their native habitat,corresponding with other hobbyists or zoologic professionals, and loggingcountless hours of trial and error. Occasionally sub­stantial investment ismade in the construction of suit­able habitats that far exceeds the monetaryvalue of the lizard in question.Enclosures and EnvironmentCagesThere is no way to generalize a basic lizard cage. There are, however,categories of habitats from which the foundation for housing most species canbe derived. In general terms lizards are categorized as arboreal orterrestrial. Remember that some arboreal lizards are occasionally bothterrestrial and arboreal. Therefore, suitable cage design may not be exclusivefor either habitat. Native habitat use is listed in Table 6.1 for commonspecies. Key requirements for all enclosures include security from escape,protection from injury, access for cleaning, and environmental control oflight, heat, humidity, ventilation, and water and food availability.True chameleons (Chamaeleo spp.) and day geckos (Phelsuma spp.) are goodexamples of primarily arbo­80 Chapter 6real lizards. Though these species vary greatly in size and inmicrohabitat distribution, most species benefit from a vertically spacious cagethat offers visual secu­rity on three sides and from above. Typically enclo­suresfor arboreal lizards contain numerous limbs, branches, or plants in both avertical and horizontal orientation. The cage is typically rectangular and mayrange from 0.3 m by 0.3 m by 0.5 m to lmby lm by 2 m. The primary, if notexclusive, construction mate­rial should be plastic screen with metal orplastic frame for chameleons and a glass or plastic aquarium for geckos. Screenallows for good ventilation and is rela­tively non-abrasive to the lizard. Wiremesh can lead to skin abrasions and may be more difficult to clean. Glass orplastic (plexi-glass) offers no ventilation and may lead to overheating, butallows for maintenance of higher humidity. The cage floor may be solid (wood,glass, or plastic) or mesh. Though a mesh floor with removable tray beneath maybe most accessible for cleaning, it potentially allows escape of insect fooditems or may cause injury to the lizard. A solid floor with removableindoor/outdoor carpet is relatively easy to clean and provides security forchameleons. A well-sealed cage and lid are required for geckos because they aremasters of escape. The cage ceiling is typically screen for both chameleons andgeckos to allow ade­quate ventilation and humidity control (Figure 6.4).Substrate for chameleons should be simple: news­paper or indoor/outdoorcarpet is best. Soils, mulches, and shavings are messy and not essential forhousing chameleons. Glass enclosures for arboreal lizards requiring higherhumidity, such as day geckos, may contain soil in which plants are grown. Thegreat majority of arboreal captive lizards do not use the substrate except tooviposit and this substrate may be provided in the form of a nesting box orpotted plant when required. Though aesthetically pleasing, particu­latesubstrates such as soil, sand, gravel, and wood chips pose a great risk tosmall (intestinal obstruction or impaction.The leopard gecko (Eublepbaris macularius) and the savannahmonitor (Varanus exanthematicus) are good examplesof primarily terrestrial lizards. As opposed to the arboreal cage design,terrestrial enclo­sures are horizontally spacious to accommodate a large cagefloor and may contain one or several diago­nal or horizontal perches ofrelatively large diameter. Smaller cages range from 0.2 m by 0.3 m by 0.5 m tomany meters in length, width, and height. Because many terrestrial lizards arerelatively strong, more durable construction materials may be required for cagedesign. The glass aquarium is the standard enclo­Figure 6.4. Arboreal habitat.sure for most small terrestrial lizards. Larger lizards, such asmonitors, commonly require custom built enclosures made from wood, glass orplastic, or wire mesh. Commonly these larger lizards are housed in outdoorenclosures where climates are favorable (Figures 6.5, 6.6).LightingLighting requirements vary greatly among species. Some lizards requireultraviolet light (specifically UV-B) for vitamin D3(cholecalciferol) synthesis and subsequent calcium absorption from thegastrointesti­nal tract (Frye 1991, Donoghue and Landenberg 1996, Boyer 1996).A general rule is that primarily insectivo­rous (Gekkonidae), primarilyherbivorous (Iguana spp, Uromastyx spp.), andomnivorous (Pogona spp.) lizards require supplemental UV-Blight and most pri­marily carnivorous lizards (monitors) do not. Many lizardowners provide artificial lighting in the form of various incandescent andfluorescent fixtures.It is important to understand that ultraviolet light does not penetrateglass or plastic; therefore, sunlightLizards 81Figure 6.S. Terrestrial habitat.Figure 6.6. An inappropriate size cage for a lizard.through windows and fluorescent lighting filtered by glass is inadequateto meet ultraviolet light require­ments. Direct sunlight is the best source ofultraviolet light for lizards and may be provided periodically (once or twiceweekly for fifteen minutes) to lizards which otherwise are maintained indoors(Ritchie 1992). Most if not all lizards become stimulated when exposed todirect sunlight and may become aggressive and very quick, making escapepossible. Lizards should never be housed in enclosed or open-top glass orplastic containers when in direct sunlight to avoid life-threateninghyperthermia. Some nocturnal lizards such as leaf-tail and flat-tail geckos (Phyllurus spp., Uroplatus spp.) avoid brightlight and are not active by day when in good health.Light fixtures for lizards should be mounted outside the enclosure sothat the lizard cannot directly contact the light (or heating element).Ultraviolet light sources should be within eighteen to twenty-four inches ofthe closest basking surface. Many claims made by com­mercially availableUV-B-producing lights are not true and there are no regulations governing thelegitimacy of such claims. Recent research (Mitchell 2009) indi­cates that thenewer coiled "screw-in" type fluorescent bulbs manufacturedspecifically for reptile enclosures provide adequate UV-B radiation for lizardsin enclo­sures. Historically, the long "tube-type" fluorescent bulbswere considered the standard of artificial lighting for reptiles. Additionallighting sources for pet reptiles include mercury vapor lights and possiblycompact halogen lights, which are new to the reptile market.HeatingMost common pet lizards require additional heating during some portionof their captive existence. Because lizards are ectothermic they seekmicrohabitats that meet their preferred optimal temperature zone (POTZ). ThePOTZ is the temperature range in which normal physiology is most efficient(Barten 1996a). It is impor­tant for the client to understand that a lizarduses a range of temperatures, not a uniform cage tempera­ture, to create thePOTZ; in the cage setting this range is commonly referred to as the thermalgradient. It is also important to understand that various physiologicconditions such as pregnancy or disease may change the POTZ for a given animal.Observing the natural history and behavior and the study of lizard physiol­ogyis important for deriving the POTZ of each species. These values are availablein many books, manuals, and journals for the species in question (Table 6.1). Lizardsachieve their POTZ by thermoregulation. By altering their exposure to light,orientation to light, and reflectivity of light (coloration), and by radiatingheat (gaping, respiration), lizards are able to regulate body temperaturewithin a few degrees.Heating a lizard cage is generally not as difficult as providing anadequate thermal gradient. The ideal heat sources should be located outside thecage so that the lizard cannot directly contact the heating element. In-cageheating elements such as hot rocks are poor choices for heating reptiles andshould never be recommended by veterinary staff. Similarly, ceramic radiantheating elements and light bulbs, which mount into incandes­cent fixtures,should not be placed inside the enclosure. All in-cage fixtures may causethermal burns to lizards through prolonged direct contact (Color Plate 6.7).Lizards have a poor sense of conductive heat and do not necessarily avoidcontact with hot surfaces (Mader 2000b). Ideally cage heating should beprovided through radiant heat from an overhead light or ceramic heatingelement. Commonly heating tape or heating blankets are placed outside andbeneath the cage. Care must be exercised to avoid regions of the substrate orcage floor where heat is excessive. Additionally, below cage heating may leadto increased evaporation of water sources and increased cage humidity.82Chapter 6Plate 6.7. Thermal burns. (Photo courtesy of Dr. Stephen J. Hernandez-Divers, University of Georgia.) (See also color plates)Some desert species such as Uromastyx spp. may require daytime baskingtemperatures that range from 37°C to 43°C (100°F to 110°F) to nighttime tempera­turesof 25°C (77°F) (de Vosjoli 1995). Montane forest lizards such as Jacksonschameleon (Chamaeleo jack-sonii) require daytimetemperatures of 25°C (77°F) and night temperatures near 17°C (62°F) (de Vosjoliand Ferguson 1995). Arboreal lizards generally do not benefit from under cageor substrate heating. Certain temperate and some sub-tropical lizards mayrequire cooler temperatures during winter months to induce brumation orhibernation that is essential for success­ful breeding. Temperature is bestmeasured with ther­mometers or temperature probes placed inside the enclosureat various locations.Humidity can be a difficult parameter to regulate in the lizardenclosure. In a smaller enclosure humidity is more difficult to regulate. Aswith temperature, many lizards benefit from a humidity gradient—another exampleof microhabitat use by lizards. In larger cages this gradient is created by theinterface between sub­strate and cage ornaments such as rocks or logs. Smallcovered plastic containers containing moistened sub­strate such as vermiculiteor moss may be provided. These are called humidified shelters (de Vosjoli 1997)and are particularly useful to assist shedding in some desert species such asleopard geckos and juvenile bearded dragons.VentilationIn well-ventilated cages, such as those for true chame­leons, hand mistingor electronic misters, vaporizers, or nebulizers are useful for increasinghumidity. These are easily regulated by automatic timers. Regulatingventilation with screen lids or the addition of small fans is helpful tocontrol humidity for glass aquariums or terrariums. Humidity is an importantfactor in both the respiratory and epidermal health of some lizards.Hygrometers are used to measure humidity in the lizard cage.Ventilation is primarily controlled to indirectly reg­ulate heat andhumidity. Ventilation can be modified by cage design or may be controlled byexternal and internal cage accessories. Small fans, such as computer coolingfans, are quiet, and capable of moving large quantities of air. To a lesserextent, moving water such as small waterfalls, misters, and passive evaporationcreate some air circulation for more humid enclosures. It is important with anyelectrical devices that all wires be fully insulated from contacting water ormetal in or on the cage and that they cannot be altered by cage inhabitants.Also, fans must be housed outside the enclosure so that the lizard cannotcontact the turning blades.Water and Food AvailabilityWater availability and water quality must be closely controlled. Somedesert species such as Uromastyx spp. do not require standing water to beavailable in the cage (de Vosjoli 1995). Instead, these animals may be removedfrom the cage and soaked in water once weekly or they may be misted in anenclosure separate from their cage once weekly. Some tropical lizards such astrue chameleons may drink only dripping water off leaves or other cageornaments. In time these lizards may learn to drink from containers or fromhand misting. The client should be educated that not all lizards readily acceptwater from containers or they are not physically capable of ingesting standingwater. If water is not provided in the form that these lizards typically drink,they will dehydrate rapidly. Water containers for all lizards should be cleanedat least weekly. Soaking with a 10% bleach solution for fifteen minutes issufficient for disinfection. Because some lizards may defecate or otherwisecontaminate larger water containers, more frequent cleaning of water con­tainersmay be required.Feeding stations for lizards are preferred over the random introductionof food items into the enclosure. Carnivorous lizards should be fed pre-killedfood items such as small mammals from a container within the cage, or thelizard may be moved to a separate cage for feeding. Most insectivores only eatmoving insects and therefore must be fed live food items such as crickets,mealworms, and waxworms. These foodLizards 83items may be introduced into small bowls within the enclosure. Manylizards readily adapt to eating from containers. Invariably some food itemswill escape into the cage and are usually consumed by the lizard. Presentingfood in containers can reduce the risk of accidental substrate ingestion. Italso may provide a central location at which the lizard may be observed whilefeeding to evaluate appetite and health. Feeding live foods such as smallmammals and crickets increases the risk of bodily damage to the lizard by thefood item. Crickets, just as mice and rats, may feed on the flesh of lizards ifdeprived of food for more than a day in the enclosure.Herbivores are generally fed prepared meals in con­tainers. Most healthyherbivorous lizards consume their daily share of food at one feeding, though innature these animals generally browse throughout the day. Uneaten food shouldbe removed from the cage on the day of feeding to prevent spoiling. Preparedfoods such as powdered, frozen, or otherwise pro­cessed herbivore foods shouldbe provided with strict attention to the manufacturers recommendations for rehydration,thawing, and feeding frequency. For her­bivorous lizards freshly preparedvegetable diets are preferable over processed diets.QUARANTINEThe most important consideration often overlooked by the owner of newpet lizards is quarantine. Many clients who own one lizard eventually increasetheir collections, establish breeding colonies, or expand their interests toother reptiles. In their excitement to introduce new pets to the home, theyignore the poten­tial for contagious infectious diseases that may affect theirentire collection of animals.Acariasis is a significant contagious disease seen In: Reptilecollections (see Parasitology). Mite infestations can lead to reducedfertility, multisystemic disease, and death in captive reptile collections, andmay be extremely difficult to eradicate once established in large collections(Mader 1996a). Intestinal parasitism is a prime concern in lizards housedtogether. Other diseases that are generally not contagious but mayopportunistically spread are bacterial and fungal der­matitis, pneumonia, andinfectious stomatitis (primar­ily from fighting).Though recommendations on quarantine vary, a minimum of thirty days ofisolation in addition to physical exam and clinical laboratory tests arerequired. Wild-caught lizards should have the quarantine period extended tosixty to ninety days with serial fecal exams performed monthly. In the absenceof fecal parasites, prophylactic deworming may be indicated in wild-caughtanimals and many herpetoculturists routinely medicate new animals without thediagnosis of parasit­ism. Clients who prophylactically deworm their pets shouldbe thoroughly informed of the potential side effects of medications and thepotential side effects of killing parasites in the patients body. Prophylactictreatment with antibiotics is not recommended unless clinical signs ofbacterial or protozoal infections are observed or clinical disease isdiagnosed.Housing during quarantine should consist of an enclosure that providescomfort and visual security for the lizard, but also provides visualization ofevery aspect of daily (or nightly) activity. Substrate, when possible, shouldbe paper to visualize and collect feces, urates, and urine. Feedings should beprovided at a consistent feeding station and supervised to observe all aspectsof feeding behavior and quantify food intake. Impeccable sanitation and cagehygiene is essential.Ornaments, hide boxes, and water bowls should be simple and eitherdisposable or easily cleaned. Minimizing accessories and having duplicates foreach cage aids in cleaning. Safe and effective disinfectants for home use arechlorine bleach at a 1:10 dilution of the commercially available concentrationand ammonia at 5% solution (McKeown 1996). The two products should never bemixed to prevent the release of poison­ous chlorine gas. Soaking surfaces forfifteen minutes is adequate for disinfection with chlorine bleach at a 1:10dilution (Ritchie 1992). When cryptosporidiosis is a concern, soakingaccessories with 5% ammonia and allowing them to dry for a minimum of threedays is advised (Bennett 1996c).Record keeping by the client is essential both for long-term captivelizards and new arrivals. Recording dates of feeding and ecdysis, environmentalparame­ters, and especially weekly or monthly weight (in grams) are all helpfulin monitoring for disease. With the exception of hibernation or parturition,lizards rarely lose weight as part of normal physiology. Juvenile lizards thatfail to grow or adults that progressively lose weight are usually diseased.Casual observations such as the frequency and consistency of defecation andurination and daily activity patterns should also be recorded.NUTRITIONOne adaptation that has allowed lizards to colonize nearly everyterrestrial (and some aquatic) habitat on earth  is their  variation  in  dietary preference.84 Chapter 6Consequently, their prime vulnerability in captive management becomesnutritional related disease when proper diet is not provided. Lizards arecommonly classified as herbivorous, insectivorous, carnivorous, or omnivorous.Though the differentiation between insectivorous and carnivorous may seemsubtle, some species are so highly specialized to eat specific arthro­pods andgastropods that they refuse to eat and fail to thrive in captivity if offeredany substitutes. Additionally, when fed proper whole animal meat diets, carnivorouslizards generally do not require supplemental ultraviolet lighting, whereas thegreat majority of insectivorous lizards do require routine ultraviolet lightexposure, even when fed calcium-enriched or supplemented insect diets (Donoghueand Landenberg 1996).Just as there is no way to describe the basic lizard cage, it isimpossible to generalize lizard diets. Each species has specific dietaryrequirements and variation in food availability in their native habitats thatdictate diet preferences on a seasonal or even monthly basis. Carnivorouslizards (monitors, tegus) ingest other ver­tebrates (fish, reptiles, birds, andmammals) as their primary diet, but remain opportunistic and usually attempt toeat anything that moves and anything that will fit into their mouth. Somecarnivorous and omniv­orous species may also eat carrion or may be canni­balistic(Balsai 1997, Donoghue and Landenberg 1996). Carnivorous lizardsthat are not fed whole animal meat products are more likely to develop nutri­tionaldisease (Donoghue and Landenberg 1996). Some herbivorous lizards areopportunistically car­nivorous or insectivorous, which, with some species incaptivity, may cause serious nutritional disease when animal protein is fed inabundance (see Common Disorders).The ultimate paradox with the cause of some nutri­tional diseases inlizards, however, is that the causes of disease may have nothing to do withfood. Temperature, humidity, landscape, water, infectious organisms (intestinalendoparasites, bacteria), and especially light (specifically ultraviolet light)commonly factor into nutritional health despite the provision of proper diet.Thus, proper husbandry becomes the key to providing proper nutrition.Nutritional requirements pertain to all lizards. Feeding behavior,digestion, the absorption and assim­ilation of nutrients, and cellularphysiologic activity are all somewhat dependent on temperature for all reptiles(Barten 1996a, Donoghue and Landenberg 1996). The POTZ (preferredoptimal temperature zone) and thermal gradient must be provided for eachspecies to optimize nutritional value of foods. Improper humidity also impactsoverall patient health and may lead to decreased feeding response. Donoghue andLandenberg (1996) provide excellent discussion of the nutrient requirements anddaily energy needs of various reptiles and the nutrient values of variousanimal, plant, and commercial food items.The quality and variety of food offered is important for all lizards.Food items should be fresh or provided promptly after thawing if frozen. Foodsoffered once to lizards should be disposed and not refrozen or pre­served andoffered again. Protein content and quality is generally met with whole animaldiets and insects. For herbivores, the entire protein requirements should beplant origin. Good plant protein sources include: romaine lettuce, spinach,alfalfa sprouts, clover, dan­delion, bean sprouts, and bamboo shoots (Donoghueand Landenberg 1996).Calcium is an essential element for all captive lizards and itsdeficiency is the cause of metabolic bone disease (MBD) that encompasses a vastsyndrome of physio­logic disorders. Calcium absorption and excretion isregulated by several factors. Calcium absorption in the small intestine isregulated by an activated metabolite of vitamin D3j cholecalciferol,which occurs in some animal tissues (Frye 1991). Vitamin D2,ergocalciferol, occurs in plants and does not apparently facilitate the uptakeof calcium in the gut of lizards and does not appear to be beneficial as a dietarysupplement for reptiles regarding calcium metabolism. (Boyer 1996). Therefore,supplements claiming to contain vitamin D should be scrutinized as to whichform of vitamin D is provided. Vitamin D3 may be exogenouslyconsumed in the form of dietary animal tissues and some dietary supplements orit may be endogenously produced when the lizard is exposed to appropriateultraviolet (UV) radiation. Cholecalciferol is synthesized in the skin oflizards, and then is hydroxylated first in the liver and then the kidney tobecome 1,25 dihydroxy-cholecalciferol, the active metabolite of vitamin D3.(Frye 1991). The consequence of this pathway is that in spite of adequatedietary calcium, lizards may be prone to MBD in the absence of adequate vitaminD3. Clinically this is most commonly the result of insuffi­cientexposure to UV-B radiation.Ultimate control of blood calcium homeostasis rests with the parathyroidglands and their production of parathyroid hormone (PTH). The occurrence ofhypo­calcemia or hyperphosphatemia results in increased production of PTH.Calcium is removed from bone (calcium resorption) to increase calcium ions inthe blood. Additionally, PTH stimulates the production of the active metaboliteof cholecalciferol (vitamin D3) to increase intestinal calciumabsorption. When calciumLizards 85levels in the blood are adequate, the thyroid hormone calcitonininhibits the effects of PTH and bone resorp­tion slows or reverses.Excess phosphorous in the diet is also a nutritional concern. Highphosphorous diets can induce nutri­tional secondary hyperparathyroidism thatultimately depletes calcium stores in bone (Frye 1991, Mader 2002a). Inaddition to the overall content of calcium in the diet, attention must be givento the calcium to phosphorous ratio (Ca:P). This ratio should be 1:1 to 2:1 forthe entire diet (Frye 1991, Donoghue and Landenberg 1996). Whole animal diets(rodents and chicks) provide this ratio. Organ meats such as heart, liver, andmuscle without bone are excessively high in phosphorous. Most commonly fedinsects have a Ca:P of 1:9 and thus require periodic to routine vitamin andmineral supplementation (Donoghue and Landenberg 1996). Salads containing leafygreens such as beet greens, broccoli leaves, outer green cabbage leaves,collards, dandelion leaves, and mustard greens are calcium-rich (Donoghue andLandenberg 1996, Boyer 1996).Nutritional supplements abound for reptiles and are required for optimalnutritional health of insectivorous and herbivorous lizards (Donoghue andLandenberg 1996). Calcium with vitamin D3 (Rep-Cal, Los Gatos, CA)or calcium and phosphorous containing powdered supplements are preferred. Somevitamin and mineral supplements contain no (Nekton-Rep, Clearwater, FL) or verylow (Herptivite, Rep-Cal, Los Gatos, CA) calcium and additional calcium must bemixed or given separately. Supplements are applied to insects by"dusting," in which the prey items are placed in a container and thepowder added. With gentle swirling of the container the supplement is attachedto the insect and then fed to the lizard. For herbivores the supplements aresprinkled over or mixed with the salad. Supplements should be provided onceweekly for adult lizards that are fed well balanced diets. Juvenile or growinglizards should be supple­mented two to three times weekly. Problems associatedwith mineral supplements include decreased palatabil-ity or refusal ofsupplemented food items; dispropor­tionate distribution, improper ratio, ordecomposition of nutrients within supplements; toxicities from over­dosing oringestion of high levels of certain nutrients; and false claims made bymanufacturers. Supplements do not compensate for the feeding of imbalanced orpoor quality diets.Herbivorous LizardsThe dietary requirements of the captive herbivorous lizard diet havebeen well documented in the literature and the veterinary staff is responsiblefor informing clients of these requirements (Barten 1996a, de Vosjoli 1993,Rossi 1998b, Donoghue and Landenberg 1996, Boyer 1996, de Vosjoli 1995, deVosjoli 1993). For years the green iguana has been the standard after which allherbivorous diets have been modeled, but the natural history of various speciesnecessitates modify­ing the approach to feeding these pets for optimal health.Barten (1996a) presents the best summary of the green iguana diet in thecurrent literature. Several of the primary to exclusive herbivorous lizardsseen in practice include green iguanas (Iguana iguana), rhinoc­eros iguanas(Cycluraspp.),desertiguanas (Dipsosaurus spp.), spiny tailed iguanas (Ctenosaura spp.), chuck-wallas(Sauromalusspp.),prehensile-tailed skinks (Corucia zebrata), and spiny-tailed agamids (Uromastyx spp.). The greeniguana is highly adaptive in its dietary preferences in a captive environmentand is known to eat commercial dog and cat foods, rodent diets, insects, fish,mice, and a wide variety of plant materials (de Vosjoli 1992).Several beliefs regarding the feeding of iguanas have been modified overthe past few years. Hatchling and juvenile iguanas do not eat insects as asubstantial portion of their diet and then switch to primarily veg­etariandiets as adults (Barten 1996a). Contrary to popular belief, leaf lettuce is anacceptable source of protein and calcium for herbivorous reptiles (Donoghue andLandenberg 1996). Iguanas of any age DO NOT require animal protein in the diet;this includes insects; whole animal or organ meat; and commercial pet foods fordogs, cats, primates, and fish. All protein in the diet of the green iguanashould be derived from plant sources.Herbivorous lizards at all life stages are generally fed more often thancarnivorous lizards and in many cases daily feeding is indicated. Adultherbivores are commonly fed every other day. Most herbivores con­serve waterwell and obtain the majority of their water needs from plants. Tropical lizardssuch as green iguanas and particularly juvenile green iguanas should haveconstant access to water. Desert species are best soaked in water in buckets orother containers once weekly to meet their water requirements. This treat­menthelps reduce the risk of certain respiratory and skin diseases that may occurfrom elevated enclosure humidity.Insectivorous LizardsInsectivorous lizards, among the most popular pet lizards today, havenutritional and feeding needs similar to herbivorous lizards. The insectivorescom­prise the majority of all modern lizards and because of86 Chapter 6their dietary diversity their nutritional needs are the least known ofcaptive lizards. The likely key to under­standing insectivorous lizardnutrition is likely not in the food items themselves, but in the food of the food itemsthemselves (Donoghue and Landenberg 1996, de Vosjoli 1997). Lizards in natureeat insects that browse on numerous plants, detritus, feces, soil, and otheranimals. The assimilation of these nutrients may be crucial for the health andsurvivability of some species. For example, in amphibians, poison dart frogs deriveskin toxins secondarily from alkaloids and other chem­icals originating inplants through the insects that they ingest in their native habitat. Incaptivity, when wild-caught frogs are fed similar insects that are not exposedto native plants, the skin toxins are greatly reduced or absent.Herpetoculturists of insect-eating lizards are becom­ing aware of theimportance of "prey item nutrition" and specialty diets to feed tocrickets have appeared on the market (Ziegler, Gardners, PA). Some research suggeststhat some high calcium diets are inappropri­ate for crickets and may affect thegrowth and repro­duction of these insects (Donoghue and Landenberg 1996). Thediet for captive insectivorous lizards should be varied and supplemented withvitamin and mineral powders. Because most domestically raised insects are lowin calcium and have improper Ca:P, calcium sup­plementation is crucial. Littleis known about the dietary needs for amino acids, vitamins, other miner­als,and trace elements. Generally these are supple­mented in addition to calcium.Insectivorous lizards as a group have the same light requirements forvitamin D3 synthesis as do herbivores (Frye 1991, Donoghue andLandenberg 1996, De Vosjoli 1993). This is particularly true of juvenileinsectivorous lizards. The author has observed numer­ous juvenile to youngadult Chamaeleo spp. present with MBD that are fed a varied dietroutinely supple­mented with calcium. The deficiency arises from insufficientUV light exposure. Questions must arise, however, regarding the required lightexposure of noc­turnal insectivorous Gekkonidae such as Phyllurus spp. and Uroplatus spp. that hide byday.The patterns by which animals choose their prey are described under theoptimal foraging theory (OFT) (Helfman 1990). It is theorized that animalschoose between energetic costs and energetic gains when selecting food items.Insectivorous lizards have been observed to choose certain species of insectseven when multiple species of a similar size of insect are present or thelizard chooses a certain size of insect when dif­ferent sizes of the samespecies of insect are available. For example, the energetic costs involved inprehend­ing, swallowing, and digesting ten 10-mg crickets may exceed theenergetic costs of capturing and eating a single 100-mg cricket for aparticular lizard. Therefore, the lizard ignores the smaller food items and searchesor waits for a larger item. This behavior is seen in captivity as the refusalof certain size foods. Lizards that are incapable of dismembering or shreddinglarge food items usually avoid catching and eating them. Similarly, largelizards typically ignore small food items that the lizard may have eaten as ajuvenile. Both the size and type of food items must be considered when feedingcaptive lizards.Some lizards eat only one or two specific prey items and may or may notaccept crickets or other domestic insects at the expense of anorexia (Moloch horridus, some Phrynosoma spp. [ants], Dracaena spp. [snails])(Obst and Jurgen et al. 1988). Most other insectivores accept domestic insectssuch as crickets, mealworms, waxworms, superworms, and roaches. Field sweepingsfor wild insects can also be offered to smaller insecti­vores, though the ownermust be cautious of pesticides and potentially venomous or dangerous insects.Insects are offered in an amount that the lizard can consume in one feedingwhich is typically several hours in a day or overnight in the case of nocturnallizards.Insects loose in a cage can be as much a hazard to insectivorous lizardsas live rodents are to carnivorous lizards. Adult crickets are capable ofchewing through skin, digits, and eyes of lizards that cannot escape from theenclosure. Mealworms are also similarly impli­cated in trauma or death tootherwise healthy lizards (de Vosjoli 1997). Feeding stations that restrict themovement of these insects can reduce the possibility of health risk to cagedlizards. Most insectivorous lizards should be fed daily, though as with adultherbivores, every other day feedings are appropriate (de Vosjoli 1992, deVosjoli 1997). Dusting with vitamin and mineral supplements is done as with variouslife stages of herbivorous lizards.Carnivorous LizardsClinically carnivorous lizards typically present less often withnutritional diseases than do herbivorous or insectivorous lizards. Carnivoresare generally fed whole animal vertebrates such as small mammals or birdswhich, when fresh, are generally well balanced with nutrients (Donoghue andLandenberg 1996). These lizards also are more likely to accept a wide varietyof food items which allows for more variety in nutrients. Several reasons basedon natural history for the nutritional stability of carnivorous lizards in cap­tivityinclude: a generally wider POTZ than herbivores and insectivores, less specifichumidity requirements,Lizards 87and with proper diet less specific light requirements, all of which makehabitat management less time con­suming and less expensive for the owner.Several intan­gible reasons for the nutritional stability of carnivorouslizards include: they are less shy about eating in captiv­ity and the availabilityof food as a whole animal requires less work by the owner to prepare the mealand provide balanced nutrition. Though several of these reasons suggest ownernon-compliance, they are unfortunately substantial causes for the prevalence ofnutritional disease in many herbivorous reptiles in the pet trade.Consideration must be given to the quality of the carnivore diet. Livefoods should never be fed to car­nivorous lizards to prevent rodent bites.Similarly, live wild-caught vertebrates and most purchased "feeder"reptiles and amphibians should not be fed to prevent the transmission of someparasitic, bacterial, and viral diseases. Fresh-killed prey items have equalnutritional value to live prey (Donoghue and Landenberg 1996). Frozen vertebratefood items are commonly offered after complete thawing. These items should havebeen frozen immediately after death, thawed only once, and disposed if notconsumed within hours after feeding. Thawed frozen tissues decompose rapidlyafter thawing and the author has observed regurgitation by lizards within daysafter the ingestion of apparently rancid food items. Adult monitors and tegusare fed several adult mice or small rats several times weekly. This feedingschedule may be adjusted for obesity or leanness.Prepared foods such as poultry meat, beef, and dog and cat foods are notsubstitutes for whole animal meals and should not be offered. Exceptions may bemade for short periods if rodents are unavailable or if assisted feeding isrequired for health-compromised individuals. In these cases canned cat foodsare the better choice for feeding these patients. A variety of prepared dietsspecifically for lizards are available through pet suppliers. Veterinarians andherpetocul-turists should thoroughly research dietary claims and scrutinizeresearch for these products before recom­mending them as a sole source ofnutrition. Lizards fed diets of primarily fish may be susceptible to thiaminand vitamin E deficiencies (Donoghue and Landenberg 1996, Barten 1996a).Hatchling and juvenile carnivorous lizards can present a few nutritionalchallenges to their owners. Because of their smaller size, these lizards maynot accept whole vertebrate food items early in life. Therefore, insects arecommonly offered to smaller lizards and newborn or "pinkie" mice areoffered to larger juvenile lizards. Because insects have a relatively poor Ca:P(1:9) ratio, dusting of these insects with calcium powders is recommended.Pinkie mice (1:1) have a lower calcium content than do weanling (1.1:1) oradult mice (1.4:1), though the Ca:P ratio is suitable and due to the relativelyshort term that these food items are offered, calcium supplementation is notlikely required (Donoghue and Landenberg 1996). Hatchling and juvenilecarnivorous lizards should be fed at least every two to three days.FINALLY, NEVER FEED LARGE ADULT CARNIVOROUS OR HERBIVOROUS LIZARDS BYHAND. The potential consequence to fingers and hands is obvious, but moreserious is the conditioned response that is created by this behavior. Lizardsare wild animals whose behavior is driven by instinct and conditioning, not byreasoning. A lizard cannot discern between the end of the food item and thebeginning of the human hand until after the bite occurs. The client should alsobe instructed to exercise caution when removing uneaten food items from cages.COMMON DISORDERSDiseases of lizards include many diseases common to reptiles in generaland a few that are unique to particu­lar species or families of lizards. Manydisorders are husbandry related. Some diseases are more common in importedlizards than in domestically captive raised lizards; therefore, it is importantto inquire or discern the origin of the patient.Not all disorders require medications. Many dis­eases require correctionof improper husbandry and supportive care. The author advocates increasingquality caloric intake for all traumatic injuries and many infectious diseasesto strengthen immune response and speed tissue repair in reptiles. Observationof POTZ and humidity is essential for the healing of all reptilian diseases.IntegumentRostral abrasions are a common skin disorder of many lizards including Iguana spp., Physignathus spp., Chlamydosauruskingi, and some Varanus spp. Abrasions areless common in Gekkonidae or in delib­erate or slow moving species such as Uromastyx spp. and Chamaeleo spp. The mostcommon cause of rostral abrasions is facial impact with glass walls ofaquariums or pacing and rubbing the nose on cage walls. Many larger importediguanas and water dragons develop these abrasions from handling during theimportation and distribution process to pet stores. Animals not adjusted tocaptivity commonly attempt88 Chapter 6Plate 6.8. Rostrum abrasion. (Photo courtesy of Zoo Atlanta.) (See also color plates)escape by incessantly rubbing on cage walls or lids or crash into wallswhen startled by movement in the room around them (Color Plate 6.8).Recovery from rostral abrasions may be prolonged and the patient may besubject to recurrent injury. Treatment must include altering the enclosure toprevent further injury. Creating visual security such as a paper covering orthe painting of glass walls or adding other visual barriers, even if temporary,is man­datory. Various antibiotic ointments may be used if indicated forinfection. Note: Inform the client that treatment through habitat or behavioralmodification is more important than medicating the lesion.Traumatic injury may occur from bite wounds, thermal burns, and skinautotomy. Both burns and bite wounds (cage mate or prey item) commonly requiresurgical debridement of damaged or necrotic tissue and primary or delayedsecondary closure. Secondary bacterial and/or fungal infections are common andsystemic antibiotics are indicated in most cases. Bacterial culture andsensitivity is indicated for all slow or non-healing wounds that do not respondto empiric therapy. Topical cleansers such as chlorhexidine (Rossi 1996, Barten1996a) or chloroxylenol (personal observation) (Vet Solutions, Fort Worth, TX )are excellent topical antimicrobial agents. These injuries invariably result inscar tissue formation and occasion­ally disfiguration. Reptile skin is slow toheal and open wounds require sequential shedding to fully close. Proper nutritionis vital for wound healing and the author recommends increased quality caloricintake for these patients to increase the rate of shedding and repair. Note:Inform the client to expect prolonged (months) healing and to expect permanentscarring to the affected skin.Bacterial and fungal dermatitis may occur as pri­mary or secondaryinfections and are typically the result of improper husbandry. It is essentialto know if the patient is captive raised or wild-caught and if any cage matesare similarly affected. Clinically these diseases are more common interrestrial species. Improper hygiene and increased humidity are sus­pected asthe primary causes of infection (Rossi 1996). Other potential causes includeacariasis, trauma from cage ornaments or accessories, immunosuppression from avariety of factors (temperature, nutrition, meta­bolic disease, overcrowding,capture and importation), prolonged exposure to water or sitting in waterbowls, and dysecdesis. Histologic microscopy, fungal culture, and bacterialculture are all indicated for diffuse or focally extensive disease. Treatmentis based on diag­nostic testing and may include enteral or parenteralantibiotics, topical antibiotics or antifungal agents, and most importantlyidentification and correction of improper husbandry. Note: Inform the client ofprog­nosis based on diagnostic testing and response to treat­ment. Correctingany existing husbandry is essential for both healing and prevention ofreoccurrence.Dysecdesis is more a clinical sign of disease rather than a diseaseitself. Shedding problems are most com­monly the result of underlying diseasesor improper husbandry, particularly low humidity and malnutri­tion. Lowhumidity may not be an entire enclosure phenomenon as much as a lack of humiditygradient. Even some desert dwelling lizards benefit from micro-environmentalhumidified shelters to aid in shedding. Occasional misting for some species isbeneficial. Other diseases that may contribute to dysecdesis are externalparasitism and possibly thyroid disorders (Rossi 1996).Complications that arise from dysecdesis are extremity necrosis,particularly toes and tails. This process arises from portions of theextremities that incompletely shed (occasionally more than once in severallayers) and form a tourniquet to the distal extremity. Devitalization is quickand necrosis follows slowly over days or weeks. Lizards with thick skin orheavy scales may show no apparent signs of necrosis for weeks. Amputation ofthe affected extremity to the next proximal viable joint is required. Similartreat­ment is required for tails (see ascending tail necrosis, below).Broken tails resulting from tail autotomy and not from traumaticamputation usually do not require medical treatment. In rare cases hemorrhagemay be profound or extend beyond one minute. In these cases pressure bandagingmay be used. An appropriate size syringe casing packed with gauze is taped tothe tailLizards 89for one day if needed. The lesion should be cleaned if indicated and thepatient maintained on a clean surface with no substrate for several daysfollowing the injury. Topical or systemic antibiotics are indicated only ifwound contamination has occurred and only then for several days. Surgicalrepair is contraindicated in auto-tomous species because this inhibits orprevents tail regeneration. Note: Inform the client to maintain a cleanenvironment and report any signs of inflamma­tion; the less manipulation of thewound, the better; and regeneration will occur over months resulting in asmaller and often darker regenerated tail.Tail amputation in non-autotomous species or ascending tail necrosis inall species may require surgery and antimicrobial therapy. Traumatic tailamputation, though uncommon, may occur in chame­leons, prehensile-tailedskinks, and rarely monitors. Also common is ascending tail necrosis thatresults from trauma to the tail such as bite wounds, handling injuries,enclosure injuries, or dysecdesis. Gradually ascending darkening anddevitalization of the tail proximal to the injury characterize this disease.Skin may slough at times, revealing devitalized vertebrae. Surgical tailamputation at a level proximal to the devitalized tissue is required. Thegangrenous nature of this disease may lead to sepsis and systemic anti­bioticsare indicated. For non-autotomous lizards, the tail stump can partially regenerateand is generally not sutured, though hemorrhage control with pressure isessential. Note: Inform the client to observe diligently for any signs ofcontinued ascending devitalization and to be aware of signs of lethargy oranorexia that may result from sepsis.Skeletal SystemMetabolic bone disease (MBD) is a somewhat over­whelming and confusingdisorder that might be best described as a syndrome with variablemanifestations. The pathophysiology of nutritionally derived MBD is describedin the nutrition section. Clinically one of the most common signs of MBD isgeneralized or hind leg weakness or paralysis; and, therefore, might best beconsidered a neurologic disorder. MBD is the primary rule-out for lizardspresented with this clinical sign. Other common signs include failure to grow,general­ized weakness, anorexia, soft or pliable mandible on palpation,palpably swollen or thickened long bone(s), fractures of long bones, andoccasionally tremors or fine muscle fasciculations. In profoundly weak lizardsthe pupils may appear to dilate and constrict errati­cally, possibly an ocularmanifestation of muscle fas­ciculations (personal observation). Presentation ofa lizard with flaccid paralysis is an emergency. These clinical signs are mostcommon in species of Iguanidae and Varanidae.In species of Chamaeleontidae clinical signs are commonly generalizedweakness, anorexia, inability to grasp or climb, loss of balance, swollenjoints, soft mandibular bones, crest deformities (Chamaeleocalyptratus), and occasionally flaccid tongue paralysis. ClinicallyMBD is related to inadequate exposure to UV light. Prognosis for recovery forseverely affected juvenile chameleons with MBD is poor at best. Tremendousnutritional support and great care in han­dling is required for rehabilitation.A detailed history of diet, dietary supplementation, and lighting areessential. Diagnostic testing includes blood chemistry and radiographs (iffractures are sus­pected). If hypocalcemia is detected, the patient should beconsidered critical and intramedullary (via catheter) or intracoelomic calciumgluconate 10% is adminis­tered at a dose of 100 mg/kg every six hours untilweakness and/or muscle tremors resolve (Boyer 1996). Blood calcium levels aremonitored routinely. Advanced cases of hypocalcemia with paresis carry a graveprog­nosis. Assess hydration and treat as indicated. Non-hypocalcemic patientsare treated with oral calcium glubionate (Neo-Calglucon) at a dose of 1 ml/kgPO every twelve hours. This treatment may continue for several weeks to monthsuntil normal appetite returns. Nutritional support is required in hypocalcemicpatients (see Techniques). Exposure to unfiltered sun­light for fifteen minutesonce or twice weekly and oral vitamin D3 supplementation isindicated. Fracture management is conservative for patients with MBD. Tractionand immobilization of forelimb and hind limb fractures with external coaptationis performed (see Techniques).MBD is physiologically a gradual onset disease. From the clientsperspective the clinical signs of MBD are rapid. Note: Educate the client aboutthe basics of MBD pathophysiology with emphasis on the interre­lationshipsamong diet, dietary supplements, and UV light exposure. Explain that adeficiency in one of these factors can lead to MBD. Most importantly stress thefact that recovery from MBD may require months and may result in some permanentdebilitation or disfigura­tion in the patient that presents with advanceddisease.Cardiovascular SystemCardiovascular diseases are rarely reported in the lit­erature. Theauthor has observed one case of suspected heart failure in an adult savannahmonitor. The patient presented with generalized limb and coelomic swelling.Aspiration of the coelomic cavity revealed straw-colored amber serous fluidthat was relatively devoid90 Chapter 6of cells. Cardiac auscultation revealed a grade III-IV/ VI holosystolicmurmur. Pulmonary auscultation was unremarkable. Unfortunately, work-up of thecase was not permitted and the deceased animal was not avail­able for necropsy.Respiratory SystemThe most common true respiratory disease in lizards is pneumonia. Inlizards etiologic agents of pneumonia are bacteria, fungi, and parasites (seeParasitology). Clinically pneumonia develops with improper husbandry and rarelyas contagious disease and gener­ally presents in the advanced stages of thedisease. Pneumonia associated with pulmonary parasitism commonly occurs as asecondary bacterial infection (Murray 1996).The most prominent clinical sign of pneumonia is dyspnea. The posturemay be altered with the neck held in extension and the mouth held open.Occasionally oral and nasal mucoid secretions are observed, though neither ofthese signs is pathognomonic for respiratory disease. Secretions originatingfrom the mouth or esophagus can appear foamy in lizards with normal respiratoryhealth. Thoracic auscultation may reveal crackles or popping sounds withpneumonia. These sounds in the absence of oral secretions are highly suggestiveof pneumonia. The absence of any air sounds may indicate lung consolidation andadvanced disease.Radiographs are the diagnostic test of choice for pneumonia.Transtracheal wash (see Techniques) with cytology and bacterial culture withsensitivity of the wash are diagnostic for the etiology of pneumonia. Forseriously compromised patients, a swab of the glottis or aspiration of trachealexudate without flushing is recommended. Fecal exam is indicated in cases inwhich tracheal wash is not possible to diagnose lung-worm infection.Treatment is initiated upon diagnosis of pneumonia and modified based oncytology and culture and sensitivity results if indicated. Pneumonia in lizardsmany times presents as an emergency and treatment must not be delayed.Antibiotics commonly used are broad-spectrum and bactericidal. These includeaminoglycosides, beta-lactam antibiotics (cephalospo­rins), fluoroquinolones,and advanced generation semisynthetic penicillins, all of which should be admin­isteredparenterally either IM or SC (Murray 1996).Recovery from pneumonia is prolonged physiologi­cally by theaccumulation of pulmonary exudates in recesses of the lungs (particularlycaudally) and an inability of achieving the MIC of antimicrobial agentsin  these  relatively  poorly vascularized  regions.Nebulization with bacterial antimicrobial agents may be beneficial.Aerosolized particles must be 3 microns or smaller to reach the lungs (Murray1996). Treatment periods are ten to thirty minutes at a frequency of every sixto twelve hours. Duration of treatment may be several days to one week pendingclinical improvement.Note: Meticulous investigation of all aspects of hus­bandry andcorrection of improper husbandry are required to develop a complete treatmentplan. Inform the client of the seriousness of the disease and be real­isticregarding prognosis. Treatment of pneumonia often requires protractedhospitalization, repeated diagnostic testing, moderate to marked financialinvestment, and tremendous patience.Digestive SystemAnorexia is the one of most common presenting com­plaints for digestivedisorders, the cause of which can be a challenge to diagnose. Though anorexiais not a disease, it is both a clinical sign of nearly all reptilian diseasesand a contributor to several other diseases. Comprehensive history is requiredbecause improper husbandry often contributes to the cause of anorexia. Ifhistory and physical exam fail to uncover improper husbandry issues or clinicaldisease, a series of diag­nostic tests is indicated, including fecal exam,blood chemistry, complete blood count, and radiography (including positivecontrast). Treat the diagnosed underlying disease and provide nutritionalsupport.Infectious stomatitis occurs as a secondary disease in lizards (Mader 19966, Barten 2002). Thisdisorder may be unobserved by clients because the patient is presented foranorexia, lethargy, weight loss, or occa­sionally oral or nasal exudate. Oralexam may reveal focal or diffuse gingival erythema, petechia, swelling, erosion,ulceration, and mucoid or purulent exudate (Figure 6.7).The glottis mucosa may be involved in diffuse disease. In severe cases,aspiration of infectious exu­dates may lead to pneumonia (Mader 1996d, Murray1996). Because the oral cavity communicates with the nasal cavity dorsallythrough the choana, exudates may be observed bubbling from the nose in theabsence of true respiratory disease.Immunosuppression resulting from a myriad of underlying causescontributes to the development of infectious stomatitis. Improper temperatures,poor nutrition, and trauma from fighting with cage mates or oral cavitymanipulation may be implicated. The infectious agent is determined throughbacterial culture and sensitivity and is commonly identified as normal oral cavitybacterial flora including Aeromonas spp. orLizards 91Figure 6.7. Stomatitis in a lizard.Pseudomonas spp, bacteria which are opportunistic pathogens.Treatment is based on degree of involved tissues, husbandry parameters,and sensitivity values. Small (2- to 3-mm) focal regions of stomatitis mayrequire only warming the environment and no antibiotic treat­ment or a singletopical antiseptic or antibiotic appli­cation. Generalized or deep infectionsmay require sedation, debridement, and a combination of topical and systemictherapy. Aminoglycosides (gentamicin, amikacin) and fluoroquinolones(enrofloxacin) are most commonly administered. Note: Inform the client thatrecovery may be protracted in severe cases of stomatitis. Routine rechecks arenecessary to monitor progress of healing of infection. Correcting improperhusbandry is of primary importance.Obstruction and impaction are common and may present days or weeks afterthe onset of the actual disease. The usual presenting complaint is anorexia,but bloating, lethargy, weight loss, diarrhea, constipa­tion, and rarelyregurgitation may be observed. Diagnosis may be suspected based on historyalone. Investigating the patients enclosure substrate, feeding habits, andnormal defecation habits is important. Confirmation of obstruction canoccasionally be made on physical exam, but commonly radiographs or exploratorysurgery are required for definitive diagno­sis. Complete foreign bodyobstruction commonly results in gas bloating which is evidentradiographi-cally; the causative item, however, may not be radio-graphicallyvisible. Complete obstruction with gas bloating is an emergency.Impaction is the result of fine particulate substrate, rodent hair,arthropod exoskeleton, or other food item accumulation in the intestines andmay develop inde­Figure 6.8. Cloacal prolapse in an iguana.pendently, in association with, or secondary to foreign bodyobstructions. Impactions are commonly palpable and visible on radiographs. Ifthe lizard is alert and marked gas accumulation is not observed on radio­graphs,enemas and/or oral laxatives are indicated (see Techniques). Soaking in tepidwater for ten to fifteen minutes may also stimulate defecation. Assess fordehydration and treat as indicated. Impaction may occur secondary to a numberof husbandry issues, dehydration, improper diet, and hypocalcemia. Weak lizardswith diagnosed or suspected obstruction should have blood chemistry analyzed.Surgical correction is required when laxatives, enemas, or other conservativetherapy fails.Intestinal parasitism is very common if not ubiqui­tous in importedlizards (Klingenberg 1993, Lane and Mader 1996). Signs of intestinal parasitisminclude anorexia, diarrhea, weight loss, failure to gain weight, and weakness.Treatment is based on diagnosis (see Parasitology). Quarantine, fecalscreening, and cage hygiene are essential in limiting reinfection. Some par­asitesare zoonotic (see Zoonoses) (Johnson-Delaney 1996).Cloacal prolapse may occur as a digestive, repro­ductive, or excretorydisorder. The prolapse may occur secondary to straining from enteritis, egglaying, and uroliths, and may comprise the colon, oviduct, or urinary bladder,or a combination of the three. Treatment is based on which organ is prolapsedand the duration of the prolapse and resultant trauma to involved tissues(Figure 6.8).The colon is a tubular, smooth structure with a lumen. Fecal materialmay or may not been seen within the lumen. The oviduct is a thin-walled,longitudinally banded structure with a lumen and no fecal material will bepresent. The urinary bladder is a globular, thin­92 Chapter 6walled, smooth structure with no lumen and may be fluid filled. Prolapseof these organs originates from the coelomic cavity cranial to the vent.Paraphimosis, or prolapse of the hemipenes, originates from the proximal aspectof the tail caudal to the vent. The prolapsed hemipenis is a solid, fleshystructure with no lumen. All organs may be darkened in color fromdevitalization or necrosis. Cloacal prolapse of coelo­mic structures is anemergency.In cases in which prolapse is recent, tissues may be cleaned andlubricated with a water-based lubricant and gently reduced through the cloaca(Bennett 1996c). A single transverse cloacal suture is loosely applied tomaintain the reduction yet still allow the passage of urates and feces. Ifswelling of the tissue is present in the absence of necrosis, swelling may bereduced with hypertonic sugar solutions followed by manual reduc­tion. Necrosisof prolapsed tissue requires surgical resection in the case of coelomicstructures or amputa­tion of the hemipenis (see Anesthesia and Surgery).Excretory SystemRenal failure is generally a secondary disease caused by either impropernutrition in primarily herbivorous lizards or by aminoglycoside toxicity in alllizards. Clinical signs and diagnostic test results may mimic those seen withMBD with the absence of bony lesions. History may indicate polyuria, anorexia,weakness, and weight loss. Blood chemistry commonly reflects hyperphosphatemia,normo- or hypocalcemia, and normal or elevated uric acid. Radiographs mayreflect enlarged kidneys that appear as masses within and slightly cranial tothe pelvic canal. Renal enlargement is occasionally palpable.The dietary etiology is theorized to be a result of excessive dietaryanimal protein. Aminoglycoside tox­icity is well documented as a cause of renalinsuffi­ciency in mammals and reptiles. Treatment consists of fluid support anddiuresis, though prognosis is typi­cally poor for recovery and long-termsurvival. Other renal diseases seen in lizards include pyelonephritis andneoplasia.Reproductive SystemLizards are presented with several reproductive abnor­malities. Dystociain females and paraphimosis in males are most common. Other disorders includecloacal prolapse of oviducts, ectopic eggs, and neopla­sia. It is possible forlizards to ovulate and deposit infertile shelled eggs in the absence of a male.When gravid or pregnant, most lizards do not eat but remain alert and activefor a period of several days prior to egg laying and many retain eggs until asuitable sub­strate or nest box is provided. Any dystocia accompa­nied byweakness or non-responsiveness despite the presence of a suitable nesting areais a critical emergency.Dystocia in lizards can be pre-ovulatory (as follicles on the ovary) orpost-ovulatory (as follicles or shelled eggs in the oviduct) (Stahl 2000).Differentiation of the two is made by radiography as the pre-ovulatory eggs arenon-shelled and located dorsally in the abdomen and post-ovulatory eggs may beshelled and are more caudo-ventral in the abdomen. Conservative management isadvised when the lizard is alert and active with pre-ovulatory orpost-ovulatory dystocia. Environmental modification such as providing a suit­ablenesting area or more visual security may be curative.Traditional mammalian treatments for post-ovula­tory dystocia refractoryto conservative management include oxytocin and calcium injections to stimulatesmooth muscle contractions. Calcium gluconate at a dose of 100 mg/kg IM or ICefollowed in one hour by oxytocin at a dose of 5 to 30 IU/kg IM or ICe are given(Stahl 2000, De Nardo 1996b). Oxytocin may be repeated within thirty minutes ofthe first injection. Efficacy is unpredictable and may only approach 50% inlizards (De Nardo 1996b). Manual reduction of retained eggs may be attemptedfor one or two eggs in close proximity to the cloaca and distal to the pelviccanal. Tremendous care must be exercised to avoid prolapse, oviductal rupture,or trauma to the kidneys. If the eggshell is not clearly visible emerging fromthe cloaca, manual reduction is contraindicated. Lizards with distal oviductalor cloacal dystocias following normal oviposition may be hypocalcemic.Many cases of dystocia require surgical manage­ment. These are weakenedand visibly distressed animals or those in which a radiographic diagnosis ofobstruction is diagnosed. Obstruction may result from eggs too large to passthrough the pelvic canal or from coelomic masses or enlarged kidneys thatprohibit the passage of eggs.Paraphimosis is managed similar to cloacal prolapse (Barten 1996b). Theprolapsed hemipenis is assessed for viability and replaced or amputated asindicated. Transverse cloacal suturing is indicated with reduction ofparaphimosis.Nervous SystemDiseases of the lizard nervous system are typically secondary tosystemic, metabolic, or nutritional disease or trauma. Hypocalcemia from thevarious forms of MBD is one of the most common causes of neurologic weakness orparalysis in captive lizards (Barten 1996b).Lizards 93Figure 6.9. Spinal cord injury with vertebral column fracture due totrauma. Note the dorsal displacement caudal to the forelimbs.The pathophysiology of hypocalcemia is described in the nutritionsection. All lizards presented with weak­ness, tetany, or muscle fasciculationsshould have blood calcium levels assessed immediately.Trauma is a common cause of neurologic disorders in lizards and iscommon in lizards that are free-ranging in homes or traveling with the owner(Figure 6.9). Both cerebral and spinal trauma occurs and is treated empiricallywith corticosteroids and time. Prognosis for even apparently severe injuriesmay not be grave if the client is able to provide adequate sup­portive care(see Emergencies),OphthalmologyPeriocular inflammatory diseases are clinically the most commonophthalmic disorders in lizards. Infec­tious agents do not cause all perioculardiseases. Many inflammatory diseases, however, result from or give rise tosecondary bacterial infections. Williams (1996) reports that the majority ofocular diseases are a sign of more generalized infection.One nutritional disorder that affects the eye is hypo­vitaminosis A.This disease is not specific to the eye, but also affects glandular mucousmembrane epithe­lium including the respiratory and digestive tract. Clinicallyhypovitaminosis A is most commonly seen in turtles and occasionally in lizards.Clinical signs include blepharitis, chemosis, and epiphora. Secondary bacterialinfection is commonly observed in these cases and topical ophthalmicantibiotics are commonly indicated in addition to weekly vitamin A injections(Williams 1996). Recovery may be prolonged to several months. A thorough reviewof diet is recommended.Figure 6.10. Retrobulbar abscess in an iguana.Several species of geckos have spectacles (see Anatomy). Subspectacularabscesses and retained spec­tacles occur as in snakes. The abscesses may beunilat­eral or bilateral and often are the result of ascending bacterialinfection from the mouth. Treatment consists of surgical drainage andirrigation of the abscess along the ventral margin of the spectacle as well astreatment of associated stomatitis. The surgical incision remains open todrain, but commonly seals in a matter of days. Subsequent shedding of thespectacle results in com­plete closure of the surgical incision and resolutionof the abscess. The spectacle revealed following shed may appear wrinkled andtypically requires several shed cycles to return to normal appearance.Foreign bodies and trauma commonly result in blepharospasm. Evaluationof the globe and periocular tissues may require sedation. Treatment of lesionsdepends upon thorough examination of the globe, eyelids, and conjunctiva(Figure 6.10).BEHAVIORThe primary reported behavior disorder of lizards is aggression and iscategorized as dominance or fear aggression, as seen in dogs and cats.Dominance aggres­sion may be conspecific (same species) or intraspecific(different species) among lizards housed together and it may be difficult toseparate from fear aggression in cases of lizard-human interactions. Aggressionis most often observed against humans in cases of large lizards such asiguanas, monitors, and tegus, especially during breeding season, and is likelyhormonally induced. This behavior is variable and may be directed at only oneperson in the household (personal observation). The author suspects thepossibility of pheromonally induced94 Chapter 6aggression in iguanas against women who may be in estrous cycle. Aggressionin large lizards directed against humans is a serious and dangerous problem(see Zoonoses). Seasonal aggression is treated with ovariectomy or orchiectomy.TOXICITY AND MISCELLANEOUS NUTRITIONAL DISORDERSToxicities occur from a variety of substances including pharmaceuticals,insecticides, dietary supplements, chemicals, and cigarette smoke (Williams1996). Pharmaceutical toxicities are most commonly seen from injectableaminoglycosides and ivermectin, oral metronidazole, and topical pyrethrin ororganophos-phate compounds. The author is unaware of Teflon toxicity in lizardsas reported in birds, but this possibil­ity should be considered. A thoroughhistory is required for diagnosis of toxic exposure, because there are rarelypathognomonic clinical signs for exposure to any of these compounds. Treatmentis supportive depending on the underlying exposure. Mader (1996a) recommendsstandard atropine, diazepam, and iso­tonic fluid therapy for lizards withpyrethrin toxicity (see Emergencies).Nutritional disorders leading to neurologic signs of disease includevitamin Bl5 vitamin E, and selenium deficiencies. Thiamine (Bj)deficiency is seen in car­nivorous lizards fed raw egg diets in which the com­poundavidin inhibits vitamin B. Vitamin E deficiency is seen in lizards fed highfatty fish diets (Donoghue and Landenberg 1996). Treatment consists of dietarycorrection and injectable vitamins as indicated.Gout is a disease of lizards and other animals with several potentialetiologies. In lizards, gout can origi­nate both from improper nutrition orsecondary to pharmaceutical toxicity. In vertebrates the pyrimidine amino acidsare metabolized into C02 and NH3 and eliminated from thebody. Purine amino acids are metabolized into various degradation products of whichuric acid is the final product in reptiles (Mader 1996c). Uric acid in highconcentrations in the blood becomes insoluble. Simplistically, gout is theresult of excessive uric acids in the blood that crystallize and precipitate intissues prior to elimination from the body via the kidneys. Common sites ofthis deposition are serosal surfaces of internal organs and synovial membranes.A common presenting complaint of gout is swollen joints or white to yellownodules of the oral mucous membranes.Gout is seen in lizards on diets high in purines, most commonly inherbivorous lizards fed a primarily animal rather than plant protein diet. Goutmay also be renally induced secondary to dehydration or renal disease mostcommonly in association with renal tubular toxicity from aminoglycosides orsulfon­amides. Even at proper dosages these antibiotics can induce renaldisease if the patient is or becomes dehydrated during treatment. Gout is amanaged disease and not curable in most cases. Medications to lower blood uricacid concentrations and anti­inflammatory agents are recommended (Mader 1996c).In cases of advanced gout palliative therapy may be insufficient. This diseaseis best prevented before it occurs with proper client education regarding dietand the judicious use of potentially nephrotoxic medications.ZOONOSESClient education regarding zoonotic diseases must be a priority for allveterinary health professionals. Unfortunately, popular literature,television/radio, and the Internet are saturated with misinformation regard­ingreptile zoonotic diseases. The threats posed to humans, however, should not beunderestimated. This information gap is prevalent within human medicine aswell, and human physicians fall victim to the lack of education reflected by thepopular press regarding disease in many domestic pets.All veterinary staff should take the following steps to understandingzoonotic disease:1. Gain a completeunderstanding of the pathophysiol­ogy and method of transmission (direct orindirect and vector) of the disease in question, both in the potential sourceanimal and in humans.2. Have a completeunderstanding of risk factors for humans to contract the disease in question,includ­ing immunosuppression and human behaviors when handling the pet.3. Know which petspecies are more likely to harbor particular zoonotic pathogens.4. Gain a thoroughknowledge of laws governing the possession and treatment of exotic species in agiven jurisdiction.Human behavior is likely to be a primary cause or facilitator ofcontracting zoonotic diseases from rep­tiles. Because many lizards areparticularly sociable and exhibit behaviors that are commonly anthropo­morphized,their owners form a human-animal bond that is similar to that seen with otherdomestic animals. Therefore, reasoning regarding the potential for zoo­Lizards 95notic diseases is commonly ignored because of emo­tional considerations.Behaviors that greatly increase the risk of contract­ing infectiousdiseases from lizards include:• Housing or handlinglizards in or near food prepa­ration or storage areas• Allowing lizards tosoak in bathtubs, basins, or containers used for human hygiene• Allowing any partof the lizard to contact a human mouth or face• Allowing lizards toroam free in any facility of human habitation• Allowing youngchildren to handle or have access to pet lizards when not under direct adultsupervision• Handling lizards byany person under treatment of immunosuppressive medication(s) or having con­tractedany immunosuppressive disease• Not washing handsand exposed skin following handling of pet lizardsOther risk factors include possessing aggressive or potentiallydangerous lizard species, disregarding proper handling techniques of anylizard, feeding pet lizards by hand, and failing to maintain proper cagesanitation.Bacterial diseases are most commonly implicated among reptilianzoonoses. Of these diseases salmonel­losis (Salmonella spp.) is most notoriousfor causing disease in humans. See Johnson-Delaney (1996) for a comprehensivediscussion of salmonellosis. Salmonellosis is directly transmitted by afecal-oral route. Transmission of infective serotypes does not require thedirect contact of fecal material by a human. Because lizards are commonlymaintained in enclo­sures where they defecate, invariably bacterial organ­ismsfrom feces may contact the skin of the pet. Handling the pet can transferinfective organisms to human skin. It is likely that disease transmission willnot occur given the combination of a relatively low number of infectiveorganisms and an immunocompe­tent host; with zoonotic diseases, however, thereis no acceptable level of risk.Other bacterial infections may occur in humans from fecal-oralcontamination or from penetrating wounds such as bites or scratches. Aeromonas spp., Pseudomonas spp., and otherGram-negative bacteria may be normal flora in the mouths of lizards. Mycobacterium spp. infections mayoccur in reptiles and are potentially infectious to humans through directcontact with skin defects and inhalation. This infection in reptiles may appearin any organ. Chlamydiopbila psittaci has been identifiedin infec­tions of various species of lizards (Jacobson 2002). Directtransmission of Chlamydia from reptiles to humans is unknown. Severalfungal infections, mycoses, that have the potential to infect humans have beenreported in reptiles.Reptiles are the definitive host for tongueworms, pentastomids, ofvarious genera that are know to infect humans incidentally (Lane and Mader1996, Johnson-Delaney 1996). Transmission is direct and fecal-oral by ingestingeggs or larvae. Because humans are incidental "dead-end" hosts, theydo not pass infective stages of pentastomids. Larval forms of these worms maymigrate and then die in humans, resulting in localized immune response andcalcification or gran­ulation of lesions.There are a variety of indirectly transmitted diseases for which lizardsmay be reservoirs of disease or carry the vectors of zoonotic disease. Avariety of ticks, mites, and biting insects are implicated in transmittingdisease such as viral, rickettsial, and bacterial diseases. Lizards have notbeen implicated in acting as a reser­voir host for these diseases, but they mayharbor ticks and mites that can bite and infect humans (Johnson-Delaney 1996).An often overlooked yet significant risk to humans from captive reptilesis trauma from bites and scratches. With all infectious diseases aside, thereis no excuse for humans to incur bite wounds from pet lizards. Some species aresimply poor choices for the average hobbyist. These include Heloderma spp., adult greeniguanas, large monitors, and some adult tegus. There is risk of bite wounds orother injuries from these species when simply performing routine maintenanceand a minimal amount or even no handling. Generally, however, injuries occurfrom careless interaction with the animals.The importance of this issue becomes evident when legal authoritiesattempt to strip the rights of pet owners to possess these animals because ofaccidental bites or the irresponsible behavior of a few people. Many localordinances restrict or prohibit the sale or possession of certain exoticanimals, particularly ven­omous reptiles and large snakes or lizards, becauseof perceived danger to humans. Accidental bites that occur at zoological parksand large snake escapes that are reported by the media contribute substantiallyto the hysteria that enables much knee-jerk improper leg­islation. Veterinarystaff have a critical role in educat­ing clients about the proper handling ofexotic animals and in advising clients about exotic animals which areunsuitable as pets.Additionally, however, veterinary staff must be aware of these laws whenadmitting or treating pets96 Chapter 6that are illegal to possess. Injuries sustained to staff or clients bythese pets (and others) are the responsibility of the practice owners when onthe premises. Similarly, advising clients regarding the home treatment ofpotentially dangerous animals should be approached with great discretion. For asomewhat complete but already outdated overview of laws regarding reptiles inthe United States see Levell (1998).HISTORY, RESTRAINT, AND PHYSICAL EXAMHistoryIn the practice of exotic animal medicine, as much can be learned abouta patient from the history as from any other diagnostic procedure. Withlizards, a veteri­nary technician or receptionist educated with a basicunderstanding of the patients husbandry needs can often develop a workingdiagnosis well before the vet­erinarian examines the patient. It is the verydiversity of husbandry requirements among species of lizards that demands afundamental knowledge of all natural history aspects of the patient.It is essential to not dismiss any observation by the client as trivialor inconsequential. The client may be the most educated person in the exam roomwith regard to the natural history of the patient, and with long-term captivelizards, the client is usually aware of a pattern of "normal"behavior. Discovering the devia­tions from normal behavior is essential toobtaining a complete history.These are several fundamental questions for clients to answer regardingtheir lizard pets:1. What is thepresenting complaint(s), what is the duration of the problem, how rapidly hasthe problem developed, and does the client believe that the problem is relatedto any external influence(s) on the lizard?2. What is thespecies, age, and sex? How long has the lizard been in the clients possession,and are there any known previous disease or health problems? Has the client oranyone else medicated the lizard or been instructed to medicate the lizard, andif so, by whom and for what reason?3. Is the lizardcaptive born or wild-caught? This is not essential to the diagnosis, but can bevery helpful in developing a diagnostic plan for infectious disease.4. In the area ofgeneral husbandry, in addition to obtaining a general overview of housing,lighting, temperature and heating, humidity, substrate, water availability,cage cleaning, and cage accessories, it is essential to ask the following: Doesthe lizard ever roam free in the house or in any area other than the cage orenclosure or has the lizard ever escaped from its enclosure? Does the lizardhave any direct or indirect exposure to any other animals presently or in thepast and are those animals similarly affected? Is the lizard ever handled orobserved by anyone except the client? Where is the cage located in the house?Is it ever moved? What are potential exposures to noxious materials such ascleaning agents, cigarette smoke, fuel exhaust, etc., and are theretemperature, light, humidity, or ventilation fluctuations?5. Regarding nutrition, determine exactly what the lizard isfed and the origin of the food (i.e. does the client collect food in theenvironment to feed or purchase the food at a pet store or grocery store?) Howoften is food offered, at what time of day is food offered, and in whatquantities is food con­sumed? In cases in which a variety of food items areoffered, which portions are usually consumed? Does the client use anycommercially available foods or vitamin and mineral supplements and if so, howoften and in what quantity? Does the client actually observe the lizard eatingthe food items or just notice that food is missing after a period of time?RestraintPortions of the physical exam, most diagnostic proce­dures, and manytreatments require restraint (Figure 6.11). The veterinary staff must be awarethat every species of lizard can bite. Most, however, will not bite or scratchunless restrained and the more firmly they are restrained, the more they willstruggle and attempt to bite or scratch the handler. Lizards with delicate skinshould not be handled for physical examination unless absolutely necessary.These species include the Malagasy geckos Geckolepis spp. (fish-scalegeckos) and Phelsuma spp. (day geckos) that may autotomize bothtails and skin with minimal physical restraint. This behavior rarely results indeath of the lizard, but it may cause permanent disfigurement. These patientscan be observed through clear enclosures such as plastic pet carriers or theycan be placed inside a 5- to 6-cm. diameter clear plastic tube for examination(Barten 1996b).There are some lizards that at all times should be considered dangerousto handle. These include all lizards greater than lm length, especially all large species of iguanas and monitors.Large lizards may be calmed by covering the head and eyes with a towel inLizards 97Figure 6.11. Proper restraint ofa lizard.addition to wrapping the body in a large towel or blanket to preventclawing (Figure 6.12). The head, however, must be fully and firmly immobilizedat all times. Occasionally these lizards cannot be safely restrained andexamined without sedation (see Surgery and Anesthesia). Other species, thoughsmaller and typically docile, are capable of producing digit ampu­tation,disfiguration, or extremely painful bites to humans. These includeprehensile-tail skinks (Corucia zebrata) and some adultTegus (Tupinampis spp.). Some smaller lizards such as the Tokay gecko (Gecko gecko) tend to beaggressive and will attempt to bite without being handled. Even small lizardssuch as fat-tailed geckos (Hemitheconyx caudicinctus) are capable ofproducing painful bites when handled and may be reluctant to release whenbiting a hand or finger (Figure 6.13).The veterinary staff should refrain from inappropri­ate contact with petlizards. This includes kissing the. .mmmmFigure 6.12. Lizard restraint using a towel.Figure 6.13. Restraint of asmall lizard.patient, placing the patient near a human face, placing fingers or handswithin the mouth of the patient, or allowing the patient to cling to clothingor hair in an unrestrained fashion. This behavior is both irrespon­98 Chapter 6sible and unprofessional and may result in serious injury to either thepatient or veterinary staff. Clients should also be informed of the potentialhealth risks that may result from these behaviors. The veterinary staff shouldnever allow the client to assist in the restraint of a potentially dangerouspatient during examination or when performing a treatment or diag­nosticprocedure. Though lizards may become some­what tame, there are no domesticatedlizards and their behavior may not be predictable.Physical ExaminationThe traditional physical exam for most companion animals is a hands-onaffair. More can be learned, however, by simple observation of the lizardpatient at rest in a cage while in the exam room or waiting area. Theseobservations can commonly be made during the traditional question-and-answersession and may quickly uncover potential emergencies that have not beenrealized by the client. First observe the posture (again, the technician mustfirst be familiar with normal posture of a particular species). Quadrupedlizards generally hold the head somewhat erect and may have a portion (if notall) of the body held sus­pended above the ground. For diurnal lizards, assessalertness. Does the lizard follow the observer in the room with eyes or head?Healthy chameleons, for example, are constantly surveying their environmentwith turret-like eyelids and generally do not sit still except when restrainedor confined. For lizards with movable eyelids (all but some geckos), are botheyes open and are they clear?Observe general body condition, paying particular attention to themuscle mass of the dorsal tail, dorsal pelvis, and dorso-lateral scapularregion. Emaciation results in diminished subdermal fat and muscle mass and theskin may have a concave contour to one or all of these body regions.Additionally, the eyes may have a sunken or recessed appearance from diminishedret­robulbar fat or from dehydration. Species that rou­tinely present withsigns of emaciation include the green iguana, spiny-tailed lizards (Uromastyx spp.),prehensile-tailed skinks (Corucia zebrata), bearded dragons (Pogona spp.), and monitors(Varanusspp.).It is important to understand that the physical changes associated withemaciation are chronic and do not occur over several days. Some lizards, whichare later­ally or dorsally compressed, may appear thin or under­weight but theyare in fact normal. Some of these species include leaf-tailed geckos (Uroplatus spp.), some truechameleons (Chamaeleo spp.), and spider geckos (Agamura spp.). Observe forsymmetry, par­ticularly of skeletal structures. Except for some skin appendagesthe external and skeletal anatomy of lizards is bilaterally symmetric.As with general body condition, the skin can be observed withouthandling the lizard. There is great structural variation among lizards in skinand scale texture. Lizards such as bearded dragons and horned lizards (Phrynosoma spp.) have roughlytextured and armored skin. Others, such as some geckos (Phelsuma spp.), haverelatively small granular scales and thin skin which is delicate. Observe formissing scales, abnormal skin coloration, crusts, dysecdysis (incom­plete shedskin), subdermal swellings, and external parasites including mites and ticks.Pay particular attention to skin folds, flaps, nostrils, eyelids, axillae, andears for mites and ticks. Observe for signs of trauma such as rostral abrasions,necrotic or missing toes, damage to the tail, bite wounds, and signs of thermalor chemical burns that may appear as ery­thema or tissue necrosis. Inspect formissing, damaged, or discolored toes or toenails. Remember that not all lizardshave four legs and five toes per leg. Ophisaurus spp. and Lialis spp. are twoexamples of legless lizards. Chamaeleo spp. have five toeswhich are fused into two gripping bundles per foot.While observing the lizard systematically pay atten­tion to respirationand the respiratory effort. As with caged birds, respiration for most lizardsat rest is rela­tively effortless and nearly imperceptible from a dis­tance.Gaping (holding the mouth open) associated with dyspnea may be the result ofupper or lower respiratory disease. Overheating, defensive posturing, andstress or anxiety may also lead to this behavior. Similarly, mucoid oral andnasal secretions are not normal, though crystalline or salt secretions may benormal in some species such as Uromastyx spp. and Iguana spp. Thoracicauscultation should be per­formed over the entire dorsal and lateral thoracicregions. When performing auscultation, a moistened paper towel or thin clothmay be wrapped over the diaphragm of the stethoscope to reduce noise from roughskin or scales.An essential part of the physical exam for most lizards is the oralexam. This examination may require physical or chemical restraint and must beperformed with consideration to safety of the veterinary staff and health riskto the patient. Some lizards (Iguana, spp., Varanus spp., Chamaeleo spp., Pogona spp., some Gecko spp.) mayvoluntarily open the mouth when approached in the cage or when restrained,making oral examination less physically challenging. In these species(excluding Gecko spp.) the mouth may be opened with gentleretraction of the dewlap while the maxilla is secured with the other hand. ThisapproachLizards 99is contraindicated in patients that have normally fragile skin (mostspecies of Gekkonidae) or those with dis­eased skin as with hypovitaminosis C.The author has observed the dewlap skin easily tear in malnourished Chamaeleo spp. suspected ofhaving hypovitaminosis C among other malnourishment-related diseases. Thegentle introduction of a rubber spatula into the mouth is useful as a speculum.Metal and wood speculums should be avoided because they may result in damage togums and teeth as well as damage to or accidental ingestion of the speculum (orportions thereof) with stronger lizards. For very small lizards plastic spoonsor plastic credit cards may be used as a speculum. For large lizards or thosewith dark pigmented oral epithe­lium an otoscopic or laryngoscopic illuminatoris useful to visualize the oral anatomy.Chemical restraint is required to examine the oral cavity with somespecies because of strong jaws and a reluctance to open the mouth. Thesespecies include spiny-tailed lizards, prehensile-tailed skinks, some monitors,some tegus, and occasionally bearded dragons. Similarly, lizards with metabolicbone disease or those with thin mandibles may suffer traumatic iatrogenicfractures from manipulation of the mouth. Tremendous caution and attention mustbe used when manipulating the mouth of adult iguanas and monitors. Anydistraction or a mistake in handling may result in serious injury or amputationof a digit to the handler. The bodies of larger lizards must be fullyimmobilized prior to opening the mouth to prevent the patient from exerting anyleverage by thrashing or spinning the body, should an accidental bite occur.Examination of the oral cavity includes observation of the choana,dentition, glottis, and mucous mem­branes. While manipulating the head, palpatefor the firmness and symmetry of the mandible and maxilla. Bones that compressor bend in a lateral fashion may signify metabolic bone disease. The mandibularsym­physis is fused in lizards. Abscesses and granulomas may occur in themandible with no apparent mucous membrane abnormalities. The oral cavity shouldbe bilaterally symmetric. The mucous membranes of the oral cavity are generallyuniform in color. Many lizards have a pink to pinkish white color to the oralepithe­lium with a somewhat glistening surface. Some lizards may have pigmentedoral epithelium. The oral mucous membranes of some old world chameleons (Chamaeleo spp.) and beardeddragons (Pogona spp.) are yellow and should not beinterpreted as icteric or jaundiced. In a healthy lizard there is little to nomucus, blood, pus, or other exudates in the mouth. The glottis should be observedthrough several respiratory cycles of inspi­ration both to observe normalmovement of glottis cartilages and to observe for any exudates from within theglottis. The choana should be clear of any exudate. The dentition and gingivashould be free of erythema or exudate. Similar to snakes, some Gecko spp. have aspectacle which covers the eye. Subspectacular abscesses are commonly observedin conjunction with and may arise from infectious stomatitis (Mader 1996d); anoral exam is always warranted with the presence of subspectacular abscesses.Examination of the external cloaca or vent also requires physicalrestraint. The vent should have appearance consistent with that of theremaining dermis with the exception of specialized scales that vary among species.Some lizards possess femoral pores that extend laterally from the vent onto theventral aspect of the hind legs and pre-femoral pores cranial to the vent. Thevent and surrounding integu­ment should be bilaterally symmetric. As with theintegument, observe for signs of trauma, swelling, exu­dates, and crusts, andobserve for prolapse of cloacal tissue or hemipenes.Abdominal palpation is a non-invasive method to evaluategastrointestinal, reproductive, and urinary systems. Palpation is performedgently with the finger­tips to create minimal stress and reduce the risk ofinternal damage to delicate or diseased patients. Caution must be exercised ifgastrointestinal obstruc­tion or bloating is suspected to prevent iatrogenicrupture to dilated gastrointestinal structures. In dor-sally compressedlizards, such as bearded dragons and uromastyx, the kidneys may be palpable inthe dorsal caudal coelom. It is difficult to differentiate the kidneys fromother abdominal structures in laterally com­pressed or very large lizardswithout forceful palpa­tion. Uroliths may be palpable as in dogs and cats. Itis also difficult to impossible to differentiate gastroin­testinal structureson palpation other than by extrapo­lating their location. Paired fat bodies arepresent in the caudal coelom. These are bilateral and may be confused withkidneys or masses in the coelom. The fat bodies are particularly evident indorsally com­pressed lizards such as bearded dragons and Uromastyx spp.Small lizards, particularly many Gekkonidae, have semi-transparentventral abdominal walls and skin. This allows for visualization of someabdominal struc­tures while the lizard is contained in a clear plastic or glasscontainer. This technique is particularly useful for visualizing eggs in thesespecies. An oviparous lizard carrying eggs is termed gravid and a viviparouslizard carrying embryos is termed pregnant. Both terms are used interchangeablyfor both conditions.100  Chapter 6Eggs are generally visible against the body wall or palpable in manygravid oviparous lizards. Pregnancy in viviparous lizard is suspected withgeneralized coe­lomic swelling, though developing embryos may not be palpable.RADIOLOGYRadiographic imaging is particularly useful in evaluat­ing skeletaldisorders in lizards. Evaluation of respira­tory disorders and gastrointestinaldisorders is also possible, though gastrointestinal imaging must com­monlyemploy contrast media. Other coelomic struc­tures that are evident onradiographs are kidneys, liver, coelomic masses, fat bodies, and occasionallyuroliths. During ovulation, ovaries and shelled or non-shelled eggs as well asdeveloping embryos may be observed; otherwise, gonads are not visible onradiographs in lizards.Radiographic equipment should have several capa­bilities. A milliampere(mA) setting of 300 mA and exposure times approaching 1/60 second (5mAs) withrelatively low kVp (45 to 60kVp) produce excellent exposures using high-detail,rare-earth intensifying screens (Silverman and Janssen 1996). A collimator isessential because multiple exposures are commonly made on a single film forrelatively small patients. The radiographic machine should have horizontal beamcapabilities, though without this, and through creative positioning of thepatient, acceptable imaging is pos­sible. A minimum of two exposures is desiredof the coelomic cavity: dorsoventral and laterolateral (lateral). Similarly,extremities should be imaged in at least two planes.For many lizards a table-top technique is employed without a grid.Exposure techniques vary widely with different radiology units. For most smalllizards (5 cm or less in thickness), small animal extremity techniques workwell. For lizards larger than 5 cm, small animal thoracic techniques yield goodexposure. Remember that the lungs of many lizards, in part, may extend caudallyto the pelvis. The author commonly uses small animal extremity techniques evenfor larger iguanas with satisfactory results. Generally settings of lower kVpare desired because bone density is rela­tively lower in reptiles than mammals(Silverman and Janssen 1996). Similarly, the coelomic body fat of reptiles istypically lower than that of adult domestic animals, making the contrast ofviscera more difficult to obtain with higher kVp. The standard dorsoventral andlateral positioning techniques may not reveal the true nature of coelomicstructures or abnormalities.Therefore, partial rotation of the patient to a 30-degree or 45-degreelateral exposure can be useful as a third exposure when evaluating the coelom.The difficulty with radiology in lizards is restraint and positioning.Large healthy or aggressive lizards should be sedated without exception. Thisminimizes bite risk and radiation exposure risk to the handler(s). Smalllizards that are slow moving or calm may be allowed to rest unrestrained on thecassette for the dorsoventral vertical beam exposure. Lateral horizon­tal beamexposures are possible without restraint for some still or chemicallyrestrained lizards. Small fast-moving or delicate lizards may be placed insidea clear plastic container or tube or cloth bag and positioned appropriately forexposure. Though some detail of the image may be lost, this may be the onlyoption to obtain radiographs of these patients. When sedated, gauze ribbons maybe used to extend limbs as needed. Tape should be avoided because it may removescales or otherwise damage skin.Contrast media is commonly employed when non-skeletal imaging isrequired. Gastrointestinal contrast studies are not only beneficial forevaluating complete or partial obstructions, but are also particularly usefulfor evaluating extraintestinal coelomic masses. Barium sulfate is the standardcontrast material for gastroin­testinal contrast imaging. Frye (1991)recommends the use of 10% barium sulfate at a maximum dose of 20 ml/kg. Bariumfor gastric and small intestinal imaging is administered via an oral ball tipdosing needle or flexible, non-rigid rubber catheter (see Techniques). Unlessthe imaging of the esophagus spe­cifically is required, administration ofbarium via a gastric tube is best. Oral cavity dosing may result in partialaspiration and loss of barium through the mouth or nostrils. In diseasedlizards gastric to colonic transit times may be delayed substantially, thoughthe author experiences partial to complete transit of barium within twenty-fourhours in non-obstructed patients.Retrograde or percloacal barium administration is indicated when distalintestinal obstruction or caudal abdominal coelomic masses are suspected.Barium is administered via a flexible, non-rigid rubber catheter. In smalllizards (iatrogenic cloacal or colonic perforation (see Techniques). The clinicianshould approximate the amount of barium required for the desired image.Diseased colon or intestine may rupture with even the slightest pressure;therefore, resistance on the syringe is not a good practice for approximatingdosing for administration of oral or percloacal barium.Lizards  101ANESTHESIA AND SURGERYOnce uncommonly performed, coelomic cavity surgery or celiotomy is nowroutine for many pet lizards. These include ovariectomy, orchiectomy, salpingot­omy,gastrotomy, enterotomy, cystotomy, biopsy, and tumor excision. Other surgeriesthat do not require celiotomy include amputation-(digits, limbs, tails,hemipenis), enucleation, fracture repair, laceration repair, prolapse(intestinal, oviductal) repair, and reconstructive surgeries.AnesthesiaInjectable and inhalant anesthetics are commonly employed both forsurgery and sedation for diagnostic or treatment procedures. The most commoninjectable anesthetics are the dissociative agents ketamine and telazol(tiletamine plus zolazepam). Ketamine is admin­istered IM or SC at a dose of 22to 44 mg/kg. A dose of 55 to 88 mg/kg is reported for surgical anesthesia(Bennett 1996a). Telazol is more potent than ketamine and is the authorspreferred injectable anesthetic. Telazol is administered IM or SC at a dose of4 to 5 mg/kg (Bennett 1996a). Its potency allows for the administration ofsubstantially less volume of injec­tion, the effects are rapid, and recovery istypically quicker than with ketamine. Telazol is best used as a pre-intubationanesthetic for surgical procedures or as a sedative for diagnostic or treatmentprocedures. Intramuscular administration, when possible, is pre­ferred forinjectable anesthetics because induction of anesthesia is typically more rapidthan with subcutane­ous administration. This is likely the result of quicker ormore complete venous absorption. For procedures more invasive than cutaneouslacerations inhalant anesthesia should be employed because movement of theanesthetized patient may continue with either ket­amine or telazol.An additional injectable anesthetic, propofol (Diprivan, Rapinovet), isalso used in reptiles for anes­thetic induction and restraint. Propofol must beadmin­istered IV or via intraosseus catheter (IO) at a dose of 3 to 10mg/kg(Schumacher 2002a). The drug is admin­istered slowly over thirty to sixtyseconds or until the desired sedation is achieved. Propofol is eliminatedrapidly from the blood and therefore is suitable for short diagnosticprocedures or to achieve intubation for inhalant anesthesia. Its anestheticeffects may be extended by slow constant rate or intermittent infu­sion. Unlessan indwelling catheter exists in the patient to be sedated, other injectable orinhalant anesthetics are preferred. Propofol is an ideal anesthetic whenrepeated, daily sedation is required.Opioids such as butorphanol (Torbugesic) provide a smoother inductionwhen administered as a premedi­cation for injectable or inhalant induction.Butorphanol is administered IM at a dose of 0.4 to 2 mg/kg (Bennett 1996a). Theauthor uses 1 mg/kg IM routinely for reptile surgical anesthesia.The benefits of the anticholinergics atropine or gly-copyrollate(Robinul) as preanesthetic medications in lizards are questionable. Atropine isadministered IM at a dose of 0.01 to 0.04 mg/kg and glycopyrrolate isadministered IM or SC at a dose of 0.01 mg/kg (Bennett 1996a). In mammalsanticholinergics are administered to decrease salivary and respiratorysecretions and for counteracting bradycardia during general anesthesia. Thesedrugs may thicken respiratory secretions in rep­tiles (Murray 1996), causingtracheal or endotracheal tube occlusion, and their efficacy at reducing theinci­dence of bradycardia is uncertain.Inhalant anesthetics are preferred for maintenance of general anesthesiain lizards. The inhalant anesthetic of choice for lizards is isoflurane(Aerrane). Another recently introduced inhalant anesthetic is sevoflurane(Schumacher 2002a). Halothane and methoxyflurane are not recommended.Isoflurane provides relatively rapid induction if used alone for short sedationproce­dures. Because ventilatory suppression is common during anesthesia,recovery, though smooth, is pro­longed (up to fifteen minutes) compared to thetypical recovery of mammals of similar size induced and main­tained onisoflurane. The author has observed no benefit of quicker induction withsevoflurane in lizard patients. Additionally, recovery is typically as long orlonger with sevoflurane compared to isoflurane for both healthy andhealth-compromised lizards. Based on the dramatic price difference betweenthese inhal­ants, isoflurane is still the inhalant anesthetic of choice forlizards (Figure 6.14).Figure 6.14. Mask anesthetic induction ofa lizard.102  Chapter 6Lizards should be intubated for inhalant anesthesia whenever possible.Intubation is relatively easy for the sedated lizard. The glottis is visible inthe floor of the mouth at the base of the tongue. Minimal lubricant, if any, isapplied to avoid obstruction of the small diam­eter tracheal tube (2mm to 4mm).Lizards that are too small for intubation may be maintained on a mask. A coneconstructed of appropriate size syringe casing covered by a rubber glove,similar to that used for rodents, is ideal.Reptilian respiratory physiology differs from that of mammals. Inreptiles the spontaneous ventilation rate is directly related to temperatureand the partial pres­sure of oxygen (P02) and in mammals respirationis driven by carbon dioxide (PC02) (Murray 1996). Thus, in highoxygen environments spontaneous ven­tilation is suppressed because the demandfor oxygen by tissues is met by the oxygen saturation of inhalant anesthesia.As with mammals, control of the airway during anesthesia is helpful for thecontrol of depth of anesthesia and is essential for assisted ventilation.Breath holding is a common problem during the induction phase of inhalantanesthesia in some lizards. Because lizards experience profound respira­torydepression during general anesthesia, assisted or intermittent positivepressure ventilation (IPPV) venti­lation is commonly required.IPPV is performed at two to four breaths per minute at a pressure ofless than 10 cm water in medium to large lizards and much less in smallerlizards (Bennett 1996a). Ideally the anesthetist should visualize rib expansionfor several cycles of IPPV to discern the ideal pressure or ventilatory volumebefore the patient is draped. Toavoid excessive pulmonary pressure and possible pulmonary rupture, the pop-offvalve should never be fully closed when ventilating reptile patients. The greatmajority of lizards are maintained on a non-rebreathing anesthetic circuit. Anoxygen flow rate of 300 to 500 ml/kg/minute is indicated. Lizards over 5 kg canbe maintained on a closed or circle circuit (Bennett 1996a). Isoflurane istypically maintained at 1.5% to 3% depending on the sedation obtained byinjectable anesthetics.Anesthetic monitoring is essential during reptilian sedation. Unlikesnakes, cardiac movement may not be detectable through the chest wall becauseof the pres­ence of a cartilaginous sternum. Contrary to some reports, theauthor has found pulse oximetry to be satisfactory in monitoring at least theheart rate of sedated lizards. For small lizards the finger probe may be placedacross the dorsal head with the infrared transducer above the head and thereceiver in the mouth. For larger lizards, the orientation is reversed on themandible, or may be placed across the tongue. The advantage of pulse oximetryis the detection of blood flow that is reflective of mechanical cardiacactivity as opposed to simply the detection of cardiac electrical activity thatmay continue after mechanical activity is compromised. Electrocardiography(ECG) is also valuable and is used with a three lead system. A Doppler bloodflow probe may be taped to the thorax over the heart for audible blood flowmonitoring.Reptile patients are warmed during surgical anes­thesia with waterrecirculating heating pads. Electrical heating pads put the patient at risk forthermal burns. Surgical temperature should match the POTZ for a given species,but a range of 78°F to 85°F is sufficient for most patients. Supplementalheating is also indi­cated during the entire phase of anesthetic recovery.Lizards sedated with injectable anesthetics may require hours to recover. Indebilitated animals, this time is prolonged. For ketamine and telazol, recoverytimes from one to ninety-six hours are reported in reptiles.SurgeryCeliotomy is commonly performed in lizards for the surgical proceduresalready listed. Surgical preparation for lizards is similar to that of smallmammals. The lizard is placed in dorsal recumbency with legs and tailrestrained by tape to the surgical table. The surgical site should be scrubbedwith mild detergent if neces­sary to remove dirt or debris. Standard surgicalprepa­ration is performed. The author uses or chloroxylenol 2% (Vet Solutions,Fort Worth, TX) as the sole surgi­cal preparation. This agent, similar tochlorhexidine, provides excellent antibacterial and antifungal activity oncontact. Surgical draping is required. A fenestrated paper drape or acombination of clear plastic and fenestrated paper drape is used. The benefitof clear plastic drape is visualization of the patient for anes­theticmonitoring during the surgical procedure (Bennett and Mader 1996).Surgical incisions are made with consideration for skin and abdominalmusculature lines of force, trauma to tissues, visualization of the desiredsurgical field, and wound healing. The long accepted standard approach toceliotomy is the ventral paramedian inci­sion in an effort to avoid transectionor manipulation of the large ventral abdominal vein (see Anatomy). Thisincision requires the transection of ventral abdominal muscle, which increasessurgical bleeding, may decrease surgical field visibility (both from bleed­ingand from left versus right coelom access), and may increase post surgical painwhen compared to a ventral midline incision through the linea alba. In largerlizardsLizards  103the ventral abdominal vein may be gently retracted during the ventralmidline incision.The most common procedures performed during celiotomy are ovariosalpingectomyor salpingotomy for dystocia, ovariectomy, orchiectomy, and enterot-omy. Inmost cases hemostatic clips are used for liga­tion of ovarian and oviductalvessels as indicated by surgical procedure. Great care must be exercised whenhandling all reproductive and mesenteric tissues in lizards, because they aredelicate and quite friable. Closure of the celiotomy incision is two layersconsist­ing of abdominal musculature or linea with absorbable suture, followedby the skin. The skin is closed in an everting pattern with absorbable ornon-absorbable tissue or skin staples. Reptilian skin heals significantlyslower than mammalian skin. Suture removal is delayed until a minimum of fourto six weeks post surgery (Bennett and Mader 1996).A common non-celiotomy surgical procedure is digit or limb amputation.This procedure is indicated when trauma sustained from bites of cage mates,bites from rodents, or fractures result in non-healing wounds or ascending limbinfection. Surgical preparation is standard as in celiotomy. Amputation isperformed at the most distal non-infected joint for limbs and prefer­ably atthe metacarpal or metatarsal-phalangeal joint for digit amputation. Generalanesthesia is required for limb amputations. Peripheral nerve block may be per­formedfor some digit amputations.Amputation of the hemipenes is indicated in cases of paraphimosiscomplicated by trauma, infection, or necrosis. This procedure may be performedwith appropriate sedation using only injectable anesthetics such as ketamine,tiletamine/zolazepam, or propofol. Aseptic preparation is standard. Amputationof one hemipene does not sterilize the lizard because the hemipenes are paired.No compromise of urinary func­tion will result from amputation, because thereis no incorporation of urinary structures in the hemipenes or penis of reptiles(Barten 1996d).Percloacal prolapse of colon, oviducts, or urinary bladder may requireamputation or resection of the affected tissues. Exposure of affected tissuesor severe trauma may result in necrosis if the prolapse is not reduced promptlyafter occurrence. Necrosis of large portions of these tissues may requireceliotomy to evaluate viability and repair the affected organ.Open reduction and internal fixation of long bone fractures in reptilesare performed following surgical approach and principles applied to mammals.Intramedullary pins, orthopedic wire, external skeletal fixation, and boneplating are employed as indicated.Orthopedic devices are removed following the prin­ciples used inmammals, though healing of fractures in reptiles is slow and hardware mayrequire removal prior to radiographic evidence of complete bone healing(Bennett 1996b).PARASITOLOGYMany reptile owners are unaware of the prevalence of parasitism in theiranimals. It is safe to assume that all wild-caught reptiles are parasitized(Lane and Mader 1996). Commonly many captive-born reptiles are sub-clinicallyparasitized. In wild animals internal parasites maintain a homeostasis with thehost animal, because the host is essential for the survival of the parasite anda means of transporting future generations of the para­site to suitable areasfor transmission to another host. Factors that maintain homeostasis include thehosts immune system and the dilution of infective stages of the parasite inthe environment that the host occupies. Thus, in many cases the captiveenvironment offers a prime opportunity for imbalances in favor of the para­sitethrough the stress and subsequent immunosup­pression of the host and throughthe increased risk of reinfection of the host due to concentration of infectivestages of the parasite.Based on an awareness of parasites in some reptiles, however, someherpetoculturists advocate the prophy­lactic treatment of all reptiles withantiparasiticides for the more common intestinal parasites (de Vosjoli andFerguson 1995). It is interesting, however, that the majority of hobbyists donot prophylactically treat for external parasites. This is perhaps because ofan under­standing of the potential side effects of pesticides applied to theanimals. The side effects of oral deworm-ing are similar. Though sometherapeutics may be rela­tively safe at high doses, the potential effects ofkilling massive loads of intestinal parasites in an already immunocompromisedanimal can be severe. The safer alternative to prophylactic treatment ofparasites is quarantine, serial parasite screening, and treatment of specificclinically identified diseases.Techniques for identifying reptilian endoparasites are the same as thosefor small mammals. Fecal floata­tion of fresh fecal material in concentratedsalt or sugar solutions and wet mount direct smears in saline are essential toscreen for reptilian endoparasites. Smaller infective stages of some parasitesmay only be observed by direct smear. Stains such as Lugols iodine solution (5grams iodine crystals and 10 grams potas­sium iodide in 100 ml distilled water)both kills motile protozoans and stains cysts to make identification104  Chapter 6easier. Lane (1996) recommends examining both stained and unstaineddirect smears in addition to the fecal floatation.External ParasitesExternal reptilian parasites consist of ticks, mites, chig-gers,leeches, and biting flying insects. Acariasis, or mite, tick, or chiggerinfestation, is a serious disease of reptiles. Clinically tick infestations aremost common in imported lizards. Mader (1996a) reports that there are sevengenera of ticks and more than 250 species of mites that parasitize reptiles.Chiggers, also called red bugs, are the larval stage of Trombiculid mites andare generally self-limiting in lizards. Reptile mites (Ophionyssusnatricis) are mobile and highly transmis­sible between reptilesand are capable of infesting mul­tiple animals in a room or household withoutdirect contact between hosts. These mites may be transmitted between hosts onthe skin or clothing of people, though human infestation is supposedly rare.Reptile skin provides many sites for attachment and protection for bothmites and ticks. Ticks are com­monly found beneath scales or in crevices suchas the junction of the limbs and body or around the eyelids. Mites may be seencrawling freely over the lizard, but commonly concentrate in protected skinfolds. It is not uncommon to diagnose mites after handling a lizard and thenobserving them on the human skin or seeing dead mites in water bowls of lizardsthat soak them­selves routinely. Lizards that increase soaking behavior arecommonly infested with mites.Eradicating mites from individual animals is easier than eradicatingthem from the premises. Infestation of one animal indicates the possibility andlikelihood of widespread infestation. Thus, prevention through quarantine ofnew animals is imperative (see Husbandry) and treating the cage and cageaccessories and maintaining cleanliness of the surrounding envi­ronment isimperative.Treatment consists of physical removal of ticks and inspection for thepresence of ticks over several weeks. For mites the best treatment ispyrethroid flea sprays such as flea sprays for dogs and cats. Pyrethroids aresynthetic pyrethrins and are less toxic to reptiles than pyrethrins. Allethrinis a common example of a pyre­throid. Note: Sprays containing pyrethrins ororgano-phosphates should be avoided (Mader 1996a). Prior to spray application,mineral oil or ophthalmic lubri­cant should be placed on the eyes of lizards.The pyre­throid spray is then applied to the entire lizard and rinsedimmediately. Avoid spraying in the mouth or onto exposed wounds or mucousmembranes. Oral exposure increases the risk of toxicity. The spray must beapplied in a well-ventilated area and not into par­tially enclosed vivariacontaining animals. All exposed mites are killed on contact. Pyrethroids areeffective against mites in the environment, but not against eggs; therefore,reapplication on a weekly basis for two to three weeks is advised. The authoris unable to confirm reports on the safety of fipronil spray as a miticide inlizards.Ivermectin (Ivomec, Merck; and generics) is reported as both a topicaland systemic treatment for mites in reptiles (Klingenberg 1993). The topicalformulation is 0.5 cc ivermectin 1% (5mg) added in 1,000 cc water and appliedas a spray. The systemic administration is 0.2 mg/kg ivermectin 1% SC or PO.Clinical experi­ence reflects unpredictable results and variable degrees oftoxicity or side effects on a species-to-species basis with the injectableprotocol, though no lethality has been observed in lizards by the author.Topical admin­istration is absolutely not reliable. The miscibility andstability of ivermectin in water as a spray is questionable.Many over-the-counter pet industry products are available for mites.These are generally "soap and water" mixtures designed to reduce thesurface tension of water and allow water to penetrate the spiracles or airwaysof mites that essentially drowns the mite. The active ingredients are generallyfatty acids (listed by scientific name) in an aqueous base.Other home remedies include the use of pest strips,organophosphate-impregnated resins designed to kill flying insects. Theseproducts are also quite effective in killing reptiles. Unfortunately, if usedin a safe manner (or by sheer luck), these products have been effective inenvironmental control of mites in large collections. The narrow safety margin,however, pro­hibits recommendation of these products.Finally, some insecticidal powders (Sevin dust, Ortho) have beeneffective in environmental control (Mader 1996a). Their use on the floor ofwell-ventilated cages of large terrestrial lizards beneath paper or carpetsubstrate is effective. This treatment is particularly effective againstinfestations refractory to other topical and environmental treatments. The enclosureis typically treated continuously for a period of one month and possiblyrepeated in one month if indicated. Note: Prepare the client for a longduration of treatment and for the strong possibility of both the contagiousnature and high relapse rate of reptilian mite infestations. Also inform of thepotential side effects of treatments both to lizards and humans frompyrethrins, pyrethroids, and organophosphates.Lizards  105Internal ParasitesInternal parasites comprise many families and induce the majority ofparasitic diseases in lizards. It is pos­sible for many parasites to remainlatent in the body and manifest disease during host immunosuppression fromstress or other concurrent disease. Intestinal parasites consist of protozoa,nematodes, and trematodes.ProtozoansMany protozoa inhabit the gastrointestinal tract of lizards asnonpathogenic or commensal organisms. The amoeba Entamoeba invadens,variousspecies of coccidia, and specifically the coccidia Cryptosporidium spp. areresponsible for the diseases amoebiasis, coc-cidiosis, and cryptosporidiosis,respectively.Amoebiasis is directly transmitted by a fecal-oral route in reptiles andis pathogenic and highly virulent to some snakes and lizards. Amoebiasis is non­pathogenicin turtles and crocodilians, but may be transmitted by both (Lane and Mader 1996). The life cycle ofamoebiasis is as follows: the passing of infec­tive cysts from a host,ingestion of cysts by a suitable host, multiplication into trophozoites in theintestinal tract, invasion of trophozoites into host tissues, forma­tion ofinfective cysts, and shedding of infective cysts.The pathogenesis of clinical disease is multifactorial and is caused bythe tissue invasion of trophozoites and cellular destruction and from secondarybacterial infection. Clinical signs include diarrhea or loose mucoid stools,anorexia, dehydration, and weight loss. Infective trophozoites may spread toother organs hematogenously, causing inflammation and potentially organ failure(Lane and Mader 1996).Diagnosis is made by fecal examination. Cysts are identified by fecalfloatation or direct saline smear and trophozoites are identified only bydirect smear. For direct saline smears, a drop of Lugols iodide is helpful toimmobilize and stain the organisms.Treatment of amoebiasis consists of antibiotics and antiprotozoalmedications. Antibiotics are adminis­tered to treat potential secondarybacterial infections or potential septicemia. Aminoglycosides such as ami­kacinat a dose of 2.5 mg/kg IM or SQ every seventy-two hours for three to fivetreatments are appropriate. Metronidazole is administered at a dose of 50 mg/kgonce weekly for two to three weeks while checking fecal samples for cysts ortrophozoites (Lane and Mader 1996). Strict hygiene and sanitation are requiredto prevent horizontal transmission.Coccidiosis is directly transmitted by fecal-oral route and is caused byprotozonans of the generaEimeria, Isospora, and Caryospora. The life cycle ofcoccidia is similar to that seen in mammals: oocysts passed in the stoolsporulate outside the body and are ingested by a suitable host, sporozoites arereleased to invade host epithelial cells and mature, and the epithe­lial cellruptures and releases merozoites which infect other cells and then can eithermultiply to infect other cells or form intracellular gametocytes which eventu­allybecome infective oocysts to pass in the stool. Clinical disease results fromcellular destruction and from secondary bacterial infection. Detection ofoocysts is made by fecal floatation or direct smear.Understanding the pathophysiology is important because infective oocystsare shed intermittently; thus, clinical disease can occur in the absence of adetectable infectious agent. Clinically lizards may be asymptom­atic or havediarrhea, anorexia, weight loss, or failure to gain weight. The author hasobserved a higher inci­dence of coccidiosis in bearded dragons (Pogona spp.) than in otherspecies of lizard with routine fecal exami­nation. This phenomenon is alsoreported in popular literature (de Vosjoli et al. 2001). Many adult lizardswith coccidiosis appear to be asymptomatic carriers, but neonates and juvenileswith coccidiosis are usually clinically diseased. Coccidiosis can cause deathin small or young lizards if undetected and untreated.Treatment consists trimethoprim-sulfamethoxazole (Sulfatrim) at a doseof 30mg/kg PO once daily for fourteen days or sulfadimethoxine (Albon) at adose of 90 mg/kg on day one, then 45 mg/kg PO once daily for fourteen days(Klingenberg 1996,; Donoghue and Landenberg 1996, Lane and Mader 1996). Stricthygiene and sanitation are required to prevent hori­zontal transmission. Repeatfecal examinations are imperative.Cryptosporidiosis is a highly virulent pathogen of snakes and lizards.There is speculation regarding zoonotic potential, but at this point thispotential is unknown (Cranfield and Graczyk 1996). Becausecryptosporidiosis is considered untreatable in all animals caution should beexercised when handling infected animals. The pathogenesis of Cryptosporidiumin reptiles is not fully understood. Direct fecal-oral transmission is known tooccur and it is speculated that there is a possibility of indirect transmissionthrough an intermediate prey item. Cryptosporidiosis is reported in Lacerta spp., Chamaeleo spp., Iguana iguana, and two species ofgeckos (Cranfield and Graczyk 1996).Oocysts are diagnosed by direct smear. Oocysts are 4 to 5 um in size andare best identified by modified acid-fast staining (Cranfield and Graczyk1996). Serial106  Chapter 6fecal tests should be performed because of the intermit­tent shedding ofoocysts. Diagnosis may be achieved through histopathology from gastric mucosalbiopsy or by cytology of gastric lavage.Though no treatments are known to be 100% effec­tive, Sulfatrim as dosedfor coccidia and the human drugs spiramycin and paromomycin have been used.Suspected or known positive animals are best isolated, not bred, and handledlast in the maintenance of a collection of animals. Many traditionaldisinfectants have proved to be ineffective in environmental control. Ammonia solutionsat 5% for a period of three days are effective for disinfection (Cranfield andGraczyk 1996).NematodesVarious nematodes infect lizards. Those infecting the gastrointestinaland respiratory tracts include various species of the familiar roundworms andhookworms; pinworms, Oxyurus spp.; hepatic worms, Capillaria spp.; strongyles,Strongyloides spp.; and lungworms of the genus Entomelas. Treatment for allintestinal and respiratory nematodes follows descriptions.Roundworms in lizards are similar to those in mammals. Transmission isindirect and diagnosis is made by fecal floatation and identification of thetypical thick-walled round to ovoid oocysts. Diagnosis may also be made byidentification of the adult worm in feces or vomitus. Because they require anindirect life cycle, these parasites are most commonly observed in carnivorouslizards and occasionally in omnivores.Hookworms [Oswalsocruzia spp.) have direct transmission by fecal-oralroute or through skin pen­etration. Diagnosis is made by fecal floatation andidentification of the typical thin-walled oval eggs. Hookworms are responsiblefor more clinical disease in lizards than are roundworms because of the mucosalattachment of adult worms in the intestines. Clinical signs may include diarrhea,anorexia, and weight loss.Pinworms [Oxyurus spp.) have a direct transmis­sion byfecal-oral route and are found as adults in the large intestine of lizards.Diagnosis is made by fecal floatation and identification of the typicallyembryo-nated cigar-shaped larvae. Mammal pinworm ova or larvae may be passed inthe stool of carnivorous lizards but do not infect the lizards themselves.Typically pin­worms are an incidental finding on fecal examination, thoughdiagnosed infections should be treated.Hepatic worms [Capillaria spp.) have both direct and indirecttransmission by fecal-oral route or through infected prey ingestion, and theoocysts somewhat resemble those of whipworms [Tricburis spp.) of dogs. Capillaria spp. typicallyinhabit the intestinal tract but may also migrate to other organs. Pathologydue to these species is unclear. Diagnosis is made by fecal floa­tation andtreatment is indicated on identification.Strongyloides spp. have a somewhat complex life cycle with directtransmission by a fecal-oral route or through skin penetration. Strongyloides spp. inhabit thegastrointestinal tract and greatly resemble the lung-worms Entomelas spp. on fecalflotation. Diagnosis for either species is made by fecal floatation andidentifica­tion of larvae [Strongyloides spp.) orembryonated eggs [Entomelas spp.). Diarrhea, anorexia, or weight lossmay be seen with Strongyloides infection. Increased respiratory secretions,pneumonia, anorexia, and weight loss may be seen with Entomelas infections.Treatment of all intestinal and respiratory nema­todes consists offenbendazole (Panacur) at a dose of 50 mg/kg PO once daily for three days, thenrepeated in three weeks followed by repeat fecal flotation (Klingenberg 1996).Because the majority of nematode parasites have direct transmission, properhygiene and sanitation are imperative.CestodesTapeworms are infrequently encountered in captive lizards. Transmissionis indirect, typically through an arthropod intermediate host as seen in dogsand cats. Diagnosis is made by observations of proglottids in the stool oridentification of oocysts on fecal flotation. Treatment consists ofpraziquantel (Droncit) 5 to 8 mg/ kg PO or IM and treatment is repeated in twoweeks (Klingenberg 1996).Treatment of intestinal parasites in lizards is not without potentialside effects. Anecdotal reports of sudden deaths in Chamaeleo spp. treated withstan­dard single doses of fenbendazole and ivermectin (Stahl 1998) are knownand the author has observed this effect on several occasions. Over severalyears the author has made similar observations of a dramatic decline in healthfollowing the deworming of some individuals of wild-caught Uromastyx spp., Varanus spp., and Chlamydosaurus spp. at a reptilewholesale distribution facility. Some of the affected animals had no apparentcompromised health prior to treatment, but were housed with conspecifics inrelatively small cages, experienced repeated movement of humans around theenclosures, and may not have been on the optimal plane of nutrition (ColorPlates 6.9-6.20).EMERGENCIESMany health disorders of lizards are potential emer­gencies simplybecause of the latency in which they arePlate 6.9. Flagellate, original magnification 40x. (Photo courtesy of Zoo Atlanta.) (See also color plates)Plate 6.12. Oxyurid, original magnification 40x. (Photo courtesy of Zoo Atlanta.) (See also color plates)Plate 6.10. Roundworm, original magnification 40x.(Photo courtesy of Zoo Atlanta.)(See also color plate 6-13-Ascarid, original magnification 40x.plates) (Photo courtesy of Zoo Atlanta.) (See also colorplates)Plate 6.11. Ascarid, original magnification 40x. (Photo courtesy of Zoo Atlanta.) (See also color plates)Plate 6.14. Coccidia, original magnification 40x. (Photo courtesy of Zoo Atlanta.) (See also color plates)107Plate 6.15. Nyctotberus, original magnification 40x. (Photo courtesy of Zoo Atlanta.) (See also color plates)Plate 6.16. Strongyle larva, original magnification 40x. (Photo courtesyof Zoo Atlanta.) (See also colorplates)Plate 6.18. Eimeria, original magnification 40x. (Photo courtesy of Zoo Atlanta.) (See also color plates)Plate 6.19. Capillaria, original magnification 40x. (Photo courtesy of Zoo Atlanta.) (See also color plates)Plate 6.17. Pinworm and eimeria, originalPlate6.20. Pinworm, original magnification 40 x.magnification 40x. (Photo courtesy ofZoo Atlanta.)  (Photo courtesy of Zoo Atlanta.) (See also color (See alsocolor plates) plates)108Lizards  109presented or other related or consequential disorders with which theypresent. A few diseases or presenting complaints, however, are consideredcritical and death is imminent without immediate medical care. Some criticalcases may present moribund or deceased and may require the same level ofdiagnostic attention to determine the cause of death.TraumaTrauma, as with any animal, may be an emergency. Many cases of traumapresent ambiguously because the patient is found in a compromised state and theowner did not observe the inciting cause. Trauma should be suspected wheneverthe onset of clinical signs is acute; that is, within hours of the patientobserved in a normal state and no history of gradual onset of lethargy,anorexia, weight loss, pregnancy, or other abnormal physiology. The presence ofa thin or dehydrated animal or any history of anorexia should indicate thepresence of another or an additional underlying disease process. Infectious ormetabolic dis­eases rarely show acute clinical signs in lizards.Diagnosis of trauma may be speculative because no external clinicalabnormalities may be apparent. Radiography is the desired diagnostic test toevaluate for abnormal anatomy. Hematocrit and blood profile parameters may benormal, though creatine kinase (CK) values are commonly elevated with skel­etalmuscle injury. Radiographically suspected intra-coelomic fluid may be aspiratedfor analysis.With a high degree of suspicion of traumatic injury, empirically deriveddoses of corticosteroids are indi­cated in addition to providing proper thermalgradient. Warmed intravenous, intraosseus, or intracoelomic fluids areindicated for hypotension. Stabilization of fractures or luxations is performedfollowing cardio­vascular and thermal stabilization.ToxicityUnless presented with the known history of chemical toxicity, theveterinary staff must be meticulous at obtaining a history to support thisdiagnosis. The clini­cal signs of chemical or pesticide toxicity in reptilesare ambiguous, which leads to a diagnosis by exclusion of other metabolicdiseases and delay in appropriate treatment. Generally, chemical toxicities inlizards are relatively acute and have no history of anorexia, paral­ysis, orweight loss preceding the onset of clinical signs.The most common exogenous chemical toxicities in lizards are exposure topesticides containing pyrethrins or organophosphates that are applied to treatmite infestations of the patient or the enclosure. Profound depression, death,or a variety of neurologic abnor­malities including muscle posturalabnormalities, tremors or fasciculations, seizures, and paralysis may occur.With reasonable suspicion of pesticide toxicity treatment is similar tothat of mammals, including cleaning or removal of the inciting cause,supportive care, and treatment with anticholinergics (see Common Disorders).Diazepam at 2.5 mg/kg IV or IM is reported for seizures (Rossi 1998a,Schumacher 2002b).Hypocalcemic Metabolic Bone DiseaseThis form of metabolic bone disease (MBD) is sepa­rated from the classicosteopathic MBD. Diagnosis of hypocalcemic MBD should be suspected of anypatient presenting with abnormal neurologic signs and no history of trauma ortoxin exposure. Physiologically this disease is gradual in onset, though theonset of clinical signs may be acute or subtle and unnoticed by the owner.Herbivorous or insectivorous lizards are clinically most affected, but alllizards are susceptible to hypocalcemia. History regarding diet and lightexposure may help to confirm suspicion of this disease prior to diagnostictesting.The most common clinical signs include hind limb paresis or paralysis,muscle fasciculations or twitching, and depression. It is not uncommon for theonly clini­cal sign to be hind limb paresis with a normal appetite and no otherphysical abnormality. The progression of clinical signs from paresis toprofound mental depres­sion is usually gradual. Hypocalcemic MBD is a criticalemergency when the patient is substantially depressed or stuporous.Diagnosis is highly suspected and supported by history in herbivorouslizards fed improper diets, no calcium or vitamin D3 supplements, orlittle to no exposure to ultraviolet light. Diagnosis is confirmed with bloodchemistry. Radiographs may be helpful in excluding other disorders such astrauma or dimin­ished bone density, but they do not confirm hypocalcemia.Treatment is supportive with warming; IV, IO, or IC fluids; and calciumgluconate at 100 mg/kg SC, IM, or IC. Treatment is long term and prognosis forrecov­ery is grave for the most critical cases.Gastrointestinal ObstructionSigns of gastrointestinal obstruction may be vague, though historysupports a gradual onset (days) of anorexia, constipation, depression, weightloss, bloat­ing, and rarely regurgitation. All species of lizards aresusceptible, but terrestrial lizards are much more likely to ingest foreignmaterials from their environment. Impaction or constipation may occur inarboreal insec­110  Chapter 6tivorous lizards, especially if dehydrated. A diagnosis of obstructionmay also be supported by a history of feeding improper foods, such as processedmeat prod­ucts to herbivores.Diagnosis is based on history, physical exam, and radiographs. Theradiographic presence of a foreign body or generalized gas distention of smalland/or large intestine is indicative of obstruction. Because large herbivorouslizards have a relatively large disten­sible gut and relatively narrow pelviccanal, obstruc­tion may occur much lower in the gastrointestinal tract than isclassically seen in dogs and cats. Obstructions at the pelvic inlet exhibitmarked abdominal bloating and commonly large and small intestinal gas disten­tion.If these signs are observed radiographically in the absence of a detectableforeign body, retrograde per­cloacal barium is indicated to identify theobstruction. On rare occasions repeated enemas administered by the owner orveterinary staff may result in colonic perforation and stricture that may mimicforeign body obstruction. With the degree of gas distention com­monly seen inobstruction, ultrasound may be of little value diagnostically.With high degree of suspicion of obstruction in the depressed patient,supportive care and surgery are indicated. Trocharization to relieve gas is notindicated because the thin gastrointestinal membranes may rupture and spilltheir contents into the coelomic cavity. Careful advancement of an oral feedingtube may aid in the reduction of bloating presurgically.DystociaDystocia, also called egg-binding, in oviparous lizards has varyingdegrees of presentation in lizards with many similarities to birds. Single ormultiple eggs may be retained and the lizard may be in varying degrees ofphysical health. Those lizards presented with dysto­cia in a profoundlyweakened state must receive imme­diate supportive care and surgery. Placementof IO catheter and fluid therapy is indicated.Diagnosis is confirmed with history, physical exam, and radiographs.Ovario-salpingectomy is indicated for lizards with dystocias of more than a fewretained eggs because surgery time is greatly extended for multiplesalpingotomy incisions that are required for multiple eggs. Lizards retainreproductive ability when ovariosalpingotomy or unilateral ovariosalpingectomyis performed.PneumoniaThough generally a straightforward diagnosis, at first appearancepneumonia may be confused with severe cases of stomatitis with no associatedrespiratory disease in lizards. History usually indicates a gradual onset ofdisease with a moderate to prolonged period of anorexia, weight loss, andincreased respiratory effort. Oral or nasal exudates may or may not be present.Thorough physical exam, including thoracic auscultation and thoracicradiographs, is required for definitive diagnosis of pneumonia. Stomatitis maybe concurrent or absent. Profound weakness and depression may be the result ofprofoundly reduced ventilatory capacity or secondary septicemia. Diagnosticsand medical treatment are discussed in Common Disorders.Oxygen therapy is generally not indicated due to respiratory suppression(see Anesthesia). IO fluid therapy and antibiotics are indicated. Nutritionalsupport may be required for prolonged periods. Asphyxiation is a concernbecause the lizard may be too weakened to expel pulmonary exudates. Passage ofa rubber feeding tube and aspiration of tracheal secretions may be performedwith caution. Transtracheal wash procedures are performed only in patients thatare not critically compromised.Cloacal ProplapseCloacal prolapse is diagnosed by physical examination alone. Thisdisease is an emergency with respect to potential necrosis and loss of tissuefrom time delay in presentation and treatment.First aid of cloacal prolapse is cleaning and hydrat-ing prolapsedtissue with isotonic solution. Following diagnosis of the specific nature ofthe prolapse, hyper­tonic solutions such as 50% dextrose may be applied toreduce swelling. Sedation or general anesthesia is often indicated to reducepatient struggling and pain. Reduction of viable tissue is first attempted man­uallywhen possible and then approached surgically. Systemic antibiotics areindicated despite the method of reduction. Corticosteroids may be administeredempirically. The occurrence of reperfusion injury in reptiles is not known.TECHNIQUESIntravenous and Intraosseous Catheter PlacementIntravenous (IV) catheter placement is generally limited to the mediumto large species of lizards, approxi­mately 20 cm or larger, in the cephalicvein, though there is no reason not to consider catheterization of smallerlizards with proper equipment and skill (Figure 6.15). Sedation is required forcatheterization (Jenkins 1996).Lizards  111Figure 6.15. Cephalic catheter placement.Standard sterile preparation of the catheterization site is performedand a transverse skin incision is made across the dorsal distal aspect of theantebrachium, just dorsal to the carpus. The incision in smaller lizards can bemade with the sharp angle of a hypodermic needle or with a scalpel blade in thecase of larger lizards. Once the vein is identified, standard catheter­izationtechnique is used with an appropriate sized intravenous catheter. The catheteris secured with tape or suture.Intraosseous (IO) catheters are indicated in smaller lizards or thosewith anatomy or disease that prohibits intravenous catheter placement. Thebones of choice for intraosseous catheterization are the femur, tibia, orhumerus. Consideration must be given to the location with respect to theability of the patient to interfere with or manipulate the catheter whilehospitalized.For femoral IO catheterization, standard sterile preparation isperformed over the distal femur and a spinal needle of appropriate size ispassed through a cutdown in the skin. The needle is advanced through thecortical bone of the distal diaphysis and then directed proximally into themedullary cavity of the bone. The tip of the needle should rest in themedullary cavity approximately one-third the distance from the proximal femur(Jenkins 1996). The catheter is then secured with taping that will alsosomewhat immobi­lize the stifle (Figure 6.16).Sterile hypodermic needles of appropriate size may be used if spinalneedles are not available. The tibia is catheterized with a proximal to distalapproach. Intravenous and intraosseus fluid therapy is performed with lactatedRingers solution (LRS) and LRS + 2.5% dextrose at a rate of 0.5 to 1ml/kg/hour (Jenkins 1996).Figure 6.16. IO catheter placement.VenipunctureBlood collection in lizards is performed from the caudal tail vein orrarely from the ventral abdominal vein. Small patients are placed in dorsalrecumbency and may be wrapped in a towel to ease restraint. Large lizards mayremain in ventral recumbency with the tail supported off the edge of a table.Fractious, dangerous, or very small and delicate lizards may require briefanesthesia for blood collection.A portion of the proximal third of the tail from the vent is selectedand aseptically prepared as if for surgery. A needle of appropriate length andgauge is selected for the patient. For lizards greater than 60 cm total length,a 22-gauge 1- to 1.5-inch needle on a 3-cc syringe is appropriate. For lizardsless than 60 cm total length, a 22- to 25-gauge 0.5- to 0.75-inch needle on a1-cc syringe is appropriate. For lizards less than 25 cm total length, a27-gauge 0.5-inch needle on a 1-cc or smaller syringe is appropriate. Insulinsyringes are commonly used for these smallest patients.Blood collection is performed in a manner similar to that ofvenipuncture of the tail vein of a cow. The needle is advanced through the skinalong the ventral midline in a perpendicular to slightly cranially directedangle until the tip of the needle contacts the vertebral body. Slight vacuum isapplied to the syringe as the needle is slowly withdrawn until blood is seenentering112  Chapter 6the needle hub. Blood collection is slow and may require fifteen tothirty seconds for large lizards and up to forty-five seconds for smallerlizards.Care is taken to slowly expel blood into the collec­tion tube(s) toprevent hemolysis from narrow-gauge needles. Lithium heparin (green top) tubesare the col­lection tube of choice for reptile biochemistry and complete bloodcount (CBC). EDTA may lyse reptilian erythrocytes when used for CBC (Mader andRosenthal 2000). Whenever possible, the needles of 25 gauge or smaller shouldbe removed from the syringe prior to transferring blood. Most labs that performreptilian blood chemistries are capable of using samples as small as 25 uL(0.25 cc). CBC may be submitted as a blood smear instead of whole blood whenonly a small sample is available for serum chemistry.The ventral abdominal vein may be accessed in very small lizards or inthose in which tail autotomy is likely. These patients should be anesthetized.The blood collection site is prepared with the patient in dorsal recumbency andaccessed along the ventral midline at a point between the sternum and one-thirdthe distance proximal to the pelvis. The bevel of the needle is directeddorsally and the needle advanced just beneath the skin while applying slightsuction (Jenkins 1996). Blood collection may be faster when comparedto collection from the ventral tail vein. Cardiocentesis is not recommended forblood collection in lizards because of the risk of trauma and the relative lackof access of the heart in lizards (Figure 6.17).Transtracheal WashMicrobiology and cytology specimens may be col­lected from the lungs ina matter consistent with that of mammals. The glottis is easily visualized inpatients that cooperate with opening the mouth. Light sedationCaudal VeinFigure 6.17. Lizard venipuncture sites.Lizards  113may be required for patients that are reluctant to open the mouth.Following a diagnosis of pneumonia a sterile catheter of appropriate diameterand length is advanced through the glottis and directed into the right or leftlung as indicated by radiographs. A sterile wire may be inserted into thecatheter and molded (using sterile technique) to aid the direction of the tipinto the left or right mainstem bronchus (Murray 1996). At no time should thetube be forced if resis­tance is encountered. A speculum is employed to keepfingers out of the mouth and aid in visualization during the procedure.Following placement of the catheter, warmed (to ambient temperature ofthe patient) sterile saline solu­tion is infused at a dose of 1 to 5 ml/kg bodyweight and then retrieved into the syringe (Murray 1996). Repeated flushing ofthe saline, gentle coupage, or gentle rolling of the patient followinginfusion, increases the return of diagnostic material. Following collection thepatient is carefully monitored for normal respiration and heart rate. Samplesshould be sub­mitted for appropriate culture and sensitivity and cytology.Portions of the sample may be preserved in EDTA or fixed on a microscopic slidefor cytologic analysis.When transtracheal wash is contraindicated, bacte­rial culture andsensitivity may be obtained from pulmonary exudates swabbed from the glottis bycul-turette. By observing the patients respiratory cycle, a microtipculturette is carefully inserted into the glottis and then retrieved in a matternot to retrieve oral secre­tions. This method may not reflect the bacterialpopu­lation present in the lower respiratory tract.Cloacal and Colonic Wash and EnemaTechniques for cloacal and colonic wash are applicable for microbiologicand cytologic sample collection, enema, and barium administration for contrastradi­ography. Colonic wash is performed in the absence of a fresh fecal samplefor parasite analysis. Retrograde percloacal colonic catheterization is not asroutine and as simple as performed in mammals and improper technique can resultin severe health consequences to the patient. Sedation is not commonly requiredexcept in fractious patients.A clean catheter similar to that used for transtra­cheal wash, asaline-filled syringe, and water-based lubricant are used. Dosage for colonicwash is approxi­mately 10ml/kg (Schumacher 2002b).Copious lubrication of the tube is recommended for all procedures.Careful and slow advancement of the catheter in a retrograde fashion throughthe cloaca will reach the colon. On occasion the urinary bladder may beaccessed accidentally. The urodeum lies ventrally and the coprodeum liesdorsally in the cranial cloaca.It is imperative not to force the catheter if any resis­tance isencountered upon advancement. The coelomic tissues may be ruptured easily andthe technician or clinician may not perceive a rupture based on the resistanceencountered. Occasionally, the slow infu­sion of fluid upon advancement of thecatheter will aid in reducing resistance, especially with constipated animals.Once the catheter has reached the lower intes­tine, saline solution is infusedand retrieved several times and gentle massage of the colon may be applied tomaximize return of diagnostic material. A swab and floatation may be performedon the retrieved sample.Administration of saline or stool softeners such as docusate sodiumsolution is applied in a similar manner to that of other companion animals.Resistance should never be achieved upon the syringe plunger with theadministration of any colonic solutions.In the event of suspected or confirmed iatrogenic colonic or cloacalrupture, surgery is immediately indi­cated for primary repair of the defect andcopious lavage of the coelom. Most cases of iatrogenic ruptures unfortunatelygo unnoticed until the animal presents with life-threatening coelomitis andsepsis.Cloacal swabs for bacterial culture and sensitivity may be obtained in amanner similar to that performed in birds. Washing of the external vent isindicated to reduce contamination of the culturette upon insertion and sampleretrieval.BandagingBandage application and wound care for skin defects are consistent withthose of other companion animals with the exception that the healing process ispro­longed. Except for deep or extensive wounds or those that may becomecontaminated, wounds on most lizards are best maintained open in a cleanenviron­ment rather than bandaged. Bandages may be cumber­some to lizards ormay be a source of rubbing or other behaviors that attempt to remove thebandage. Tape is contraindicated on all geckos or other lizards with fragileskin.Bandage application may be indicated for tail autotomy and amputationstemporarily after surgery. Application of antibiotic ointments and gauze-packedsyringe casings are ideal to allow hemorrhage control and preventcontamination. Typically these bandages are required for only a few days.External coaptation of limbs is commonly per­formed as part of fracturemanagement using materials and techniques applied for other companion animals.The same principles of stabilizing one joint above and114  Chapter 6below the fracture are followed. A potential splint for larger lizardsis their own body. Under sedation fore-limbs are secured to the lateral chestwall, with care not to compress the chest cavity, especially in sedatedanimals. A similar application may be employed with the hind limb to the tail.With this technique, however, proximal humeral and femoral fractures may notreceive adequate reduction in motion of the proximal bone fragment, resultingin malalignment.Spica splints are ideal for both forelimb and hind limb unilateral orbilateral fracture management. Under sedation the rigid splint for forelimbhumeral fractures is incorporated into the soft bandage ventrally across thesternum and in the hind limb the splint is applied dorsally across the dorsalpelvis. The soft support bandage of the hind limb is wrapped in a figure-eightpattern incorporating both hind limbs dorsally, creat­ing abduction of bothhind limbs. A similar technique is applied forelimb soft bandage. Thistechnique allows for the cloaca to remain free of bandage material and toreduce contamination of bandage material (Bennett 1996b). For more distalfractures of limbs a modified Robert Jones bandage incorporating or encased bya plastic syringe casing and stirrups is ideal.Carpal, tarsal, and digital fractures may be bandaged with soft bandagematerial. A ball bandage comprised of a cotton ball applied to the palmar orplantar aspect of the affected foot is wrapped by soft bandage (Bennett 1996b).For all bandage applications, lizards should be maintained on clean non-organicsubstrate such as paper or carpet, including those lizards requiring a higherhumidity environment. Strict attention is given to cage and bandage sanitationand hygiene.Assist FeedingOne of the most common signs of any disease state in lizards isanorexia. Assist feeding is employed when the normal feeding response isdiminished or when the animal is physically incapable of normal prehension orswallowing of food or water.The technique for assist feeding may also be applied to gastric oralmedication administration and diagnos­tic gastric lavage. Some species oflizards may require sedation to access the oral cavity {Uromastyx spp., Corucia zebrata, and occasionally Iguana spp. and Varanus spp.). These species,especially Uromastyx and Corucia, are candidates forpharyngostomy tube placement when repeated force feeding or oral medica­tion isrequired.Assist feeding of lizards is accomplished in several ways. Voluntaryfeeding for smaller lizards is applied when the patients normal feedingresponse or mobility is compromised, but with a little enticement the patientwill readily prehend and swallow food. For large or dangerous lizards, tongs orforceps are used to intro­duce food. Assist feeding is used for patients thatcan swallow but are otherwise reluctant to prehend prey items; the mouth may begently opened and the food item placed into the mouth for the patient toswallow. Prepared foods such as vegetarian gruels may be fed by syringe in thismatter. Assist feeding is used for patients that are depressed and will notswallow or are incapable of chewing; food is provided by gastric orpharyngostomy feeding tube.For insectivorous and carnivorous species that are fed only every otherday or every few days in normal health, the normal feeding schedule may remainthe same. It is important for all lizards to not over feed, especially ifassist feeding normal dietary food items. Constipation or obstruction canresult from overzeal-ous feeding in these patients. For those species fedspecially prepared gruels either by mouth or through a feeding tube, dailyfeeding is recommended because it is likely that these diets are more rapidlydigested and absorbed when compared to the diet of normal health.The procedures of tube assist feeding are similar to those applied forneonatal companion animals. The stomach of quadruped lizards is measured to thelast few ribs. Anguiform lizards are treated as snakes for tube feedingpurposes. Rubber catheters or stainless steel ball-tipped dosing needles areappropriate to use as feeding tubes. Because of the stresses imposed on thepatient from restraint and opening the mouth by assist and force feeding,feeding frequency is generally no more than once daily for these patients. Alternatively,placement of a pharyngostomy tube accommodates smaller volume multiple dailyfeedings (Figure 6.18).Diets are based on identifying the patient as car­nivorous (includingjuvenile omnivorous) or herbivo­Figure 6.18. Assist-feeding.Lizards  115rous (including adult omnivorous). The amount of feeding is a calculateddaily energy need based on standard metabolic rate (SMR) measured in kcal/day.The formula is SMR = 32*BW77 where BW = body weight in kg. Alert andrelatively non-compromised patients receive 75% to 100% of daily energy needsin the first twenty-four to forty-eight hours. Weak or debilitated patientsreceive 40% to 75% of their daily energy needs in the first several days(Donoghue and Landenberg 1996). The amount offeeding of the daily energy requirement is gradually increased to 100% as thepatients health and responsiveness improve. And, because the goal of forcefeeding is to bring the patient back to voluntary feeding, the amount andfrequency of force feeding decreases or may abruptly stop pending the patientsrecovery.A variety of enteral diets are available for both human and veterinaryuse. These include: for omni-vores Ensure (Ross Laboratories, Columbus, OH),for herbivores Sustacal Enriched (Ross Laboratories, Columbus, OH), and forcarnivores Clinical-Care feline and canine liquids (Pet-Ag, Elgin, IL). Theavailable energy in kcal/ml as well as protein, fat, carbohydrate, and fibercontent are available on the packaging.Therapeutic AdministrationTreatment of lizard patients with pharmaceuticals is performed in amanner consistent with that of mammals with several exceptions. First, the oraladministration is not always the route of choice: (1) Oral access may bedifficult or stressful for some patients receiving daily medications; (2)gastrointesti­nal transit time and factors affecting absorption of medicationsvaries among species; (3) inexperience or reluctance of the client inadministering oral medica­tions may lead to unnecessary trauma to the patientor noncompliance by the owner. When properly coun­seled, however, most clientsenjoy the opportunity to take an active role in restoring the health of theirpets.Examples of antibiotics commonly administered orally in lizards are enrofloxacininjectable and com­pounded suspensions (Baytril), griseofulvin suspension(Fulvicin), metronidazole injectable and compounded suspensions, sulfamethazine(Albon), trimethoprim-sulfamethoxazole (Bactrim), and compounded tetracy­clines.Additionally, many injectable antibiotics or ophthalmic preparations may beapplied directly to oral mucous membranes rather than by injectable method toachieve higher drug concentrations at the site of infection. The parasiticidesfenbendazole (Panacur) and praziquantel (Droncit) are administered PO. Theauthor does not recommend the application of antibiotics to drinking water orto food items for lizards because of potential drug inactivity and thedifficulty in accurate dosing.Injections are performed using five methods. Subcutaneous (SC) andintramuscular (IM) techniques are most common. Intracoelomic (ICe) technique isused for large volumes of fluids or for drugs that need rapid systemicabsorption such as calcium gluconate. Intravenous and intraosseous aretypically performed through an indwelling catheter.It is generally uncommon for clients to administer injectablemedications to mammalian patients for routine infections. This practice isrelatively common for reptile patients, but it must be approached with greatattention to both the clients ability and the patients cooperation.Considerations include:1. What is the risk ofinjury to both the client and patient from the proposed procedure?2. Is the clientcapable of adequately restraining the patient while administering themedication?3. Is the clientcapable of determining if an undesirable side effect has occurred thatprohibits further treatment?4. Is there risk forabuse of the medication dispensed?When dispensing injectable medication for the client to administer,adhere to the following:1. Dispense themedication premeasured in syringes for each dose and only the amount for thespecified number of doses. Administration should be only by the SC or IM routefor home administration. If long-term treatment is required, dispense a portionof the amount and only refill the medication with a recheck exam or consultation.Accurately and fully label drug name, concentration, route, frequency, andduration of administration with no abbrevia­tions. Never dispense medicationsthat are poten­tially dangerous to humans at the prescribed dose (large dosesof aminoglycosides, chemotherapeu-tics, narcotics).2. Describe, show, andallow the client to practice administration of the medication. Sterile salinemay be used for a practice injection.3. Instruct the clienton the appropriate uncapping and capping of needles and handling of the sterileneedle.4. Counsel the clienton potential side effects of the drug and potential side effectsadministration. Describe "what can possibly go wrong" scenarios.5. Provide the nameand number of an employee at the clinic who can be reached at any time if thereis a problem.116  Chapter 66. Have the client bring all medical waste products to the hospital orclinic for disposal.Subcutaneous injections are made in the lateral scapular region. Theskin is not drawn or lifted above the body wall as is common practice inmammals. The needle is advanced into the subcuticular space, gentle aspirationis applied to check for incidental venous access, and the injection isadministered. Serial injec­tions are alternated between the left and rightsides and among different locations within the region. Subcutaneous injectionsare contraindicated in most Chamaeleo spp., all Phelsuma spp., and manyother Gekkonidae because of skin autotomy, scarring, and skin discolorationcaused by the injection. PO admin­istration is indicated in these species.Intramuscular injections are administered in epaxial muscles or tricepsmuscles in large lizards. IM injections are generally not possible in smallerlizards. When possible, intramuscular injections are preferred for lizards todecrease the risk of skin inflammation.Intracoelomic injections are administered in the right lower quadrant ofthe abdomen slightly cranial dorsal to the rear leg (Klingenberg 1996). Drugs administeredin this way are sterile fluids, calcium gluconate, potassium penicillin, andsome injectable anesthetics.It is essential to understand not only the intended use of themedication, but also potential undesired or side effects. Side effects may bethe result of a single administration, a series of administrations, a route ofadministration, or a cumulative dose. Individual varia­tion as seen in mammalsmay also occur in reptiles. Side effects also involve the restraint ormanipulation necessary to administer a particular administration. Whenconsidering the use of therapeutics, the old adage "do no harm" mustbe remembered.EUTHANASIAEuthanasia of captive lizards may be required for several reasons. Theprocedures for lizard euthanasia more closely resemble those of domesticlaboratory animals than of dogs and cats. The relative inaccessi­bility ofperipheral veins for injection of euthanasia solution necessitates injection ofeuthanasia solution directly into the heart (Mader 1996b) or occasionally intothe occipital sinus or foramen magnum. Intracoelomic injection of euthanasiasolution can be performed, but cardiac arrest may be prolonged and detection ofdeath uncertain. The client must be fully prepared for euthanasia techniquesprior to perform­ing the procedures.Humane euthanasia in the veterinary hospital is best performed underheavy sedation with the dissocia­tive agents ketamine or telazol. Ketamine at adose of 100 mg/kg IM or telazol at a dose of 25 mg/kg IM will assure adequatesedation (Mader 1996b). Euthanasia solution as specified by the manufacturerfor mammals is applied to lizards. Injections may be given intracar-dially witha sternal or lateral percutaneous approach to the heart. If the patient isdehydrated or severely debilitated and the cardiac approach is not possible,injection into the occipital sinus is indicated.REFERENCESBalsai M. 1997. General Care and Maintenance of Popular Monitors andTegus. Escondido: Advanced Vivarium Systems.Barten SL. 1996a. Biology: Lizards. In: Reptile Medicine and Surgery,edited by Mader DR. Philadelphia: W.B. Saunders Co. 47-61.Barten SL. 1996b. Differential Diagnosis by Symptoms: Lizards. In:Reptile Medicine and Surgery, edited by Mader DR. Philadelphia:W.B. Saunders Co. 324-232. Barten SL. 1996c. Specific Diseases andConditions: Bites from Prey.In: Reptile Medicine and Surgery, edited by Mader DR.Philadelphia: W.B. Saunders Co. 353-355. Barten SL. 1996d. SpecificDiseases and Conditions: Paraphimosis.In: Reptile Medicine and Surgery, edited by Mader DR.Philadelphia: W.B. Saunders Co. 395-396. Barten SL. 2002. Diseases ofthe Iguana Oral Cavity. In: Proceedingsof the North American Veterinary Conference (16). Gainesville,FL.Bennett RA. 1996a. Special Techniques and Procedures: Anesthesia.In: Reptile Medicine and Surgery, edited by Mader DR.Philadelphia; W.B. Saunders Co. 241-247. Bennett RA. 1996b. SpecialTechniques and Procedures: FractureManagement. In: Reptile Medicine and Surgery, edited by MaderDR. Philadelphia: W.B. Saunders Co. 281-287. Bennett RA.  1996c.  Specific Diseases  and  Conditions:Cryptosporidiosis. In: Reptile Medicine and Surgery, edited byMader DR. Philadelphia: W.B. Saunders Co. 359-363. Bennett RA, Mader DR.1996. Special Techniques and Procedures:Soft Tissue Surgery. In: Reptile Medicine and Surgery, edited byMader DR. Philadelphia: W.B. Saunders Co. 287-298. 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In:Proceedings of the North American Veterinary Conference (14). Gainesville, FL.961-964.Mader DR. 2000b. Thermal Burns in Reptiles. In: Proceedings of the NorthAmerican Veterinary Conference (14). Gainesville, FL. 965-67.Mader DR. 2002a. Metabolic Bone Diseases in the Green Iguana.In: Proceedings of the North American Veterinary Conference(16). Gainesville, FL. 921-922. Mader DR. 2002b. Ventral MidlineApproach for the LizardCoeliotomy. In: Proceedings of the North American VeterinaryConference (16). Gainesville, FL. Mader DR, Rosenthal K. 2000. ProperCollection of LaboratorySamples.  Proceedings  of the  North  American VeterinaryConference (14). Gainesville, FL. 958-960. McKeown S. 1993. The GeneralCare and Maintenance of DayGeckos. Lakeside, CA: Advanced Vivarium Systems. McKeown S. 1996.Introduction: General Husbandry and CaptiveManagement. In: Reptile Medicine and Surgery, edited by MaderDR. Philadelphia: W.B. Saunders Co. 9-19. Mitchell MA. ArtificialLighting for Reptiles: What We Know andWhat you Need to Know. In: Proceedings of the North AmericanVeterinary Conference (23). Gainesville, FL. pp 1783-1785. Murray MJ.1996. Specific Diseases and Conditions: Pneumonia andNormal Respiratory Function. In: Reptile Medicine and Surgery,edited by Mader DR. Philadelphia: W.B. Saunders Co. 396-405.Obst FJ, et al. 1988. The Completely Illustrated Atlas of Reptilesand Amphibians for the Terrarium. Neptune City, NJ: TFH. Ritchie BW.1992. Class Notes: Exotic Animal Medicine. Universityof Georgia College of Veterinary Medicine. Rossi J. 1998a. Emergency Medicineof Reptiles. Proceedings of theNorth American Veterinary Conference (12). Gainesville, FL. Rossi J.1998b. Whats Wrong with My Iguana? Escondido:Advanced Vivarium Systems. Rossi JV. 1996. Special Topics: Dermatology.In: Reptile Medicineand Surgery, edited by Mader DR. Philadelphia: W.B. SaundersCo. 104-117.Schumacher J. 2002a. Anesthesia of Reptiles. In: Proceedings of theNorth American Veterinary Conference (16). Gainesville, FL: ESVA.Schumacher J. 2002b. Critical and Supportive Care of Reptiles. In:Proceedings of the North American Veterinary Conference (16). Gainesville, FL.Silverman S, Janssen, DL. 1996. Special Techniques and Procedures:Diagnostic Imaging. In: Reptile Medicine and Surgery, edited byMader DR. Philadelphia: W.B. Saunders Co. 258-264. Stahl SJ. 1998.  Common Medical Problems of Old WorldChameleons. In: Proceedings of the North American VeterinaryConference (12). Gainesville, FL. 814-817. Stahl SJ. 2000. ReptileObstetrics. In: Proceedings of the NorthAmerican Veterinary Conference. Gainesville, FL. 971-974. Williams DL.1996. Special Topics: Ophthalmology. In: ReptileMedicine and Surgery, edited by Mader DR. Philadelphia: W.B.Saunders Co. 175-184.CHAPTER SEVENSnakesRyan Cheek, Shannon Richards, and Maria CraneINTRODUCTIONKeeping snakes in captivity has become increasingly popular over theyears. With the increase in captive specimens there has is a large demand forveterinarians and veterinary technicians who are educated in proper husbandryand treatment of reptiles. The veterinary staff must be willing to keep up withcurrent treatment protocols (through continuing education courses orliterature) because reptile medicine is ever changing and still evolving. Oneimportant tool in the diagnosis of any reptile is a thorough history. This isimportant because most reptiles in captivity become ill due to improperhusbandry. Snakes kept in ideal conditions in captivity can live ten to twentyyears (depending on the species). This chapter contains general husbandryinformation on snakes to assist the veterinary staff through the diagnosticprocess.CAPTIVE-BRED VERSUS WILD-CAUGHTIt is important to know whether a captive snake has been wild-caught orcaptive-bred. Wild-caught snakes are those that have been taken from theirnatural habi­tats and sold through the pet trade. Unfortunately, this is acommon occurrence in the reptile industry. Wild-caught specimens typically haveparasites (ticks, mites, and various internal parasites) and can take a longtime to adjust to a captive environment, if they do at all. They also can havea host of other illnesses such as respiratory infections that become apparentwhile in captivity due to stress.Feeding wild-caught snakes can prove to be chal­lenging as well due totheir reluctance to eat in captiv­ity. This reluctance to eat is usually due tothe difficulties that a wild-caught snake may have adjust­ing to a captiveenvironment (especially if husbandry guidelines are not being followed) and notbeing offered the natural diet to which it is accustomed. For example, a snakefeeding primarily on frogs in its natural environment may not be receptive tothe white lab mice that are sold commercially as snake feeders. This is not tosay that it will never feed on mice in the future, but it will take some timeto adjust and may take some trickery.Captive-bred snakes are those that have been bred and raised in acaptive environment. These are obvi­ously better specimens due to their lack ofexposure to the diseases and parasites found in wild-caught speci­mens.Captive-bred snakes also accept commercially available diets better (such asfeeder rodents) when offered and are not as finicky about accepting prekilledprey items, which is the recommended method of feeding. Although thetemperament of a snake can never be guaranteed, those that are captive-bredtend to be more docile overall and can become more accus­tomed to handling.Captive-bred specimens should always be recom­mended to potential buyersto better ensure the snakes overall health. There are many reputable snakebreed­ers who can provide a more reliable history on the snake. In many casesthese snakes are less expensive than those bought from pet retail stores.BEHAVIORSnakes are solitary animals and should be housed sepa­rately unlessattempting to breed. Some can exhibit territorial behavior and be aggressive toother inhabit­ants. Signs of aggressive behavior toward other snakes includebiting, constricting, and head pinning. The head pinning is a courtshipbehavior as well. During breeding season, some of these behaviors are observedmore often. If these signs of aggression are observed with snakes being housedtogether, one should be removed immediately. As with any animal, if snakes arefighting, care should be taken if interference is119120  Chapter 7necessary to avoid being bitten while trying to separate the combatingsnakes. Using hooks or tongs is recom­mended when human interference iswarranted.Another downside of housing snakes together is that some species (i.e.king snakes) eat other snakes as part of their natural diet. Therefore, allking snakes should be kept separate. Size or gender does not affect the snakesinstinctive predatory behavior.Finally, it is also important to know whether the snake is diurnal(active during day hours) or nocturnal (active during night hours). Knowingwhen the snake is the most active will aid in making several decisions such ashandling and ideal feeding times.ANATOMY AND PHYSIOLOGY IntegumentAs in mammals, the skin of snakes plays several crucial roles. The skinis the cellular protective barrier from the snakes outside environment. Itprotects the body from microbes and parasites, resists abrasions, and buffersthe internal environment from the extremes of the external environment. Theskin holds other tissues and organs in place while being elastic enough toallow for respiration, movement, and growth. The skin also serves other rolessuch as physiological regulation, sensory detection, respiration, andcoloration.The snakes skin consists of two main layers, the dermis and epidermis.The epidermis is covered com­pletely by keratin. This layer of keratinouscells, stratum corneum, shields the living tissue below. The stratumgerminativum, the innermost layer of the epi­dermis, divides continuously toreplace the outer layer of dead keratinous cells. As the cells in the stratumgerminativum are pushed outward, they slowly flatten, die, and keratinize toform the stratum corneum. The stratum corneum is composed of three layers, theOberhautchen layer, the beta-keratin layer, and the alpha-keratin layer, fromthe surface inward, respectively.The dermis consists of two layers, the stratum com-pactum and thestratum spongiosum. The stratum compactum is the innermost layer of the dermis.It consists of densely knit connective tissue. The stratum spongiosum consistsof connective tissue, blood vessels, glands, nerve endings, and other cellularstructures.Ecdysis, or shedding of the skin, is a normal occur­rence for theduration of the snakes life. Young snakes shed much more often and begin tohave a longer resting period as they reach adult size. Because the top layer ofsnake skin consists mostly of keratin, which is dead material, it is incapableof expanding during the snakes growth process. Therefore, it needs to be shedevery so often. The cells of the upper stratum germinativum, theouter-generation layer, begin to proliferate and differentiate. The germinativelayer begins to divide, producing new layers of cells. These new cells form theinner generation layer, which is the precursor to scales, or theouter-generation layer, for the next ecdysis cycle. At this stage the newepidermal layer is ready. The Oberhautchen then fills with lymph and enzymaticaction produces a cleavage zone and the old epidermis is shed (Zug et al.2001).Before a snake sheds, it secretes a lubricant under­neath the outermostlayer of skin to assist with the shedding process. This lubricant is mostnoticeable on the snakes eyes, which become opaque or blue in color due tothis lubricant being secreted. The snake will begin to shed its skin sometimeafter this optical opacity or dullness in appearance is noticed.It can take a week or two before the entire shedding process is over andshould be repeated at regular inter­vals. The snake may attempt to use anyfurnishings in the enclosure to assist in removing the dead skin. Thefurnishings should be nonabrasive to avoid causing injury. The snake may alsoattempt to soak in its water bowl to assist in shedding. Water softens the oldskin and makes it easier to remove. If the humidity is too low, the snake mayhave problems shedding.A snake sheds its entire outer layer of skin all at once. All snakes,with the exception of large boids, should shed in one piece. If there arenumerous pieces of the snakes shedded skin or some still present on the snake,the shed is abnormal. Snakes with abnormal shedding may need husbandry changesor may have ectoparasites and should be checked thoroughly. Age, nutrition,species, reproductive status, overall health, and hormonal balance also play arole in frequency of ecdysis.If some shedding is still present on the snake, soaking or spraying canused to try to assist in the removal of the skin. Infections can occurunderneath the old skin if the skin is allowed to build up and not slough offnaturally.Snakes should not be handled or fed while they are in shed. Their sensesare dulled (eyes opaque) and because they feel vulnerable, they can also bevery defensive. To avoid potential bites, handling is not recommended duringthis time. It is unlikely that the snake will eat, so feeding should not occuruntil after it has shed. If offering live prey items, feeding should not occurwhile the snake is in shed due to the higher potential for rodent bites.Snakes are either entirely or partially covered by overlapping scales.The surface of each scale is com­Snakes  121posed of beta-keratin while the interscalar space, or sutures, iscomposed of alpha-keratin. This distribu­tion of keratin gives a protectivecovering while allow­ing for flexibility and expansion. Certain species ofcolubrids and viperids are nearly scaleless. These species may only have labialand ventral scales. The remainder of the body is covered in a smooth kerati­nousepidermis. This anomaly is a recessive homozy­gous trait.Snakes have paired scent glands at the base of their tails. These glandsopen at the outer edge of the cloaca. A large amount of semisolid, malodorousfluid is released for defensive behavior in some species and for courtingbehavior in other species.Musculoskeletal SystemSnakes possess a very complex cranial skeleton. They have acartilaginous anterior chondrocranium, the portion of the cranium that coversthe brain (Zug et al. 2001). This anterior portion of the chondrocra­niumconsists of continuous internasal and interorbital septa and a pair of nasalconchae (Zug et al. 2001). The chondrocranium calcifies between the eyes andears and forms the basisphenoid. Farther posteriorly, a pair of exoccipitals,the supraoccipital bones, and the basioccipital form just below and behind thebrain. These occipital bones encircle the foramen magnum. The exoccipitals andthe basioccipitals form a single occipital condyle and the articular surface ofthe skull and atlas.The maxilla is loosely connected to the other cranial bones. It connectsto a special process on the prefrontal bone. They are connected via a movablearticulation. The maxilla is also loosely connected to the cranial bones by theectopyerygoid (Romer 1997). The snout structures, premaxilla, nasal,septomaxilla, and vomer are movable as a separate series of bones from themaxilla and are also loosely connected to the cranial bones. This adaptationallows snakes to swallow large prey.The mandible is highly specialized to allow for a large gape whenswallowing large prey items. The mandible lacks a mandibular symphysis; anintraman-dibular hinge allows for the mandible to flex in the middle, and anarticulated streptostylic quadrate allows the mandible to move sideways.The vertebral column in snakes is divided into the atlas and axis, 100to 300 trunk or precloacal verte­brae, several cloacal vertebrae, and ten to120 caudal vertebrae (Zug et al. 2001). Each precloacal vertebra has a ribattached. The zygapophyses, the interverte­bral articular surfaces, possess aposterior and anterior pair on each vertebra. The anterior zygapophyses flareoutward and upward while the posterior zygapophyses flare inward and downward.The angle of the zyg­apophyses gives reptiles their flexibility or rigidity.Snakes are able to have such great flexibility due to these articular surfacesbeing angled toward the hori­zontal plane (Figure 7.1).The muscular system of snakes consists of several hundred multisegmentalmuscle chains composed of elongated and interconnecting segmental muscles andtendons. Movement is achieved through individual contraction patterns of themuscle chains. There are six types of locomotion divided into two classes(Pough et al. 2001). Lateral undulation and slide-pushing have no static pointsof contact with the substrate. Rectilinear, concertina, sidewinding, andsaltation do have static points with the substrate.Lateral undulation is the most widely used method of locomotion insnakes. At fixed points in the snakes environment, force is generated byhorizontal waves traveling down alternating sides of the body. These fixedpoints can be a rock, tree, or any other physical object that the snakecontacts. At each point the body generates a force that pushes itposterolaterally. Slide-pushing is similar to lateral undulation but does notuse fixed points in the physical environment. Slide-pushing involves very rapidalternating side body waves that generate sliding friction to propel the snakeforward.Concertina locomotion is very slow and consumes large amounts of energy.It is a very complex system of locomotion. First, the anterior portion of thebody remains still while the posterior portion draws up in a series of tightcurves. The posterior end is then station­ary and the anterior end extendsforward. The sequence then repeats. Concertina locomotion is most effectivelyused on the ground where static friction is used to prevent rearward slippage.Sidewinding is most commonly used on shifting soil such as mud or sand.Most snakes appear to have theFigure 7.1. Snake skeletal anatomy. (Drawing by Scott Stark.)122  Chapter 7ability to sidewind. The forces in sidewinding are directed verticallyon the substrate. Sections of the body are alternately lifted, moved forward,and then set down. This produces a series of tracts that are parallel-producingforward motion.Saltation involves a very rapid straightening of the body from anteriorto posterior, lifting the entire body off the ground. This is used only bysmall species. Rectilinear motion relies on the lateral muscles to work at thesame time. The costocutaneous superior muscles pull the skin forward relativeto the ribs. The ventral scales then anchor themselves to the ground. Thecostocutaneous inferior then pulls the ribs and with them the rest of the bodyforward relative to the stationary ventral scales. This form of locomotion isused by large-body snakes such as boids and vipers.Cardiovascular SystemThe HeartThe heart size, shape, structure, and position all depend on thespecies anatomy, physiology, and behavior. Heart position has a directcorrelation with arboreal, terrestrial, and aquatic habits (Vasse 1994).Terrestrial species have a heart that is close to the head and blood vessels inthe distal portion of the body that dilate to receive extra blood. The heart ofarboreal species is also located close to the head so that blood can moreeasily reach the brain when hanging vertically. Marine species have a heartthat is found in the middle of the body so the pumping effort is minimal. Theydo not have blood accumulation in the tail and the low blood pressure is compensatedfor by the external water pres­sure (Vasse 1994).The heart consists of three chambers, a right and left atria and asingle ventricle. The ventricle is further divided into the cavum arteriosum,cavum venosum, and cavum pulmonale. Although the ventricle lacks a septum, thesnake can still separate oxygenated and deoxygenated blood and can maintaindifferent sys­temic and pulmonary pressures because the heart is functionallyfive chambered (Pough et al. 2001). A muscular ridge in the ventricle separatesthe cavum pulmonale and the cavum venosum. The cavum arte­riosum is locateddorsal to the other two compart­ments and communicates with the cavum venosumthrough an intraventricular canal. There are two inflow routes, the right andleft atria, and three outflow routes, the pulmonary artery and the left andright aortic arches. The right atrium receives blood from the sinus venosus.The sinus venosus is a large chamber on the dorsal surface of the atrium. Itreceives blood from four veins, the right and left precaval vein, the postcavalvein, and the left hepatic vein. The left atrium receives blood from the rightand left pulmo­nary veins.Blood flow through the heart starts when both atria contract. Theatrioventricular valves open and allow blood to flow into the ventricle. Whenthe atria con­tract, the valve between the right atria and the cavum venosumseals off the intraventricular canal, allowing the oxygenated blood from theleft atrium to flow into the cavum arteriosum and the deoxygenated blood fromthe right atrium to flow into the cavum venosum and then to the cavumpulmonale. When the ventricle contracts, the blood pressure inside the heartincreases.Because resistance is lower in the pulmonary circuit, deoxygenated bloodis expelled from the cavum pul­monale through the pulmonary artery. When theven­tricle shortens, the muscular ridge that separates the cavum venosum andthe cavum pulmonale comes into contact with the wall of the ventricle andcloses off the passage between the two compartments. The atrioven­tricularvalves are forced shut as the pressure inside the ventricle increases. When theatrioventricular valves are shut, the oxygenated blood from the cavumarteriosum is pushed through the intraventricular canal into the cavum venosumand out the left and right aortic arches. At this point, the pressure insidethe cavum venosum is more than twice that in the cavum pulmonale.Another remarkable ability of snakes, as well as other squamates andchelonia, is the ability to perform intracardiac shunting. Intracardiac shuntsare classi­fied as left-to-right or right-to-left. In a right-to-left shunt,the deoxygenated blood that should normally be flowing out to the pulmonarycircuit is being expelled out to the systemic circuit via the aortic arches.This shunt increases the amount of circulating blood and decreases its oxygencontent. Primarily, the right-to-left shunt is used to increase the body tem­peratureand bypass the lungs during breath-holding. The left-to-right shunt is used tohelp stabilize the oxygen content of the blood. The direction and degree ofintracardiac shunting depends on the pressure dif­ferences between thepulmonary and systemic circuits and the washout of blood remaining in the cavumvenosum.The renal-portal system exists in all fish, reptiles, and birds. Itcollects blood from the caudal portion of the body and carries it to thekidneys. The blood is then filtered and returned to the heart via the postcaval vein. Blood that travels through the renal-portal system only goesthrough the convoluted tubules and not the glomeruli (Holz 1999).Snakes  123The location of the heart, being so cranial, has two disadvantages.First, when a snake holds its head down, blood flow to the tail is compromised.Second, and most important, when the head is up or the entire body is in avertical position, the blood from the tail must travel all the way to the heartagainst gravity. The veins of snakes do not have valves to prevent back flow sosnakes have adapted three ways to ensure that the blood continues to flowtoward the heart even while being vertical. The contractions of the smoothmuscles that line the vessels help push the blood toward the heart. Snakesundulate or contract their skeletal muscles, massaging the blood toward theheart. The tight skin of arboreal species acts as an antigravity suit, furtherassisting the blood in traveling toward the heart.The lymphatic system in snakes, as well as all rep­tiles, is anelaborate drainage system. Microvessels collect lymph from throughout the body.These micro-vessels merge into larger vessels that eventually empty into largerlymphatic trunk vessels and then into lym­phatic sinuses. All three parts, thetrunk, vessels, and sinuses, empty into veins. The lymph can be bidirec­tionalbut mostly flows toward the pericardial sinus and into the venous system.Reptiles have a pair of lymph hearts located in the pelvic region but do notpossess lymph nodes.Respiratory SystemSnakes have upper respiratory anatomy similar to that of mammals. Airenters and leaves the trachea through the glottis located in the back of thepharynx. The glottis and other cartilage form the larynx. The trachea of snakeshas incomplete cartilaginous rings. The ventral portions of the rings are rigidand the dorsal portion is membranous.Most snakes only have a single right lung and a small nonfunctioningleft lung. The right lung is gener­ally one-half or more of the snakes bodylength. In most species, the posterior one-third is an air sac. In thosespecies that do have a very small functional left lung, it is about 85% smallerthan the right. The right bronchi enters the lung and empties into a wall thatis lined with faveoli. The faveoli are richly supplied with blood. Most of thegaseous exchange occurs in the faveoli (Zug et al. 2001). Snakes that have onlyone functioning lung possess a tracheal lung, a vascular sac that contains manyfaveoli for gas exchange. The tra­cheal lung extends from the point where thetracheal rings are incomplete dorsally and posteriorly until it touches theright lung. The air sac, or saccular lung, is not used as a site for gasexchange but as a site for air regulation.All reptiles breathe using a negative-pressure venti­lation (Pough etal. 2001). During inspiration, the intercostal muscles expand the ribs theentire length of the body, dropping the pressure inside the lungs to belowatmospheric pressure and drawing in air. Then the intercostal muscles relax andthe glottis closes, closing the respiratory tract. The snake then pauses forseveral seconds to several minutes before exhaling. Terrestrial and arborealspecies normally have a period of apnea between respiratory cycles. The ribs inthe anterior portion of the body are unable to expand for proper inspirationwhen snakes are swal­lowing large prey. During ingestion of prey, the pos­teriorribs expand, causing the saccular lung to inflate and deflate, moving airthrough the respiratory system (Table 7.1).Nervous SystemThe central nervous system is organized the same way in snakes as it isin all reptiles and similar to mammals. The brain of snakes is divided into theforebrain and hindbrain. The forebrain contains the cerebral hemi­spheres,thalamic segment, and optic tectum, and is further broken down into thetelenchephalon, dien-cephalon, and mesencephalon. The cerebral hemi­spheres arepear shaped. They contain olfactory lobes that project anteriorly and end inolfactory bulbs (Zug et al. 2001). The thalamic region, which is tube shapedwith a thick wall, is hidden by the cerebral lobes and the optic tectum. Thedorsal portion of the thalamic region has two dorsal projections. The anteriorprojec­tion is the parietal body and the posterior projection, the epiphysis,is the pineal organ. The pineal organ is glandular in most snakes. The ventralportion contains the hypothalamus. The optic tectum is located on the dorsalpart of the posterior portion of the forebrain and the ventral part containsthe optic chiasma. The hindbrain contains the cerebellum and medulla and isalso broken down into the metencephalon and myel-encephalon. Both are small inextant species of reptiles. Reptiles also have twelve pairs of cranial nerves.Table 7.1. Approximate Organ Location in Snakes.First quarter  Trachea,esophagus, heartSecond quarter  Heart, liver, lung, stomach Thirdquarter  Stomach, gallbladder, gonads,small intestine, pancreas, spleen,adrenal glands Fourth quarter  Colon, kidneys,cloaca Tail Hemipenes, muskglands124  Chapter 7The spinal cord runs the entire length of the verte­bral column. Eachvertebra contains a bilateral pair of spinal nerves, each of which contains asensory and motor root that fuse near their origin. The diameter of the spinalcord is uniform all the way down to the end.Sense OrgansCutaneous Sense OrgansBoids, pythonids, and viperids have specialized struc­tures in thedermis and epidermis that contain heat receptors (Zug et al. 2001). These pitorgans sense infrared heat and are located in different locations in eachtaxon. In the boids, the pit organs are scattered on unmodified supralabial andinfralabial scales. Boids have intraepidermal and intradermal types. Pythonidshave a series of pit organs in the labial scales. The heat receptors lay on thefloor of each pit. In viperids, the pit organs are located bilaterally betweenthe eyes and the nares. The opening of each pit is forward facing and isoverlapped by other receptors. The heat recep­tors are contained inside amembrane that stretches across the pit, further enhancing its heat-seekingability.EarsThe ears of snakes have the same two functions as they do in mammals,hearing and balance. The middle ear in snakes is virtually nonexistent (Platel1994). It is a very narrow cavity that does not contain a tympanic membrane butdoes contain one ossicle, the columella, that abuts the quadrate bone fortransmission of vibra­tions. The inner ear of snakes is very similar to that ofmammals. The utricle and saccule make up the semi­circular canals that ensurebalance. Vibrations are received in the inner ear via the columella and passthrough the cochlear canal and onto the basilar papilla. Even with the absenceof an outer ear and the virtual absence of a middle ear, snakes are adept athearing (Platel 1994). Snakes pick up vibrations from the sub­strate on whichtheir head rests because the columella senses vibrations from the quadrate bonethat is located on the upper jaw (Funk 1996). It is believed that arbo­realsnakes can pick up aerial vibrations, enabling them to catch avian prey inmidflight.SmellIt is difficult to determine the amount of olfactory sensation snakeshave. Snakes have a large number of olfactory nerves, which leaves no doubtthat they are macrosmatic animals. Their olfactory abilities do not work alone;they are closely associated with the vom­eronasal sense as well as sight.Vomeronasal SenseThe vomeronasal organ, or Jacobsons organ, which is connected to theoral cavity by the vomeronasal duct, plays a vital role in predation. Itdetects nonaerial, nonvolatile particulate odors by the chemo-receptors on theforked tongue. The snake then carries that scent to the vomeronasal organ. Thesensory cells inside the vomeronasal organ react with certain molecules thatthen transfer the scent to the accessory olfactory bulbs, other encephaliccenters, and the nucleus globosus. The vomeronasal organ is also used forinterspecies relations. Snakes can use the vomeronasal organ to sense a den forhibernating and for reproductive behaviors such as picking up pheromones.EyesThe snake has very different eye anatomy than other reptiles.Embryologically, the eyelids of snakes fuse to form a transparent spectacle,which has an extensive vascular network that is optically transparent (Zug etal. 2001). The anterior layer of the spectacle is shed during each ecdysiscycle. The spectacle is separated from the cornea by an epithelial-linedsubspectacular space. The globe of the eye is kept moist via secretions made bythe harderian glands. The nasolacrimal ducts drain from the medial canthus tothe roof of the oral cavity at the base of or just behind the vomeronasalorgan. The globe has poorly developed rectus muscles and limited rotationalmuscles. Snakes lack the scleral ossicles and cartilage of lizards andchelonians. Snakes possess a soft and pliable lens and they focus by theforward movement of the lens by increased pressure of the vitreous applied bythe ciliary muscle. The iris contains striated muscle, making dilation andcontrac­tion of the pupil voluntary.The retina, pupil shape, and lens color have gone through evolutionarychanges to better fit the species lifestyle (Platel 1994). Diurnal speciesusually have a round pupil, yellow lens, and a retina made of all cones.Crepuscular species have a paler lens and the retina contains both rods andcones. Nocturnal species have a vertical slit-shaped pupil, a colorless lens,and a retina consisting of mostly rods with very few cones. These are justgeneralized statements, with many exceptions. For example, crepuscular ornocturnal pythons have a round pupil and a retina that contains a largequantity of both rods and cones.Snakes have a very wide range of vision from 125 degrees to 135 degreesfor most species. They also can perceive depth and distance using binocularvision. The area that both eyes can see is between 30 degrees and 45 degrees(Platel 1994).Snakes  125Digestive SystemThe digestive system in snakes is a linear tract (Funk 1996). It startswith the mouth that opens directly into the buccal cavity. The buccal cavitycontains rows of teeth on the upper and lower jaw, the vomeronasal organs, theprimary palate, the internal nares, and a highly specialized tongue. Aniliids,the false coral snakes, have developed a partial secondary palate. Themorphology of the tongue is variable depending on the feeding behavior of thesnake. The buccal cavity contains many glands throughout the entire cavity.Multicellular glands, a component of the epithelial lining of the tongue,produce and secrete mucous that coats the prey, making passage down theesophagus smooth. Snakes also have five types of salivary glands: labial,lingual, sublingual, palatine, and dental. Venom glands are modified salivaryglands. The pharynx con­tains a muscular sphincter that controls the opening ofthe esophagus (Figure 7.2).The esophagus is a muscular walled tube that con­nects the buccal cavityto the stomach. In snakes, the esophagus may be one-quarter to one-half of thebodyFigure 7.2. Oral cavity of asnake. (Drawing by Scott Stark.)length. The stomach is a very large muscular tube that has the primaryrole of mechanical digestion and start­ing the chemical digestion process. Thestomach lining has numerous glands that produce secretions to aid in digestion.The pyloric valve controls the food bolus that enters into the small intestine,which is a long, narrow, straight tube. It also has glands to help with thedigestion process. At the junction with the large intestine, there is a markeddifference in the size. The large intestine has a diameter several times thatof the small intestine. Boidea have a small cecum located at the proximalcolon. The large intestine is the weakest and most thin-walled structure in thedigestive tract. The large intestine ends at the anus and then leads to the dorsalportion of the cloaca, the coprodaeum.The primary function of the liver in snakes is the same as in mammals.The liver, which is elongated and spindle shaped, produces bile that is storedin the gall bladder and then sent to the duodenum via the common bile duct.Bile aids in the digestion of fat. The pancreas produces digestive fluids intothe duode­num. It is usually located in a triad with the spleen andgallbladder, or some species have a splenopancreas (Figure 7.3).Because the feeding behavior of snakes is not all the same, differentphysiological and morphological changes occur with different feeding behaviors.Snakes that eat small, frequent meals tend to have a digestive system that isalways in an active state. On the otherFigure 7.3. Visceral anatomy. (Drawing by Scott Stark.)126  Chapter 7hand, snakes that eat large, infrequent meals maintain their digestivesystem in an inactive state until a prey item has been ingested. At that pointthe gut begins to increase secretions of hydrochloric acid and digestiveenzymes. Within one day, the small intestine doubles in size and other organsin the digestive, respiratory, and circulatory system also gain size. When thediges­tive tract is activated, the metabolic rate increase as much asforty-four times that of the resting metabolic rate. The energy needed toactivate the intestinal tract must be received from stored reserves before thediges­tive process begins for the new prey. Infrequent feeders usually maintaina metabolic rate half that of frequent feeders.Urinary SystemSnakes have a bilateral pair of lobulated and elongated kidneys. Theyare located in the dorsal caudal coelo­mic cavity, and the right kidney islocated cranial to the left kidney. The kidneys are metanephric in struc­tureand have few nephrons and lack a loop of Henle and a renal pelvis (Divers2000). The ureters empty into the urodeum in the cloaca. Snakes do not have aurinary bladder.Snakes excrete nitrogenous waste as uric acid. Uric acid is a purine andis synthesized in several interlock­ing pathways. It is very insoluble inwater. In the kidney tubule, urine stays dilute. Water is reabsorbed when theurine reaches the cloaca, making the urine solution more concentrated and someof the uric acid precipitates. The precipitation of uric acid reduces itsconcentration, acid allowing more water to be reab­sorbed. Again, this leads tomore precipitation of uric acid. This process allows nitrogen to be excreted,using very little water. The end product is a white or gray semisolid pastymaterial containing uric acid.Endocrine and Exocrine GlandsPituitary GlandThe pituitary gland is the so-called master gland of the body. Itconsists of two parts, the neuropophysis and adenopophysis. The neuropophysisproduces hor­mones that stimulate the adenopophysis or act directly on thetarget organs. The adenopophysis releases six hormones: adrenocorticotropin,follicle-stimulating hormone, luteinizing hormone, prolactin, somatotro­pin,and thyrotropin.Pineal ComplexThe pineal complex consists of an epiphysis and a parapineal organ. Theyact as light receptors and are associated with cyclic activities such ascircadian rhythms and seasonal cycles. As a gland, both organs releasemelatonin. All snakes have a pineal gland that lies on the brain but does notexit the skull as in some iguanids.Thyroid GlandThe thyroid is located in the throat adjacent to the larynx and tracheaand is nearly spherical. Snakes can have either a single or paired thyroidgland. The thyroid is responsible for accumulating iodine and pro­ducing andregulating hormones that control growth and development as well as ecdysis.Parathyroid GlandThe parathyroid is located just cranial to the thyroid. It functions asa blood calcium regulator.PancreasThe pancreas in snakes, as in mammals, functions as an endocrine andexocrine gland. As an exocrine gland it secretes digestive enzymes, and as anendocrine gland it secretes the hormone insulin via clusters of cells calledthe islets of Langerhans.GonadsThe gonads produce the sex hormones. Their function is closely regulatedby the brain and the pituitary. Hypothalamohypophyseal hormones and gonadotro­pinsare produced by the brain and the pituitary, respectively, when the gonads aretriggered by a hor­monal response. Along with stimulating reproductivestructures, the sex hormones also produce secondary sexual characteristics andprovide a feedback mecha­nism to the hypothalamic-pituitary complex.Adrenal GlandsThe adrenal glands are a pair of bilateral glands located anterior tothe kidneys. They have many functions: produce adrenaline and noradrenaline;affect sodium, potassium, and carbohydrate metabolism; and affect the androgensand the reproductive process.REPRODUCTIVE BIOLOGY AND HUSBANDRYThe Male AnatomyAll male snakes have a right and left testicle and a pair of hemipenes.The testicles are in the shape of an ovoid mass that consists of seminiferoustubules, interstitial cells, and blood vessels. They are located dorsomedi-allywithin the coelomic cavity between the pancreatic triad and the kidneys. Theright testis is located justSnakes  127cranial to the left. Snakes do not have an epididymis. The hemipenes arelocated in the base of the tail and are held in place by a retractor muscle.Sperm is pro­duced in the seminiferous tubules. During copulation, spermtravels to the hemipenis through the Wolffian ducts. The sperm is able to enterthe female by means of the sulcus spermaticus located on the outside of thehemipenis. During copulation, only one hemipenis is used. Many snakes,especially boids, have vestigial (pelvic) spurs. These spurs are used incopulation as stimulation and to help position the two cloacae together (Figure7.4).The Female AnatomyThe paired ovaries are located similarly to testes. They consist ofepithelial cells, connective tissue, nerves, blood vessels, and germinal cellbeds encased in an elastic tunic. An inactive ovary is small and granular.Active ovaries are large, lobular sacs filled with spheri­cal vitellogenicfollicles. Snakes do not have a true uterus. The oviducts empty directly intothe cloaca and have an albumin-secreting and shell-secreting function.FertilizationPrior to egg production, fertilization occurs in the upper portion ofthe oviducts when the sperm and egg unite. Fertilization is usually delayed fora few hours to years after copulation. The sperm storage structures facilitatestorage of sperm for long periods of time. This process of delayedfertilization permits females to mate with other males, allowing multiplepaternity among the offspring and having a higher fecundity rate, although notall snakes practice this.Figure 7.4. Large pelvic spurs. (Photo courtesy of Ryan Cheek.)Sexual MaturitySexual maturity in snakes depends on many factors. Husbandry andnutrition are more important than age. Ultimately, it is the size of the snakethat determines sexual maturity. Due to the large difference in care providedto captive snakes, the age of sexual maturity consequently is different aswell. With proper hus­bandry and nutrition, snakes grow quickly and becomesexually mature within their first or second year of life.Follicle Maturation and the Fat CycleThe female begins to store fat in the months before her reproductivecycle (Ross et al. 1990). This fat plays a major role in the reproductivecycle. Vitellogenesis, the production of yolk, only occurs if enough fat isstored. Furthermore, snakes may not eat at the end stages of gestation, so thefat bodies are used for energy. The follicles mature within the ovaries. Whenthe follicles are mature and palpable, some ova are released into the oviductwhile other ova may be released before or after copulation. At this point thesnake finds a male and copulates and the female becomes gravid. After theproper gestation period, the female either lays eggs or gives live birth. Atthis point the female is very thin and weak after using all of her fat depositsduring gestation and/or incubation. She cannot stimulate fol­licular maturationuntil the fat stores have been built back up. She begins to eat and increasesher fat bodies, and after a couple to several months she is back to full weightand can begin the follicular maturation cycle again.CourtshipIt is important to know and observe signs of courtship so proper changescan be made. If communal cages are kept, insubordinate specimens should beseparated from the courting pair. Temperature cycling patterns should bestarted before or at the first signs of copula­tion. Specimens should beremoved or added if either of the specimens seen courting is inappropriate forbreeding.Many courtship behaviors are observed in snakes; most are not speciesspecific. Following is an explana­tion of four common courtship behaviors thatare seen in many taxa (Ross et al. 1990).1. The tactile chase behavior is characterized by the male pursuing thefemale in often jerky and erratic movements. The male may flick his tongue overthe females body and begin to crawl over her dorsum, trying to align his bodywith hers. The female will continue to crawl away if unreceptive to thebehavior.128  Chapter 72. In the tail searchcopulatory attempt the male rotates his tail under the females tail in anattempt to bring both cloacae together. A receptive female will then lift hertail or allow her tail to be lifted by the male. The male may use his spurs tostimulate the female to lift her tail.3. Tactile alignmentis characterized by the male align­ing his tail with the females, using hisspurs as stimulation and to help align the cloacae.4. Intromission andcoitus occurs when a female raises her tail and everts her cloaca to a male.The male then aligns the two cloacae and copulation occurs. This behavior isalso known as cloacal gaping.Oviparous, Ovoviviparous, and ViviparousOviparous snakes are those that lay eggs that are pro­tected by a hardshell. Around 70% of snakes are oviparous. Some of the more common oviparousspecies seen in a veterinary practice are king snakes and milk snakes (Lampropeltis spp.), rat and cornsnakes (Elapbe spp.), and all pythons. Oviparous snakes goto much trouble finding an appropriate place to lay their eggs. Some lay in anatural cavity, hollow stumps, or small mammals burrows, while others digtheir own burrow or make a nest. Most pythons incu­bate their eggs by huggingthem and increasing their own body heat through rhythmic contractions of theirabdominal musculature.Ovoviviparous snakes incubate the eggs inside the oviducts until theeggs hatch. This process ensures proper humidity and temperature levels withinthe mothers thermoregulative capabilities. Ovoviviparous snakes are foundmainly in places where the ground is too cold to incubate eggs (Saint-Girons1994). There are many disadvantages to ovoviviparous snakes. The gravid femalemoves very slowly, which opens her up to predation; she is only able to eatvery small prey, which are hard to find at times; and she must focus more onthermoregulation. Some examples of ovovi­viparous snakes are all boas, allvipers, and garter snakes (Thamnophis spp.).Snakes do not practice true viviparity.EGG ANATOMYAfter fertilization, the embryo begins to develop on the dorsal surfaceof the yolk. The yolk is then covered by the yolk sac and attached to theembryo by the yolk stalk at the umbilicus. Nourishment is provided by the yolkvia the blood vessels of the yolk sac. The amnion is a fluid-filled sac thatsurrounds and protects the embryo. The allantois is a closed sac that collectswaste products. The chorion is a membrane that surrounds and protects the embryoand yolk sac. The shell mem­branes that cover these three membranes provide gasexchange throughout the shell. The blood vessels in the shell membranes and theyolk stalk combine to form the umbilicus. As the egg passes through theoviducts, the shell and shell membranes are gradually applied by the shellglands.Timing and Frequency ofReproductionEnvironmental factors trigger the breeding season in most species. Whilesome species breed year round, breeding season usually begins in the springafter a hibernation period for temperate species. Most equa­torial speciesbreed year round. There are exceptions to these rules. Some tropical boidsreproduce in the cooler part of the year, though temperature changes have agreater diurnal change than seasonal change. Many species in areas where thereis a rainy season, such as the monsoons in Southeast Asia and India, time theirreproductive cycle with the rainfall.It is not common for a snake to reproduce more than once in a singleyear due to the lengthy gestation periods and need to gain back a large amountof fat deposits. The entire reproductive process, starting with folliclematuration and ending with the snake back at full weight, can take severalmonths to more than a year, depending on species.Maternal CareVery few snakes show any maternal care. Some pythons coil around theeggs to incubate them and protect them from predators. Some viviparous speciesshow mater­nal care by helping the newborns out of the amniotic sac andconsuming the infertile yolk sac.EGG INCUBATION AND MANAGEMENTArtificial IncubationIt is recommended that eggs only be artificially incu­bated byexperienced herpetoculturists. Many herpe-toculturists artificially incubateeggs to increase the chance of hatching. In captivity, it is difficult for thefemale snake to keep the relative humidity high enough to incubate her owneggs. If the decision is made to artificially incubate the eggs, theherpetoculturists must be prepared several days before the female lays theeggs, and the incubator should be ready several days in advance. It shouldmaintain a constant tem­perature and humidity that is ideal for the speciesbeing incubated. For most species, a temperature rangeSnakes  129of 86°F to 91°F is ideal. Eggs do not benefit from temperaturevariations so a constant temperature should be maintained. It is not critical tomeasure the relative humidity, although a high relative humidity should bemaintained. As long as condensation appears on the sides of the incubator, thehumidity should be high enough.When the female lays the eggs, herpetoculturists should move quickly toremove them. The eggs become adherent within a few hours after oviposition. Itis preferable that the eggs be laid singly in the incubator so they can beproperly monitored; the conditions inside the enclosure also may be inadequatefor proper incubation, which can be detrimental to the eggs. Eggs can dehydratewithin forty-eight to seventy-two hours. Gently remove the eggs and place themin the pre­heated incubator. The incubator should be checked several times aday for proper temperature and humid­ity and the eggs should be checked forviability.Maternal IncubationMaternal incubation should be performed for several reasons. The eggsshould be maternally incubated if the female is too large or aggressive tosafely remove the eggs, if she unexpectedly laid eggs and an incubator was notready, or if normal incubation parameters are not known. The humidity in thecage should not fall below 75%. Because of the high humidity that must bemaintained, the cage should be kept in a very clean environment with adequatecirculation. The tempera­ture in the cage should be constant. The incubatingfemale should not have to thermoregulate, which requires an excessive amount ofenergy that many incubating females do not have. The cage should be kept at 88°F for most python species. If maternal incubation was chosen due to a lack ofexperience in artificial incubation, extensive research on the natural historyof the species should be conducted to deter­mine the proper incubatingtemperature.Incubator DesignIncubators can be bought commercially or easily made. The basicrequirements of an incubator are: the con­struction should prevent excessiveheat and humidity loss, there must be a constant and reliable heat source, andthere must be a thermostat to control the tempera­ture. The actual design ofthe incubator can vary as long as the above three rules are met.Some general guidelines should be followed when constructing anincubator. It should be uniformly heated. An easy way to accomplish this is byusing heat tape that can be evenly positioned on the bottom of the incubator.Hot water can also be used. An inner con­tainer should be installed that doesnot rest on the bottom of the incubator to allow the heat to be evenlydistributed throughout the entire incubator. The ther­mostat should besensitive enough to control the temperature fluctuation within one degree, andthe temperature should be monitored from the outside of the incubator. Toensure adequate humidity, the incu­bator and eggs should be sprayed with waterthat is the same temperature as the incubator every two to three days. Theincubator should be lined with Styrofoam to maintain a proper temperature. Thebest substrates are vermiculite, sphagnum moss, potting soil, sand, shred­dednewspaper, pea gravel, and paper towels.Determining Egg ViabilityA viable clutch should be uniform in size, have a bril­liant whitecolor, and be pliable or elastic (Ross et al. 1990). If an egg is smaller,discolored, or hard or rubbery, it usually is not fertilized. Some femalesnakes reject an unfertilized egg from the clutch. If an egg does not adhere tothe rest of the clutch, it should still be incubated until signs of egg deathappear. Wrinkles or depressions at the time of oviposition are not signs ofnonviability. A fertilized egg does not show significant change during theincubation period. An unfertilized egg quickly begins to show signs ofdecomposition.It can sometimes be very difficult to determine the viability of an egg.If the viability is uncertain, the egg should be incubated until further signsappear. The rest of the clutch will not be in danger. The texture of an egg orirregular calcification should not be used as an indication of nonviability.Another method for determining egg viability is a technique called can­dling,which uses of a high intensity light to transil-luminate the egg. A viable eggshould have a network of blood vessels and an embryo during the late stages ofincubation. The absence of blood vessels indicates a nonviable egg.Manual PippingSometimes manual pipping is necessary for the embryo to live. An eggshould be manually pipped only if most eggs in the clutch have hatched, no eggshave pipped by the estimated due date, or the due date is unknown. Manualpipping is a very delicate procedure that with time and practice can be a veryeffective method of saving a clutch. All that is needed to perform thistechnique is a pair of iris scissors and thumb forceps. A small perforation ismade in the shell with the iris scissors. With the scissors pointing up towardthe inner surface of the eggshell, a small incision is then made in the shell.Another small incision is made at the site of the puncture creating a V-shapedincision. The130  Chapter 7wedge can be elevated using the thumb forceps and removed. If doneproperly, the shell membranes should all still be intact. During this process,one should avoid cutting large blood vessels; small vessels are impossible toavoid. The embryo should not be visible.The shell membranes should be gently separated from the shell with thethumb forceps, starting at the window that was made and then working outward.More pieces of shell can be removed as the membrane is separated. The embryocan then be stimulated when a large enough window has been made.To stimulate the embryo, prod it gently with a blunt tip instrument. Ifit is alive, the embryo will move freely in the egg. The embryo should beintermittently stimulated until the neonate has emerged from the shell. Thisprocess usually takes twelve to twenty-four hours.HOUSINGThe following points must be considered when obtain­ing housing for asnake: (1) the size (length) of the snake to be housed, (2) whether it is aterrestrial or an arboreal species, (3) security of the housing (escape proof),(4) proper ventilation, (5) access for necessary cleaning/disinfecting.Aquariums are certainly suitable and aesthetically pleasing enclosuresfor most species of snakes, but can be quite costly to obtain, especially whenhousing some of the larger species. Ideally, the length of the enclosure shouldbe no less than half of the length of the snake being housed. When housingarboreal species (i.e., green tree python), the enclosure should have morevertical space than horizontal to allow for place­ment of perches for thesnake. If an aquarium is used, it is important that a lid can be securedappropriately. Lids that rest on top of the aquarium without any lockingmechanisms are NOT appropriate for snakes because they are escape artists. Aquariumlids should allow proper ventilation (i.e. screen lids) if the aquar­ium itselfdoes not have any ventilation holes (most do not). The lid must not present apotential fire hazard if heat lamps are used above it. Plastic lids, forinstance, will melt (Figure 7.5). Any aquariums with cracks should be avoideddue to the potential for the glass to shatter, resulting in injury to theanimal.Building an enclosure for a snake is usually the preferred method ofacquiring housing. It is less expen­sive in most cases and allows forcustomizing accord­ing to the snakes needs. Customizing an enclosure can beenjoyable as long as a couple of guidelines are fol­lowed. Obviously, it is notideal to construct a cageFigure 7.5. Inappropriate bousing for a snake. (Photo courtesy of Ryan Cheek.)solely of wood without any way to view the snake. Glass or Plexiglasshould be included when construct­ing a wooden enclosure. Screen can be used onthe sides or even the top of the enclosure to ensure proper ventilation. Withoutproper ventilation, bacteria accu­mulate, making the enclosure stagnant. Usingscreen on the top also allows for proper lighting/heat fixtures to be affixedwhile preventing the snake from contact­ing the fixtures. To prevent burns,heat lamps should not be placed inside the enclosure where the snake cancontact them.An enclosure should not be constructed solely of screen, however,because it can become too drafty. The wood used should be sanded and free ofabrasive sur­faces to prevent potential injuries to the snake. It also must betreated or painted to allow regular cleaning without damaging the wood and sothat feces and such do not soak into the porous wood. Priming and paint­ing theinside of the enclosure white can assist in spot­ting problems such as mites inthe caging. The white paint also reflects the light better.Different locking mechanisms can be chosen, depending on what ispreferred to access the inside of the cage. Everything from hinged doors withpadlocks to sliding glass doors are suitable for securing the custom enclosure.Commercially available enclosures such as Neodesha and Visions cages arespecifically made for keeping reptiles. These are perfectly suitable forhousing snakes if one does not mind the added expense and as long as anappropriately sized enclosure can be obtained.SubstrateMany different types of substrate are used in snake enclosures (Figure7.6). There also is a lot of debate about what is appropriate and what can beharmful.CDFigure 7.6. Various common commercially available substrates. (A) ReptiBark (fir bark). (B) Ground coconut shell. (C) Calcium carbonate granules. (D.)Cypress mulch. (Photos courtesy ofRyan Cheek.)131132  Chapter 7It is necessary to read as much literature about the snake as possibleto obtain more information about its natural habitat to better assist in makinghusbandry-related choices.Cedar and pine shavings are not recommended as substrate for anyreptiles. The oils and natural aroma of these shavings can be toxic to snakesand can even lead to respiratory disorders. Shavings can also lodge in thesnakes oral cavity, which could cause stomatitis (mouth rot). Although somecompanies claim that these shavings are great for snakes because they repelmites and ticks, use of any cedar or pine shavings should be avoided.Aspen shavings can be used for some of the snake species that require anarid climate. They should not be used for snakes that require high humiditybecause there are more suitable substrates for maintaining high humidity. Theaspen shavings must treated through a baking process, which can help toeliminate any poten­tial for parasites contained in the shavings and to ensurethat they are free of toxic oils. Aspen shavings can also become lodged in thesnakes mouth so as a precaution, the snake should not be fed on aspenshavings.Indoor/outdoor carpet or Astroturf is commonly used as substrate. It isaesthetically pleasing and does not present any immediate harm to the snake. Itcan be purchased by the yard at most local hardware stores. Routine cleaningand disinfecting is more demanding than with other substrates because thecarpet needs to be replaced frequently and is more expensive than some options.When a snake defecates or passes urates, the carpet absorbs some of the matterand needs to be washed or replaced or it will become pungent and allowbacterial and/or mold growth. Animals with parasite infections should have thecarpet changed completely to avoid recontamination.Aquarium gravel and corncob should not be used. Some gravel can beabrasive and both can cause impac­tions if ingested in large amounts.Sand is used often for desert species, and there are many contradictingstatements regarding its use in any reptile enclosure. There is debate aboutwhether it causes digestive problems and obstructions. However, sand is thenatural substrate of many desert species. Any loose substrate that is ingestedin large amounts could potentially cause these problems as well as sto­matitis.The snake should not be fed in the enclosure to reduce the chance of thishappening. Some people feed their snakes in plastic tubs or boxes to eliminatethe opportunity to ingest substrate while feeding.Some people buy play sand at the hardware store to use as substrate,while others buy the sand sold at pet stores for reptile substrate. Some of thecommercial brands of sand used as substrate for reptiles claim that if it isingested the sand is less likely to cause impac­tions than regular play sanddue to its calcium contents and fine grain. However, caution should still beused when feeding any reptile on a sand substrate. Furthermore, too much ofcalcium consumption can be just as harmful as calcium deficiencies. Those whochoose to use sand as a substrate can let personal preference dictate theirchoice. The key is to ensure it is not being ingested, and if that is the casethen the substrate should be changed.Cypress mulch is another good substrate, especially for species thatrequire higher humidity. It can make an enclosure look very natural and it isrelatively inex­pensive. It is important to make sure that it is actuallycypress mulch and not another type of mulch (i.e. eucalyptus) because these canbe very aromatic and lead to respiratory problems. The mulch can be mixed withsphagnum moss if the goal is to make a natural appearing environment.Newspaper is frequently used as substrate, espe­cially when an multiplesnakes are kept. Newspaper is plentiful, inexpensive, and easily obtained. Itis absor­bent and easily replaced during routine cleanings. It is especiallygood for animals in quarantine, and it is the substrate best suited for feedingbecause the chances of it being ingested are not as great as loose substrate.Although it is not as aesthetically pleasing as some forms of substrate, it isdefinitely easier to maintain.Potting soil should be used with caution. Most potting soils havefertilizers and other chemicals that could be toxic to snakes. If topsoil isused, make sure that it is organic and free of chemicals. Topsoil can be a goodsubstrate to use for snakes that require high humidity because of its abilityto retain moisture. This can be used for terrestrial and burrowing species.Caution should be used if tree limbs, substrate, or any other objectsare collected from outside. They can contaminate the enclosure with parasites,molds, fungus, etc. Sterilization can be attempted with these objects viaboiling/baking or disinfecting with a diluted bleach solution to minimizecontamination. Tree limbs taken from outside should not have any sticky sub­stancessuch as sap on them.Good judgment must be used when choosing an appropriate substrate.Knowing the geographic range of the particular snake housed will aid in makinghus­bandry decisions.Heating and LightingSnakes are ectothermic, which means they rely on their surroundings toregulate their body temperature. Unlike mammals, they are unable to do this ontheirSnakes  133own. Therefore, snakes kept in captivity require heating and lightingsupplementation (Table 7.2). Failure to maintain appropriate temperatures forthe particular snake can lead to respiratory disorders, food regurgitation,anorexia due to lethargy, and even death.Whether the snake is desert-dwelling or tropical, it is necessary tomaintain an enclosure that mimics its natural surroundings and climate zone.Ideally, snakes need a warm basking area to maintain good health as well as acooler area to retreat to if they get too warm. Thermometers must be used toensure that necessaryTable 7.2. Husbandry Data for Selected Species of Snakes.Common nameScientific nameAmbient temperature Average  in Fahrenheitlength*  (day)**Humidity  Geographic rangeBoasCommon boaBrazilian rainbow boaEmerald tree boa Rosy boaPythonsBall pythonBlood python Burmese python Green tree pythonCarpet python Reticulated pythonBoa constrictorEpicrates cenchriacenchria Corallus caninus Lichanura trivirgataPython requisPython curtusPython molurusbivittatus Moreliachondropythonviridis Morelia spilota Python reticulatusAfrican rock python  Python sebae ColubridsCommon king snakes  Lampropeltis getulaCorn snakesRat snake Milk snakeGopher/Bull/ Pinesnake Garter/Ribbon snakesElaphe guttataElaphe obsoleta Lampropeltis triangulum Pituophis spp.Thamnophis spp.~6-105-74-6 2-33-53-6 12-20 4-66-10 10-2512-20 4-5 4-55-7 2-54-72-480-85 50-70% Central America andSouth America 80-85 75-90% Brazil75-82 85-90% Amazon Basin80-85 20-30% Southern CA, AZ,Mexico80-85 60-65% Central Africa,Western Africa, Borneo80-85 70-75% Borneo Islands,Malaysia, Sumatra 80-85 70-80% S.E. Asia75-85 85-90% Australia, NewGuinea80-85 60-70% Australia80-85 65-70% Thailand, Indonesia,Philippines (S.E.Asia)80-85 65-70% Africa75-85 30-50% North & SouthAmerica75-85 50-60% Eastern UnitedStates, Midwest United States75-85 50-60% North America75-85 50-60% North & SouthAmerica75-85 30-50% United States &Mexico75-80 60-75% United States* Lengths refer to average adult lengths (in feet) not absolute min./max.lengths.**Temperatures given are average ambient temperatures; basking spotsshould be 5-10°F higher with a nighttime drop of 5-10°F.134  Chapter 7temperatures are being met. These can be bought at most pet stores and haveadhesives so they can be easily placed into the enclosure. Ideally, one thermom­etershould be affixed in the enclosure where the hottest temperature is achievedand one should be affixed in the cool zone. If the snake is a terrestrialspecies, the thermometer should be placed close to the bottom. With arborealspecies, the thermometers should be placed near the areas where the snake canperch (Figure 7.7).Heat rocks are sold as an artificial heat source for reptiles. These arenot reliable heat sources and can in fact injure the snake. The heating elementis not on a thermostat and can become extremely hot. The snake can sustainserious burns if it is allowed direct contact with the rock. At other times therock can be cool to the touch, providing no supplemental heat at all. While theauthor does not recommend heat rocks, if they are used they should be buriedunder the substrate so the snake does not have direct contact with them, andthey should not be the only source of heat provided.Heating tape and pads and under-tank heaters are good sources of heatfor snakes. They also sold com­mercially in the pet trade and if usedcorrectly, are safer than heat rocks. The pads and tape can be placed on theoutside of the enclosure underneath the tank where the snake cannot have directcontact with the units but still benefit from the heat being emitted. Theseheating mechanisms distribute the heat more evenly and in some cases cover theentire length of the enclosure. If a heating pad that has a temperature settingcontrol is used, the setting should be kept on low. If the enclosure is made ofthick wood or if there is a thick layer of substrate, the pad can be placed onFigure 7.7. Thermometer and hygrometer. (Photo courtesy of Ryan Cheek.)medium if the low setting is not producing enough heat to benefit thesnake. The bottom of the enclosure should always be tested (via touch orthermometers) thoroughly to ensure it does not get too hot. A high settingshould never be used. Do not trust that the snake will move if the heatingelement gets too hot. Thermal burns are easily prevented if caution is used andregular checks are performed on the heating elements.Heat lamps are acceptable primary heat sources and they also provide thesnake with necessary day and night cycles if actual lights are used. Theselamps can be used in conjunction with under-tank heaters for snakes thatrequire high temperatures. Clamp light fixtures are relatively inexpensive andcan be pur­chased from a local hardware store (Figure 7.8). These can be placedon top of the enclosure (on a screen, not plastic or flammable material) orclamped to a surface allowing the light to be directed into the enclosure.Bulbs should be selected based on the snakes tem­perature needs and thedesign of the enclosure itself. Incandescent bulbs, ceramic heat emitters, orflood lamps can be used for heating purposes. The wattage of the bulb dependson the dimensions of the enclosure and the snakes temperature needs. In mostcases, a 50- to 75-watt bulb is sufficient. Extremely high wattage bulbs orthose used for food warming pur­poses should not be used because they getextremely hot. The heat-emitting bulbs should be sufficiently distant from thesnake so that burns do not occur, and the snake should not have direct accessto the bulbs. Burns can be sustained from any heat source, including bulbs, ifthe snake is allowed direct access to them or if they are not placed at a safedistance from the snake.Figure 7.8. Clamp light fixture. (Photo courtesy of Ryan Cheek.)Snakes  135The snake is allowed a good basking area when the lamp is placed at oneend of the enclosure. The other end should be free of any heat sources toprovide a cooler zone to retreat to (Figure 7.9).Lights used as heat sources should not be kept on all the time. Timerscan be used to control when the light comes on and turns off. This assists inmaintain­ing natural photoperiods or day/night cycles. Ideally, the snakeshould have around twelve to thirteen hours of daylight followed by eleven totwelve hours of dark­ness to mimic nighttime. The timers can be set to mimicthe different seasonal day/night cycles by syn­chronizing them with thedifferent day/night cycles that change slightly from season to season. Forexample, there are longer daylight hours in the summer than in winter;therefore, daylight should be provided for approximately thirteen hours,whereas in winter eleven hours of daylight is typical.It is particularly important to follow the photope-riod in snakes ifbreeding is being considered. Some snakes are only receptive to breeding duringcertain seasons, so these seasonal changes must be recreated in captivity forsuccessful breeding activity. However, if bulbs are the only source of heatbeing used, it may be necessary to purchase night bulbs to ensure the snakedoes not get too cool during the night hours. A slight drop in temperature atnight is a natural, but too much can lead to illness. Night bulbs emit heat yetallow darkness. Red, blue, black light, ceramic or com­mercially available nightbulbs can be purchased to achieve this. Reading the temperature gauges in theenclosure assists in deciding whether night bulbs are necessary. Keeping theenclosure in a temperature-controlled room and away from drafty areas (i.e.windows) aids in preventing drastic temperature changes at night when the heatlamps go off.UV lighting or natural sunlight certainly could be beneficial to thesnake, but it is not detrimental to the snakes overall health as with diurnallizards if it is not provided (Figure 7.10). It should be clear, though, thatthere no any bulb available that can replace natural sunlight. During thewarmer months, if the snake is kept outside, which is not recommended, specialpre­cautions are necessary. Glass or Plexiglas enclosures should not be used atall outside because they can get extremely hot in the direct sunlight and proveto be fatal to the snake. The inside of the enclosure can become hot much likein a car with the windows rolled up and no air flow. When other enclosures areused outside a shaded area should always be provided for the animal. Snakesmust be able to retreat to an area that is not receiving direct sunlight whenthey are finished basking or they will become overheated.Wiring the heating device (bulbs or pads) to a ther­mostat can assist inmore accurately maintaining tem­peratures and decrease the chance of thermalburns. This is not to say that thermostats are always accurate or 100%dependable, but it certainly helps. Frequent temperature checks should beperformed when syn­chronizing thermostats.Water and HumidityDepending on the geographic range the snake derives from, it may benecessary to supplement humidity as well as heat. Tropical species (i.e.emerald tree boas) need relatively high humidity and require some form ofsupplementation. In some cases, it may be necessary to make husbandry choicesto prevent high humidity, as with desert species that require aridenvironments.Hygrometers (humidity gauges) can be purchased with thermometers andplaced inside the enclosure to provide humidity readings. This provides informa­tionabout when humidity needs to be increased or decreased so any changes necessarycan be made for ideal conditions.High humidity can be maintained by misting the entire enclosure and eventhe snake. The mist should be fine and not extremely cold or hot water. It maybe necessary to mist multiple times a day for tropical species. Some peopleeven set up misting systems on timers to provide constant and consistenthumidity (see Figure 7.7).Remember that humidity is the presence of moisture in the atmosphereitself. If the enclosure does not allow humidity to stay contained, then itmust be modified or a different enclosure should be used. For snakes thatrequire high humidity, enclosures made exclusively of screen are not ideal dueto the inability to keep moisture within the enclosure. The moisture willescape. Aquariums are good for maintaining humidity; however, an appropriatelid is necessary. Furthermore, ensure that the enclosure have some sort ofventilation to prevent the air and substrate from becoming stagnant. Typically,if water is added to supplement humidity (via misting, etc.), it should beevaporated at least within twenty-four hours. The enclosure is lackingappropriate ventilation if it does not evaporate. It may take some trial anderror to get the humidity right. When obtaining tropical species that requirehumid environments, appropriate methods should be estab­lished before placingthe snake in the enclosure. However, most species may not require any supple­mentationif appropriate enclosures and substrates are used.A water supply is essential for all snakes and can assist in maintaininghumidity as well. The enclosure136Snakes  137Figure 7.10. UV light bulb. (Photo courtesy of Ryan Cheek.)Figure 7.11. This is not an appropriate method of providing water to a snake. (Photo courtesy of Stacy Bailey.)should contain an appropriately sized water container. Some snakes enjoysoaking in the water prior to shed­ding, so the snakes size should beconsidered when choosing an appropriate bowl. Small ceramic bowls work well forsmaller snakes (they can not be tipped as easily as lightweight bowls) andplastic tubs work well for larger snakes. Be careful not to overfill becausethe snake can cause large amounts of water to spill over when submerging. Thewater should be changed if it becomes soiled or stagnant, and no less than oncea week. A water container placed over the heating element (heating pad or tape)creates some humidity and evaporates quickly so the water levels should bewatched closely. If the species requires low humidity, obviously the watershould not be placed near the heating elements (Figure 7.11).Substrate can play a vital role in maintaining high humidity. Substratematerials such as topsoil, moss(sphagnum or peat), and mulch are great substrate choices for speciesthat need high humidity. They absorb and hold moisture well unless too muchwater is added. Regular mistings in conjunction with appro­priate substrate arekeys in maintaining high humidity. Items such as newspaper, shavings, or rockgravel allow pooling and are not ideal for humid terrestrial environments.Other Cage FurnishingsHide boxes are easily constructed and really make a difference in thesnakes overall demeanor. A snake that has a place to go where it feels secureis less stressed in its captive environment. This has also been known to assistin the feeding response in some snakes (i.e. ball python). Hide boxes can beconstructed from everything from boxes, plastic pots, and Tupperware (notclear), to logs. They also may be purchased from reptile supply stores anddealers. No matter how elab­orate or simple they are, hide boxes serve the samepurpose and should be provided.Tree branches or some sort of perching material should be provided forarboreal species. PVC pipe can be used for this purpose as well. The perchshould not be any bigger in diameter than the largest part of the snakes body.Anything larger makes perching diffi­cult. Make sure all perching materials aresecured properly and free of abrasive surfaces.Decorative rocks are nice additions to an enclosure but can also injurethe snake if there are sharp edges. Snakes often use cage furnishings to assistthem when shedding by rubbing against them. Nothing with rough texture shouldbe placed in the enclosure.QUARANTINEAll reptiles brought into a home or facility should undergo a quarantineperiod. This is especially neces­sary in environments where numerous reptilesare housed. There are some diseases in reptiles that can wipe out wholecollections if proper quarantine pro­cedures are not used (i.e. inclusive bodydisease).A room should be set aside for quarantine purposes and should be absentof other animals, especially other reptiles. During the quarantine period,physical exams and fecal exams should be performed to check for internal andexternal parasites. Ideally, a fecal culture for salmonella should be performedas well. Salmonella is transmissible to other reptiles and is zoonotic. Thequarantine period should be no less than thirty days. Some facilities have asix-month quarantine period for all reptiles. The quarantine period should beextended138  Chapter 7if the snake becomes ill and continued until the snake is healthy.Proper cleaning and disinfecting is very important during this time. Theenclosures should be set up to meet the snakes individual requirements butalso should allow for frequent cleaning. Newspaper is a good substrate to usefor quarantined animals due to the ease of cleaning. It is easily changed andis cheap to replace. When the snake defecates or passes urates, the substrateshould be changed completely. A dilute bleach solution (one-half cup bleach to1 gallon of water) should be used to clean surfaces in the enclo­sure. Makesure the surfaces are dry before placing the snake back in the enclosure.Gloves should be worn when cleaning soiled cages to prevent contamination. Anycage furnishings should be properly disinfected or replaced.NUTRITIONAll snakes are carnivores that feed on whole prey items. Their digestivesystem is made to digest whole prey and they cast out or defecate the parts ofthe prey that are not digested, such as fur. Eating whole car­casses providesthem with added nutrients such as calcium from bone so that no furthersupplementation is needed. Feeding packaged meat and poultry prod­ucts is notan appropriate, balanced diet for snakes. Feeding in this manner may beconvenient for some, but it is not as nutritionally beneficial as whole preyitems. It should be remembered that just because a snake eats something readilydoes not mean it is nutri­tionally sound. It is the responsibility of the personwho cares for the captive snake to make sure its nutri­tional needs areproperly met.Although some commonly kept species feed on invertebrates, most readilyfeed using commercially bred mice and rats. What to feed the snake depends onmultiple factors: (1) availability of prey item, (2) natural diet, (3) whetherthe snake was captive-bred or wild-caught, and (4) size of the snake.Prey ItemsWith the increase in popularity of keeping snakes in captivity, there isa larger and more diverse market for buying varieties of food items. At onepoint, the most accessible food items were pet rodents at pet stores. Not onlywas this costly, but the pet rodents nutri­tional needs were probably not asclosely monitored as those that are sold as food items. It is essential thatany prey item is fed a nutritionally sound diet. Those that were starved, fedinappropriately, or otherwise neglected are of little nutritional benefit tothe snake that eats them. Just going through the motions of feeding the snakedoes not ensure nutritional require­ments are being met. Remember, you are whatyou eat.Today, many companies breed insects and rodents specifically for fooditems, and they offer every growth stage of rats and mice. Commerciallyavailable snake food includes various stages of mice, rats, gerbils, rabbits,guinea pigs, chickens (and other birds such as guinea chicks). For smallersnakes (i.e. garter and ribbon snakes) that feed primarily on invertebrates,there are crickets, various worms, and even small fish available for feedingpurposes. In some cases, other reptile and/or amphibian species, such as anolesor frogs, may be used to encourage finicky eaters to feed in captivity.However, most of the commonly kept species feed on rodents. Below are some ofthe terms used when specifying the stage of feeder rodent desired if standardadult size is not ideal:• Pinkies: baby mice,no fur present yet• Fuzzies: baby micethat have just gotten fur• Hoppers: juvenilemice that have fur and all adult characteristics but are not as large as adultmice• Pups: usuallyunweaned or nursing baby rats• Weanlings: babyrats that are no longer nursing• Otherwise (forrats): small, medium, large, or jumbo is used to obtain the desired size.Choose an appropriately sized meal by offering a prey item that is nolarger than the biggest part of the snakes body. Some people try to gauge preysize by the size of the snakes head. This can be deceiving because the snakewill dislocate its jaw for feeding; therefore, it can feed on prey items thatare much larger than its head. Gauging by the actual body itself helps toensure that the snake is being fed a large enough prey item and yet one that isnot so big that could cause an uncomfort­able, large, bulging appearance.Another benefit of easily accessible commercial rodent breeders is theability to purchase rodents prekilled and/or frozen. Some people find itdishearten­ing and difficult to feed live rodents to snakes. In the wild, thesnake feed on live prey, but with the avail­ability of prekilled prey on themarket, there is no need for this in captivity. Captive-bred specimens readilyfeed off prekilled or previously frozen prey items. Offering live prey tosnakes causes unnecessary suffer­ing to the rodent, and the snake can endurerodent bites as a result. Significant rodent bites can cause manydermatological problems; some even warrant systemic antibiotics and/or topicaltreatments of a dilute betadine or chlorhexidine solution. Scars fromSnakes  139bite wounds are usually apparent in snakes that are offered live preyitems (Color Plate 7.1).Offering previously frozen prey rather than live prey has many otherbenefits. It is usually cheaper to and may be purchased in bulk rates iffreezer space is available. Another benefit is that a frozen rodent iscertainly less likely to introduce parasites to the snake and/or enclosure.Rodents are one of the main sources of parasitic contamination in captivesnakes. They can harbor mites, for instance. If a frozen prey item hadparasites (endoparasite or ectoparasite), the parasites will most likely bedead due to the freezing process. This is not to say, however, that it isacceptable to knowingly offer parasite-infested animals as food just becausethey were frozen. Buying snake food from a reputable company helps to make surethe snakes nutritional needs are met.Do not attempt to feed a frozen rodent to the snake; it must first bethawed out. Putting the rodent in a zip lock bag and submerging it in hot wateris an easy way to do thaw it. Some people even place the rodent on a warmsurface (under a heat lamp, on a heat pad, etc.) to ensure the rodent isproperly thawed. Microwaves are not an option for thawing rodents.Feedings only need to occur about once a week to every fourteen days foradult snakes due to their slow digestive process. For juveniles, it may benecessary to feed twice a week to ensure that proper nutritional requirementsare being met during the growth process. If a snake refuses one meal, do notpanic. This occurs occasionally and the snake will not starve in one weekstime. If several consecutive meals are skipped, then the snakes inappetenceneeds to be addressed.To avoid bites, some reptile hobbyists believe that snakes should not befed inside their primary enclo­sure, especially if the only time the enclosureis openedPlate 7.1. A snake suffering from trauma from a prey item. (Photocourtesy of Dr. Sam Rivera.) (Seealso color plates)is when the snake is being fed. This creates a feeding response andmakes bites more likely to occur. Feeding outside the primary enclosure issafer and also can help to ensure that any loose substrate located inside theprimary enclosure is not ingested during feeding.Why Wont My Snake Eat?Some people claim that their snake will not take previ­ously frozen preyand will only accept live prey items. Some people have snakes that arereluctant eaters in general. Below are some feeding guidelines and tips tofollow for all reluctant eaters.Some snakes, such as Boidae and pit vipers, have heat-seeking pits thatthey rely on for locating their warm-blooded prey. Some people confuse thesepits for nostrils. These bilateral openings are located on the skin of theupper lip, usually under the nares. If they confront a cold prey item(previously frozen), they are unlikely to show any interest; therefore, makesure that the prey item is warm, using the warming techniques described above,before offering it to the snake.Motion also can trigger a snake to feed. Tongs should always be usedwhen placing a prekilled rodent into the enclosure. This is especially truewhen one entices the snake by moving the prey item around. Many snakebitesoccur during feedings and can be easily avoided if using tongs (not hands) whenfeeding and keeping a safe distance from the snake.There are several things to check for if the snake was wild-caught andis not feeding in captivity. Wild-caught specimens are frequently reluctant toeat in captive environments. Remember that they have been taken from theirnatural habitat and placed in a cage. Furthermore, in most cases they are beingoffered prey they would have never encountered in their natural habitat. Forexample, a green tree python feeds pri­marily on birds, frogs, and occasionalsmall mammals in its natural habitat. Once in captivity, it is offered whitemice. This is an unnatural prey item and small mammals are not a large part ofthe natural diet to begin with. This is not to say that it will never acceptcommercially bred rodents in captivity, but adjusting to a new captiveenvironment is tough.Initially at least try to offer a natural diet. Try feeding coloredrodents rather than the typical white feeder rodents if the snake is reluctantto eat white rodents. Although more expensive than mice and rats, gerbils areanother option to be used for prey. This sometimes helps with wild-caughtsnakes that are reluctant to eat because gerbils look more like a naturalsource of prey than white rodents do. Wild-caught specimens will most likely bereluctant to take prekilled prey initially because they are accustomed to liveprey140  Chapter 7items. Therefore, attempting to feed prekilled or frozen prey items tonewly acquired wild-caught snakes will most likely be unsuccessful and willtake time. Besides the moral issues with keeping wild-caught snakes, this isanother reason why they should be avoided as purchases.Some people attempt to speed up the process of getting a wild-caughtsnake to accept commercially bred rodents by scenting them. This does work occa­sionally.Scenting them is achieved by rubbing a natural prey item on the rodent to leavea scent. This works mostly for hobbyists who keep multiple species of reptilesand amphibians. For example, if trying to feed a mouse to a snake that mostlyfeeds on lizards and frogs naturally, a person can rub the feeder rodent on alizard or frog that is kept in their collection. This will leave the scent ofthat animal on the rodent, and possibly trick the snake into eating it.Another common reason a snake may refuse food is inadequate heat. If asnake is cold, it will most likely refuse food. A snake needs to be warm toproperly digest food. Regurgitation occurs frequently in snakes kept too cold.A snake that is too cold spends most of its time in a heat-preserving postureand is not inter­ested in feeding at all. Make sure all heat requirements arebeing met when dealing with a reluctant eater.As a rule, when a snake refuses prey, all husbandry requirements shouldbe checked to ensure they are being met properly. Even something as simple asabsence of a hide box (a secure place) will cause a snake to refuse prey.Note: If a snake is about to shed, it will most likely refuse food. Fooditems should not even be offered until the snake has fully shed to avoid excessstress.Snakes that are ailing from respiratory disorders or other illnessesmost likely stop feeding as well. The onset of illness affects their appetites,just like any other animal. It is extremely important for the snakes owner toread as much literature as possible on the snake being kept. Once again,knowing the natural geographic range of the snake help in making hus­bandrydecisions, which may be the root of many problems. All too often, snakes areimpulse buys and the buyer does not bother with reading up on the requirementsand responsibilities involved with that particular snake.TRANSPORTATIONThere are several ways to transport a snake. Snake bags are the mostcommonly used and can be burlap sacks, pillow cases, laundry bags, or otherlinens that are breathable fabric and can be secured. The snake should beplaced in the sack and then the sack should be knot tied at the open end. Thebag should then be grabbed above the knot because a bite can still occurthrough a bag. The bag should be moved using tongs if the snake is venomous.Venomous snakes should be transported in something more durable to safeguardagainst bites.Plastic tubs or clean paint buckets with lids can be used as well. Thisworks well for larger species if a large enough bag cannot be obtained. Oneshould ensure that the lid snaps down or can be secured prop­erly in case thesnake pushes on it. Breathing holes must be cut in the plastic if tubs orbuckets are used taking care not to create abrasive or sharp edges that thesnake could contact.DISEASES AND CLINICAL CONDITIONSDiseases Affecting the Reproductive TractCloacal prolapse is a common problem seen in snakes. The prolapse can bethe colon, hemipenes, uterus, or oviduct. It is usually caused by excessivestraining or during copulation. It is important to determine which organ hasprolapsed before initiating treatment. The hemipenes are solid and do not havea lumen. The colon is smooth and has a lumen. Feces are normally be seen if thecolon is prolapsed. The oviduct or shell gland has longitudinal striations witha lumen. There are no feces present if it is the oviduct or shell gland.Hemipenile prolapse, or paraphimosishas several causes, includinginfections from bacteria, fungus, or parasites; swelling secondary to forcedprobing; forced separation during copulation; constipation; or neuro­logicdysfunction in the hemipenes retractor appara­tus, cloacal vent, or anal sphinctermuscles. Treatment should begin immediately after diagnosis. The pro­lapsedhemipenis should be cleaned, lubed, and replaced. If replacement isunsuccessful or the hemipe­nis is necrotic, the hemipenis should be amputated.Snakes have two hemipenes, so reproductive ability is not affected.A prolapsed colon is caused by excessive straining, usually fromconstipation. The tissue must be moist­ened and replaced. Most colon prolapsescan be replaced through the cloaca, but occasionally surgery is required. Whenthe tissue is replaced it must also be inverted. If replaced properly, a pursestring suture is not required. Because this condition is not the primaryproblem, both conditions must be treated.Oviductal or shell gland prolapses are most com­monly seen during normaloviposition or parturition. They are treated much the same as a colon prolapse.Snakes  141The prolapsed tissue must be kept moist and replaced through the cloaca.Resection is recommended if a large amount of the oviduct is prolapsed or ifthe tissue is necrotic.Dystocia is another common reproductive disorder. There are two types ofdystocia in reptiles, obstructive and nonobstructive (Lock 2000). Anobstructive dys­tocia is caused by an anatomic inability to deliver the eggs orlive young or by a complication during oviposi­tion. The anatomic defect may befetal or maternal. Some common maternal anatomic defects that are seen insnakes include misshapen pelvis, oviductal stricture, nonoviductal masses,oviduct scarring from previous infection, or retained eggs or fetuses fromprevious pregnancy. Fetal defects include an egg that is too large or eggs thathave adhered. Diagnosis is made through a physical exam, history, andradiographs or ultra­sound. Treatment includes the surgical removal of the eggsor fetuses.Nonobstructive dystocias are mostly caused by poor husbandry, infection,or poor physical condition (Lock 2000). Improper temperature, humidity, diet,and nesting site can all cause a dystocia. Oviposition requires great strength.Most captive-raised snakes do not have the muscle mass that wild snakes have,which makes it very difficult to deliver eggs or live young. Treatments includemassaging the eggs down, percutaneous ovocentesis, posterior pituitary hor­mones,and, as a last resort, surgery. When massaging, care must be taken to not trapa portion of the oviduct posterior to the egg or live young. If this happens,massage the egg or embryo back to its original position and start over (Ross etal. 1990).Percutaneous ovocentesis can be performed in ovip­arous snakes. A needleis inserted into the egg through the ventrum and the contents aspirated. It isimportant that the coelomic cavity is not contaminated with egg contents. Theegg should pass naturally within forty-eight hours. Posterior pituitaryhormones such as oxy­tocin can be used to assist with the oviposition. Surgerymust be performed if all attempts have been made and the eggs or embryos are stillretained. Successful incu­bation of eggs after a dystocia is rare. Live fetuseshave been raised after a salpingotomy, but it is not common. The prognosis forthe female is good following a dys­tocia. The future reproductive status isalso good as long as there were no complications and at least one of thereproductive tracts was left intact. The female is more likely to retain eggsand live young again.Disorders of the IntegumentDysecdysis, or difficulty in shedding, is the most common disorder affectingthe integument. Causes of dysecdysis are numerous but mostly associated withpoor husbandry. Some common husbandry problems associated with dysecdysis aretoo high temperature, too low humidity, no shedding implement such as a rock orlog, and malnutrition. Other causes of dysec­dysis include systemic disorders,metabolic disorders, stress from excessive handling, loud noises, vibrations,overcrowding, or anything that limits the snakes movements. Treatment includessoaking the snake in tepid water for one to eight hours a day and treating theunderlying problem.Increased ecdysis frequency can occur in snakes. Hyperthyroidism anddermatitis are the main causes of this condition. Frequent ecdysis is also thenatural function of healing after a severe trauma.There are many clinical signs of dermatosis. Abscesses, abrasions,blisters, bullae, discoloration, and nodules are all signs of a diseasedintegument (Rossi 1996). Abscesses are the most common derma-tologiccondition seen in captive reptiles. They are commonly caused by bites from preyor cage mates. Most abscesses are filled with a solid exudate. Treatment forabscesses includes surgically removing the abscess, irrigating the area, andusing antibiotics pending a culture and sensitivity.Bacterial dermatoses are also a very common condi­tion. The most commonbacterial infection is caused by Pseudomonas spp. Other commonbacterial patho­gens include Salmonella spp., staphylococcus,and streptococcus, as well as many other possible bacterial pathogens.Fungal dermatoses are commonly seen in snakes that live in humidenvironments. The clinical signs are much the same as in bacterial infections.Clinical signs of both fungal and bacterial infections include a brown togreenish yellow discoloration, blisters, ulcers, nodules, crust, andgranulomas.Vesicular dermatitis, commonly known as blister disease, is common insnakes kept in dirty, very humid enclosures (Rossi 1996). Fluid-filled blistersappear all over the body and are quickly contaminated with bac­teria, andsepticemia and death quickly follow without treatment.Another bacterial infection caused by poor cage hygiene is ventraldermal necrosis (Lawton 1991). Snakes kept in dirty enclosures can developinfections underneath their ventral scales. The signs include pete-chiation,echymosis, and eventual necrosis of the ventral scales. Fluid therapy is oftenneeded due to the fluid loss from the damaged skin.Contact dermatitis occurs when the snake is exposed to harsh chemicalssuch as pesticides, cleaners, and harsh aromatic compounds.142  Chapter 7The diagnosis for all dermatosis includes a physical examination andhistory, culture (aerobic, anaerobic, and fungal), and cytology (Rossi 1996). Treatment usuallyinvolves topical or systemic antimicrobials and husbandry and nutritionalchanges. During the treat­ment of any of these dermatoses the snake should behoused on clean paper. The paper should be changed daily and the cage should bedisinfected daily until the condition has resolved.Disorders of theCardiovascular SystemCardiovascular disorders are not commonly seen in snakes. The clinicalsigns are nonspecific, ranging from weight loss to a change in skin color.Nutritional dis­orders such as hypocalcemia, hypovitaminosis E, andhypercalcemia with hypervitaminosis D3 have been associated withcardiovascular disease. Infectious dis­eases affecting the cardiovascularsystem are usually secondary to a systemic illness. There is potential forendocarditis with any Gram-negative bacterial patho­gen. If bacterial sepsis issuspected, a blood culture should be taken. There have been reported cases ofcongestive heart failure associated with infectious disease and withcardiomyopathy diagnosed.Disorders of the NervousSystemSpinal osteopathy has been observed in all species of snakes (Bennett1996b). The exact etiology is unknown. This condition has not been observed inwild popula­tions. There are several possible causes to this disorder. It issuspected that a virus found in mice or a virus of snakes that is spread bymice may be a causative agent. Septicemia is suspected because bacteria areoften cul­tured from the spinal lesions. An immune-mediated disease secondaryto septicemia is also suspected. Finally, chronic trauma from excessivehandling is thought to be a cause of this disease.Clinical signs include focal or multifocal swelling along the dorsum,pressure inducing a pain response, hyperflexic cranial to the lesion, motordeficits, trem­bling, and spinal deformities. The diagnosis is made viaclinical signs and radiographs. The snake is still able to function on its ownin the early stages of this disease. As the disease progresses, the snake willno longer be able to move, constrict, or swallow prey. Treatment includes bloodand local aspirate cultures, antibiotics, and surgical debridement.Organophosphate and carbamate toxicity have been reported in snakes.Treatment is similar to that of mammals. The snakes should be given atropineand fluid therapy to maintain hydration and renal function. Their temperatureshould be decreased to slow con­duction velocity of nerves to control seizures.Disorders of the RespiratoryTractRespiratory infections are the most common illnesses in snakes. They canbe caused by bacterial, viral, fungal, or parasitic pathogens (Driggers 2000).Bacterial pneumonia is the most common cause of respiratory illness, andGram-negative pathogens are the most common. Viral infections are under diag­noseddue to the lack of diagnostic assays. Fungal infections are rare but have beenreported. Common clinical signs of pneumonia include cyanosis, bubbles comingfrom the nares or glottis, wheezing or crackles heard during auscultation, andpetechiae of the oral cavity. Stomatitis is commonly seen in snakes withpneumonia (Driggers 2000).The diagnostic plan should include culture and sen­sitivity, cytology,and radiographs. A transtracheal wash should be performed to obtain samples forthe culture and cytology. Antibiotics should be started and changed pending theresults of the culture and sensitiv­ity. Fluid therapy should be initiated withdehydrated snakes. The most common cause of pneumonia in snakes is husbandryrelated. It is crucial to keep the snake within its POTZ and keep properhumidity levels. The cage also must be kept clean at all times.Other causes of respiratory disease include masses, trauma, aspirationof substrate, and dehydration. Dysecdysis can also compromise the respiratorytract, causing disease (Driggers 2000).Disorders of the UrinarySystemUnfortunately, early detection of renal dysfunction has not beenobserved in reptiles. Renal diseases are among the most common problems inolder snakes.Gout, though not as common in snakes as it is in other families ofreptiles, does occur. It is the result of excessive protein metabolism orcatabolism. In this case uric acid production is greater than uric acidexcretion. All diseases that lead to renal failure can cause gout (Miller1998). Gout is found in two forms. In the first, urates are deposited onmesothelial sur­faces. Urate deposits commonly occur on the pericar­dial sac,the peritoneum, the capsule of the liver, and within the parenchyma of thekidneys. In the other form, urate deposits are made in joints, tendon sheaths,ligaments, and periosteum. Both forms of gout can occur simultaneously.Treatment involves diuresis and diet change to a low-purine diet. The prognosisis poor.Bacterial nephritis is a common disease associated with the urinarysystem. It is often secondary to other bacterial infections or animmunosuppressive event (Miller 1998). The primary cause should be detected andtreated accordingly.Snakes  143Disorders of the EyeRetained spectacles are a common reason snakes are brought into theveterinary clinic. Spectacles are retained when dysecdysis occurs. To removethe retained spectacle, place the snake in a very damp environment fortwenty-four hours and then wipe the eye with a gauze sponge or damp tissue. Theretained spectacle usually will come off easily. If it does not, the snakeshould be kept in a warm damp environment until the next ecdysis cycle andproper ecdysis occurs.Surgical intervention should be a last resort. This is a delicateprocedure and should be done carefully so the eye is not damaged. Sterilelubricant should be applied to the eye and the spectacle gently removed withforceps. If the old spectacle is still attached firmly, force should not beused to remove it. It may take several days of soaking and/or applyinglubricant to fully remove the retained spectacle or any retained piece of shed.Intraspectacular dermatitis occurs as a localized dermatitis or as partof a more generalized dermatitis. The majority of these cases are caused byretained spectacles. Often, enucleation is the treatment.Bullous spectaculopathy is caused by obstruction of the nasolacrimalduct (Williams 1996). The obstruc­tion is usually secondary toeither infectious stomatitis or a congenital obstruction. The lacrimal fluid isnot able to drain from the eye, which causes the distended subspectacularspace. Long-term treatment involves surgically removing a 30-degree wedge ofthe ventral spectacle, allowing for drainage.Subspectacular abscesses are usually the result of an ascendinginfection in the oral cavity (Williams 1996). Treatment for theseabscesses involves a wedge resec­tion of the spectacle and flushing. The debrisshould be cultured and the snake should be started on appro­priate antibiotics.Disorders of the DigestiveSystem Infectious StomatitisInfectious stomatitis is a disease that is caused by poor husbandry andnutrition, stress, poor feeding tech­niques, or trauma. It is crucial that thesnake be kept in its POTZ and that proper humidity be maintained. When properhusbandry is not met, the snakes immune system is weakened, allowing foropportunistic bacteria to reproduce. Stress from being in overcrowded cages,excessive handling, or loud noises can also weaken the immune system. Snakesthat are fed live prey commonly have small abrasions in their oral cavity thatcan lead to an infectious stomatitis. Finally, snakes that rub on the sides ofthe cage have rostral abrasions that lead to an infectious stomatitis (ColorPlate 7.2).Plate 7.2. Stomatitis in a snake. (Photo courtesy of Dr. Stephen J. Hernandez-Divers,University of Georgia.) (See alsocolor plates)Vomiting and RegurgitationVomiting can occur for many reasons. Stress can make a snake vomit. Ifdisturbed after a meal, a snake may get nervous and vomit its meal. Also,feeding a prey that is too large, feeding a prey that is partially auto-lyzed,and keeping the snake below its POTZ are all common causes of vomiting.Infectious diseases such as parasitic infections, inclusion body disease, andbac­terial infections can also cause vomiting in snakes. Regurgitation isusually associated with lesions in the esophagus, oral cavity, or pharynx.Diagnosing Lumps and BumpsLumps and bumps are a common finding in snakes. They occur on theoutside as well as on the inside. When a lump or bump is found on the surfaceof the snake a fine needle aspirate should be performed. Cytology, culture, andsensitivity should be performed144  Chapter 7on the sample. If the lump or bump is palpated in the coelomic cavity, aradiograph or ultrasound should be performed to determine the origin. A sampleshould be obtained and cytology performed. Causes of lumps and bumps in snakesrange from parasites to abscesses to neoplasia. Once the diagnosis is made,treatment should begin accordingly.Viral DiseasesParamoxyvirus is mainly found in viperids but has been isolated in mosttaxa of snakes (Schumacher 1996). It is transmitted through secretions of therespi­ratory tract. Clinical signs are characterized by severe respiratorydisease. Neurologic signs such as head tremors, excitement, star gazing,flaccid paralysis, or convulsions can also be seen (Bronson and Cranfield2006). A presumptive diagnosis of paramoxyvirus should be considered when apneumonia is unrespon­sive to antibiotics. A hemagglutination test has beendeveloped and can be used to measure antibodies against ophidian paramoxyvirus.Titers reflect expo­sure. A rising titer in paired samples is necessary for adiagnosis of active disease (Ritchie 2006). A diagnosis can also be made byhistological examination of post­mortem lung, liver, kidney, splenopancreas,and brain samples. There is no treatment for paramoxyvirus. Supportive care andantibiotics to treat secondary bac­terial infections should be in the treatmentplan. The prognosis is grave. If an outbreak of paramoxyvirus occurs in acollection, all sick snakes should immedi­ately be quarantined and stricthygiene procedures must be followed.Inclusion body disease (IBD) is another serious viral infection that isonly found in boids (Figure 7.12). It is believed that this disease is causedby a retrovirus. Species of boa constrictors have been found to harbor speciesof retroviruses that do not cause disease (Marschang 2001). The route oftransmission is unknown. It is suspected that arthropods play a role in thetransmission. In boas, the most common first clinical sign seen isregurgitation. In pythons, the first clinical signs may be stomatitis andpneumonia (Ritchie 2006). The disease progresses to severe neurologic signssuch as head tremors, disorientation, flaccid muscle paralysis, and the loss ofthe righting reflex. Secondary bacterial infections are common. Eventually thesnake will become anorectic and die. The disease progresses much more rapidlyin pythons than boas (Schumacher and Ylen 2006).Diagnosis can be made by histologic exam of the liver, kidney, stomach,pancreas, and brain. There are no treatments for IBD except for supportive careand treating secondary bacterial infections. The snake willFigure 7.12. Inclusion body disease: note the absence of righting reflex. (Photo courtesy of Dr. Stephen J. Hernandez-Divers,University of Georgia.)eventually die from this virus. Prevention of this disease involvesstrict quarantine procedures when introduc­ing new snakes into to anestablished collection. If confirmed carriers are identified in the collection,euthanasia is recommended to prevent more specimens from becoming infected withthe virus.Zoonotic DiseasesSnakes possess very few zoonotic diseases (Glynn 2001) (Table 7.3).There are two ways in which zoo­notic diseases are passed (Siemering 1986). Oneis by direct contact with the infected animal. The other is by indirectcontact, which can be from contaminated feces, urine, secretions, blood, soil,fomites, and aero­sols. Zoonotic diseases, for the most part, are easilyavoided by following a few simple rules. Do not use the bathtub, sink, orshower as a place to soak a snake. Do not kiss a snake. Wash hands afterhandling a snake. A physician should be consulted a snake bite occurs and thearea should be washed thoroughly. Finally, one should never clean any of thecage furnish­ings where human food is kept or prepared.The most talked about zoonotic disease associated with reptiles issalmonellosis. It is believed that most reptiles carry salmonella organisms intheir intestinal tract and sporadically shed the organisms in their feces. Anestimated 93,000 cases of reptile-associated human salmonellosis is diagnosedeach year (Glynn 2001). All clients that either own a reptile or are con­sideringowning a reptile for a pet should be educated about salmonella. Salmonellosisis easily prevented by simply following the guidelines above.Snakes  145Table 7.3. Common Zoonotic Diseases in Reptiles.PathogenThreatto humansSalmonella spp. Campylobacter spp. Klebsiella spp. Enterobacter spp. YersiniaenterocoliticaPseudomonas spp. Mycobacterium spp.Coxiella burnetiiTAKING A HISTORYTaking a complete history of a snake patient is the first crucial stepin diagnosing and treating a sick snake. Such topics as signalment, presentingcomplaint, hus­bandry and nutrition information, and any previous medicalhistory are keys to proper diagnosis and treatment.SignalmentSignalment includes the common and scientific names (ball python, Python regius), age, amount of timein owners possession, whether it was captive-bred or wild-caught, and whetherit is kept as a pet or as a breeder. It is important that the common andscientific names of the snake are acquired when the appointment is made. Withapproximately 2,400 extant species of snake, it is impossible for a singleperson to know the natural history, husbandry, and nutritional needs of everyspecies. Therefore, it is important that the medical staff be prepared ahead oftime to ensure that the owner meets proper husbandry and nutritional needs.Many species of snake also have two or more common names, which can makeidentification very difficult. For example, most Americans refer to Python regius as a ball python,whereas most Europeans refer to Python regius as the royalpython. By knowing the scientific name of the snake, proper identification canbe made, and the appropriate information can be relayed to the owner.Another key component to signalment is the age of the snake. If theactual age of the snake is unknown, then the amount of time that the owner hashad pos­session of it is important information. The average life span ofcaptive snakes is very short. However, snakes are capable of living to a verygeriatric age, with someMode of transmissionspecies known to live more than thirty years. Such short life spans aremostly associated with poor husbandry.At this point in the history-taking, the origin of the snake should benoted. Wild-caught snakes are often imported in very substandard conditions andarrive at the pet store with a subclinical disease. Internal and externalparasites and respiratory infections are most commonly seen with importedspecimens. Captive-bred specimens, generally speaking, are much tamer, are freeof disease and parasites, and live longer than wild-caught specimens. It isalso important to urge owners to buy captive-bred specimens due to thedepletion of wild populations caused from the collec­tion of wild animals forthe pet trade.Note whether the snake is kept as a pet or a breeder. Snakes kept solelyas pets usually do not need to be hibernated, photoperiods do not need tochange throughout the year, and nutritional needs usually do not changethroughout the year. Snakes kept for breeding do have nutritional and husbandrychanges throughout the year. Temperate species should be hibernated, whichtakes several weeks of preparation. If hibernation is not done properly, thesnake can become very sick and possibly die while hibernating. With regard tonutrition, many female snakes do not eat while gravid. The females normallystart eating again when the clutch is laid, the clutch hatches, or the livebabies are born. Special nutritional needs must be met before the breedingseason starts and when the female snake starts eating again. Also, to ensure asuc­cessful breeding season, the photoperiod must be changed to simulate thenatural photoperiod.All snakes that are large enough should be sexed. It is a very simpleprocedure that should be included in the initial exam.GastrointestinalDiarrhea and acute gastroenteritis Diarrhea and genitourinary infectionsDiarrhea and genitourinary infections Gastroenteritis and severe abdominal painCutaneous, respiratory, and digestive Cutaneous and subcutaneous noduleQ-feverFecal-oral contact Fecal-oral contact Direct contact Direct contactEnvironmental contactIngestion, inhalation, or scratches or bites Fecal oral contact,inhalation of oral orrespiratory mucosa, or bites or scratches Inhalation or direct contact146  Chapter 7Presenting ComplaintThe presenting complaint is the reason the owner brought the snake to beexamined. Some common presenting complaints include wheezing, dysecdysis,anorexia, and lethargy. Approach the presenting com­plaint as if it were thatof a dog or cat. The owner should be asked when the problem started, if therewere any husbandry/nutritional changes, if he noticed any other problems, andso on. The medical staff is like a team of detectives that must gather as muchevidence as possible to come up with a diagnosis and treatment plan. It isimportant to get as much informa­tion from the owners as possible.Husbandry and Nutritional InformationThe single leading cause of death in captive snakes is poor husbandryand/or nutrition. It is up to the veteri­nary technician to find out everydetail of the hus­bandry practices and advise the owner if corrections need tobe made. This part of the history takes fifteen to twenty minutes. It iscrucial to take time and record every detail. Following is a list of questionsthat should be asked at the initial exam:• What is the day andnight temperature range?• What is theday/night cycle?• What light sourcesare available?• What are theprimary and secondary heat sources available?• What is thehumidity in the enclosure?• What humiditydevices and methods are used?• How big is thecage?• Where is the cagelocated?• What is the cagemade of?• Is the cagedesigned for an arboreal or terrestrial species?• What substrate isused?• How often is thecage cleaned and disinfected?• What type ofdisinfectant is used?• What cagefurnishings are available (rocks, branches, hide box, etc.)?• How is wateroffered (drip system, misting, bowl, etc.)?• What food items areoffered and what time of day are they offered?• Is the snake fedlive, frozen-thawed, or fresh-killed prey items?• How is the preyoffered (feeding tongs, set in the bottom of the cage, in a separate cage,etc.)?• What is the feedingschedule?• How are the preyitems stored?• Where were the preyitems acquired?• What is theecdysis/defecation schedule?• Are there otherreptiles or other animals in the same air system?• Are any of theseanimals sick or have any died within the past three months?• Is properquarantine performed on new and sick specimens?Previous Medical HistoryAny previous medical condition or diagnostic tests should be noted inthe record. The owners fecal check and deworming schedule should also be notedin the record.PREPARING FOR THE PHYSICAL EXAMThe exam room must be prepared ahead of time to ensure a quick andcomplete physical exam. The exam room needs to be snake proof. The doors mustbe sealed so the snake cannot escape under the door, large drains in the sinkshould be covered, air vents should be covered with mesh to prevent the snakefrom crawl­ing in, and any other holes or cracks that the snake can get intoshould be covered or sealed to keep the snake from escaping or getting stuck.Appropriate-sized sex probes with lubrication for sexing and a spatula orcredit card for oral examination should be in the exam room. Restrainingdevices such as snake hooks, clear plastic restraining tubes, and capture tongsshould be readily accessible for aggressive or venomous species. Large snakescould need two or more people for proper restraint. It may be necessary to haveother technicians or assistants close by in the event that more help is needed.Other essential instru­ments that are needed for a physical exam are a goodlight source, ophthalmic scope, stethoscope, fecal col­lection system, andmagnifying glass to check for external parasites.RESTRAINTAs stated previously, snakes can be very unpredictable and should betreated as such to avoid being bitten. Even the most docile of snakes will biteif they feel threatened or cornered. Watch for warning signs such as hissing oran S-shaped striking posture before attempting to handle a snake (Figure 7.13).Whether restraining or simply holding the snake, it is important to doso properly. If not held properly, not only can one get bitten, but the snakecan sustain injuries, too. The body should always beSnakes  147Figure 7.13. A snake in a striking pose. (Photo courtesy of Ryan Cheek.)supported as much as possible. With larger snakes, it will take morethan one person to hold and offer neces­sary support.When manually restraining the snake, ensure that someone has control ofthe head. This should be the first part of the body restrained. The head shouldbe held right at the base and without applying too much pressure around theneck area. This could obstruct the trachea, causing a strangling effect, andthe snake could suffocate. In addition, the snake could panic, making it verydifficult to manage. The rest of the body can be held with a free hand or byassistants when handling large or aggressive snakes. Do not place a snake(especially large snakes and/or constrictors) around the neck. While this iscommonly done, it can be dangerous. If the snake feels threatened and inse­cureit will begin to constrict around the neck.Different tools can be used to move snakes or assist in immobilization,including hooks, tubes, and tongs, all of which are discussed below. Snakehooks allow a person to move a snake without having to touch the animal or gettoo close. This is advantageous when handling aggressive snakes. A hook can beused to get a snake out of an enclosure, as a guide, or as a pinning device.For example, to remove a snake from an enclo­sure, the hook is used to hook thesnake one-third of the way down its body and then gently lift it. The hook canthen be used to pin the head to take control of it, but extreme caution must beused because any thrash­ing by the snake can cause severe spinal cord injury.Only handlers experienced with the hook should use the pinning technique. Ifthe snake is hooked too close to the head or tail, it will usually slide rightoff. It may be necessary to use more than one hook for larger snakes (Figure7.14).Figure 7.14. Proper use of asnake hook. (Photo courtesy of RyanCheek.)Snake hooks are also used when coercing a snake into a snake tube forphysical exam or immobilization. They can be purchased at most reptile supplyshops (Figures 7.15, 7.16).Snake tubes are open-ended, clear, hard plastic or acrylic tubes thatare used to hold a snake and view it safely during examination. The tubesdiameter must be just large enough for the snakes head to fit into, but notallow the snake to turn around in. One end of the tube should be aimed towardthe snakes head and a snake hook used to entice the snake into the tube. Onceone-third to one-half of the snakes body is in the tube, the handler shouldgrasp the snake and the base of the tube so it cannot back out. A face mask canbe placed on the other end of the tube to admin­ister gas anesthesia andimmobilize the snake com­pletely, if necessary. This is the safest way tomanage aggressive snakes and venomous species. Most of these tubes arepurchased from reptile supply stores or hard-148Chapter 7Figure 7.IS. Snake tongs at the top and two snake hooks below. (Photocourtesy of Ryan Cheek.)Figure 7.16. Using a hook to coax a snake into a plastic tube. (Photocourtesy of Zoo Atlanta)ware stores (if appropriate materials are found) and come in varioussizes.Another method of capturing an aggressive snake is to place a clearshield over its head. Once the shield is in place, the handler can grasp rightbehind its head taking control of it.Snake tongs can be used for many purposes. The most common use is forfeeding (Figure 7.17). Offering food items via tongs is obviously safer thanusing ones hands to offer prey. Tongs allow the feeder to keep a safe distancefrom the snake and the prey item. Although some people use tongs to assist inrestraining snakes, this method is not recommended. Grabbing the snake withtongs can apply too much pressure and, depending on the part of the body thatis grasped, the snake can be injured. Snakes can also easily free them­selvesfrom tongs if not grasped properly. Tongs canFigure 7.17. Feeding a python with tongs. (Photo courtesy of Ryan Cheek)be used to assist in tubing the snake but not as a primary handlingmechanism.An undesirable method of restraint is to allow a snake to partiallyswallow prey. This allows the handler time to take control of the head and thebody before the snake can strike. However, often the snake regurgitates theprey, making this technique undesirable.To avoid bites, some reptile hobbyists believe that snakes should not befed inside their primary enclo­sure, especially when the only time theenclosure is opened is when the snake is being fed. This creates a feedingresponse and makes bites more likely to occur. Feeding outside the primaryenclosure is therefore a safer practice and also can help to ensure that anyloose substrate located inside the primary enclosure is not ingested duringfeeding.THE PHYSICAL EXAMAfter a very thorough history has been taken and the exam room isprepared, a complete physical exam should be performed. It should begin as soonas the owner brings the snake into the exam room. The snake should be observedas it moves around its environ­ment. Body and muscle tone, proprioception, andmobility should also be observed. Any abnormalities should be noted. Anaccurate weight in grams or kilo­grams as well as the snout-to-vent length(SVL) should be measured to determine organ location and monitor growth injuvenile snakes. The cloacal temperature should be recorded to help determinethe thermal envi­ronment in which the snake lives.There are several approaches to performing a physi­cal exam. Someclinicians prefer a head-to-tail evalu­Snakes  149ation, whereas others have a specific order of body systems that areexamined. It is important to do the same routine with every physical exam sonothing is left out or overlooked.IntegumentThe skin should be checked for parasites, thermal burns, trauma, skintenting or ridges to assess hydra­tion, dysecdysis, and bacterial or fungalinfections. If ecdysis is currently in process, the stage of ecdysis should berecorded.Respiratory SystemThe upper and lower airways should be auscultated for any crackles orincreased respiratory sounds. Remember that most snakes only have a right lungwith the excep­tion of the boids, which have a right lung and a small leftlung. The nostrils should be clear of debris and any discharge. The glottis caneasily be observed for proper function and for any inflammation. When theglottis opens during respiration, look down the trachea for any swelling,mucous, or foreign material.Cardiovascular SystemAuscultation of the snakes heart can sometimes prove to be difficult.It is crucial that the exam room be silent. Using a damp cloth or gauze spongecan help enhance the heart sounds. The heart is generally around 25% down thebody from the snout. A heart rate should be obtained during auscultation.Peripheral pulses should be assessed via the use of a Doppler flow detector.The Doppler can be placed on the ventral tail vein or just cranial to the heartat the base of the glottis.Neurologic ExaminationNeurologic exams are very simple to perform on snakes (Bennett 1996b).The exam starts with the initial presentation of the snake. Watch for anyjerking motions, absent or slow righting reflex, or the inability to strike atprey. The site of a spinal cord injury can be found by using the rightingreflex. Snakes will right themselves up to the point of the injury. Ahypodermic needle may be used to stimulate the panniculus reflex. Aneurologically normal snakes skin twitches up to the point of spinal injury. Acranial nerve exam should be performed if a neurologic disorder is suspected.The following methods can be used to examine the twelve cranial nerves insnakes:CN I: A snake with a properly functioning olfactory nerve recoils fromthe smell of noxious odors. Alcohol can be placed in front of the snakes noseto see if it reacts to the smell.CN II: Because reptiles have an iris that is composed of skeletalmuscle, pupilary light reflex cannot be used to determine the function of theoptic nerve. Carefully watch the eye movements of the snake to assess thefunction of the optic nerve.CN III, CN IV, CN VI: This group of cranial nerves is extremely hard toassess in snakes. They are responsible for eye movement coordination.CN V: Snakes with a malfunctioning trigeminal nerve have abnormal jawfunction and a loss of feeling around the face. They cannot thermoregulate orfind prey.CN VIII: The acoustic nerve is difficult to assess.Snakes may show signs of nystagmus, head tilt,rolling, and abnormal righting reflex. CN IX, CN XI, CN XII: Dysphagiaand abnormaltongue movements can be seen in a snake if oneor more of these cranial nerves is damaged ormalfunctioning. CN VII and CN X: The facial and vagus nerves areimpossible to assess in snakes.PalpationsThe entire length of the snake should be palpated for any abnormalitiessuch as enlarged organs, internal masses, lumps, and bumps. In breedingfemales, eggs and preovulatory follicles can be felt on palpation. Digitalpalpation of the cloaca can reveal several abnormalities and should beperformed on all snakes that are large enough. An otoscope or endoscope can beused as well.Ophthalmic ExamAs discussed in the anatomy section, snakes have a transparent spectaclethat covers the cornea. The eyes should be clear and smooth. Any retained shedscan easily be seen and removed. Any other abnormalities should be furtherexamined with an ophthalmic scope.Fecal ExamAll snakes that come in for a physical exam should have a fecalexamination performed. This exam should include a fecal floatation and twodirect fecal smears, one prepared with a normal saline solution and the otherprepared with a Lugols iodine solution.Oral ExamBecause most snakes become distressed during the oral exam, it is oftenbest to perform the oral examination last. Gently open the mouth using aspatula or plastic card. Determining the proper mucosa color can be difficult.Most species have a pale mucosa color while others may have a more pink orbluish color. It is150  Chapter 7important to know the normal color for that species before the physicalexam is performed. With all species the oral cavity should be moist without anystringy or tenacious mucus. The clinician should look for any caseous exudates,hemorrhage, and necrosis.RADIOLOGYCreating a Technique ChartA separate technique chart should be made for snakes. A variable kVp orvariable mAs technique chart can be made, although a variable mAs techniquechart is preferable. The technique chart should start at 2 cm and go to atleast 20 cm. Describing the proper method of creating a technique chart is outof the scope of this text. There are numerous texts that describe this processin detail. It is an easy but time-consuming task that if performed correctlywill save much time when a radiograph is needed.PositioningAs with all other animals, two views should be taken, lateral anddorsoventral (DV). Snakes should not be radiographed in the coiled positionbecause this can distort internal organs and decrease detail. The snake shouldbe stretched out over the cassette. If properly collimated, two or more regionsof the body can be radiographed on one film. If possible, radiograph both viewsof the same region on one film to make inter­pretation much easier. If multiplefilms are required, the films should be labeled to match the region taken.There are several methods of doing this. The method that this author uses isbased on the number of films required to radiograph the snake. If four filmsare needed, the first film is labeled 1/4, the second film is labeled 2/4, andso on (Figure 7.18).RestraintWith the exception of very sick snakes, most snakes will not be stillenough to radiograph without proper restraint. For docile snakes, manuallyholding them on the table is sufficient enough restraint for proper tech­nique.For less-docile snakes, placing them in clear plastic tubes allows for properpositioning and tech­nique. If this method is used, the kVp or mAs, depend­ingon the technique chart used, may need to be slightly increased to compensatefor the plastic. As a last resort, chemical restraint, either injectable orinhalant anesthesia, can be used. If injectable anesthesia is used, ashort-acting drug or one that is reversible is pre­ferred. Some injectableanesthetics can last for hours or even days in reptiles.Figure 7.18 Radiograph of asnake taken while it is in a bag. (Photo courtesy of Ryan Cheek)ANESTHESIAAnatomy and Physiology ConsiderationsThe lungs of reptiles are very fragile. When performing intermittentpositive pressure ventilation (IPPV) always stay under 20 cm water to avoidpulmonary rupture (Bennett 1996a). Reptiles do not have a diaphragm, sorespiration is accomplished through other muscles throughout the thoracic andabdominal areas. Some of the muscles are paralyzed when the reptile reaches asurgical plane of anesthesia, making IPPV necessary. Keep in mind that manysnakes can breath hold and convert to anaerobic metabolism. Many species canlive for hours without oxygen. This adaptation makes induction difficult toimpossible in some species if inducing with inhalant anesthesia.Preanesthetic Examination and ConsiderationsBefore placing a snake under anesthesia a very thor­ough physicalexamination should be performed. A minimal amount of diagnostics, including apacked cell volume and total solids, also should be recorded to help determinethe health status of the snake. More diagnostics may be needed such as abiochemical profile, complete blood count, fecal analysis, radio­graphs, orcultures if infection is suspected. Any abnor­malities on the physicalexamination or diagnostic testing should be treated or stabilized before theanes­thetic episode. The snake should be fasted for one to two weeks for anyelective procedures or nonemer­gency anesthetic procedures. The cardiopulmonaryfunction can be compromised if a large prey is still being digested in thestomach.Snakes  151Intravenous fluid therapy is needed for any debili­tated snake or duringlong procedures (Bennett 1997). If the snake is dehydrated, rehydration shouldoccur before beginning the anesthetic episode. Any of the crystalloids areappropriate for use in reptiles (Lawton 2001). There is much debate over theuse of any fluids containing lactate (Wright 1999). Lactate in reptiles buildsto high levels after muscle fatigue and can only be metabolized by the liver.There has been no research performed on this issue as of the date ofpublication of this text. Until further research has been conducted, it is recommendedthat fluids containing lactate not be used on a long-term basis in reptilepatients. If lactated Ringers solution is chosen for fluid therapy, potassiumchloride must be added to prevent hypokalemia. If fluids are neededinteroperatively, an intravenous cath­eter must be placed in either the jugularvein or directly into the heart. The interoperative fluid rate should be 5 to10 ml/kg/hour.Preanesthetic MedicationsPreanesthetics are not routinely used in all reptiles. Preanestheticscan be used to provide safer handling of larger snakes to facilitate smootherinductions for general anesthesia. They may also help decrease the amount ofdrugs needed for induction.AnticholinergicsAnticholinergics such as atropine sulfate and glycopyr-rolate for themost part are unnecessary as a preanes­thetic medication. Glycopyrrolate hasbeen shown to help prevent bradycardia; however, bradycardia is usually not aconcern in reptile anesthesia.Injectable AnestheticsThe use of injectable anesthetics in reptiles is very unpredictable. Thesame dose given to two individuals of the same species can yield completelydifferent levels of sedation (Bennett 1996a). Once the injection is given, thedepth of anesthesia cannot be controlled. Reptiles have a very slow metabolism;therefore, recovery time can take from a couple of hours to a week with someanesthetics. Reptiles require a very high dose of narcotics to produce anysedative effects; as a result, narcotics are not recommended in reptiles.Use of barbiturates is questionable in reptiles. It is unknown howreptiles eliminate barbiturates from their body. It is believed that they relyon metabolism for eliminating barbiturates instead of redistribution tononnervous tissue (Bennett 1996a). Thiobarbiturates have a recovery time ofseveral days. This can be quickened by increasing the ambient temperature inthe cage. The ultra short barbiturates work well in reptiles with a relativelyshort recovery time of only a few hours. As with all injectables, there is asignificant variation in response.Ketamine is frequently used in snakes for sedation and induction, andcan also be used as a surgical anes­thetic. Due to metabolic scaling, largerspecies require the lower end of the recommended dose (Bennett 1997). When usedalone, moderate to high doses of ketamine have been associated with increasedheart rates, respiratory depression, hypertension, apnea, bradycardia,prolonged recovery times, and death (Bertelsen 2007). However, when ketamine iscom­bined with benzodiazepines or alpha-2-agonists, better muscle relaxationoccurs and there is a reduction in the required dose (Bertelsen 2007).Medetomidine has been used with great success in snakes. When given, itgreatly reduces the amount of induction needed and also at higher doses givesenough sedation for quick procedures. Medetomidine is revers­ible withatipamezole. Medetomidine when given with ketamine shows better anestheticeffects than when given alone.Telazol, a combination of tiletamine and zolaze-pam, is recommended as atranquilizer or induction agent and not the sole anesthetic. Telazol given at adose of 2 to 5 mg/kg will sedate the snake enough for diagnostic procedures orfor intubation. High doses of telazol have been associated with prolongedrecovery times (Schumacher and Yelan 2006).Propofol is a very short-acting nonbarbiturate that can be used as aninduction agent or for short surgical or diagnostic procedures. The onlydisadvantage of propofol is that it must be given intravenously, which can bevery difficult in some snakes (Schumacher 2002a). The advantages of propofolare that it pro­duces very rapid induction and recovery times, has minimalaccumulation with repeated doses, and pro­duces very little hangover effectafter recovery.Several neuromuscular blocking agents have been used in snakes. Theiruse should be limited to nonpain-ful diagnostic procedures because these drugsdo not produce unconsciousness or analgesia. Intubation with IPPV is necessarybecause respiratory paralysis is likely.Inhalant AnestheticsInhalant anesthetics have become the standard of practice for reptiles(Bennett 1997). There are many advantages of inhalant anesthetics versusinjectable anesthetics. First, the level of anesthesia is much more preciselycontrolled. Another significant advantage is that the patient is intubated andreceives supplemental152  Chapter 7oxygen. The recovery time of inhalant anesthetics is much quicker thanwith injectable anesthetics. Usually the patients are recovered in less thanone hour after the anesthetic episode. A nonrebreathing system is rec­ommendedfor patients that weigh less than 5 kg and an oxygen flow rate of 300 to500ml/kg/minute is recommended. Patients that weigh more than 5 kg can use arebreathing system at an oxygen flow rate of 1 to 2 L/minute. IPPV isrecommended in all anesthetized reptiles at a rate of two to four breaths perminute.Methoxyflurane has been used successfully in snakes. The disadvantage ofthis inhalant is that it produces slow induction and recovery times, and 50% ofthe drug is metabolized by the liver, making it inappropriate in patients withany liver problems. Elapids and some pythons have shown sensitivity tomethoxyflurane.Halothane produces a quicker induction and recov­ery thanmethoxyflurane. In addition, only 12% of halothane is metabolized by the liver,making this drug a better choice for patients with liver problems. Wheninducing with halothane, start with a low concentra­tion and slowly increase toprevent irritation. This process can induce breath holding. Venomous speciesseem to require a higher concentration of halothane, with viperids requiringmore than elapids.Isoflurane is the inhalant anesthetic of choice of this author. It iscompletely eliminated by the lungs so it causes no metabolic compromise, andcan safely be used on debilitated or compromised patients. Induction is quick,taking five to ten minutes, with recovery taking less than thirty minutes onmost patients.The newest inhalant anesthetic on the market is sevoflurane. Sevofluranegained popularity in the human and veterinary market because of the lowblood-gas solubility, which allows for very fast induc­tion and recovery timesand improving the control of anesthetic depth (Schumacher 2002b). In humans,cardiovascular stability is better maintained with sevoflurane than withisoflurane. Sevoflurane is also completely eliminated by the lungs. There hasbeen very little research conducted on the effects of sevoflu­rane in reptiles.Clinical experience shows that species and individuals respond differently tosevoflurane, with some being much more resistant than others (Schumacher2002b).Tracheal intubation is easy on snakes (Figures 7.19, 7.20). The tracheasits at the base of their tongue and is easily visible when the mouth is open.AnalgesicsIt was once believed that reptiles do not feel pain. However, reptileshave the neurologic components,Figure 7.19. Endotracheal intubation ofa snake. (Photo courtesy of ZooAtlanta.)Figure 7.20. Stabilizing the endotracheal tube with a tongue depressor.(Photo courtesy of Zoo Atlanta.)antinocieceptive mechanisms, and behavioral responses to pain that otheranimals have (Bradley 2001). Reptiles can and do feel pain and therefore analgesicsshould be provided. Because pain is easier to prevent than treat, analgesicsshould be given before an antici­pated painful procedure. Snakes also sharemany of the same signs of pain as domestic species. Commonly, snakes showssigns of avoidance of handling, with­drawal, restlessness, agitation, beingeasily startled, or anorexia when they are in pain. Some more obvious signs ofpain are holding the body less coiled at the site of pain, stinting onpalpation, and being tucked up and writhing in the affected area.RecoveryRecovering patients should be placed in an environ­ment that is quietand within the species POTZ. Close attention should be paid to therespirations because allSnakes  153anesthetics compromise the respiratory system. Also observe the patientfor any pain or discomfort and treat with analgesics accordingly. If thepatient received fluids during the procedure, the fluids should be con­tinueduntil the patient is fully recovered.Anesthetic MonitoringThe depth of anesthesia in snakes is very difficult to assess. As snakesbecome anesthetized, relaxation begins cranial and goes caudal and is reversedwhen recovering. One of the first reflexes a snake loses is the rightingreflex. Other reflexes to check are the cloacal reflex and the tail pinch tohelp determine the depth of anesthesia. At a surgical plane, snakes shouldstill have a tongue withdraw; they will lose this if they are beyond thesurgical plane. Each anesthetized snake should be connected to an electrocardiogramas well as a Doppler flow device because the cardiovascular system is verydifficult to assess. The heart rate and respiratory rate should be monitoredcontinuously starting when the patient is induced and ending after the patientis fully recovered. Pulse oximetry is only useful in reptiles to monitor trendsin arterial oxygen saturation.SURGERYThe basic principles of surgery are universal. Aseptic techniques shouldalways be used. The patient should be prepared for surgery, induced with anesthesia,intu­bated, and placed on maintenance inhalant anesthesia. The surgical siteshould be prepared with an initial scrub with an approved surgical scrub suchas chlorhex-idine or betadine to remove any dirt or debris from the substrate.When the patient is stable under anesthesia, it can then be moved into thesurgical suite. Once inside the surgical suite, all assistants should put on acap and mask to maintain asepsis. The patient should be properly positioned andtaped down to secure it to the table. Snakes can be positioned either insternal, dorsal, or left or right recumbency. Once the patient is secured tothe table, a sterile surgical scrub should be performed. The fluids used toprep the patient should be warmed to prevent cooling the patient. The patientshould also be kept at its POTZ during the entire procedure and throughrecovery. This can be achieved by using a circulating hot water pad or hotwater bottles.Wound HealingWound healing in snakes has been studied extensively (Bennett and Lock2000). When a wound forms, pro­teinaceous fluid and fibrin fills the space toform a scab. A single layer of epithelial cells grows under the scab and thenproliferates to restore the full thickness of the epithelium. Underneath thislayer of epithelial cells, macrophages and heterophils move in to clean up anypathogens. Fibroblasts migrate to the area, forming a fibrous scar. Heterophilsare present until maturation has occurred. Ecdysis seems to help with the woundhealing process (Bennett 1997). It has also been observed that incisions thathave a cranial to caudal orientation heal faster than transverse incisions.Furthermore, staying in the upper end of the species POTZ promotes good woundhealing (Bennett and Lock 2000).The incised skin of reptiles has a tendency to heal inverted. The skinshould be closed using an everted suture pattern such as mattress pattern. Skinstaples can also be used for skin closure. The sutures should be removed infour to six weeks and preferably after the next ecdysis cycle.Common Surgical ProceduresCeliotomies are routinely performed on snakes. The incision for aceliotomy should be made between the first two rows of scales dorsolateral tothe large ventral scales (Bennett and Lock 2000). This approach is per­formedto avoid the large midabdominal vein. A zigzag incision is made between thescales in the softer skin. Celiotomies are commonly performed for foreign bodyremoval and exploratory surgery.The most common surgery of the respiratory tract is removal of granulomasfrom the trachea. The approach is the same as for a celiotomy. The granu­lomais found and removed. The two ends of the trachea are then anastomosed and theincision is closed. The snakes are usually back to breathing nor­mallyimmediately.Gastrointestinal surgeries are routinely done to repair abnormalities.These abnormalities may include foreign body removal or resection andanastomosis.Surgery on the reproductive tract is usually not performed to prevent areproductive problem (Lock 2000). The most common female reproductive surgicalprocedure is dystocia and ovariectomy or ovariosal-pingohysterectomy. The lasttwo procedures are per­formed to prevent another dystocia, to remove cysts ortumors, or to prevent another prolapse. The most common surgical procedure onthe male reproductive tract is penile amputation. The hemipenis will prolapseand become inflamed and will not be able to be retracted. Often the hemipeniscan be replaced, but occasionally it will become necrotic and have to be amputated(Figure 7.21).154Chapter 7Figure 7.21. A snake in surgery. (Photo courtesy of Dr. Stephen J. Hernandez-Divers, University of Georgia.)PARASITOLOGY Diagnosing ParasitesParasitic infections are relatively easy to diagnose. A fresh stoolsample should be obtained, being careful not to collect any urates. When anappointment is made for a snake, the client should be asked to bring in a freshstool sample. The client can put the stool sample in a plastic sandwich bag andkeep it in the refrigerator for up to three days. It is not recommended thatthe stool sample be stored in a refrigerator that also stores food for humanconsumption. A double or even triple bag system can be used if the sample isstored with food for human consumption. If a fresh sample is not available, acolonic wash can be performed to obtain a sample. Three diagnostic tests shouldbe performed: a flotation, centrifugation, and saline prepared direct smear.The fecal flotation is used to diagnose nematode ova. The centrifuge helpsdiagnose protozoan cysts. The direct smear is used to diagnose moving or liveparasites. The techniques used to perform these diagnostics are the sametechniques used for diagnosing parasites in small animals. Some parasites, likeCryptosporidium, require specialized diagnostic testing.COMMON PARASITES OF SNAKESExternal ParasitesTicksTicks are a common finding on snakes. Ticks can be very difficult tofind on snakes, especially if the snake has dark skin. Rarely are ticks in sucha high number on snakes to cause anemia, but they can transmit blood parasitesand viruses. All ticks should be removed with extra care to remove all themouthparts from the skin.MitesOphionyssus natricis, the snake mite, is a common finding in petsnakes. The mites are small and appear red, gray, or black. Snakes that areinfected may spend long periods of time soaking in water or appear to rub ortwist their bodies. Visualizing the mite is the only diagnostic method. Ifmites are suspected, a clean white paper towel or hand towel can be rubbed downthe entire length of the snakes body. Often, the mites will come off onto thetowel making for easier visual­ization. Treatment includes cleaning anddisinfecting the cage and ivermectin. Ivermectin can be made into a spray orused as an injection. It is also recommended that all wood and porous cagefurnishings be removed and paper be used as a substrate until the mites havebeen eradicated from the area.Internal ParasitesProtozoaAmoebiasis Of the many species of amoebae that are found insnakes, Entamoeba invadens is the mostpathogenic (Lane and Mader 1996). This amoeba causesa very high mortality and morbidity rate in snakes. It is transmitted via theingestion of infected reptile feces. This parasite has a direct life cycle,making it very difficult to eradicate from snakes. Clinical signs of amoebiasisare anorexia, dehydration, and wasting away. Later stages of the disease showclinical signs of ulcerative gastritis and colitis. This organism can spread toother tissues, causing renal and hepatic necrosis and abscesses. A diagnosis ismade through a positive culture. Treatment of this disease includes abroad-spectrum antibiotic, an amoebicide, and supportive care. The snakes canalso be kept at a temperature of 95°F.Coccidia Coccidiosis is a common finding in captive snakes. Inwild snakes, coccidiosis is a self-limiting infection, but in captivity,coccidia can cause severe illness and in young or small species it can causedeath. Coccidia has a direct life cycle. Sulfonamides are the preferredtreatment.Cryptosporidium is becoming a serious coccidial infection in snakes. Theexact source of infection is unknown but it is believed that snakes contracttheSnakes  155parasite by either contact with shedding reptiles or from mammalian preyitems. Clinical signs for the disease includes midbody swelling, weight loss,and regurgitation. The midbody swelling is a result of chronic gastrichypertrophy caused by the parasite. Cryptosporidiosis is diagnosed byvisualization of oocysts on a microscopic exam. A dimethyl sulfoxide (DMSO)acid-fast fecal exam should be performed for proper diagnosis. Cryptosporidium spp. oocysts aredifficult to find due to their small size of less than 4 microns. The oocystscontain no sporocysts and four sporozoites. There are no safe and effectivetreatments for cryptosporidiosis. Trimethoprim sulfa, spiramycin, and paromomycinhave been shown to reduce clinical signs and reduce or eliminate oocyteshedding. These drugs are given in conjunction with supportive care includingfluids, high environmental temperatures, and tube feeding. It is not known ifthere is a zoonotic potential with this disease, so proper precautions shouldbe taken.Flagellated Protozoa Many genera of flagellates are found insnakes. Most are nonpathogenic, although there is the potential of Giardia spp. to causedisease. Clinical signs include anorexia and weight loss (Barnard 1996).Metronidazole is the treatment of choice for flagellates.CestodesThe life cycle of cestodes involves many intermediate hosts. Snakes thatare susceptible to cestode infections are those that are fed amphibians, fish,or crustaceans.NematodesSeveral species of nematodes affect snakes. The life cycle involves oneor several intermediate hosts. Nematode infections usually appear subclinicalbut signs can appear with severe infections. The only species of great concernare the Rhabdias spp. and Strongyloides spp. (Barnard1996). Rhabdias spp. are known as the lungworm in snakesbecause these nema­todes migrate to the lungs. There are few clinical signswith minimal inflammatory response. Severe infections show signs of dyspnea andmouth gaping. The diag­nosis of lungworms can be made by discovering eggs andfree-stage larvae in the oral secretions or feces. Strongyles are nematodesthat feed on the blood of the host. Clinical signs include anorexia, weightloss, hem­orrhagic ulceration, and gastrointestinal obstruction. A fecal examis performed for diagnosis. Treatment for all nematodes includes any of severalanthelmintics and supportive care (Color Plate 7.3.)Plate 7.3. Ocular larva migrans in a snake. (Photo courtesy of Zoo Atlanta.) (See also color plates)Blood ParasitesExtracellular and intracytoplastic blood parasites are commonly seen insnakes. These parasites rarely cause disease and are normally found on routineblood smears. Extreme cases can cause hemolytic anemia. If anemia is found, anantimalarial medication is indicated.Preventing ParasitesWith parasites, like most other diseases, prevention is easier than thecure. A few simple guidelines should be followed. The enclosures should be keptclean and disinfected often. New specimens should follow proper quarantineprocedures. Do not feed wild prey items; feed only frozen prey to the snakes.If live prey must be fed, start a breeding colony at home with a parasite-freemale and female. Varying the prey offered can help to break any parasite lifecycle (Lane and Mader 1996).EMERGENCY AND CRITICAL CAREAs more and more snakes are kept as pets, the need for proper emergencyand critical care is increasing.156  Chapter 7The basics of emergency and critical care in snakes are the same as inany other animal. The patient is assessed and diagnostics and treatments arequickly started. An emergency is defined as a sudden, generally unexpectedoccurrence or set of circumstances demanding urgent action. Unfortunately, theneed for urgent care is in the eye of the owner and not trained medical profes­sionals.Many owners wait days to months after first noticing a problem with their snaketo seek medical attention, so that the initial problem turns into an emergencysituation.Phone CallsMany owners call the veterinary hospital seeking advice on their petsnake to determine if emergency medical treatment is necessary. Many problemswith snakes that are reported after hours can wait until the morning when theregular veterinarian is available. Most diseases have been developing for weeksto months and initiating treatment can wait another several hours. It isimportant that the technician screening the phone calls be familiar with snakes.Some clinical signs in dogs could be very serious, while in a snake they arevery normal. A common phone call that is not an emergency is an owner worriedthat his or her ball python (Python regius), or any otherspecies, has not eaten in a week or some­times several months. Obviously, for asnake this is not an emergency. Some of the more common emergencies that doneed to be seen immediately are trauma, bite wounds, burns, hypothermia,hyperther­mia, dyspnea, and cloacal prolapse. Common none­mergency clinicalsigns in snakes are lethargy, anorexia, dystocia, and constipation.Initial Presentation and HistoryA veterinary technician should make a quick assess­ment to determine theurgency of care as soon as the patient comes into the veterinary hospital. Ifthe patient is stable, a thorough history should be obtained. If the patient iscritical and needs immediate care, the patient should be taken to the attendingveterinarian and a quick history should be obtained. This history shouldinclude such questions as: What is the ambient tem­perature in the enclosure?Is the snake eating and drinking normally? Do you feed live or dead prey? Whatheat sources are used? Has your snake been lethargic? Have you seen anycoughing, wheezing, or nasal discharge? Has your snake regurgitated any food?Have there been any other medical problems in the past?A more complete history can be obtained after the patient is stable andmore time can be focused away from the patient. More questions may need to beasked pending the results of the physical examination.DiagnosticsThe clinician will have a diagnostic plan after the physical examinationhas been performed. This plan may include a fecal analysis, biochemicalprofile, com­plete blood count, packed cell volume, total protein, orradiographs.TreatmentTreatment should begin after the diagnosis is made. For dehydrated orseverely ill snakes, fluid therapy should be initiated. Intravenous fluidtherapy is preferable but other methods of fluid therapy will suffice. The fluidsshould be warmed to the preferred body temperature for the species beingtreated. The snake should be placed in a cage that is heated to the speciesPOTZ. A full-spectrum UV light should also be provided. Analgesics should beadministered to patients that are in pain. Finally, other therapeutics shouldbe started to treat the clinical signs and disease. Nutritional support shouldbe started only after the patient is stable.EMERGENCY CONDITIONS TraumaTrauma of any kind should be treated as an emer­gency. Bite wounds arecommon in snakes. Bites nor­mally occur from cage mates and live prey itemsleft in the cage unattended. Lacerations are not as com­monly seen in snakes.Most commonly they occur from exposed ends of wire mesh used on cages. Largesnakes can easily break through glass cages, causing severe lacerations. Bitewounds and lacerations are treated by either primary closure or secondary inten­tionhealing. If the wound is left open, antibiotic oint­ments rubbed on the woundwork well as a barrier. Systemic antibiotics should be used on all bite woundsor lacerations. Analgesics should also be used.HypothermiaOccasionally snakes escape from their enclosure and are found in a placethat is excessively cold, causing metabolism to cease. Frostbite may be seen onthe tip of the snakes tail. If not necrotic, some pigment will be lost.Hypothermic snakes are not able to digest food and often regurgitate prey. Itis common to see respira­tory disease several days to weeks after an episode ofhypothermia. Snakes should be warmed up slowly over several hours andsupportive care should be started.Snakes  157HyperthermiaHyperthermia often occurs when the owner lets the snake outside in aglass or plastic enclosure in direct sunlight. Radiant heat quickly warms thesnake and it is not able to get into a cooler environment. Treatment forhyperthermia includes subcutaneous or intracoelo­mic fluids and a quickcool-water bath to decrease the core body temperature. Steroids may also beindicated.DyspneaSnakes do not normally open-mouth breathe. If acute dyspnea occurs thesnake should be seen immediately. Dyspnea can be caused by several pathogens ordisease processes, but it is most commonly associated with pneumonia.Thermal BumsThermal burns are one of the most common emergen­cies seen in practice.Often, snakes do not show clinical signs of a burn for several days, makingthem difficult to treat. Thermal burns are most commonly caused by amalfunctioning heat source or improper use of a heat source. The two mostcommon causes of thermal burns in snakes are hot rocks (or what this authorrefers to as death rocks) and heat lights that snakes coil around.Burns are classified as superficial, partial thickness, or fullthickness. A superficial burn involves only the epidermis. The snake may appearto be in pain and have some discoloration on its scales. In severe super­ficialburns some scales may be singed. Snakes with a superficial burn have a goodprognosis. Antibiotic therapy should be initiated if any infection is noted.The snake should be housed in its POTZ and should heal by the next ecdysis.Little or no scarring is seen with superficial burns.Partial-thickness burns involve complete destruc­tion of the epidermisand extend into the underlying layers of skin. These burns appear red, oozeplasma, and will blister. Partial-thickness burns are also very painful.Treatment can take several months to com­pletely heal. Analgesics should beadministered imme­diately because these burns are very painful. The burn shouldbe flushed thoroughly and supportive care should be started. It is not uncommonfor these patients to be in shock. After cleansing the burns, a burn cream suchas 1% silver sulfadiazine should be applied and a sterile nonstick bandageshould be placed. Wet to dry bandages can also be used. The bandages should bereplaced every day. The snake should be housed in a glass or Plexiglascontainer with no substrate until the wound is completely healed. The cageshould also be disinfected daily. Antibiotics should be started to preventinfections that are common in burn victims.Full-thickness burns are characterized by a black eschar. They are notpainful because all of the nerves in the skin have been destroyed. Full-thicknessburns have a poor to grave prognosis and require very inten­sive treatment. Thewound initially should be treated with a thorough cleansing and fluid therapyto treat for shock. The burn should be debrided to promote healing and abandage should be placed. Antibiotics should also be started. Daily bandagechanges and debridement are necessary for successful treatment. As the skinheals, the wound will become very painful. Analgesics should be started as soonas the patient feels pain. It can take months to a year for full granulation tooccur. The owners must be told of the poor prog­nosis, long-term care, andfinancial expense of treating a full-thickness burn before treatment begins.CRITICAL CARE MONITORINGThe same principles apply to monitoring a critically ill snake as applyto monitoring a critically ill dog or cat. Neurologic, respiratory, andcardiovascular function all must be monitored and assessed.The cardiovascular system should be monitored by using a Doppler andelectrocardiogram. A heart rate should be obtained from both the Doppler andECG (Figures 7.22, 7.23). Auscultation should be performed to monitor therespiratory system. The breath sounds should be clear without any wheezing orcrackles. A respiratory rate should be obtained and recorded. The patientshould also be observed for dyspnea. A neuro­logic exam should be performeddaily. The snake should also be housed in its POTZ.Figure 7.22. ECG lead placement on a snake. The head is to the right.(Photo courtesy of Zoo Atlanta.)158  Chapter 7Figure 7.23. ECG lead placement close-up to show detail. (Photo courtesyof Zoo Atlanta.)SEX DETERMININATIONSnakes do not possess external genitalia, so determin­ing the sex cansometimes be challenging. There are several acceptable methods used todetermine the sex of snakes. Of the methods available, there are variousdegrees of simplicity and accuracy. It is important to choose a method thatbest suits the particular snake. For a snake that is kept as a pet, it is bestto stick with a more simple method of sex determination. Snakes kept forbreeding should be sexed using the most accu­rate method for that species.Secondary Sexual CharacteristicsWith the exception of the boids, most snakes do not show any secondarysexual characteristics. Male boids sometimes have larger cloacal spurs thanfemales. Only technicians that are very familiar with boids will be able toaccurately determine the sex by using this method. Another secondary sexualcharacteristic that can be used to determine the sex is looking for a smallbulge in the tail, because the hemipenes are kept inside the tail. Usingsecondary sexual characteristics is a simple method but is the least accurate.Manual EversionA more accurate method of sex determination is manu­ally everting thehemipenes. This method is best used in juvenile snakes or those that are toosmall for other methods. This method of sex determination is often referred toas popping. For this process, firmly roll one thumb up the base of the tail,starting distal and working proximal to the cloaca. If it is a male, thehemipenes will pop out. Care must be taken not toFigure 7.24. Probes used for sexing snakes. (Photo courtesy of Ryan Cheek.)apply too much pressure or the hemipenes can be damaged. This method isunreliable in large snakes and some colubrids in which manual eversion of thehemipenes is not possible.Cloacal ProbingThis is the preferred method of sex determination. It is very simple andaccurate if done properly. The probe used can be anything that is straight andhas a blunt end. Commercial sex probes are available in sets of variousdiameters. Insert the lubricated probe into the cloaca and angle it caudally.Position the probe just lateral to the midline. Then gently slide the probecaudally into the base of the tail. If the snake is male, the probe will enterthe inverted hemipenis and slide down several millimeters. If the snake is afemale, the probe will either not be able to enter the tail base or will goonly a couple of millimeters. Female snakes have blind diverticula that aresmaller in diam­eter and shorter in depth than the hemipenes. A major cause oferror in sexing is using a probe that is too small. A very small probe canenter the diverticula in females, giving a false diagnosis. The technician mustalso be careful not to be forceful with the probe. The probe should slidesmoothly with very little force needed. Generally, the distance the probeenters the base of the tail is measured in either millimeters or number ofsubcaudal scales. This number should be recorded in the file with the sexdiagnosis (Figures 7.24, 7.25).Hydrostatic EversionHydrostatic eversion is the most accurate yet difficult method of sexdetermination. It involves injecting iso-Snakes  159BCFigure 7.25. Sexing a snake. (A) Appropriate placement of probe prior to insertion. (B) Initialinsertion of the probe. (C) Advancingthe probe. (D) In males the probe advances farther than in females. (Drawingsby Scott Stark.)tonic saline into the base of the tail just caudal to where thehemipenes would be located. Keep inject­ing the saline until the hemipenes areeverted or resis­tance is felt on the syringe. A possible danger of thisprocedure is injecting the saline into the hemipenes instead of caudal. Forvery large snakes, anesthesia is required to perform this procedure. Thismethod is very accurate because the hemipenes are everted in males, and if thesnake is female, the swelling around the cloaca allows for visualization of theoviductal papillae.CLINICAL TECHNIQUES Administration of Medications IntravenousIntravenous (IV) injections can be given in the tail vein or directlyinto the heart. Use the same technique used for venipuncture to give theinjection. Another vein that can be used for IV injections is the palatinevein. This vein is located in the oral cavity and is best suited for very experiencedphlebotomists due to its small160  Chapter 7size. The palatine vein should only be used in snakes with a healthyoral cavity and no signs of stomatitis.SubcutaneousSubcutaneous (SC) injections can easily be given when the snake iscoiled and skin folds appear. The needle should be placed between the scales onthe lateral coelomic body wall, aspiration applied to the syringe to ensure ablood vessel has not been entered, and then the injection given. If the snakeis not coiled, a small piece of skin can be lifted and the injection given.IntramuscularIntramuscular (IM) injections can be given in the epaxial and lateralmuscle groups. The needle is placed between the scales, aspiration applied tothe syringe to ensure a blood vessel has not been entered, and then theinjection given.IntracoelomicThe snake should be restrained in dorsal or lateral recumbency forintracoelomic (ICe) medication admin­istration. The needle is placed betweenscales in the lower quadrant of the coelomic cavity, being careful to be farenough caudal to avoid the lung. It is very important to aspirate back on thesyringe before inject­ing. If any blood or other questionable fluid is aspi­rated,the needle should be removed and a new syringe and medication should beprepared. If giving ICe fluids, the fluids should be warmed up to the snakesPOTZ before administering.OralOral (PO) medications are very easy to give to snakes. The medication isdrawn up into a syringe and then a red rubber catheter is attached to the end. To prevent the red rubber catheter frompassing into the trachea, a catheter should be chosen that is too large to fitinto the trachea. The mouth should be opened to ensure that the catheter hasgone down the esophagus. After checking for correct placement, administrationof the medication can begin. With another syringe filled with water, themedication should be flushed down to ensure that no medicine is left in thecatheter. This method can also be used to force feed snakes.VenipunctureTail VeinThe snake can be placed in either dorsal or ventral recumbency (Figure7.26). With the bevel of the needleFigure 7.26. Venipuncture using the tail vein. (Photo courtesy of Ryan Cheek.)facing cranial, the needle is inserted exactly on midline at a 45-degreeangle. While maintaining gentle suction, the needle is advanced until a flashof blood is seen. Occasionally the coccygeal vertebrae will be hit first andthe flash of blood will be seen as the needle is withdrawn. The needle shouldbe inserted caudal to the hemipenes and scent glands. With smaller snakes, agentle suction and release may be done to receive enough blood to performdiagnostic testing.CardiocentesisLocate the heart by either manual palpation or Doppler. Apply pressurejust caudal and cranial to the heart to stabilize it. After the heart has beenstabilized, the needle is inserted at a 45- to 60-degree angle. The needle isadvanced until a slight pop is felt and the needle has entered the heart.Aspirate back until enough sample has been taken. Occasionally, pericardialfluid may be aspirated. If this happens, the needle should be withdrawn and theprocedure started over with a fresh needle and syringe (Figure 7.27).Palatine VeinAs stated previously, the palatine vein is only recom­mended in a snakewith a clean oral cavity and no signs of stomatitis. This technique only workson very docile or anesthetized snakes. Restrain the snake with its mouth open.A 25- to 27-gauge needle should be advanced into the vein, and then aspirategently to prevent the vein from collapsing. Due to the chance of contaminationfrom the saliva, this vein is best used only for IV injections.Snakes  161Figure 7.27. Cardiocentesis. (Photo courtesy of Zoo Atlanta.)Intravenous Catheter Placement Jugular VeinA cut-down incision is required for this procedure. The skin should besurgically prepped. The incision should be made at the junction of the ventralscutes and lateral scales just cranial to the heart, about four to sevenscutes. It is necessary to bluntly dissect to expose the vein. After the veinhas been exposed, the catheter is inserted until a flash is seen in the hub.The catheter is then advanced into the vein. The skin is closed using suturesand with the catheter sutured to the skin. A bandage can be placed to keep thecatheter site clean.HeartIn an extreme emergency, a catheter can be placed in the heart for ashort time. The technique used for venipuncture can be used to place thecatheter. Once the catheter is placed, it should be secured with suture ortape.Force FeedingProperly restrain the snake with its mouth open. An appropriate-sizedprey item is grasped with large hemostats and a large amount of lubrication isapplied to the entire body of the prey. It is then inserted into the snakesmouth, gently forcing it down. Once the prey is completely inserted, milk theprey down the esophagus until it reaches the stomach. Be very careful that theprey does not scratch the esophagus with its incisors or claws. An easy way toprevent this is to trim the claws and teeth before force feeding.Snakes can also be force fed by using the same technique for giving oralmedications (Figures 7.28, 7.29). Liquefied whole prey or artificially preparedAFigure 7.28. Feeding a snake. (A) Restraint with the mouth open forinsertion of prey. A tongue depressormay be used to open the mouth. (B) Using a pair of large hemostats, the prey is gently pushed down into theesophagus. (Drawings by Scott Stark.)foods can be used. For neonates or smaller snakes a device called apinkie press can be used.Tracheal and Lung WashRestrain the snake with its mouth open. Pass a sterile red rubbercatheter into the trachea. Once the catheter162  Chapter 7cFigure 7.29. Force-feeding a snake. (A) The snake is properly restrainedand a tongue depressor is used to open the mouth. The prey is then insertedinto the oral cavity. (B) The prey is almost completely into the oral cavity.(C) The prey is then gently pushed down the esophagus. (Photos courtesy of Ryan Cheek.)Figure 7.30. View of theglottis. (Photo courtesy of RyanCheek.)is in place, infuse sterile saline into the trachea and lung. Do notplace more than 5 ml/kg into the lung. After the sterile saline has beenadministered, aspirate back as much of the saline as possible. The saline canbe injected and aspirated as many times as needed to receive a proper amount ofsample (Figures 7.30, 7.31).Colonic Wash and EnemaInsert a well-lubricated red rubber catheter into the colon. To enter the colon, the cloaca should beentered and the catheter aimed ventrally. With a syringe filled with saline,begin flushing the saline into the colon and aspirating it back. This stepshould be repeated several times to get an adequate sample. This process alsohelps soften stools in constipated snakes. After aspiration, the sample canthen be ana­lyzed for parasites, cytologic examination, and culture (Figure7.32).Snakes  163Figure 7.31. Tracheal wash. (A) With the snake properlyrestrained, the mouth is opened. (B) A tongue depressor is used as a mouth gag,and the red rubber catheter is inserted into the trachea. (C) 0.9% sodiumchloride is then gently flushed into the trachea and then aspirated back.(Photos courtesy of Ryan Cheek.)Figure 7.32. Colonic wash. (Drawing by Scott Stark.)VENOMOUS SNAKESIt is not recommended to keep venomous snakes in private collections,especially by novice hobbyists. In some cases, it may be illegal to keepvenomous snakes without proper permits. For this reason, it is rare that onewould be brought into private practice for medical care. If this occurs,however, proper protocols need to be implemented. Whether a veterinary practiceis even equipped for safe handling of venomous snakes needs to be addressed. Atthe very least, snake tongs, hooks, and tubes are needed for safer handling.Someone trained in handling venomous snakes is also needed. Although tubing andhandling techniques can be prac­ticed on nonvenomous snakes, there is obviouslymore risk involved in dealing with the venomous ones, and others could be putat risk as well.Most procedures on venomous snakes should be done while the snake isunder anesthesia, which involves either tubing or placing the snake in an immo­bilizationchamber. Do not attempt to manually restrain the head of a venomous snake.Those who milk snakes for venom have to do so but it is not a safe method ofrestraint. Some fangs are long enough to still penetrate a hand whilerestraining the head.An envenomation protocol also needs to be in place at the facility. Mosthuman hospitals (if they carry antivenin at all) only have those of indigenousspecies. Therefore, imported species are riskier to handle due164  Chapter 7to the lack of accessible antivenin. Most facilities that handlevenomous snakes keep the different types of antivenin in stock, not necessarilyfor self-administra­tion should a bite occur, but to bring to the nearesthospital if the hospital does not have any on hand. This is difficult though,due to both the expenses involved and the lack of accessibility. Expirationdates on the antivenin also must be closely monitored.Be sure to have a line of communication established with local hospitalsto know who is able to handle a venomous snakebite. Contacting the local poisoncontrol facility to establish a protocol is helpful as well. Once again, theseare all issues that must be addressed before venomous snakes are managed at thefacility. Minutes count should a venomous snakebite occur. Time cannot bewasted on calling hospitals to see if they can handle that particular bite. Ifthis seems like too much of a hassle, then handling/treating venomous snakesshould not be performed at that facility at all.EUTHANASIAUnfortunately, not all patients can be saved. For­tunately, veterinarymedicine has the privilege of being able to humanely euthanize sufferinganimals with ter­minal illnesses. Euthanizing snakes can prove to be adifficult task. There are several humane methods of euthanasia that areacceptable in snakes. Only the methods that this author feels are humane willbe discussed here.This authors preferred method of euthanasia in snakes starts with aninjection of telazol or ketamine HC1. If injectable anesthetics are notavailable, inhal­ant anesthesia can be used. Due to the ability of snakes tohold their breath for long periods of time this can be a very lengthy process.After the snake is anesthe­tized, a cardiac stick is performed and an overdoseof a barbiturate is injected. In very small species or very dehydrated snakes,a cardiac stick can be difficult. In that case, a simple IC injection of abarbiturate can be performed. It can take several minutes to several hoursbefore the snake is finally deceased using this method.The toughest part of euthanizing snakes is deter­mining death. There isnot a good answer to the ques­tion. Is the snake deceased? An electrocardiograph,auscultation of the heart, or a Doppler can all be used to determine if thesnake is deceased. Due to the fact that reptile hearts can still beat forseveral hours post­mortem or can even beat once or twice per minute postmortem,these three tests can prove to be inaccu­rate. Many reptile clinicians haveheard stories of the snake coming back to life twenty-four hours after theeuthanasia. This can be easily avoided if the snake is left in the hospitalovernight for observation.BEING A RESPONSIBLE SNAKE OWNERAs a part of the veterinary team, the technician is responsible forproperly informing and educating clients about the needs of particular animals.It is also important to offer guidance when purchases are being considered.Knowing what is involved in snake care and knowing specifics about differentspecies of snakes aids in giving advice to those considering purchasing a snakeas a pet. Offering consultations to clients before purchases help to eliminatemany of the prob­lems that arise after a snake is purchased. Snakes, ingeneral, do not make good pets. This should be kept in mind when offeringadvice to potential buyers. Buying a snake that will reach lengths of 20 feetor more is obviously not a choice that should be made by most people, either.These snakes usually become neglected and the owners sometimes begin to fearthem due to their size and their predisposition, which may become aggressive.More and more people are beginning to devise ways to get rid of theirsnakes when it is no longer conve­nient to own them. All too often these snakesare impulse buys that are thought of as disposable belong­ings. The mostappalling of these occurrences is when people let them go in their backyardswhen they dont want to deal with them anymore. Most captive speci­mens are noteven indigenous to the country where their owners set them free. Not only willthis most likely kill the animal, but it can upset the natural balance of thatparticular ecosystem. Some even choose to freeze the snake as their way ofhumanely euthaniz­ing the animal so they will no longer be burdened. There isnothing humane about freezing a live animal. It is, in fact a slow, painfuldeath.If an owner no longer wants a snake, then attempts should be made toplace it in a home or facility ready and able to meet its needs. Most of thetime, this occurs with the larger species of snakes. They can reach astoundinglengths and girths and can be extremely dangerous, not to mention the size ofthe enclosure needed to properly house them. These are obviously not for novicekeepers and should be dis­couraged when an inexperienced individual inquiresabout obtaining one.Another point to be made about being a responsible snake owner isunderstanding that many people fear them. Taking snakes out to public places toshow them off is not doing the public any good, and especially notSnakes  165the snake. Being around a lot of commotion can scare the snake and cancause the people to panic as well. This in turn, is doing more injustice to thesnake than one would think. The public, as a whole, has a terrible phobia ofsnakes and forcing the issue by bringing snakes into public places makes itworse. If individuals want to display their snakes, they should offer educa­tionalexhibits and lectures. By displaying them in this way they can create alearning environment and offer people the choice of whether to participate ornot. A phobia (no matter how silly one thinks it is) is a phobia, and it is notsomething that can be a forced change.REFERENCESBarnard SM. 1996. Reptile Keepers Handbook. Florida: KriegerPublishing Company. 71-73. Bennett RA. 1997. Reptilian Surgery, Parts 1and 2. In: PracticalExotic Animal Medicine, edited by Rosenthal KL. New Jersey:Veterinary Learning Systems. 32-38. Bennett RA. 1996a. Anesthesia. In:Reptile Medicine and Surgery,edited by Mader DR. Philadelphia: W.B. Saunders Co. 30,243-244.Bennett RA. 1996b. Neurology. In: Reptile Medicine and Surgery, editedby Mader DR. Philadelphia: W.B. Saunders Co. 142-145.Bennett RA, Lock BA. 2000. Nonreproductive Surgery in Reptiles.In: Veterinary Clinics of North America: Exotic Animal Practice.Philadelphia: W.B. Saunders Co. 718-721. Bertelsen  MF. 2007.  Squamates  (Snakes  and Lizards.   In:Zoo Animal and Wildlife Immobilization and Anesthesia,edited by West G, Heard D, Caulkett N. Iowa: BlackwellPublishing.Bronson E, Cranfield MR. 2006. Paramyxovirus. In: Reptile Medicine andSurgery 2nd edition, edited by Mader DR. Missouri: Saunders Elsevier.Bradley T. 2001. Pain Management Considerations and Pain-AssociatedBehaviors in Reptiles and Amphibians. In: Proceedings of the Association ofReptilian and Amphibian Veterinarians. Eastern State Vet Assn. 45.Divers SJ. 2000. Reptilian Renal and Reproductive Disease and Diagnosis.In: Laboratory Medicine: Avian and Exotic Pets, edited by Fudge AM.Philadelphia: W.B. Saunders Co. 217.Driggers T. May 2000. Respiratory Diseases, Diagnostics, and Therapy inSnakes. In: The Veterinary Clinics of North America: Exotic Animal Medicine.Philadelphia: W.B. Saunders Co. 524-528.Funk RS. 1996. Snakes. In: Reptile Medicine and Surgery, edited by MaderDR. Philadelphia: W.B. Saunders Co. 40-42.Glynn MK, et al. 2001. Knowledge and Practices of CaliforniaVeterinarians Concerning the Human Health Threat of Reptile-AssociatedSalmonellosis. Journal of Herpetological Medicine and Surgery 11(2): 9-13.Holz PH. 1999. The Reptilian Renal-Portal System: Influence on Therapy.In: Zoo and Wild Animal Medicine: Current Therapy 4th ed., edited by Fowler MEand Miller RE. Philadelphia: W.B. Saunders Co. 249.Lane TJ, Mader DR. 1996. Parasitology. In: Reptile Medicine and Surgery,edited by Mader DR. Philadelphia: W.B. Saunders Co. 190-202.Lawton MP. 2001. Fluid Therapy in Reptiles. In: Proceedings of the NorthAmerican Veterinary Conference. Eastern States Vet Assn. 788.Lawton MP. 1991. Lizards and Snakes. In: Manual of Exotic Pets, editedby Beymon PH, et al. Ames: Iowa State University Press. 254.Lock BA. May 2000. Reproductive Surgery in Reptiles. In: VeterinaryClinics of North America: Exotic Animal Practice. Philadelphia: W.B. SaundersCo. 734-737.Marschang RE. 2001. Isolation of Viruses from Boa Constrictors, Boa constrictor spp., withInclusion Body Disease. In: Proceedings of the Association of Reptilian andAmphibian Veterinarians. Eastern States Vet Assn. 37.Miller HA. April 1998. Urinary Diseases of Reptiles: Pathophysiology andDiagnosis. In: Seminars in Avian and Exotic Pet Medicine, edited by Fudge AM.Philadelphia: W.B. Saunders Co. 96-98.Platel R. 1994. Nervous System and Sensory Organs. In: Snakes: A NaturalHistory, edited by Bauchot R. New York: Sterling Publishing. 51-55.Pough FH, et al. 2001. Herpetology. 2nd ed. New Jersey: Prentice-HallInc. 200-206, 272.Ritchie B. 2006. Virology. In: Reptile Medicine and Surgery, 2nd ed.,edited by Mader DR. Missouri: Saunders Elsevier.Romer AS. 1997. Osteology of the Reptiles. Reprint. Malabar, FL: KriegerPublishing. 126, 209.Ross RA, et al. 1990. The Reproductive Husbandry of Pythons and Boas.The Institute for Herpetological Research, Stanford, CA. 55-60, 103.Rossi JV. 1996. Dermatology. In: Reptile Medicine and Surgery, edited byMader DR. Philadelphia: W.B. Saunders Co. 106-114.Saint-Girons H. 1994. Growth and Reproduction. In: Snakes: A NaturalHistory, edited by Bauchot R. New York: Sterling Publishing. 99.Schumacher J, Yelen, T. 2006. Anesthesia and Analgesia. In: ReptileMedicine and Surgery 2nd ed., edited by Mader DR. Missouri:Saunders Elsevier. Schumacher J. 2002a. Anesthesia in Reptiles. In:Proceedings of theNorth American Veterinary Conference. Eastern States Vet Assn.946.Schumacher J. 2002b. Sevoflurane in Reptiles. In: Proceedings of theNorth American Veterinary Conference. Eastern States Vet Assn. 950.Schumacher J. 1996. Viral Diseases. In: Reptile Medicine and Surgery,edited by Mader DR. Philadelphia: W.B. Saunders Co. 229.Siemering H. 1986. Zoonoses. In: Zoo and Wild Animal Medicine, 2nd ed.,edited by Fowler ME. Philadelphia: W.B. Saunders Co. 64.Vasse Y. 1994. A Cardiovascular System Working Against theForces of Gravity. In: Snakes: A Natural History, edited byBauchot R. New York: Sterling Publishing. 75. Williams DL. 1996.Ophthalmology. In: Reptile Medicine andSurgery, edited by Mader DR. Philadelphia: W.B. Saunders Co.181.Wright K. 1999. Fluid Therapy for Reptiles. In: Proceedings of the NorthAmerican Veterinary Conference. Eastern States Vet Assn. 817.Zug GR, et al. 2001. Herpetology: An Introductory Biology of Amphibiansand Reptiles. 2nd ed., New York: Academic Press. 49-57, 173.CHAPTER EIGHTCheloniansSamuel RiveraINTRODUCTIONTurtles belong in the class Reptilia, which is divided into four orders,Chelonia (all turtles), Crocodylia (crocodilians), Squamata (snakes andlizards), and Rhynchocephalia (tuatara). There are approximately 270 species inthe order Chelonia. This order contains a primitive group of animals thatevolved into a shelled form millions of years ago and is considered the mostprimitive group of living reptiles. Chelonians include turtles, tortoises, andterrapins. The terms "turtle," "tortoise," and"terrapin" are sometimes confusing because they have differentmeanings in different parts of the world. In the United States, tortoise refersto terrestrial chelonians; turtles often refer to aquatic or semiaquaticchelonians with the exception of the box turtle, which is terrestrial; andterrapins are semi-aquatic, hard-shelled chelonians. Because of the confu­sionin terminology, chelonians are often listed by their binomial scientific name,which is uniform around the world.Hundreds of species of chelonians are kept in captiv­ity (Color Plates8.1, 8.2, 8.3). Unfortunately, many ofPlate 8.1. Male eastern box turtle showing red eye. (See also colorplates)the diseases seen in captive chelonians are related to improperhusbandry and/or inadequate diet. Accurate identification of chelonian speciesaids in the evalua­tion of husbandry and nutritional management. The goal ofthis chapter is to provide a basic understand­ing  of chelonian  husbandry,  nutrition,  biology,Plate 8.2. Sulcata tortoise. (See also color plates)Plate 8.3. Aldabra tortoise. (See also color plates)167168  Chapter 8basic clinical techniques, and common health problems.ANATOMY AND PHYSIOLOGY Musculoskeletal SystemIn this section, the North American eastern box turtle (Terrapene Carolina Carolina) will be described.The most remarkable feature of turtles is their shell, which is divided in twoparts. The dorsal part is the carapace and the ventral part is the plastron.The carapace normally consists of approximately fifty bones. The nuchal bone isthe most cranial along the dorsal midline. It is followed by seven neural, onesuprapygal, and a pygal bone, consecutively. The neural bones are attached tothe vertebrae. The costal bones are located on either side of the neural bones.The peripheral bones are located on the lateral aspect of the costal bones andextend from the nuchal to the pygal bones on both sides of the carapace (Figure8.1).The plastron consists of nine bones. The cranial part of the plastron iscomprised of the entoplastral bone, which is surrounded by the epiplastralbones cranially and two hypoplastral bones caudally. The hypoplastral bones arefollowed caudally by a second pair of hypoplastral bones and a pair ofxiphiplastral bones, consecutively. The bones of a turtle shell articu­latewith each other by a suture. Box turtles have a movable hinge locatedtransversely between the two pairs of hypoplastral bones.The bones of the shell are covered with structures made of keratinizedepithelium called scutes. The most cranial scute along the dorsal midline isthe cervical scute, which is followed caudally by five vertebral scutes. Thescutes adjacent to the vertebrals are the pleurals. The scutes outlining theperiphery of the plas­CarapacePlastronFigure 8.1. Skeletal anatomy. (Drawing by Scott Stark.)tron are the peripherals. The plastron has six pairs of scutes. Thecranial pair is the gular, followed by the humeral, pectoral, abdominal,femoral, and anal scutes, consecutively. The movable hinge is located betweenthe pectoral and abdominal scutes. This hinge allows the plastron to be foldedup to enclose the head and forelimbs within the shell. The pelvic and pectoralgirdles are contained within the rib cage that is fused to the carapace.The bones of the limbs of most chelonians are similar to those of othervertebrates.Respiratory SystemTurtles breathe through a pair of nostrils located at the dorsocranial aspectof the premaxilla. The glottis is located at the base of the tongue. Thetrachea is relatively short and bifurcates into two mainstream bronchi thatopen into the dorsal aspect of the paired lungs. The lungs are large,compartmentalized struc­tures with a reticular surface containing bands ofsmooth muscle and connective tissue. The lungs attach dorsally to the ventralaspect of the carapace and ven-trally to a membrane that is attached to thestomach, liver, and intestinal tract. Turtles do not have a dia­phragm.Respiration is achieved by the contraction of the proximal muscle mass of thepectoral and pelvic limbs (Wood and Lenfant 1976). Aquatic turtles can exchangeoxygen through the mucosal surface of the oral cavity and cloaca. Soft-shelledturtles can exchange oxygen through their skin (Girgis 1961).Gastrointestinal SystemThe tongue of turtles is large and unable to distend from the oralcavity. They have salivary glands that produce mucus but not digestive enzymes.The esopha­gus courses along the neck. The stomach lies on the leftcranioventral side of the coelomic cavity and has a gastroesophageal and agastroduodenal valve. The small intestine is relatively short. The pancreas ispale pink and can be located near the spleen or in the mes­entery along theduodenum. The liver is large, saddle-shaped, and located ventrally under thelungs. The liver has two lobes and it envelops the gall bladder. It also hasindentations for the heart and stomach. The small intestine joins the largeintestine at the ileocolic valve. The cecum is not well developed. The largeintestine is the primary site of microbial fermentation in herbivorous turtles.The digestive tract empties into the cloaca (Figure 8.2).Genitourinary SystemThe paired kidneys are located on the ventrocaudal aspect of thecarapace, cranial to the acetabulum. TheChelonians  169Figure 8.2. Visceral anatomy. (Drawing by Scott Stark.)paired gonads are located cranial to the kidneys. The urogenital ductsempty into the neck of the urinary bladder, which is bilobed with a thinmembranous wall. Male turtles have a single, large, dark-colored penis. It islocated in the floor of the cloaca and it is not used for urination.Many turtles are sexually dimorphic. The male tor­toise has a concaveplastron. The males of aquatic turtle species have long nails on their frontfeet. Generally, the tail is relatively larger in males than in females(Figures 8.3, 8.4).Circulatory SystemChelonians have a three-chambered heart consisting of two atria and oneventricle. Like other reptiles, turtles have a renoportal circulation system.Its function is to provide an alternate blood supply to the renal tubularcells, and prevent ischemic necrosis when the arterial blood supply to the glomerulusis compromised (Holz 1999).HUSBANDRY AND NUTRITIONHundreds of species of turtles are seen in the pet trade, and it isbeyond the scope of this chapter to coverFigure 8.3. Female reproductive anatomy. (Drawing by Scott Stark.)turtles by species. A brief overview on the husbandry of aquatic andterrestrial turtles will be discussed. The general public often seeks advicefrom veterinarians and their support staff about the care and feeding of theirnewly purchased turtle. It is essential to have a basic understanding of thehusbandry and feeding practices of chelonians. Whenever possible, the turtleshould be identified so accurate information on its husbandry and eating habitscan be obtained.Aquatic TurtlesAquatic turtles are one of the most labor intensive reptiles tomaintain. Inadequate husbandry often results in health problems. The housingrequirements depend on the size and the number of turtles kept. As a rule ofthumb, the combined surface area of all the turtles carapaces should not exceed25% of the tanks floor surface area (Anonymous 1990). The water should be asdeep as the width of the turtles shell, so that if overturned it will be ableto right itself. The simpler the setup, the easier to clean, and clean water isessential to the health of turtles. The best way to keep the water clean is bydoing full water changes. The larger the volume, the less the frequency ofwater changes. The number of animals, the feeding fre­quency, and the type offood offered also determine170  Chapter 8Figure 8.4. Male reproductive anatomy. (Drawing by Scott Stark.)the frequency of cleaning. Avoid drastic temperature changes whenreplacing the water because this can be detrimental to the turtles health. Afiltration system minimizes but does not eliminate the need for complete waterchanges (Figure 8.5).Adequate environmental and water temperature are important for goodhealth. Turtles are ectothermic: they rely on the environmental temperature toregulate their body temperature. Turtles have a preferred optimal temperaturezone (POTZ), which is the tem­perature at which they are the most comfortable.The POTZ also allows for normal physiologic functions to occur, such asdigestion and fighting disease. Most aquatic turtles have a preferred optimumwater tem­perature of 24°C to 29°C (75°F to 82°F). A dry area should beavailable so the turtle can dry off and bask, a process by which turtles canregulate their body temperature. An incandescent 50- to 150-watt light bulbwith a reflector directed toward the basking area creates a hot spot forbasking. Place the basking light approximately twelve to eighteen inches awayfrom the basking area.Figure 8.5. Aquatic habitat. (Drawing by Scott Stark.)An adequate diet is essential for good health. Aquatic turtles areomnivorous with a few exceptions. Younger, rapidly growing animals tend to eata larger percentage of meat but switch to eating more vegetable matter as theyget older (Frye 1991). A varied diet is the key to a healthy turtle. Too muchof one food item can often lead to nutritional imbalances. Fish (goldfish, guppies,and bait minnows) is accepted by many turtles. Chopped, skinned adult mice area good source of vitamins and minerals. Earthworms and a variety of insects canalso be fed. Many adult turtles can be fed dark green leafy vegetables and asmall amount of fruits. Most pet turtle owners will a commercial pel­leteddiet. Turtle owners who feed strictly pelleted food should always be encouragedto supplement the diet with other food items to provide the most bal­ancednutrition possible. Adult turtles can be fed two to three times per week, andyoung turtles should be fed daily or every other day. Aquatic turtles eat inthe water and can be quite messy. Some turtles can be trained to eat in aseparate container, which minimizes but does not eliminate the need forfrequent water changes.Some species of chelonians spend the majority of their time in the waterbut some time on land. The semiaquatic environment, a variation of the aquaticone, is appropriate for these chelonians. This setup involves all the same featuresof an aquatic setup but includes a land portion for basking (Figure 8.6).Terrestrial TurtlesLand turtles can be kept in a variety of enclosures, depending on thesize and number of animals kept. Where weather permits, tortoises should bekept outside, which allows the animals plenty of room to exercise and graze.Healthy tortoises can be placed outdoors when the temperature is above 18°C(65°F) and the midday temperature reaches 24°C (75°F) or above (Boyer and Boyer1996). The outdoor enclosureChelonians  171rFigure 8.6. Semiaquatic habitat. (Drawing by Scott Stark.)should have a hiding place and a shaded area. The sides of the enclosureshould be made of wood or any solid material that can provide a visual barrier.Wire fencing is not recommended because tortoises can injure themselves whiletrying to climb or push through the fence. The walls should be at least threetimes the height of the largest tortoise. Some tortoise species like to dig;therefore, wire can be buried around the perim­eter, at least ten to twelveinches, to prevent escape.Tortoises can be kept indoors. Generally they require more space thanmost reptiles of similar size. As a general rule, the combined size of all thetortoises carapaces should not exceed 25% of the enclosures floor (Anonymous1990). Aquariums, or a wide variety of plastic containers, can be used forsmall tortoises. Larger species can be kept in enclosures made of wood orcement. A garage or spare room can serve as a holding area for tortoises.The room temperature should be between 24°C and 32°C (75°F and 90°F). Athermal gradient between 75°F and 90°F is ideal to allow for thermoregulation.This gradient can be created by placing a basking light at one end of theenclosure. The basking light should be placed eighteen to twenty-four inchesaway from the animals. At night, supplemental heat can be pro­vided withheating pads placed under the enclosure, ceramic heaters with a reflector, ornight heat lights. Acceptable substrates include cyprus mulch, large coniferbark nuggets, alfalfa pellets, newspaper, and indoor-outdoor carpeting, amongothers. Inappropriate substrates include sand, fine gravel, cat litter, crushedcorncob, or walnut shells because these can lead to gastrointestinalimpactions. Pine and cedar shavings are not recommended because of the presenceof oils that can adversely affect the respiratory tract. The cage should becleaned several times per week. The sub­strate can be changed as needed.Figure 8.7. Setup for a small tortoise. (Photo courtesy of Ryan Cheek.)If the tortoises are kept indoors all year, a source of UV light must beprovided. There is a wide variety of UV lights and the manufacturersinstructions must be followed closely. Two points to keep in mind are that mostUV bulbs must be kept at a minimum dis­tance from the animals to be effective,and the lifespan of the bulbs is limited and they must be replaced on a regularbasis. Natural light is ideal and must be pro­vided whenever possible (Figure8.7).Tortoises are mainly herbivores. In the wild, they eat a variety ofleaves, stems, flowers, and fruits; in addition, some eat snails, earthworms,and other invertebrates. The ideal diet should be made of 85% vegetables (darkleafy greens, grasses), 10% fruits, and 5% high-protein foods (Boyer and Boyer1994). The high-protein foods can be provided once or twice weekly.Alternatively, a commercially made pelleted diet can be provided andsupplemented with high-fiber food items. Adult animals can be fed two to threetimes per week, whereas juveniles can be fed daily or every other day.COMMON DISEASES Metabolic Bone DiseaseThis disease is caused by an improper calcium and phosphorus ratio inthe diet and/or a vitamin D3 defi­ciency. Turtles fed liver, heart,or muscle meat often develop metabolic bone disease. The resulting calciumdeficiency often leads to a depletion of calcium from bone, resulting infibrous osteodystrophy. Clinical signs include anorexia, soft and/or deformedshell, and abnormal scute growth. The treatment involves diet correction andproper vitamin D3 supplementation.172  Chapter 8Vitamin A DeficiencyThis is a common presentation in aquatic and terres­trial turtles. It iscaused by feeding a diet deficient in vitamin A. The clinical signs includeconjunctivitis, blepharitis, swollen eyelids, nasal discharge, dyspnea, and earabscesses. The condition is treated with par­enteral vitamin A and dietcorrection.Vitamin A ToxicityThis can be caused by excessive supplementation or administration ofparenteral vitamin A. The clinical signs include dry, flaky skin, or sloughingof the skin with secondary bacterial infection. Treatment requires systemicantibiotics if secondary bacterial infection is present, and discontinuation ofparenteral vitamin A or any source of over supplementation.Diseases of the Shell"Shell rot" is a term used to describe infections of the shellinvolving loss of scutes. The terms "wet" and "dry" shellrot are used to describe the appearance of the lesions. The wet form is usuallyassociated with a hemorrhagic discharge between the scutes and it is oftenassociated with bacterial infections. The dry form has a dry appearance and isoften associated with fungal or bacterial infections. In some mild cases ofshell rot, the lesions can be treated topically. Aquatic turtles need to be keptdry for thirty to sixty minutes after topical treatment. Septicemic cutaneousulcer­ative disease (SCUD) is a common disease seen in aquatic turtles. Theclinical signs include cutaneous ulcerations, anorexia, and lethargy. Treatmentof any shell lesion involves debridement and topical antimi­crobial treatment.In some cases, systemic antibiotics may be indicated.Traumatic injuries to the shell are relatively common, especially inwild chelonia. In many cases, radiographs can help determine the extent of thedamage. The prognosis is poor if the spinal cord is damaged. Once the animal isrelatively stable, the wounds must be cleaned, debrided, and flushed withsterile saline and diluted disinfectant (i.e. chlorhexi-dine). Be careful whencleaning full-thickness fractures with exposed coelomic cavity. Turtles withfull-thick­ness fractures or severe soft-tissue trauma need sys­temicantibiotic treatment (Figure 8.8).Repair of ShellSuperficial cracks on the shell can be repaired using sterile fiberglasscloth impregnated with polymerizing epoxy resin. Contact with the soft tissueshould be avoided. Dental acrylic can also be used. Full-thickness fractureswhere the coelomic cavity has been exposed require surgical repair. In additionto shell repair, these animals require fluid and nutritional support and anti­biotictherapy. They often have a prolonged recovery and adequate treatment is neededuntil the turtle is eating on its own and is free of infection.Overgrown BeakSome turtles develop an overgrown beak in captivity. This has beenassociated with an inadequate diet. The overgrown beak needs to be trimmed on aregular basis. For the most part this can be done without seda­tion. A Dremeltool works well (Figures 8.9, 8.10).Respiratory DiseaseRespiratory disease is one of the most common pre­sentations in clinicalpractice. Turtles do not have aFigure 8.8. Traumatic injury to the shell. (Photo courtesy of Ryan Cheek.)Figure 8.9. Overgrown beak. (Photo courtesy of Dr. Stephen J. Hernandez-Divers, University of Georgia.)Chelonians  173Figure 8.10. Trimming an overgrown beak with a Dremel tool. (Photocourtesy of Stephen J.Hernandez-Divers, University ofGeorgia.)diaphragm and as a result they cannot clear discharge in their lungs bycoughing. Some predisposing factors to respiratory disease include improperdiet, inade­quate temperature and humidity, unhygienic condi­tions, and/orinappropriate substrate. Clinical signs of respiratory disease include amucopurulent nasal dis­charge, ocular discharge, dyspnea, open-mouth breath­ing,anorexia, weight loss, and lethargy. Aquatic turtles may show inability to swimnormally as they lose control of buoyancy. Pneumonia can be caused by bacteria,viruses, mycoplasma, and certain parasites. The diagnosis is based on theclinical signs, radio­graphs, transtracheal wash, and culture and sensitivityresults. Treatment includes bactericidal antibiotics, nebulization, warmth,fluid therapy, and nutritional support.GoutGout is a condition that involves the deposition of uric acid in thevisceral organs and/or joints. It can be caused by kidney disease, dehydration,and diets high in protein. Clinical signs include lethargy, anorexia, lameness,and swollen joints. The diagnosis can be made by measuring serum/plasma uricacid levels, radiographs, and cytological evaluation of the material in theaffected joints. The treatment involves the cor­rection of the primary problem,but it is often unrewarding.Gastrointestinal Tract DiseaseA wide range of diseases affects the gastrointestinal tract ofchelonians. Stomatitis, parasites, foreign bodies, bacteria and fungalenteritis, and amoebic enterohepatitis are some of the most common con­ditionsencountered in private practice. The clinicalFigure 8.11. Penile prolapse. (Photo courtesy of Zoo Atlanta.)signs of gastrointestinal disease include anorexia, vom­iting, weightloss, lethargy, dehydration, and abnormal stools. The diagnosis is based on acomplete blood count, plasma biochemistries, fecal examinations, radiographs,endoscopy, and in some cases ultrasonog­raphy. The treatment is based on thedisease present. Fluids and nutritional support are an important part of thetherapy.Reproductive DisordersDystocia is one of the most common reproductive problems seen inchelonians. The clinical signs include anorexia, lethargy, straining, andsometimes bloody discharge from the cloaca. The diagnosis of dystocia is basedon radiographs. The predisposing factors include poor environmental conditions,metabolic disease, and improper husbandry.Cloacal prolapse in females during parturition and penile prolapse inmales during copulation are common presentations in chelonians. This can becaused by trauma, infection, or cloacal impaction. Severe cases of penileprolapse often require amputation (Figures 8.11, 8.12).Aural AbscessesWhile relatively common to see, the pathogenesis of aural abscessesisnt completely known. Improper hus­bandry and malnutrition may be predisposingfactors. Treatment involves surgical intervention. The tym­panic membrane isincised and exudate removed, fol­lowed by debridement and lavage of the wound.An antibiotic ointment may then be applied to the wound. The wound is left openand lavaged daily, followed by ointment application until the wound heals bysecond intention (Figure 8.13) (Murray 1996).174  Chapter 8Figure 8.12. Cloacal prolapse. (Photo courtesy of Zoo Atlanta.)Figure 8.13. Aural abscess. (Photo courtesy of Dr. Stephen J. Hernandez-Divers, University of Georgia.)ZOONOSESThe greater number of zoonotic diseases associated with keeping turtlesinvolve bacterial pathogens. The most widely recognized disease issalmonellosis. Children, immunosuppressed individuals, and the elderly are atgreater risk of contracting salmonellosis. In the 1960s and 1970s, a largenumber of human cases of salmonellosis were linked to pet turtles as the sourceof infection. In 1975, laws were enacted banning the sale of baby turtles witha carapace length of 4 inches or less. In 1999, the Centers for Disease Controlestimated that of the millions of cases of human sal­monellosis reportedbetween 1996 and 1998, only 7% per year was associated with reptile oramphibian contact (CDC 1999). The vast majority of human sal­monellosis(approximately 80%) cases was associated with eating contaminated food.The genus Salmonella contains many species with thousands of differentserotypes. Many of theses sero­types have been isolated from healthy turtlesand have been associated with human salmonellosis. The symp­toms in humansinclude abdominal pain, diarrhea, nausea, vomiting, and fever. Owners should bemade aware of the potential health hazard when keeping turtles as pets.Proper sanitation is essential to decrease the risk of exposure. Thereis no effective or practical way to eliminate the bacteria from the intestinalflora of posi­tive animals. The bacterial burden in the environment greatlyincreases when the feces are allowed to build up in the enclosure. This causescontamination of the turtles environment and body surface, increasing the riskof transmission to humans, which is why it is so important to practice stricthygiene when keeping turtles. By cleaning frequently, the bacterial contami­nationin the enclosure will be greatly reduced. Perhaps the decline in percentage ofhuman cases of salmonellosis associated with pet turtles has been due to theincreased awareness and practice of adequate hygiene.Aeromonas, Campylobacter, and Pseudomonas of reptile originhave been associated with illness in humans. Reptiles can also be affected byseveral species of Mycobacterium that are known to cause disease in humans. Mycobacterium can cause a varietyof lesions in reptiles. The route of transmission for humans is through directcontact or inhalation of contaminated particles.The hallmark of disease prevention and decreased risk of exposure topotential zoonoses is adequate hygiene. This goes for both the pet owner andthe health care provider. When sick turtles are hospital­ized, it is imperativethat they be kept in a clean envi­ronment and handled carefully to preventcontamination of the hospital environment.OBTAINING A HISTORY AND PERFORMING A PHYSICAL EXAMINATIONA thorough history is one of the most important aspects of the clinicalevaluation. Improper diet, enclo­sure, temperature, and humidity are oftenmajor con­tributors to illness. Always ask about previous illness. Any changein appetite, behavior, weight, and defeca­tion (consistency and frequency)should be recorded. The origin of the animal (wild-caught versus captive-bred,bought from a pet store versus a private breeder) must be ascertained. Alsoinquire about other animalsChelonians  175in the collection and whether there are other types of turtles and/orother reptiles in the household. Were any animals bought recently? Was theanimal quaran­tined? All these questions will help to formulate a picture ofthe animals husbandry and potential expo­sure to pathogens.A visual exam should be part of an initial evalua­tion. Assess motorfunction if the animal is willing to walk. Check the plastron and carapace forany evi­dence of trauma or infection. Look at the skin of the legs and nails.Evaluate the head, eyes, nares, oral cavity, and tympanic membrane. Note anydischarge, redness, or swelling. The lungs of chelonians can be auscultated byplacing a wet hand towel between the carapace and the stethoscope to enhancethe surface contact.RESTRAINTThe neck of most turtles has an S-shaped curve that allows the animal towithdraw the head within the shell. In most turtles the head can be extended byapplying gentle pressure with the thumb and index finger behind the mandibles.In many cases the head can be grabbed by reaching from underneath. Turtlesquickly withdraw the head when approached from the top. Once you have a holdbehind the temporoman­dibular joints, apply gentle traction to overcome theturtles resistance; be careful not to be too forceful. It is important toavoid dorsoventral pressure with your fingers because this can cause damage tothe soft tissue of the neck and trachea. This technique is limited by the size,physical condition, and disposition of the turtle.The head of box turtles can be a little harder to exteriorize because abox turtle can move the cranial part of the plastron upward, making the shellan almost impenetrable fort. In this case a tongue depres­sor or smoothstainless steel speculum can be used to pry the shell open. Insert your toolbetween the cara­pace and plastron and apply gentle pressure down­ward. Onceexposed, a limb can be grabbed and an attempt made to restrain the head asdescribed above.A more gentle approach is to place the turtle in a small amount of warmwater. Most turtles will attempt to get out of the water and when they do, anattempt can be made to restrain a limb or the head. If the first attempt torestrain the turtle fails, the animal should be placed in its holding containerand tried later. Patience is your best ally.In aquatic species, with long nails, a towel can be used to wrap theanimal and hold the legs within theFigure 8.14. Proper restraint. (Photo courtesy of Dr. Sam Rivera.)shell. Nails can inflict painful scratches to the handler. The towel canalso be used to keep the head inside the shell in aggressive species. Rememberthat turtles, like other animals, stress easily when handled excessively(Figure 8.14).RADIOLOGYRadiographs are an important diagnostic tool in the assessment of themusculoskeletal, respiratory, gastro­intestinal, and reproductive systems. Thedorsoventral (DV), lateral, and anterior-posterior views are recom­mended. TheDV radiograph can be easily taken by placing the turtle on the table. Mostoften it will stay still long enough to take the radiograph. For the lateraland anterior-posterior views, a horizontal beam is desired. Elevate the turtleby using a round container that fits under the plastron. Make sure the feet donot come in contact with the container. It is desirable to keep the patient inthe sternal position. Tilting the turtle on its side is not recommended becausethis often causes distortion of the lungs and visceral and repro­ductive organs(Figure 8.15).ANESTHESIAThe overall health of the patient should be established to assess theanesthetic risk. Turtles should be well hydrated prior to anesthesia. Theenvironmental tem­perature is also important. When anesthetized, turtles shouldbe kept at their POTZ. Keeping them slightly warmer during recovery isrecommended.There are several techniques for anesthetizing che­lonians. Thepreferred method is the use of parenteral176  Chapter 8Figure 8.15. Restraint for radiographs. (Drawing by Scott Stark.)drugs. Chelonians can be anesthetized using inhalation agents via maskor chamber induction but they can hold their breath for a long time, makingthis tech­nique time-consuming. If gas induction is used, the uptake of theanesthetic agent can be increased by manipulating the limbs in and out. Thisenhances ven­tilation of the lungs. The IM and IV routes are fre­quently usedfor the administration of induction agents.Once the turtle is anesthetized it can be maintained using isoflurane orsevoflurane. The animal can be intubated using a proper size endotracheal tube.Alternatively, small red rubber catheters can be modi­fied to serve asendotracheal tubes. In small patients, large-bore intravenous catheters can beused. The laryngeal opening is located near the based of the tongue. A cottontip applicator can be used to gently move the tongue cranially while insertingthe endotra­cheal tube. It is recommended to use a speculum to keep the mouthopen and prevent the animal from biting the endotracheal tube. Keep in mindthat large chelonians have a strong jaw tone even if slightly sedated and cancause serious damage to fingers.Monitoring anesthesia in chelonians can prove chal­lenging. An EKG isideal to monitor the cardiac func­tion. An ultrasonic Doppler can be used tomonitor the peripheral pulse in the limbs. The withdrawal and palpebralreflexes are sometimes helpful but not always reliable. A pulse oximeter with acloacal probe can often be used to monitor oxygen saturation. It is rec­ommendedto use intermittent partial pressure ventila­tion in chelonians (four to eightbreaths per minute), which helps ventilate the lungs and keeps an adequate flowof oxygen and anesthetic agent in the lungs.PARASITOLOGYTurtles can be affected by a wide range of parasites. It is important tocollect a fresh fecal sample. Dry feces are not recommended for use becausemany protozoan organisms die as the feces dry. Advise the client to collect thefeces at home, place the sample in multiple sealable plastic bags, and keep itrefrigerated. Reiterate to the client the dangers of keeping reptile feceswhere food for human consumption is kept. If the sample is to be keptrefrigerated, extreme hygiene is important to prevent cross contamination. Thesample can be refrigerated overnight, but longer refrigeration is notrecommended. The fecal exams must be done using fecal material and not urates.If a fresh sample is not available, a cloacal wash (see below) can be done toobtain a sample.Direct fecal exam: Using a small wooden stick, place a smallamount of feces on a microscope slide. Place a cover slip on top and examineimmediately. The longer the sample sits the more likely motile pro­tozoans willdie. Do not use a cotton tip applicator because the cotton can absorb a substantialamount of the sample. Certain cysts can be difficult to identify. The samplecan be stained by adding one drop of Lugols solution. It is ideal to preparetwo direct smears, one stained and one unstained. The Lugols solution killsmotile protozoans. Some of the protozo­ans commonly encountered are Hexamita,Balantidium, Nyctotherus, and coccidia.Flotation: The flotation technique is done in the same manner as thatfor small animals. Use as much fecal sample as possible to increase the chancesof finding parasite ova.Cloacal wash: Using a soft rubber catheter, instill a small amount ofsaline solution in the cloaca. Collect the fluid for examination. This samplecan be used for direct exam and flotation.Turtles can be subclinical carriers of pathogenic amoeba species. Entamoeba invadens is an example of anamoeba that causes low morbidity in turtles but can cause severe illness anddeath in snakes and lizards. Nematodes, trematodes, and cestodes are common inturtles, particularly wild-caught animals. It is impor­tant to keep in mindthat chelonians are also affected by ectoparasites. Ticks, leeches, andcuterebra larvae can be found in turtles.EMERGENCY AND CRITICAL CAREThe most common emergency seen in private practice is trauma. Wildturtles hit by cars are unfortunatelyChelonians  177seen too often. The initial stabilization of the patient requires properassessment of the injuries, antimicro­bial therapy, fluid support, and adequateenvironmen­tal temperature. When a turtle with severe trauma is presented, theshell as well as the limbs, head, and neck must be evaluated for the presenceof blood. Once the wounds are identified, they must be cleaned thor­oughlyusing sterile saline and a disinfectant. Antibiotics may be required to avoidinfection of the wounds, which can lead to fatal septicemia. Turtles withmassive trauma can become dehydrated quickly. Adequate fluid support isessential for a full recovery. Fluids can be given subcutaneously or in theintracoelomic cavity. Once the patient is stabilized, it should be kept at itspreferred optimal temperature zone. This allows for the immune system and otherphysiologic functions needed for healing to work efficiently. It is also impor­tantto provide nutritional support to the patient as soon as possible. Wildchelonians will not eat on their own initially, and need to be force-fed.Adequate nutri­tion is important for a full recovery. Chelonians with severetrauma take a long time to heal, but if they are handled properly from the timeof initial presentation the recovery time can be reduced significantly.CLINICAL TECHNIQUES Blood CollectionThe sites for blood collection in chelonians are the jugular, brachial,subcarapacial, tail (ventral and dorsal), and femoral veins, as well as theoccipital sinus and heart. Chelonians can prove challenging for bloodcollection. It is always a good idea to be familiar with multiple venipuncturesites. The supplies needed depend on the size of the animal. Prior to blood col­lection,slides, hematocrit tubes, small-volume (0.5 ml) heparinized tubes, alcoholswabs, needles (22- to 27-gauge), and syringes (0.5- to 3-ml) should beprepared. In patients smaller than 300 g, use a 25- to 27-gauge needle in a0.5- to 1-cc syringe. In patients greater than 300 g, a 22-gauge needle in a3-cc syringe can be used. Larger needles (20 g) can be used in turtles weighingmore than 5 kg (Figure 8.16).Jugular VeinThe jugular vein is relatively superficial and located dorsally on theneck. Some turtles may need sedation for jugular venipuncture. In most turtlesblood can be collected from this location as long as the head can beexteriorized. The neck should be held in the extended position. In somepatients the vein can be visualized by applying digital pressure at the base ofthe neck;however, this is not always the case. Once the vein is located, theneedle should be inserted at a 30-degree angle and negative pressure applied asthe needle is advanced. The syringe will fill with blood as soon as the vein isentered. In some cases, the flow is slow. Once blood fills the hub of theneedle, stop advancing and release suction on the plunger. Sometimes the veinwill collapse. Reapply gentle suction until the desired amount of blood isobtained.Brachial VeinThe animal should be placed in sternal recumbency. Either forelimbshould then be gently pulled to expose the brachial-antibrachial joint. Thebrachial vein is located deep to the triceps tendon. This tendon can bepalpated on the caudal aspect of the extended leg. The needle should beinserted perpendicular to the skin, in the groove located ventral to the distalend of the tendon. Once the skin is entered, negative pressure should beapplied and the needle advanced. Redirecting the needle may be necessary tofind the vein. Once the vein is entered, the vein blood will flow into thesyringe.Subcarapacial VeinThis vessel is located on the ventral aspect of the cara­pace along thedorsal midline. The animal should be restrained in sternal recumbency with thefront end elevated at a 45-degree angle. With one hand, the head should be heldinside the carapace. With the index finger of the other hand, the firstvertebrae that is fused to the carapace along the dorsal midline should bepalpated. The needle is inserted in the midline position and slowly directed tothe space between the carapace and the vertebrae. Negative pressure should beapplied as the needle is advanced. Blood will fill the syringe as the vein isentered.Ventral Tail VeinThe turtle is restrained vertically with the plastron facing thephlebotomist or in dorsal recumbency. Keep in mind that placing the animal indorsal recumbency is stressful; therefore, this should be done for the shortestamount of time possible. The tail should be extended and held as straight aspossible. The needle should then be inserted in the ventral midline, distal tothe vent. Keep in mind that the further distal one goes, the smaller thediameter of the vein. The needle is then inserted at a 60-degree angle with thehub directed cranially. The needle should be advanced until the vertebral bodyis hit. Apply nega­tive pressure and gently move the needle out (1 to 2 mm)until blood flows. This site is generally not178  Chapter 8Sub-carapacial Veinproductive because only a small volume can be obtained. Larger turtlesin good physical condition can hold the tail close to the body, making the tailvery difficult to exteriorize.Dorsal Tail VeinThe animal should be restrained in sternal recum­bency. The tail shouldbe held as straight as possible and the needle inserted in the dorsal tailmidline. Insert the needle, at a 30- to 45-degree angle, proximally near thejunction between the tail and the caudal margin of the carapace. The needle isthen advanced until the vertebral bodies are encountered. Negative pressureshould be applied and the needle moved gently out (1 to 2 mm) until bloodflows. If the tail cannot be exte­riorized, the needle should be inserted inthe proximal aspect of the tail midline and the steps followed as describedabove.Femoral VeinThe turtle should be restrained vertically with the plas­tron facing thephlebotomist or in dorsal recumbency. Keep in mind that placing the animal indorsal recum­bency is stressful; therefore, this should be done for theshortest amount of time possible. The femoral vein courses through the femoraltriangle (the space through which the femoral vessels run to and from thehindlimb), which is located at the most proximal end of the medial aspect ofthe hindlimb. With one hand, the hind leg should be extended, and the otherhand should be used to withdraw the blood sample. This, like many of the othertechniques, is a blind stick. The needle should be inserted at a 45-degree angleand suction applied as the needle is advanced. Blood will fill the syringe asthe vein is entered. Repositioning the needle should be minimized becausenerves and other vessels located in this area can be damaged.Chelonians  179Occipital Venous SinusThe animal should be restrained in sternal recumbency and the headextended. The caudal aspect of the skull is then palpated. The sinus is locatedin the dorsal midline near the cranial cervical region. The needle should beinserted at a 60-degree angle. Negative pres­sure should be applied once theskin is penetrated as the needle is advanced. The syringe will fill with bloodas the sinus is entered. Sometimes the needle can be repositioned to eitherside of the midline as the sinus can extend laterally. Be careful not to go toodeep.HeartThis technique is relatively invasive because it requires drilling ahole through the plastron. A sterile drill or intramedullary pin can be used toperforate the plas­tron. The site of entry is where the ventral midline sutureintersects the caudal suture of the pectoral scutes. The needle is theninserted perpendicularly as suction is applied. The correct location of theneedle can sometimes be corroborated by the slight move­ment of the syringecaused by the heartbeat. Once blood is collected, the hole must be repairedusing dental acrylic or epoxy resin. This is the authors least desirable sitefor blood collection and it is used rarely.ADMINISTRATION OF MEDICATIONS Routes ofAdministrationIntramuscular Route: Antimicrobial agents and certain anesthesiainduction agents are often given intramus­cularly. Intramuscular injections aregiven in the muscle mass of the front legs. Chelonians have a reno-portalcirculation system. It is believed that medica­tions injected in the caudalhalf of the body are filtered by the kidneys before entering the generalcirculation. However, this concept has been challenged in recent studies (Holz1999). Until more is known about the role renoportal circulation plays infiltering parenteral drugs, these medications should be given in the front halfof the body, particularly drugs with potential nephrotoxic side effects.Subcutaneous Route: Subcutaneous injections can be given in theinguinal and ventral neck skin folds. Fluid replacement can be given at a rateof 20 ml/kg every twenty-four to forty-eight hours.Intravenous Route: The jugular vein can be used for theadministration of fluids. This and the subcarapa­cial vein can be used for theadministration of intra­venous anesthetics.Intracoelomic Route: The coelomic cavity can be accessed throughthe prefemoral fossa, the space just cranial to the pelvic limb into which thelimb is retracted when the animal feels threatened. The intra­coelomic route ismost commonly used for the administration of fluids. Restrain the turtle inlateral recumbency; this will cause the viscera and reproduc­tive organs toshift away from the injection site. Insert the needle parallel to the plastronand direct it crani­ally in the ventral aspect of the fossa. If the needle isdirected dorsally, there is a risk of injecting the fluids in the lungs. If theneedle is directed medially, the fluids can go in the bladder. If the turtleurinates, the needle may be in the bladder; pull and reposition the needle.When injecting fluids into the coelomic cavity, keep in mind that the needledoes not have to be inserted very deep. The fluids can be given at a rate of 20ml/kg every twenty-four to forty-eight hours.Oral Route: The supplies needed to administer oral medications orforce-feeding are round-tip stainless steel tubes or red rubber catheters,speculums, and syringes of various sizes. Many sick turtles are anorexic.Nutritional support is essential for a full recovery. The most chal­lengingpart in many cases is opening the mouth. Some turtles will open their mouthswhen restrained. Take advantage of this and insert a speculum or feeding tubequickly. If this fails, the mouth must be pried open. The upper beak in turtleshangs slightly over the lower beak. A blunt tool can be inserted under theupper beak and inserted in the mouth. Once in the oral cavity, twist the toolto pry the mouth open. Once the mouth is opened, the feeding tube or speculumcan be inserted. The tube feeding volume is 1% to 2% of the body weight everytwenty-four to forty-eight hours. Hold the head fully extended; measure thedistance from the mouth to the mid plastron. Insert the feeding tube to thedesired length and administer the feeding formula.Intraosseous Route: This route is not frequently used but isavailable when needed. The two most com­monly used sites are the tibia and theplastrocarapace bridge that connects the plastron and carapace on the lateralaspect of the body. An intraosseous needle with a stylet is desirable. A 22- to20-gauge needle with a 25-gauge needle inside to serve as a stylet can be used,which keeps the primary needle from becoming clogged (Figure 8.17).Cloacal Route: Fluids and deworming medications can be administeredvia the cloaca. A lubricated red rubber catheter or ball-tipped stainless steeltube can be placed in the cloaca and the desired medication delivered. It isrecommended to hold the turtle at an angle, with the cloaca elevated above theturtles head to improve the absorption rate (Bonner 2000).Nebulization: One of the most common problems seen in  clinical  practice  is respiratory  disease.180  Chapter 8Figure 8.17. Intraosseous catheter. (Drawing by Scott Stark.)Nebulization is a relatively stress-free method to deliver medicationsinto the respiratory system. Turtles have lower respiratory rates than mammalsand birds; therefore, the nebulization time must be extended. In many cases,turtles must be nebulized for an hour or longer to ensure that an adequateamount of medica­tion is administered.Intravenous Catheter PlacementJugular catheterization is reserved for patients that are extremely weakand in a very critical condition (Figure 8.18). Patients that are relativelystable make it diffi­cult to maintain and clean the catheter site. The pro­cedurefor IV catheter placement in a jugular vein is as follows:1. Scrub the area ofthe jugular vein in the anesthetized patient.2. Make afull-thickness incision on the skin.3. Identify thejugular vein using blunt dissection.4. Insert the IVcatheter of adequate size, depending on the size of the turtle.5. Place a butterflytape over the catheter and cap and suture to the skin.IV bolus fluids can be given at a rate of 1-2 ml/kg over a fifteen- tothirty-minute period.EUTHANASIAIn some cases, euthanasia is the most humane course of action. Illanimals with a poor to grave prognosis orBFigure 8.18. Jugular catheter placement. (A) Proper restraint forjugular catheterization. (B) Placement of jugularcatheter. (Photos courtesy of RyanCheek.)severely injured animals may require humane euthana­sia. The hardestpart of euthanizing turtles is knowing whether or not they are dead. This canbe a tricky ques­tion to answer. Some of the signs that help determine if thepatient is dead include absence of a heartbeat, no response to pain (i.e.corneal reflex), rigor mortis, cya­notic mucous membranes, and sunken flateyes. An EKG or ultrasound can be used to assess the heartbeat; however, keepin mind that in turtles the heart can con­tinue to beat several hours aftereuthanasia.The authors preferred method of euthanasia in turtles is lethalinjection. The euthanasia solution can be given intravenously or intracoelomically.In some cases, it is recommended that the turtle be kept in the clinicovernight to ensure the animal is dead. Several sources have referred tofreezing as an alterna­tive method for euthanasia but this is consideredinhumane.Chelonians  181REFERENCESAnonymous. 1990. Guideline for the housing of turtles and tor­toises:Minimum standard housing guidelines for pet shops, wholesale animal dealers,and other commercial establishments. New York Turtle and Tortoise SocietyNewsletter 19(5).Bonner BB. 2000. Chelonian therapeutics. The Veterinary Clinics of NorthAmerica, Exotic Animal Practice, edited by Fronefield SA. 3(7): 257-332.Boyer TH, Boyer DM. 1994. Tortoise care. Bull Assoc Reptil AmphiVet. 4(1): 16-27. Boyer TH, Boyer DM. 1996. Turtles, tortoises, andterrapins. In:Reptile Medicine and Surgery, edited by Mader DR. Philadelphia:W.B. Saunders Co.Centers for Disease Control and Prevention. 1999. Reptile-associatedsalmonellosis—selected states 1996-1998. MMWR. 48, 1009.Frye FL. 1991. A practical guide for feeding captive reptiles.Melbourne: Krieger Publishing. Girgis S. 1961. Aquatic respiration inthe common Nile turtle,Trionyx triunguis. Comp Biochem Physiol. 3: 206. Holz PH. 1999.The reptilian renal portal system—a review. BullAssoc Reptil Amphi Vet. 9(1): 4. Murray M. 1996. Aural abscesses. In:Reptile Medicine and Surgery,edited by Mader DR. Philadelphia: W.B. Saunders Co. Wood SC, LenfantCJM. 1976. Respiration: Mechanics, control,and gas exchange. In: Biology of Reptilians, vol 5, edited by GansC. San Diego: Academic Press. 225-274.CHAPTER NINEHerpetoculture and ReproductionDavid Martinez-JimenezINTRODUCTIONThe reptile pet industry is a growing field with an estimated 13.4million pet reptiles in more than 4.8 million households in the United States,averaging about 2.8 reptiles per household (APPA 2007/2008). While the numberof wild-caught reptile imports has decreased with the establishment ofcommercial regu­lations and captive breeding, current reptile imports in theUnited States are still estimated at about 2 million per year. Captive breedingis therefore a more sustain­able and reasonable approach for the pet market.Proper management and husbandry remain the major obstacles tomaintaining a healthy reptile collec­tion. Reptile medicine is still in itsinfancy. The impor­tance of neonatal care and reptile breeding has a growingsignificance in the management of these captive reptile collections. Propercaptive population management is essential to decrease inbreeding and diseasespread, and therefore preserve the health of the collection.This chapter covers the fundamentals for a healthy reptile collectionand the principles behind captive breeding.CAPTIVE-BRED VERSUS WILD-CAUGHTDespite the increase in reptile pet ownership, reptile imports remainabout the same. This can be explained by the increase of captive-bred reptiles.From 1989 to 1997, 18.3 million reptiles were imported (HSUS 2001). Import ofreptiles has seriously harmed many wild populations and, in many cases,continues to occur because captive breeding has not yet been mas­tered for allspecies of reptiles, such as chameleons (HSUS 2001) (Table 9.1).Captive breeding is a more sustainable way of nour­ishing the growingreptile pet market. Furthermore, it facilitates regulation of the pet market,decreasing the chances of introducing foreign diseases into the environment.For example, the U.S. Department of Agriculture banned the import of sometortoises from Africa because they were carrying ticks, which were vectors ofheartwater disease, a highly contagious wasting disease of ruminants (HSUS2001).Although reptiles are not domesticated, captive breeding programspromote those individuals that are tame and nonaggressive to reproduce incaptivity (high number of offspring and longer reproductive life) and developresilience to the stress of captivity. Therefore, captive breeding also leadsto a type of domestication in itself.Animal welfare is another important reason for decreasing the import ofwild-caught reptiles for pets. Wild-caught reptiles can be captured by meansharmful to the animals and environment. They are often kept in substandardconditions without food and water while waiting for transportation, which leadsto a high mortality rate. Even with the best care, it is estimated that 90% ofall imported reptiles to the United States die within the first year (HSUS2001).QUARANTINEQuarantine is the isolation of animals and people to prevent the spreadof infectious diseases. The recom­mended quarantine period for reptiles isabout three months, but up to six months for snakes because of the risk ofophidian paramyxovirus.  QuarantineTable 9.1. Species of reptiles(8,734 species), divided by tax a. > Amphisbaenia (amphisbaenians) 168 species Sauria (lizards) 5,079 species Serpentes (snakes) 3,149 species Chelonia (turtles and tortoises) 313 species Crocodylia (crocodiles) 23 species Rhynchocephalia (tuataras) 2 species 183184  Chapter 9should be carried out in a separate room that does not exchange air withother facilities. Individuals in quar­antine should be examined at thebeginning of the quarantine for evidence of external parasites (e.g. snakemites, Ophionyssus natricis) and signs ofillness. Body weight, eccdysis (normal skin shedding), behav­ior, feeding, andurination/defecation should be moni­tored throughout the quarantine period andrecorded appropriately. Accurate record keeping is vital for the assessment ofthe collection health and disease identification.Quarantined animals should be handled last, after attending to theanimals in the established collection. Cages, furniture, and bowls should beproperly identi­fied so they do not leave the quarantine area, and they shouldnot be exchanged among quarantine animals. The quarantine area should have footbaths and foot pump water faucets and soap dispensers to prevent crosscontamination. Furthermore, individual cage accessories (bowls, hide boxes,etc.) should be kept to a minimum and should not be cleaned together with otheraccessories from other cages.Cages should be maintained in a way to facilitate cleaning anddisinfection (e.g. using disposable paper towels as substrate) to minimize theexchange of pathogens between quarantine cages. Commonly used disinfectantsinclude household bleach (sodium hypo­chlorite) at 1:30 concentration (1 partof bleach per 30 parts of water; in other words, 30 ml/liter of water or 1/2cup/gallon), 5% ammonia solution (effec­tive against coccidia and Cryptosporidia), and quater­naryammonium (effective against common reptile pathogens) at 1:200 to 1:400 forreptile cages and bowls. Other substances commonly used are shown in Table 9.2.Quarantine is managed according to the "all-in-and-all-out"principle. Once a group of reptiles has started quarantine, those individualsremain as a group and no other reptiles enter the quarantine section or areauntil the quarantine is over. The introduction of new reptiles impliesbeginning the quarantine period all over again.Ideally, three negative fecal tests for gastrointestinal parasites andprotozoa are required. Each fecal testing is performed three to four weeksapart. Once parasit­ism is diagnosed, appropriate treatment is immediatelystarted. Those parasites with direct life cycles (e.g. coccidia) areparticularly difficult to eliminate, requir­ing a regular screening anddeworming schedule. Complete blood analysis should be performed at thebeginning and end of the quarantine period. In the case of healthy animals,this establishes normal baseline values for future reference in the collection.Individuals that become sick should be isolated, and any casualty or euthanasiamust have a complete necropsy and tissue sampling for histopathology.Pest control is important not only at quarantine, but also for thecollection in itself. Arthropods (insects) can facilitate spread of infectiousdisease between exhibits, cages, and collections.MANAGING LARGE COLLECTIONSManaging large collections of reptiles requires a thor­oughunderstanding about each species (natural history, husbandry requirements,etc.), reptile zoono­sis, regulations (local, national, and international), andpreventive medicine. Preventive medicine includes individual identification,sanitation and disinfection, nutrition, physical examination and quarantine,para­site and disease surveillance, necropsy, and pest control.A population management plan is required to main­tain a large collectionof animals. The following ques­tions should be asked: What is the size of theanimal collection? How many different species will there be? What is thepurpose of the collection (private hobby, captive breeding for commercialpurposes, education, zoological, etc.)? How is the surplus of animals managed?How is the genetic pool of the collection monitored? Once the purpose of thecollection is estab­lished, it is possible to focus on fulfilling the collec­tionsspecific requirements to successfully manage it.Record keeping is fundamental. Data may include feeding details, wasteoutput (fecal/urate), sheddings, weight, reproduction details (number of offspring),and any medical condition. Reproductive data should include temperature andhumidity cycling, light cycles, monitoring of time of introduction, courtshipbehav­ior, and mating. Gravid females should be monitored throughout thegestation time and oviposition (egg-laying) to maximize offspring and avoidreproductive-related problems such as dystocia. Once the oviposition occurs, itis very important to document the number of live offspring, stillborn, andslugs for viviparous species, and the number of healthy-looking eggs, abnormaleggs, and slugs in the case of oviparous species.It is important to maintain a proper identification system for thecollection so that there is a system of documenting mortality, percentage ofviable off­spring, compatible breeding pairs, etc. For larger col­lections ofanimals, a visual (physical pattern, carapace marking, etc.) and a permanentsystem (e.g. microchip) is ideal. See Table 9.3 for proper microchip placementin reptiles.Table 9.2. Disinfectants and their characteristics.TypeStrengthEffectivenessAdvantages/ DisadvantagesContact timeChlorine (e.g. sodium hypochlorite)2-10%Iodophors (e.g. betadine)10-100%Biguanides (e.g. chlorhexidine)90 ml/galAlcohol (e.g. ethyl alcohol or isopropyl alcohol)Full strengthFungi, bacteria, algae, enveloped and non-enveloped viruses. Goodagainst tuberculosis microorganism and mycoplasma. Not effective againstspores.Fungi, bacteria, and enveloped and non-enveloped viruses. Good activityagainst tuberculosis organisms and mycoplasma. Poor sporocidal activity butbetter than chlorine products.Fair bactericidal (most Gram-positive and few Gram-negative), viricidalagainst enveloped viruses, sporocidal and low to moderate fungicidal activity.Good activity against tuberculosis organisms and mycoplasma.Strong bactericidal (both Gram-positive and Gram-negative), slightfungicidal, and viricidal (effective against enveloped viruses). Not effectiveagainst bacterial spores and non-enveloped viruses.Corrosive, irritant to mucous membranes, eyes, and skin in highconcentration. Germicidal activity decreases in high water pH (ideally between6-8) and when temperature is below 65°F. Inactivation in presence of organicmaterial and some soapsInactivated bypresence of organic debris and alcohol. Stains skin, fabric, and porousmaterial.Not an irritant. Maintains effectiveness in presence of organic matteror alcohol, but affected by alkaline pH (precipitation of the activeingredients).Long contact time and inactivated by organic matter. Tissue irritant butnoncorrosive. Poses a fire hazard.Several minutes for maximal efficacy (10minutes1-5 minutes depending on theconcentration.5-10 minutes.20 minutes.185Table 9.2. ContinuedTypeStrengthEffectivenessAdvantages/ DisadvantagesContact timeOxidizing agents  Full strength (e.g. hydrogenperoxide)Phenol-based compounds (e.g. Lysol, synPhenol-3)AmmoniaQuaternary ammonium compounds (e.g. Roccal, Parvosol, etc.Full strength5%1:200 to 1:400Aldehydes (e.g. glutaraldehyde)Full strengthGreat for anaerobic bacteria, but not viricidal. Tissue irritant.Blended and/or stabilized peroxides can be used for disinfection of equipmentsurfaces. Stabilized peroxides may be blended with iodophors or quaternaryammonia. Some products are effective against a much broader range of pathogensincluding both enveloped and non-enveloped viruses, vegetative bacteria, fungi,and bacterial spores. Examples include: Hyperox, Virkon S.Fair bactericidal (especially Gram-positive bacteria) and viricidal(enveloped viruses). Not effective against non-enveloped viruses or spores.Fungicidal.Coccidia andCryptosporidia. Good bactericidal, moderate fungicidal activity, andpoor viricidal (effective against enveloped viruses). Poor activity againstnon-enveloped viruses and not effective against fungi and bacterial spores.Good activity against tuberculosismicroorganisms and fair activity against mycoplasma. Bactericidal,viricidal,fungicidal and sporocidal. Effective against tuberculosis organisms and Chlamydophila spp.Inactivated by organic matter. Not effective against bacterial or fungalspores.1-10 minutes.Not inactivated by presence of organic matter. Skin irritation ifprolonged exposure and corrosive to skin. Toxic to cats and reptiles.Inactivated by organic matter and soaps, and poor activity in hard waters.Low toxicity but prolonged contact can be irritating.Effective in the presence of moderate organic matter. Corrosive, toxic,and irritant to the eye, skin, and respiratory tract10 minutes.10 minutes.20 minutes.186Herpetoculture and Reproduction  187Table 9.3. Sites for microchip placement in reptiles. Based onguidelines of the British VeterinaryZoological Society.AnimalSuggested siteChelonians (turtles and tortoises)Sauria (lizards)Ophidia (Snakes)CrocodiliansSubcutaneously in the left hind leg or intramuscularly in thin and smallspeciesLeft quadriceps muscle or subcutaneously in that area. In very smallspecies, subcutaneously on the left side of the bodySubcutaneously on the left side of the neck area at about twice thelength of the headCranial to nuchal clusterReproducing reptiles in captivity can be complex. Husbandry is veryimportant because reptiles rely entirely on their environment to successfullyrepro­duce. A period of cool temperature is necessary for most species toinitiate reproductive behavior. Seasonal cooling is usually referred to ashibernation or bruma-tion (Figure 9.1.); in any case, this is very complex andspecies specific. Therefore, the author strongly recom­mends extensiveliterature research on the species before breeding. Another important factorfor repro­duction is space availability, which can affect proper copulation andegg deposition. Unfit reptiles are more prone to egg retention or dystocia(Figure 9.2.). Another common cause of dystocia is improper laying conditionssuch as lack of a nesting box.Sanitation and disinfection requires a routine sched­ule. Properly done,it requires a written protocol of cleaning and disinfecting agents used, aswell as when and how to use them. Disinfectants can only be used after removalof organic matter and cleaning.Nutrition should be based on the species main­tained. Diet can becomplex and it can be almost impossible to reproduce to what would beencountered in the wild. Vitamin and mineral supplements are usually required.Generally, neonates and youngsters require supplementation on a daily basis orevery other day and adults require it about once a week. Palatability andcomposition of invertebrates vary considerably upon stage and species. Certainspecies of wild insects may contain pollutants and can potentially be toxic(e.g. lightning bugs). Commercial pellet diets are avail­able in the market;however, the nutritional require­ments are not completely known and they shouldnot be used as the only food source.Figure 9.1. A temperature-and humidity-controlled hibernaculum allowingnormal reptile hibernation or brumation. (Courtesy of David Perpihan, LV, MSc, College of Veterinary Medicine, University of Georgia.)Figure 9.2. Egg retention (dystocia) in a green iguana (Iguana iguana).Notice the distended abdomen full ofcalcified eggs. (Courtesy of DavidPerpihan, LV, MSc, College of Veterinary Medicine, University of Georgia.)188  Chapter 9Reptile species should be examined bi-annually or annually depending onage and reproductive stage. The implementation of physical examinations, quar­antine,and necropsy aids disease surveillance within the collection. Early detectionof an infectious and metabolic disease permits prompt correction and lowermorbidity and mortality.Pest control has important implications for personal safety as well asprevention of disease spread within the collection. Possible pest speciesshould be carefully identified and a control plan instituted. Whatever systemis implemented, this must be safe for the species in the collection. Thequality of the program must be carefully monitored and recorded. For example,rodent traps should be inspected regularly and the number of animals trappedmonitored for control purposes. An increase in the number of rodents trappedmay simply correlate with a change in management, such as waste disposal.MANAGING LARGE COLLECTIONS OF DANGEROUS SPECIESDangerous reptile species are those that either can inflict seriousinjuries from a bite (e.g. crocodile), strangulation (e.g. large boid), orvenom (e.g. rattle­snake). The same principles discussed above for keeping alarge reptile collection apply for dangerous species. However, these types ofspecies require further safety issues such as proper caging and in most cases,a legal permit. In cases in which multiple people are handling dangerousspecies, an emergency written pro­tocol is fundamental. An appropriate protocoladdresses every danger in the case of injury or escape, minimizing thelikelihood of mortality or permanent disability. Every protocol must bespecific for the type and number of dangerous reptiles in the collection, andin the case of certain venomous species, maintenance of antivenom may berequired. The American Zoo and Aquarium Association and the AmericanAssociation of Poison Control Centers list the amount and location of availableantivenoms for most venomous species. In any case, it is strongly advisable tonotify the local hospital about the ownership of venomous species so thatmedical staff is prepared in the case of a venomous animal bite.Dangerous species require proper labeling and their handling isrestricted to appropriately trained people. Access is restricted by the use ofa lock and the cages must be properly secured at all times. This is especiallyimportant in the case of venomous species. Venomous reptiles are coded as 1 or2 depending upon the poten­tial of a life-threatening injury. Code 1 animalsare those capable of causing death, long-term illness, or permanent disability,whereas code 2 animals are unlikely to cause severe or long-lasting effects.In the event of injury and escape, the victim is responsible forsecuring the area first and then seeking medical care. A first-aid kit shouldbe available and personnel should be trained in providing first-aid care.A capture plan should also be part of the protocol. This part of theprotocol should include the immediate measures to secure the area, a contactlist of people responsible to respond to an escape, equipment neces­sary forsafe capture and handling, etc. If the animal cannot be safely captured, humanekilling may be indicated.METHODS OF SEX DETERMINATIONThere are different ways of sexing reptiles but none of them isapplicable for all reptile species. The following are methods of sexdetermination in reptiles:• Sexual dimorphism• Probing• Manual eversion ofhemipenes or popping• Hydrostaticeversion of hemipenes• Digital palpation(crocodilians)• Plasma testosterone• Morphometricmeasurements• DNA sexing(karyotyping)• Ultrasonography• LaparoscopySexual DimorphismSexual dimorphism is the difference in appearance between males andfemales of the same species. This is usually apparent in some chelonians(turtles and tortoises) and sauria (lizard) species. Sexual dimor­phism isgenerally apparent in adults, but it can be very difficult in sub-adults andjuveniles. General guidelines for the identification of chelonian males are alonger tail with a cloacal opening beyond the rear carapacial shell margin anda plastral concavity (Figure 9.3.). Some other species-specific characteristicsare long front leg toenails in slider turtles (Pseudemys spp., Trachemys scripta),paintedturtles (Chrysemys picta), and map turtles (Graptemys spp.); a red irisin the male eastern box turtles (Terrapene Carolina Carolina); and more prominentmental glands, gular scutes, and body size in male desert tortoises (Gopherusagassizii). The female leopard tortoise (Geochelonepardalis) has larger toenails in the rear legs than the males andthefemale map turtles and diamondback terrapins are significantly largerthan the males.Although many lizard species are monomorphic, male lizards have a pairof hemipenes located at the base of the tail. In mature iguanids, geckos, andvara-nids, a paired bulge from these hemipenes may identify the individual as amale. Some lizards, especially agamids, geckos, and iguanids, also have poreson their ventral thighs (femoral pores) or on the ventral procloacal skin(precloacal pores). The pores are rela­tively larger in adult males thanfemales (Figure 9.4.). Male monitors have a bone structure in their hemi­penescalled the hemibaculum. The varanus species reported to have hemibacula are acantbarus,beccarii, caudolineatus, eremius, giganteus, gilleni, gouldi, indicus,karlscbmidti, komodoensis, olivaceus, panop-tes, salvadorii, storii, tristis, and varius. In these species,the radiography can be used to make apparent the presence of the hemibacula(Funk 2002). Other dimorphism among lizards is based on ornamentation such asthe three large rostral horns in male Jacksons chameleon (Chamaeleojacksoni), or more robust appearance (especially of the head) inmales such as iguanas and gila monsters (Heloderma suspectum).Sexual dimorphism among snakes is very rare. Among boids, the spurs,located just lateral to the vent, are larger in males than in females. Thesespurs are used for tactile stimulation of the female during courtship. The spursize is highly reliable in the case of the rosy boa (Charinatrivirgata) and the sand boas (Eryx spp.).Herpetoculture and Reproduction  189Figure 9.4. Sexual dimorphism in a lizard species, bearded dragon (Togona vitticepsj.Themale is on the right and female on the left. Femoral pores and tail bulge fromthe hemipenes are obvious in the male. (Courtesy of David Perpihan, LV,MSc, College of Veterinary Medicine,University of Georgia.)ProbingProbing is a technique in which a lubricated blunt-tipped probe is usedfor sexing. Only water- or saline-based lubricants should be used because someother lubricants may be spermicidal. This technique is onlyABFigure 9.3. Sexual dimorphisim in a chelonian species, red-footedtortoise (Geochelone carbonariaj. (A) Male chelonianscommonly have longer tails with the cloacal opening beyond the rear carapacialshell margin. (B) Plastral concavity is more pronounced in male chelonians thanfemales to facilitate mating. (Courtesy of DavidPerpihan, LV, MSc, College of Veterinary Medicine, University of Georgia.)190  Chapter 9valid for squamata (lizards and snakes). In males, the sexing probe goesfarther down into the tail as it enters the hemipenial pocket. The depth of thehemipenial sac varies among species. In females, probing results in the totalinability or limited ability to insert the probe into the tail base. This isthe result of probing a pair of blind diverticula, and female lizards may havea tiny homologous structure called hemiclitori. Common species in which thesediverticula are well developed, creating difficulty sexing by this method,include the monitors (Varanus spp.) and the blood python (Python curtus).Manual Eversion of Hemipenesor PoppingPopping or manual eversion of the hemipenes is a common method fordetermining the sex of neonatal colubrid snakes. This is accomplished by firmlyrolling ones thumb proximally up the tail base toward the cloaca. In femalesthe oviductal papillae can sometimes be identified as two small reddishopenings located laterally in the cloaca.Hydrostatic Eversion ofHemipenesHydrostatic eversion of hemipenes consists of the injection of isotonicsaline solution (as much as 100 ml) into the tail just distal to where thehemipene is located. If the technique is performed correctly, the hydrostaticpressure created by the saline solution causes the hemipenes to evert (Figure9.5.). This also causes swelling of the tissue surrounding the cloaca, and maypartially evert the cloaca through the vent. For largerFigure 9.5. Everted hemipenes in a lineated leaf-tailed gecko (XJroplatuslineautusj. (Courtesy of DavidPerpihan, LV, MSc, College of Veterinary Medicine, University of Georgia.)species such as boids, monitors, iguanas, and gila mon­sters anesthesiamay be required because the retractor penis muscle can counteract thehydrostatic pressure created, therefore preventing the eversion of thehemipenes.Digital PalpationDigital palpation is the preferred method for crocodil­ian species. Thisinvolves palpating the ventral aspect of the cloaca for the presence of a penisin the other­wise smooth-walled cloaca.Plasma TestosteronePlasma testosterone concentration has been used for sexing chelonianjuveniles, with or without the use of follicle-stimulating-hormone (FSH)stimulation test (Owens et al. 1978, Lance et al. 1992, Rostal et al. 1994).Males typically have higher levels than females. However, this test also haslimitations because older females may have normal elevated testosterone levelsand prolonged handling of both sexes has been reported to elevate testosteronelevels (Rostal et al. 1994, Innis and Boyer 2002).MorphometricMorphometric is the use of body measurements to determine sex. However,this is not a reliable way to differentiate males and females because there aremany exceptions among species. It is more common for males to be larger thanfemales in lizards. Female turtles are generally larger in body size than males.However, this may be different in tortoises. The male desert tortoise (Gopherusagassizii) is larger than the female.DNA SexingKaryotyping is the use of DNA to determine gender. It can be used forboth temperature-dependent sex determination (TSD) species and those that arenot TSD species (Demas et al. 1990, Innis and Boyer 2002). Although thistechnique is feasible, it has received little attention.Ultrasonography and LaparoscopyUltrasonography may be useful identifying males and females byidentification of ovaries, follicles, or eggs in the coelomic cavity offemales, and testis or the hemipenes in the case of males (Figure 9.6.).Laparoscopy has been also used for sexing. This is a surgical procedure inwhich an endoscope is guided through their coelom to directly visualize thetestis or ovarian tissue (Figure 9.7.). The advantage is that it permits visualevaluation of the reproductive tract and detection of possible abnormalities.Herpetoculture and Reproduction  191Figure 9.6. Coelomic cavity ultrasound in a gravid female. Note thepresence of the follicles (increasedround echogenicity) as they lack ofthe more mineralized egg shell. (Courtesy ofDavid Perpihan, LV, MSc, College of Veterinary Medicine, University of Georgia.)REPRODUCTIVE BEHAVIORThe development of secondary sexual characteristics coupled withcourtship behavior is an indication that sexual maturity is approaching (Innisand Boyer 2002). Sexual maturity depends upon the reptile size rather thanactual age (Taylor and Denardo 2005). In captiv­ity, reptiles reach sexualmaturity at a younger age than their wild counterparts. For instance, captiveleopard tortoises (Geochelone pardalis) may repro­ducesuccessfully in four to six years, whereas their wild-born counterparts do notreach sexual maturity for fifteen years (Innis and Boyer 2002). As a roughgenerality in captive species, snakes usually mature in two to three years,small lizards in one to two years, large lizards in three to four years, andchelonians in five to seven years (Denardo 2006).In most reptile studies to date, high plasma levels of testosterone andcorticosterone coincide with the mating period. The female estradiol levelincreases at the onset of the mating season and decreases at the onset of thenesting season. Progesterone levels are high close to ovulation and thebeginning of the nesting season, and they decrease during the nesting season(Schramm et al. 1999). Therefore, monitoring the reproductive cycle is possiblevia plasma chemistry and hormone assays (Innis and Boyer 2002).The most common stimulus to reproduction in rep­tiles is a change intemperature. The reproductive cycleBFigure 9.7. Endoscopic visualization of(A) a testis in a male green iguana (Iguana iguana,) and (B) an ovary ina young female Hermanns tortoise (Testudo hermanni,). (Courtesy of Xavier Vails Badia, LV, Clinica Veterinaria Exotics,Barcelona, Spain.)in chelonians is linked to the temperature and humid­ity determined bytheir natural habitats. For species in temperate climates, reproductiveactivity is restricted to the warmer months of the year when the days arelonger. In general, females ovulate and are fertilized in the spring, nest inthe late spring and summer, and begin folliculogenesis for the following yearsegg in late summer and fall. An exception to this is tropical boids (boas andpythons), which tend to breed during the cooler period (Denardo 2006). Intropical climates,192  Chapter 9the reproductive cycle follows the rainfall patterns, when temperatureand day length fluctuations are minimal (Innis and Boyer 2002).Light also plays an important role in sexual behav­ior. Behavioralstudies have proven the importance of full-spectrum lighting (UVA, UVB, andvisible light; 280 to 700nm) and its role not only in motion percep­tion andforaging but also intersexual recognition.Courtship and Mating BehaviorSome degree of courtship behavior is noted in most species. Courtshipmay last from minutes to hours, and it may even resume on subsequent days. Mostterres­trial tortoises such as the Mediterranean tortoises (Testudo spp.) display alunging behavior toward the females, battering the anterior edge of theircarapace against the female. The male red-footed tortoise (Geochelonecarbonaria) may stand in front of thecfemale with its neck stretched low to the ground, moving it rhythmicallyside to side while uttering low-pitched, grunting sounds. In some NorthAmerican aquatic species (e.g. red-eared slider, Trachemys scripta),malesfibrillate their elongated nails of the forelimbs near the females face (Innisand Boyer 2002).Copulation is a short event only lasting for several minutes. Manychelonian and lizard species display biting behavior as the male mounts thefemale from behind (Innis and Boyer 2002). In snakes, the male of the colubridneck-banded snakes (Scaphiodontopbis annulatus) grabs, holds, andbites the female during copulation as part of the mating behaviour (Sasa andCurtis 2006).During copulation, one hemipenis is everted into the females cloaca inthe case of snakes and lizards (Figure 9.8.). In the case of chelonians andcrocodil-ians, a single penis arising from the floor of the cloacaBFigure 9.8. Snake copulation. (A and B) Copulation in the timberrattlesnake (Crotalus horridusj. (Courtesy of BWSmith, Animal South LLC.) (C) Copulation ofthe common boa constrictor (13oa constrictor^. (Courtesy of Susana Ringenbach, MVZ, Fauna Silvestre,Merida, Mexico.)Herpetoculture and Reproduction  193is everted. In both cases, the sperm flows through a single groovecalled the seminal groove or sulcus sper-maticus from the vas deferens down thepenis or hemi­penis and down to the anterior portions of the females cloaca.The spermatozoa travel upward through the oviduct where fertilization occurs.In some species such as iguanids, sperm storage allows the female to laysubsequent clutches (Funk 2002).Reproduction Without MatingAmphigonia retardata, or sperm storage, has been described inturtles and snakes. This adaptation allows a female to produce several clutchesfrom a single mating in one season and to reproduce in subsequent seasons. Theviability of the storage sperm is not indef­inite and varies with the species,ranging from several months to up to six years (Mader 2006).Another strategy to reproduce without mating is parthenogenesis. In thiscase, the female becomes gravid in the absence of a male and produces onlyfemale offspring (Mader 2006). Interestingly, genetic polymorphism is present tosome extent, albeit the lack of genetic recombination.Studies have shown in true parthenogenetic species, such as the Caucasian rock lizard (Darevskiaunisexu-alis), that mutations can make a significant contribu­tion topopulation variability (Badaeva et al. 2008). Parthenogenesis has been reportedin more than thirty species of lizards and some snakes. Some common examplesinclude members of genera Cnemidophorus (whiptails), Darevskia (rock lizards), Hemidactylus (geckos), Komododragon (Varanus komodoensis), and snakes such asthe Rhamphotyphlops braminus (blind snake) (Table 9.4.).Table 9.4. Reptile families in which parthenogenesis has been described.Family Gekkonidae(geckoes) Family Agamidae (agamids) Family Chamaelonidae(chameleons) Family Xantusiidae (nightlizards) Family Lacertidae (lacertids)Family Teiidae (whiptailsand tegus) Family Typhlopidae (blindsnakes)5 species1 species 1 species1 species5 species (e.g. GenusDarevskia) 15 species (e.g. GenusCnemidophorus) 1 speciesFOLLICLE AND EGG DEVELOPMENTVitellogenesis is the major step of follicle maturation with theaccumulation of yolk. Estrogen triggers the liver to convert the lipid from thebodys fat stores to vitellogenin, which is selectively absorbed by the fol­licles.Calcium also accumulates in the yolk during this stage so that the yolk acts asa main calcium reservoir for the embryo. Furthermore, a significant amount ofcalcium is drawn from the eggshell in oviparous species. The mature ovum isten-fold to 100-fold larger than its previtellogenic size. In the oviduct, theovum becomes an egg when albumin and a shell are added for oviparous species.In the case of viviparous species, placentation takes place. Thismaternal-embryonic relationship varies among viviparous species with the mostextreme example being some skinks (Mabuya spp.), in which themother contributes more than 99% of the neonatal mass through a chorioallantoicpla­centa (Denardo 2006).CLUTCH DYNAMICSThe frequency with which reptiles reproduce depends on the species,environmental conditions, and health status of the specific individual.Reproduction has det­rimental effects for female reptiles because they ceasefeeding during the latter stages of pregnancy. The length of time during whichfeeding is reduced varies but it is much shorter in oviparous (weeks) than inviviparous (months) species. This limited amount of energy allocated toreproduction therefore has direct effects on offspring and clutch size.Invariably, the amount of energy is extraordinary, especially in snakes, inwhich where more than 40% of the females body mass can be allocated toreproduction (Denardo 2006).Clutch size is extremely variable in reptiles. For oviparous species, itranges from one in the case of anoles (Anolis spp.) and thepancake tortoise (Malocochersus tornieri) to 200 in the greensea turtle (Chelonia mydas). In viviparousspecies, the numbers may be slightly lower with a range from one in the case ofshingleback skinks (Trachysaurus rugosus) to ninety-two inthe garter snake (Thamnophis radix) (Denardo 2006).Many oviparous species can produce more than one clutch per year. Thisis more common among cheloni­ans and lizards than snakes. Due to the restraintsof viviparity, viviparous reptiles are limited to a single clutch per year.194  Chapter 9Box 9.1. Oviparity and Viviparity of Commonly Kept Reptiles. (Adaptedfrom Denardo 2006 in Reptile Medicine and Surgery, Mader DR, ed., Elsevier.)OviparousAll crocodilians All chelonians Most lizardsAll monitors (Varanus spp.) Most iguanidsIguanas (Iguana spp.) Water dragons (Pbysignathus spp.) All geckosMost chameleons Veiled chameleon (Chamaeleo calyptratus) Panther chameleon (Chamaeleopardalis) Some snakes All pythons Most colubridsKing snakes and Milk snakes (Lampropelis spp.)Rat snakes and Corn snakes (Elaphe spp.)ViviparousSome lizards Some skinksBlue-tongued skinks (Tiliqua spp.)Shingle-backed skink (Trachysaurus rugosus) Prehensile-tailedskink (Corucia zebrata) Some chameleonsJacksons chameleon (Chamaeleo jacksonii) Some snakesMost boas (except Charina reinhardti, Eryxjayakari) Most vipersAll rattlesnakes (Crotalus spp.) SomecolubridsGarter snakes (Thamnophis spp.)OVIPAROUS, OVOVIVIPAROUS, OR VIVIPAROUSThe oviducts function in lizards and snakes is fertiliza­tion, spermstorage, egg transport and eggshell deposi­tion, maintenance of the earlyembryo, and expulsion of the egg or fetus. In viviparous species, the oviductalso contributes to the placenta, which is responsible for gas exchange andnutrient provision to the fetus (Blackburn 1998).Three modes of reptile reproduction have long been recognized:oviparous, ovoviparous, and viviparous. Ovoviparity was applied to thosespecies in which the young are born alive but there was not placentalconnection between the mother and the offspring. However, more recentinvestigations have demon­strated some nutrient transfer; therefore, the termovo­viparity may be inappropriate (Funk 2002).Thus, the term oviparity refers to the condition of laying fertilizedeggs and viviparity refers to the condi­tion of giving birth to live offspringregardless of how nutrient exchange may have occurred between the mother andthe offspring. Chelonian and crocodilian species are oviparous, while 20% ofsquamates (some lizard and snake lineages) are viviparous (Funk 2002,Benirschke 2007) (Box 9.1).Although viviparity has a clear advantage over ovi­parity, there areseveral disadvantages worth mention­ing. Sustaining the fetuses over anextended period of time limits the female to a single clutch per year. Bearingthe offspring also has detrimental effects to the female because viviparousfemales cease feeding during the latter stages (Denardo 2006) (Figure 9.9.).However, viviparous reptiles have the advantage of regulating incubationtemperature and enhancing the fitness of the offspring. Therefore, aphylogenetic tran­sition from oviparity to viviparity has occurred in coldclimates (Webb et al. 2006).EGG INCUBATION VERSUS MATERNAL INCUBATIONA number of factors determine the length of gestation, such as season,ambient temperature, housing, and food supply, among others (Mader 2006).Parental care in reptiles is minimal with few exceptions among crocodilian andpythons. Female pythons are known to brood their eggs during incubation bycoiling around them until hatching. Periodic rhythmic contractions of herabdominal musculature is capable of maintaining a mean body temperature of7.3°C over the mean ambient surface temperature (Mader 2006).EGG INCUBATION METHODSViable eggs are usually firm, dry, and chalky white. Soft-shelled eggsin all snakes, most lizards, and some chelonians are pliable, while the eggs ofcrocodilians, many chelonians, and some lizards are hard-shelled and thereforerigid (Figure 9.10.).Artificial incubation is relatively simple. Incubators can be easilydesigned and maintained by fulfilling three basic requirements: properregulation of tem­perature and humidity, even distribution of heat, and areliable thermostat to control temperature. AlthoughHerpetoculture and Reproduction  195insulation prevents the loss of heat and humidity, some degree ofventilation should be permitted (e.g. small holes on the lid of the eggchamber). A study on sea turtle eggs showed that poor ventilation increasesincu­bation time and reduces survival of embryos (Funk 2002). Commercialincubators are available for rep­tiles, and even chick incubators can be usedwith minor modifications such as stopping the movement of the egg trays. Mostincubators are designed according to a double-chamber principle so that theeggs are located inside a box, which is inside the larger incubator chamber. AStyrofoam cooler can be used as a cheaper alternative for the containmentchamber of the nest box. Plastic storage boxes can be used as a nest or insidebox. The lid should fit tightly so that the air humidity approaches saturation.The moistened sub­strate material is filled halfway, and then water is addedappropriately so that it is only slightly damp.BFigure 9.9. Viviparity in a rainforest hognose viper (Torthidiumnasutumj. (A) Hognose viper giving birth. (B) Offspringsurrounded by the placenta membrane. (C) Necropsy of a rainforest hognose viper in which several fetuses arecontained within a plancenta membrane within the oviduct. (Courtesy of Alejandro Ramirez, student of veterinary medicine and supervisor of the group in Ophidism-Scorpionism Universityof Antioquia, Colombia.)Figure 9.10. Hard-shelled eggs ofthe Mediterranean spur-thighed tortoise (Testudo graecaj. (Courtesy of Jose Luis Crespo Picazo, LV, Nexo CMA Valencia, Spain.)196  Chapter 9Heat is provided by heating coils, strips, and pads, and a thermostatassures that the temperature stays con­stant within the inner chamber with theset-up based on the species eggs. As long as the three main prin­ciples ofreptile egg incubation are fulfilled, any con­tainer with controlled heat,humidity, and ventilation may be suitable (Figure 9.11.).Although there is no scientific study indicating oth­erwise, the eggsshould be placed in the incubator in the same orientation as they were laid. Apencil mark on top of the egg may help maintain the orientation when the egg ismoved. Soft-shelled eggs are then half-buried within the moist substrate andseparated from each other by a small distance (Figure 9.12.). Hard-shelled eggsmay be placed in a small depression in the substrate. Maintaining a certaindistance between the eggs prevents the spread of disease processes among theeggs. When two or more eggs are strongly adhered to each other, they will haveto be half-buried together. Attempting to separate those eggs may lead to perma­nentdamage.Incubation requirements for most reptilian eggs are similar. Veryimportant factors to remember in reptile reproduction are ambient temperature,humidity, and substrate.TemperatureAmbient incubation temperature directly affects the length of incubationand, in some species, gender determination (Table 9.5). There are two types ofsexFigure 9.11. A hand-made incubator can be easily designed by creating anenvironment of controlled temperatureand humidity, and even distribution of heatand some degree of ventilation.(Courtesy of Jose Luis Crespo Picazo,LV, Nexo CMA Valencia, Spain.)determination systems: genotypic sex determination (GSD) determined bythe sex chromosomes and temperature-dependent sex determination system (TSD) inwhich temperature affects sex determination (Wibbels et al. 1991; Delmas et al.2008). The rele-tsFigure 9.12. After egg deposition, the eggs are removed and placed intothe incubator chamber.(A) Egg laying of a Mediterranean spur-thighed tortoise (Testudo graecaj. (Courtesy of Jose Luis Crespo Picazo, LV, Nexo CMA Valencia, Spain.)(B) The egg chambercontains the half-buried eggs set into the moistened substrate and separatedfrom each other by a small distance. Maintenance of a certain distancebetween the eggs prevents the spread ofdisease processes among the eggs. (Courtesy ofDavid Perpinan LV, MSc,College of Veterinary Medicine,University of Georgia.)Herpetoculture and Reproduction  197Table 9.5. Patterns oftemperature sex determination in reptiles.Sauria (lizards)Family GeckonidaeAfrican fat-tailed gecko (Hemitheconyxcaudicinctus) 26°-29°C (78.8°-84.2°F) results in females30°-32°C (86°-89.6°F) results in males34°-35°C (93.2°-95°F) results in femalesJapanese gecko (Gekko japonicus)Females at higher temperatures, males at lower temperaturesLeopard gecko (Eublepharis macularius)26.7°-29.4°C results in 90% females>32.2°C results in 90% malesRainbow lizard (Agama agama)26°-27°C (78.8°-80.6°F) results in females29°C (84.2°F) results in malesJacky dragon (Amphibolurus muricatus)Tuataras (Sphenodon sp.)Chelonians (turtles and tortoises)Some BataguridaeCarettochelydaeCheloniidaeDermochelydaeEmydidaeTestudinidaePelomedusidaeKinosternidaeMacroclemys temminckii (Chelydridae) Some Bataguridae All crocodiliansPattern IIPattern IAPattern IBPattern IBPattern II Pattern IBPattern IA Pattern IA Pattern IA Pattern IA Pattern IA Pattern IAPattern II Pattern II Pattern II Pattern IIPattern II is assumed in all crocodilians. Pattern IB is still suggestedfor some species (Alligator sinensis, Caimen crocodiles yacare, and Paleosuchustrigonatus) due to the limited available data.Note: Pattern I-IA: Males produced at low temperatures and femalesproduced at high temperature with a single transition zone. IB: Males producedat high temperatures and females produced at low temperatures with a singletransition zone. Pattern II: Females produced at both low and high temperatureswith males produced at intermediate temperatures; two transition zones.Authors disclosure: This table is not intended to represent all reptilespecies in which gender is determined by temperature (TSD). Not all reptilespecies have been studied, and in many cases there is not enough scientificdata about temperature ranges. Occasionally a reptile species has been reportedhaving TSD pattern IA or IB, and later evidence has proven that it may follow adifferent pattern, such as pattern II.vance of TSD over GSD is still unknown but may be related toenvironmental fitness (Warner and Shine 2008). However sex determination isvery complex in reptiles and even both systems can be present in a singlespecies. Sex determination in the montane scincid lizard (Bassianaduperreyi) is regulated geneti­cally by sex chromosomes but temperaturescan over­ride chromosomal sex generating phenotypically male offspring from XXeggs in cool nests (Radder et al.2008). TSD occurs in all studied crocodilians and tua­taras, it is verycommon in chelonian, less frequent in lizards and unknown in snakes (Delmas etal. 2008). Although TSD has evolved in several lineages of lizards, there isless information than among the other reptile taxa. The time in which TSDoccurs in called the thermosensitive period and is about the middle one-thirdof the embryonic development (Wibbels et al. 1991; Delmas et al. 2008). TSD maybe also evident198  Chapter 9in viviparous lizards in which sex ratios fluctuate with thermalconditions. In the Spotted skink (Niveoscincus ocellatus) there is a higherproportion of male off­spring in colder years (Wapstra et al. 2008). There aretwo distinct patterns of TSD. In Pattern I, there is a single transition zoneat which eggs incubated below this temperature zone result predominantly inmales and above the temperature zone predominantly in females. Pattern II hastwo transition zones with males predominating at the intermediate zone andfemales at both extremes. Pattern I occurs chiefly in turtles in which theadult females are larger than the adult males while Pattern II is primarilypresent with females being smaller than males or non-dimorphic species (no dif­ferencebetween males and females). Some Sternotherus and Cbelydra are exceptions suchthat a constant incu­bation temperature within the transition zone yields 100%males (Eti 2009).Incubation length is usually reduced by high tem­peratures, but itincreases the risk of congenital defects (Denardo 2006). Furthermore,abnormally high or low temperatures will affect on the health of the hatchlings(Mader 2006). In general, incubation temperature ranges from 26°C to 32°C (80°Fto 90°F) (Denardo 2006).Gestation periods vary. Eggs of most snakes and small lizards hatch in45 to 70 days, and 90 to 130 days for eggs from larger lizards such as iguanasand monitor lizards. Gestation lengths cannot only vary among species, but alsowithin the same species and within the same clutch. Incubation time of theleopard tortoise (Geocbelone pardalis) can range from 250to 540 days and from 30 to 40 days variation within same clutch (Denardo 2006).SubstrateCommonly used substrates include perlite, vermiculite, potting soil,sand, sphagnum moss, and shredded paper. There is also commercially availablesubstrate for reptile incubators based on a pre-prepared mixture of the alreadymention substrates. Perlite and vermicu­lite are preferred by many hobbyists asthey are very light, absorbent, siliceous material that naturally resistsmolding. In any case, the purpose of the substrate is to provide a media thatwill retain water and maintain humidity within the egg container whilepreventing excessive fungal growth.HumidityThe amount of water added to the substrate varies but should be enoughto create clumping of the media without dripping of water. Water will be requiredthroughout the incubation period and therefore, more may need to be added.Dampened sphagnum moss can be used to cover the eggs to help preventdesiccation; however it will prevent or make more difficult visual checking ofthe viability of the eggs.It is advisable to weigh the incubation box and its eggs periodically sothat water can be added to keep the box at its original weight. If water needsto be added, water should be at the same temperature as the incubator.DIAGNOSING EGG PROBLEMSIn order to diagnose egg problems it is important to understand thebasic differences among reptilian eggs. The eggshell in snakes and most lizardsis leathery and soft; however the egg of chelonian, crocodilians and geckos ishard as they have a calcareous shell. Both soft-shelled and hard-shelled eggshave three internal membranes (the amnion, the chorion and the allantois) thatretard outward water diffusion and allow embry­onic respiration. Even thehard-shelled eggs will take water from the environment to some extent and swellin size during embryonic development. All the nutri­ents will come from theyolk and the white, and any remaining yolk in the egg will be incorporated intothe hatchlings coelomic cavity (Mader 2006).The death of the egg can occur when the environ­mental conditions foregg development are not ful­filled. Incorrect humidity (high or low),temperature (high or low) and improper ventilation are very common problemsthat can cause egg death. Other potential causes are excessive handling or trauma.In any case, it may be difficult to determine the cause the embryonic death.Reptiles from temperate zones can stand temperature ranges better than tropicalspecies. For instances, the embryos of the tropical green iguana (Iguana iguana) fail to develop attemperatures varying for more than 2°C from the optimum 30°C (86°F) (Funk2002).Health assessment of the eggs is based on daily monitoring for color andtexture changes. A collapsed egg is a sign of dehydration but not necessarilyegg death. Marked changes in color or texture or fungal growth are usuallysigns of a non-viable egg, either from egg that has died or from a non-fertileegg (Table 9.6.).Two diagnostic methods of assessing the health of an egg are"candling" and ultrasonography for non-calcified eggs (mostsquamata). A high-intensity light source (e.g. transilluminator) placed indirect contact with the side of the egg in a dark room can reveal a developingvascular pattern in a viable egg as theHerpetoculture and Reproduction  199Table 9.6. Common signs encountered during egg incubation, treatment,and prevention.ProblemSignsTreatmentPreventionDiapauseTraumaFails to developEgg death Fails to developInfertile eggFungal growth Depression or deformityDessication  Egg shrinkageFungal growth  Mold on egg surfaceSlugsWaxy yellow deformed and shrink eggsCorrection of environmental conditionsProper environmental conditionsNo treatmentClean fungus gently withcotton tip No treatmentRehydrate with warmspring water Remove growth with acotton tip, and sprinkleantifungal powder (e.g.athletes foot powder) No treatmentSome eggs enter diapause andresume growth after properenvironmental conditions Proper environmental conditions,proper monitoring and design ofincubator Sex determination of individuals,correct level of maturity, andproper pairing Avoid excessive humidity andcontact between eggs Mark eggs orientation with a penciland avoid trauma or excessivehandlingProper monitoring of humidity andtemperature Prevent excessive humidity and avoidcontact between eggs. Remove anydead eggs.Discard unfertilized ova. It may imply an underlying issue with thefemale. Seek veterinary attention.embryo grows or a homogenous diffuse yellow-white luminescence in adeath egg. Ultrasonography must be used carefully because the ultrasound gelcan poten­tially damage the eggs by clogging the oxygen exchange pores.Ultrasonography of the developing embryo requires a high-frequency ultrasoundtransducer (7.5 to 10 MHz) to properly assess development (Mader 2006). In anycase, ultrasonography can not only be used to distinguish the general stages offollicle and egg development, but it can also be used to reasonably predictbirth by monitoring the loss of yolk, with birth occurring about a week afteryolk can no longer be detected (Denardo 2006).CARING FOR THE NEWBORNReptilian neonates are born precocious. In other words, they are fullyindependent and capable of sur­vival from birth. Adult reptiles rarely provideany care for their offspring. Parental care can be defined as the parentalactions after oviposition or parturition that may increases the offspringschances of survival (Funk 2002). Parental care has been documented in at least100 species of reptiles but it is limited and nonessential for survival of theoffspring (Denardo 2006). Among lizards, there are few examples of maternalcare but this is basic and limited to nesting care against preda­tors in thecase of some skinks. Nest guarding has been also documented in chelonians (e.g.Burmese mountain tortoise, Manouria emys), snakes (e.g. Kingcobra, Ophiophagus Hannah, and cobras, Naja spp.), andvirtually all species of crocodilians. In the case of the skink Eumeces obsoletus, the female assistsduring hatching and subsequently licks their cloacas, and sup­plies them withfood up until about the tenth day (Mader 2006). As a part of nest guarding,crocodilians assist the neonates in emerging from the nest and guard them afterhatching. Rattlesnakes remain with their offspring until the neonates firstshed (Denardo 2006).In captivity, neonate care can be divided into three categories:environmental conditions, space, and proper food. The care provided to newbornsis minimal and merely a scaled-down version of the care given to adults.Hatching can take from one to four days. In the case of chelonians, theneonates shell begins to unfold, facilitating yolk absorption. Absorption ofthe yolk sac may take several days after hatching so neo­nates should be keptin a clean and moist environment.200  Chapter 9In general, hatchlings are maintained at or near the incubationtemperature, and many breeders leave them in the incubator for the first fewdays. A plastic con­tainer with clean, moist paper towels is also commonly usedfor the first few days. Once the yolk sac is fully absorbed and the umbilicussealed, the neonates can be transferred to a cage with other substrate.Neonates are very prone to dehydration, and thus humidity should be close to100%. After leaving the incubator, temperature should be close to the adultstemperature range, with slightly higher humidity. Higher humidity can be easilyaccomplished by using moistened paper towels and a humidity box, a confined boxcontaining moistened paper towels with a small opening that allows theyoungsters to get in and out easily. Being such a confined and closed space,this allows a relative humidity of almost 100% as long as the substrate is replacedon a daily basis. Other, more natural sub­strates can be used as the youngstersgrow but paper is generally the preferred option because it is cheap and easilycleaned.Aggression is very common among neonatal lizards and snakes as part ofthe survival instinct. Providing enough space is therefore fundamental for themto thrive and decrease stress. The hatchlings should be separated if aggressionis obvious. Separating the clutch into smaller groups not only decreases aggres­sionbut also helps monitor the health status of the group (weekly weightmonitoring) and their appetite.Feeding the NeonateHatchlings usually begin feeding within one and four­teen days ofleaving the egg; most neonatal snakes do not eat until their first shed atabout one to three weeks after hatching (Mader 2006). Appropriate feeding iscritical for proper growth and development. The yolk provides nutrients for thefirst few days but proper food type and size is fundamental thereafter. A thor­oughunderstanding of the dietary requirements of the species is essential. Somespecies prey on particular species that are not commercially available,requiring "scenting" to train the neonate to eat alternate fooditems. This is accomplished by rubbing the proper food item (e.g. fish or frog)against the alternate food (e.g. rodent). Herbivore reptiles can be offered amix of fresh vegetables, which should be finely chopped to the appropriatesize. Insectivorous and carnivorous rep­tiles can be offered insects such ascrickets, mealworms, grubs, wingless fruit flies, termites, slugs, small fish(guppies or comets), pinky mice, small lizards (anoles or geckos), small frogs(toads can be toxic), chick legs, hatchling quails, and mouse parts. In anycase, the offered food item should never be larger than the width between thereptiles eyes; otherwise, it is poten­tially too large to be ingested.The food nutritive value should be enhanced with commercially availablevitamin and mineral supple­ments, and this is especially important for herbivoresand insectivores species. There are two basic methods for vitamin/mineralenhancement: dusting and gut loading. Dusting implies sprinkling the supplementover the food item. This technique may decrease the palatability of the fooditem so careful monitoring is required to assure that the food is completelyeaten. In the case of insects, if these are not ingested immedi­ately they canself-groom and remove these powders and therefore decrease the supplementavailable for the reptile. Alternatively, an enriched media can be offered tothese insects for a few days before being fed to the reptiles. This is calledgut loading.Assisted feeding may be required in cases of anorexia. This can beaccomplished by the use of an appropriate-size stomach tube to deliver the foodinto the stomach. Commercially available foods or purees of appropriate fooditems (rodent parts, eggs, vegeta­bles, etc.) can be used. Assisted feeding isprovided by forceful placement of the food into the reptiles mouth. It canpotentially damage the back of their mouth (oropharynx) and esophagus, and isstressful. Snakes can be stimulated to eat by using a technique called"slap feeding" by gently tapping the snakes nose with the food item.This tends to initiate a reflex in the snake to strike and grasp the food item(Mader 2006).REFERENCESAPPA. 2007/2008. APPAs 2007/2008 National Pet Owners Survey.Badaeva T, Malysheva D, et al. 2008. Genetic variation and de novomutations in the parthenogenetic Caucasian rock lizard Darevskia unisexualis.PLoS ONE 3(7): e2730.Benirschke K. 2007. Jacksons chamaleon Chamaeleonjacksonii xantholophus. In: Comparative Placentation, edited byBenirschke K. Ithaca, NY: International Veterinary Information Service.Blackburn D. 1998. Structure, function, and evolution of the ovi­ductsof squamate reptiles, with special reference to viviparity and placentation. / Exp Zool 282(4-5): 560-617.Delmas V, Prevot-Julliard A-C, et al. 2008. A mechanistic model oftemperature-dependent sex determination in a chelonian: the European pondturtle. Fund Ecol 22(1): 84-93.Demas S, Duronslet M, et al. 1990. Sex-specific DNA in reptiles withtemperature dependent sex determination. / Exp Zool 253: 319-324.Denardo D. 2006. Reproductive biology. In: Reptile Medicine and Surgery,editedby Mader D. St Louis: Saunders Elsevier: 376-390.Eti, turtles of the world. Temperature dependent sex determination. www.eti.uva.nl/turtles.ETI. Accessed October 8, 2009.Herpetoculture and Reproduction  201Funk R. 2002, Lizard reproductive medicine and surgery. Vet ClinExot Anim 5(3): 579-613. HSUS. 2001. The trade in live reptiles:Imports to the United States.Washington DC.Innis C, Boyer T. 2002. Chelonian reproductive disorders. Vet ClinExot Anim 5(3): 555-578. Lance V, Valenzuela N, et al. 1992. Ahormonal method todetermine the sex of hatchling giant river turtles, Podocnemisexpansa: application to endangered species research. Amer Zool32: 16A.Mader D. 2006. Perinatology. In: Reptile Medicine and Surgery, edited byMader D. St. Louis: Saunders Elsevier: 365-375.Owens D, Hendrickson J, et al. 1978. A technique for determiningsex of immature Chelonia mydas using radioimmunoassay.Herpetologica 34: 270-273. Radder R, Quinn A, et al. 2008. Geneticevidence for co-occurrenceof chromosomal and thermal sex-determining systems in a lizard.Biol Lett 4(2): 176-178. Rostal D, Grumbles J, et al. 1994.Non-lethal sexing techniques forhatchling and immature desert tortoises (Gopherusagassizii).Herp Mono 8: 83-87.Sasa M, Curtis S. 2006. Field observation of mating behavior in theneck-banded snake Scaphiodontophis annulatus (Serpentes:Colubridae). Rev Biol Trop 54(2): 647-650.Schramm B, Casares M, et al. 1999. Steroid levels and reproductive cycleof the Galapagos tortoise, Geochelone nigra, living underseminatural conditions on Santa Cruz Island (Galapagos). Gen Comp Endocrinol114(1):108-120.Taylor E, Denardo D. 2005. Sexual size dimorphism and growth plasticityin snakes: an experiment on the western diamond-backed rattlesnake (Crotalus atrox). JExp Zool A Comp Exp Biol 303(7): 598-607.Wapstra E, Uller T, et al. 2008. Climate effects on offspring sex rationin a viviparous lizard. / Anim Ecol. Sep 22.Warner D, Shine R. 2008. The adaptive significance oftemperature-dependent sex determination in a reptile. Nature 451: 566-568.Webb J, Shine R, et al. 2006. The adaptive significance of reptilianviviparity in the tropics: testing maternal manipulation hypoth­esis. Evolution 60(1): 115-160.Wibbels T, Bull J, et al. 1991. Chronology and morphology of temperaturedependent sex determination. / Exp Zool 260: 371-381.Section 4 AmphibiansCHAPTER TENAmphibiansBrad WilsonINTRODUCTION, TAXONOMY, AND NATURAL HISTORYA fascination with amphibians has gripped mankind since the firstrecorded history. It continues today through scientific discoveries ofremarkable healing and disease resistance properties of amphibian tissues, thediscovery of potential therapeutic compounds in amphibian skin, and theunderstanding of potential human health consequences to environmental altera­tion.Interest in captive amphibians over the last two decades has increased tremendouslyand the knowl­edge gained regarding the husbandry, physiology, and breedinghabits of many species has likely exceeded that of any other "exoticpet" group during this time period. Awareness of the demand for healthcare in these animals and the willingness of many clients to treat these petshas stimulated and necessitated a demand for more education by veterinariansand vet­erinary technicians.TaxonomyThe biological saying "ontogeny recapitulates phylog-eny" ismost appropriately applied to the natural history of amphibians. The life cycleof the amphibian from egg to adult (ontogeny) is the abridged version of themonumental evolutionary adaptations of amphibians (phylogeny) that enabled thevertebrates to leave water and colonize the land 350 million years ago (Wright2001e; Goin, Goin, and Zug 1978). Modern amphibians comprise more than 4,000(Wright 2001g) species that are classified into three orders based on anatomiccharacteristics. The orders are listed with the modern accepted nomenclaturefol­lowed by commonly used traditional nomenclature in parentheses: thecaecilians, Gymnophiona (Apoda); the sirens, salamanders, and newts, Caudata(Meantes and Urodela); and the frogs and toads, Anura (Salientia). See table10.1 for species commonly kept in captivity.Amphibians of the order Gymnophiona, Caecilians, are uncommonly kept aspets and even less commonly observed clinically. Originating in the eastern andwestern tropics, caecilians may be terrestrial (yellow-striped caecilian, Ichthyophiskohtaoensis) or totally aquatic (Typblonectescompressicaudd) as adults. To many, caecilians resemble snakes oroversized earth­worms. All known species are limbless with greatly reducedeyes. Some species are oviparous (egg-laying) and some are viviparous(live-bearing). All known species are carnivorous and consume various arthro­pods,annelids, or gastropods. Because of their secre­tive nature, it is likely thatmany species remain undiscovered. Longevity of captive caecilians is reportedat nine years (Goin et al. 1978).The order Caudata, tailed amphibians, consists of salamanders, newts,sirens, and amphiumas. Sirens were once classified in a separate order, Meantes(Trachystomata). The majority of species inhabit North America, with onespecies in Africa and no species in Australia or Antarctica (Goin et al. 1978,Duellman and Trueb 1994). Many species of all sub­orders are maintained aspets, though few are com­mercially available. Few species venture far fromwater or moist environs and most species require water for some portion ofreproduction or development. Some species are fully aquatic, some facultativelyaquatic, some terrestrial, and some American newts (Notophthalmusviridescens) are aquatic as larvae, terrestrial as juveniles, andaquatic again as adults. Salamanders are carnivorous as both larvae and adultsand consume various arthropods, gastropods, arach­nids, annelids, crustaceans,and other vertebrates including mammals. The longevity of salamanders is knownto be up to fifty-five years for the Japanese giant salamander (Adrias japonicus) (Goin et al. 1978).Generally, the larger species have a longer lifespan than smaller species.The order Anura, tailless amphibians, consists of frogs and toads. Thisorder represents the great major-205Table 10.1. Amphibians Commonly Kept in Captivity.Common name/ species nameOriginHabitatSize (cm)1T/H2Repro3Feed4Care5Handling concerns6GymnophionaYellow-striped, SE AsiaIchthyophiskohtoaensis713 Aquatic caecilian,SAmericaTyphlonectes spp.713CaudataCryptobranchidae (Giant salamanders)Hellbender, N AmericaCryptobranchus alleganiensis7Sirenidae (Sirens)Greater siren, Siren e N Americalacertina7Amphiumidae (Amphiumas)Amphiuma, Amphiuma  e N America means7Proteidae (Neotenic salamanders)Mudpuppy, Necturus e N Americamaculosus7Ambystomatidae (Mole salamanders)Axolotl, Ambystoma C Americamexicanum7 Tiger salamander,NAmericaAmbystoma tigrinum7 Waterdog, Ambystoma NAmericatigrinum9Plethodontidae (Lungless salamanders)Arboreal salamander, w N AmericaAniedes lugubris1011Palm salamander, Bolitoglossa spp.13Ensatina, Ensatina spp.1011C,S America w N Americafossorial, tropical  50 aquatic,tropical  to 50aquatic, temperateaquatic, temperateaquatic, temperateaquatic, temperateaquatic, tropicalterrestrial,fossorial temporaryaquatic;terrestrialterr/arbor,temperateforest terr/arbor,tropical forest terrestrial,temperateforestto 75 80to 1004020 25 20108 to 14725/mod  oviparous an,ar25152020152020mod; large  docile, sturdy;escapeviviparous  an,aroviparous  cr,ar,voviparous  ar,cr,voviparous  ar,cr,veasy; mediumdiff+; large+#docile, sturdy; escapeoccas. aggressive, sturdymod; large+  occas. aggressive, sturdymod; large+  aggressive, sturdyoviparous  ar,cr,v,g diff; large#  docile, sturdyaggressive, sturdyoviparous ar,cr,v  easy;medium22/mod  oviparous ar,an,v  easy;small   aggressive, sturdyn/aan,ar,cr,v  easy; small aggressive, sturdy14 to 17/ oviparous ar mod14 to 20/ oviparous t,ar high14 to 17/ oviparous ar modmod; smalldiff+;medium mod; smalloccas. aggressive, sturdydocile, fragiledocile, sturdy > Red salamanders, N America semiaquatic, 15 20/mod oviparous an,ar docile,   Pseudotriton spp.11   streams, forests       mod; sturdy               small     Anura                 Pipidae (Clawed frogs)                 Dwarf frog, Africa aquatic, tropical 4 25 oviparous an,ar easy; small docile, sturdy Hymenochirus                 curtipess13                 Surinam toad, Pipa S America aquatic, tropical 20 25 oviparous v,an,ar mod; large+ docile, sturdy pipas13                 African clawed frog, Africa aquatic, tropical 12 25 oviparous v,an,ar easy; docile, sturdy Xenopus laeviss13             medium   Pelobatidae (Spadefoot toads)               Asian leaf frogs, SE Asia terrestrial, to 15 20-22/ oviparous ar,v mod; docile, sturdy Megopbrys spp.13   tropical   mod     medium   Bufonidae (True toads)                 Harlequin toads, C,S America terrestrial, to 5 15-20/ oviparous ar,t diff+; docile, fragile Atelopus spp.9   montane tropical   high     medium   American toad, Bufo N America terrestrial, to 10 20/low oviparous ar,g,v easy; docile, sturdy americanus13   temperate         medium   Marine toad, Bufo C,S America terrestrial, temp/ 23 22/low oviparous ar,g,v easy; large occas. aggressive, marinus13   tropical           sturdy Asian tree toads, SE Asia terrestrial, to 10 25 to 27/ oviparous t diff; large docile, fragile to Pedostibes spp.13   tropical   high       sturdy Microhylidae (Narrow mouth toads)               Tomato frogs, Dyscophus Madagascar semiaquatic, to 10 25/mod oviparous ar easy; docile, sturdy spp.813   tropical         medium   Malaysian toad, Kaloula SE Asia terrestrial/ 7 25/high oviparous ar,t easy; docile, sturdy pulcbra*13   fossorial, tropical         medium   Dendrobatidae (Poison dart frogs)               Dendrobates, Phyllobates, C,S America terrestrial, 1.5 to 5 22 to 30/ oviparous ar,t easy to diff; occas. aggressive Epipedobates spp.1213   tropical   high     varies —see below Hylidae (Tree frogs)                 Red-eyed treefrog, C America arboreal, tropical 7 25/high oviparous ar easy; docile, sturdy Agalychnis callidryas14             medium   Green treefrog, Hyla N America arboreal, 6 25/mod oviparous ar easy; docile, sturdy cinerea13   temperate         medium   Monkey frogs, C, S America arboreal, tropical to 10 25/low oviparous ar mod; med to docile, sturdy Phyllomedusa spp.14       to mod     lg   Table 10.1. ContinuedCommon name/Size > species name Origin Habitat (cm)1 T/H2 Repro3 Feed4 Care5 Handling concerns6 Whites treefrog, Litoria Australia arboreal, desert/ 10 25/low oviparous ar easy; docile, sturdy caerulea714   forest   to mod     medium   Ranidae (True frogs)                 Mantellas, Mantella Madagascar terrestrial, 3 18 to 22/ oviparous ar,t easy; small+ docile, fragile to 13 spp.   tropical   high       sturdy American bullfrog, Rana N America semiaquatic, to 20 22/mod oviparous v,ar easy; large+ aggressive, sturdy catesbeiana13   temperate             African pyxie frog, Africa semiaquatic, to 20 25/mod oviparous v,ar easy;large+ aggressive, sturdy Pyxicephalus   temperate             adspersus13                 Eyelash frog, Solomon terrestrial, 8 25/mod oviparous ar mod; docile, sturdy Ceratobatrachus Islands tropical         medium   guentheri13                 Leptodactylidae (Tropical frogs)               Surinam horned frog, S America terrestrial, 20 25/mod oviparous v,ar diff; medium aggressive, sturdy Ceratopbrys cornuta13   tropical             Ornate horned frog, S America terrestrial, 12 25/mod oviparous v,ar easy; aggressive, sturdy Ceratopbrys ornata13   tropical         medium   Average maximum adult size.2Average day temperature/relative humidityfor adults of species or typical of genus in captivity. 3Oviparous(ovi-) = egg laying; viviparous (vivi-) = live birth.4Diet of the adult amphibian in nature listed in order ofimportance for each species: an = annelids; ar = arthropods; er - crustaceans; g = gastropods; t = termites and ants; v = vertebrates. Manyanimals will adapt to domestically raised food items.5Difficulty for captive maintenance ofwild-caught and some captive-born animals. (Generally, captive-born animalsadapt well with proper conditions.) Second value is minimum terrarium size. Easy = adapts well toterrarium; moderate = specialized feeding, temperature, housingrequired; difficult = only most experienced keepers; difft-cult+ = should only beattempted by zoological parks. Small - 10 gallonterrarium; medium = 15 to 20 gallon terrarium; large = 30 gallonterrarium; large+ = 55 gallon or specially constructed; # = mayrequire chilled water.^Typical response of patient to handling (all animals will resisthandling): Docile = will not attempt to bite, no specialdefenses. All caecilians may escape; terrarium must be well sealed. Occasionallyaggressive = may attempt to bite, but generally will not causeinjury to handler. Can bite and seriously damage or kill cage mates. Avoid skinor direct/indirect mucous membrane contact with wild-caught dart frogs and allmarine toads. Aggressive = species that will routinely bite as defense(Amphiuma) or con­ditioned feeding response (mole salamanders) or will attemptto eat any cage mates (frogs, mole salamanders). Amphiumas, pyxie frogs, andhorned frogs must be approached and handled with caution; bites from adultanimals may cut skin and may be painful. Fragile = amphibians thatmay be easily stressed, damaged, or killed by handling. Sturdy = amphibians that arenot likely damaged from responsible handling. 7Wright (2001g, 3-14).8Mattison (1987). 9Lotters (1996). 10Stebbins(1985). "Petranka (1998). 12Walls (1994). 13Obst etal. (1988). 14de Vosjoli (1996).Amphibians  209ity of all species of modern amphibians and the major­ity of captiveamphibians, A great number of species are available in the pet trade ascaptive-born animals. Frogs are to amphibians as lizards are to reptiles. Frogshave managed to adapt to and to populate many ter­restrial, arboreal, andaquatic (and even several flying or gliding) habitats on earth. Adaptation andspecial­ization of skin, diet, and reproductive strategy have all made this expansionpossible. Several species of frogs are totally aquatic and several are adaptedto estivate in the driest deserts for months or years. All adult frogs arecarnivorous and the majority of their larvae, tad­poles, are herbivorous. Sometadpoles are omnivorous and some are carnivorous. Adult frogs feed on manyinsects, crustaceans, annelids, and other vertebrates, and some species arespecialized to feed primarily on other frogs (Ceratopbrys spp,, Hemipbt-actus spp.). The knownlongevity for some species is up to thirty-six years (Goin et al. 1978).Amphibians begin development as fertilized eggs, and with most speciesthe eggs hatch into free-swim­ming gilled larvae, and then the larvaemetamorphose into adults. The post-hatching larvae depend upon a moistenvironment such as water, inside a gelatinous terrestrial egg (some speciesundergo direct develop­ment and metamorphose to adults inside the eggs), insidea brooding adaptation of the parent (Gastrotheca cornuta and Pipa pipa), orinside a uterus-like oviduct (some amphibians are live-bearing or viviparous).Not all amphibian larvae require standing water to com­plete development.Similarly, all adult amphibians do not depend on standing water to reproduce,though traditionally most amphibians do return to water both to mate and todisperse eggs. Some amphibians are entirely aquatic and cannot survive out ofwater for any extended periods of time, whereas others inhabit deserts or mayestivate for extended period (years) with no exogenous water. Completelyaquatic amphib­ians are represented in all three families. Some sala­mandersare neotenic, in which metamorphosis to the typical adult form never occurs yetthe larvae develop gonads internally and the larvae are capable ofreproduction.Though most numerous in temperate to tropical environments, amphibiansare distributed worldwide. Frogs are found among nearly every habitat on earthexcept the open ocean and Antarctica. Particularly interesting among the frogsis their colonization of harsh deserts. Adaptation for desert environments ismost widespread among the frogs of Australia as seen in both terrestrial (Arenopbrynerotunda) (Mattison 1987) and arboreal (Litoria spp.) species andamong the South African terrestrial species (Breviceps spp.).Several South American species (Atelopus spp.) are adaptedto cool elevations well over 10,000 feet (Lotters 1996) and some species ofNorth American frogs (Rana sylvatica) are known to freezesolid during hibernation and then thaw following winter to resume normalphysiology (Duellman and Trueb 1994, Mattison 1987, Stebbins 1985).The veterinary technician should be familiar with herpetologicalscientific nomenclature and common terminology. It is not uncommon thatscientific order, family, or group names of both plants and animals may bemodified for use in general conversation or popular and scientificpublications. For instance, when speaking of the three orders of amphibians,frogs and toads (Anura) are commonly called anurans. Salamanders (Caudata) arecalled caudates. In the salamanders and frogs the family names are commonlymodified when discussing several of the larger families: the mole salamanders(Ambystomatidae) are ambysto-matids, the lungless salamanders (Plethodontidae)are plethodontids, the poison dart frogs (Dendrobatidae) are dendrobatids, thetree frogs (Hylidae) are hylids, the true toads (Bufonidae) are bufonids, andso on.A great deal of this chapter focuses on frogs. This is due to the factthat frogs are, by far, the most popular and widespread amphibian group in thepet industry. Much of the medicine, anesthesia, and surgery techniques appliedto frogs are extrapolated to all amphibians. The general discussion ofamphibian medicine focuses on metamorphosed juvenile and adult amphibians witha separate general discussion of larvae. The husbandry and disorders of larvaecan differ significantly from the adults of some species.ANATOMY AND PHYSIOLOGYGeneral anatomy is similar across all three orders of amphibians and isdiscussed as applies to all amphib­ians. Anatomical specializations andclinically signifi­cant differences in anatomy are described for the threeorders. Physiology varies tremendously, even among genera and species of thesame order, and clinically significant differences are noted in the followingdiscussion.IntegumentThe evolutionary development of amphibian skin is one of the greatestadaptations that enabled verte­brates to leave the water and exist on land. Theepi­dermal layer of amphibian skin is shed routinely (ecdysis) in a mannerconsistent with that of lizards and snakes. Ecdysis may occur piecemeal orentirely,210  Chapter 10and some caecilians, frogs, and salamanders consume the shed skin—aprocess called keratophagy or derma-tophagy. The dermis layers of skin serve arespiratory function and are highly vascularized. Some caecilians possess smallscales that are embedded in the skin (Goin et al. 1978, Duellman and Trueb1994).The respiratory function of amphibian skin is par­ticularly importantfor larvae, adult caecilians, most adult salamanders, and many frogs. Severalspecies of amphibians and one family of salamanders (Plethodontidae) haveabsent or greatly reduced lungs and rely on cutaneous respiration for themajority of oxygen and carbon dioxide exchange. The hellbenders (Cryptobranchus spp.) and giantAsian salamanders (Adrias spp.), both of which are aquatic, have welldeveloped lateral skin folds which increase surface area for cutaneous gasexchange. An interesting behav­ior exhibited by Cryptobranchus spp. is a rockingmotion in which the salamander sways the body from side to side in slow movingor poorly oxygenated water, presumably to "ventilate" the skin(Duellman and Trueb 1994, Petranka 1998).The amphibian epidermis is rich with glands. Some epidermal glandsproduce secretions that moisten the skin to facilitate cutaneous respirationand some frogs (Phyllomedusa spp.) secrete waxy substances that protectagainst dehydration and dessication (Wright 2001b). Poison glands are presentin all salamanders and frogs. These are most notable among the poison dartfrogs (Dendrobatidae) of Central and South America and toads worldwide. Of allamphibians the skin secretions of Phyllobates terribilis, the golden dartfrog of Colombia, are the most toxic (Walls 1994). The Chaco Indians ofColumbia use skin secretions of three species of Phyllobates to coat blow dartsused to hunt monkeys, hence the common family name of these frogs. Of the 170species of Dendrodatidae, only P. terribilis is consideredlethal to man from simply touching the toxin. Interestingly, wild-caught dartfrogs of all species fed domestic diets in captivity and frogs born incaptivity lose the majority of their skin toxins (Daly et al. 1994).Several species of toads and salamanders possess large parotid glandsdorsally on the head, just caudal to the skull. These glands are elliptical andcommonly the site of profuse toxin excretion. Skin toxins from many frogs andtoads are dangerous to domestic animals such as dogs and cats. The author hasobserved a 20-kg Labrador Retriever suffer violent vomiting, diarrhea, andconvulsions following the accidental ingestion of a Cuban treefrog (Osteopilusseptentrio-nalis). Anecdotal reports exist of deaths in dogs and catsfollowing exposure to or ingestion of toxic secre­tions of marine toads (Bufo marinus). In general, allterrestrial frogs and toads should be considered poten­tially dangerous to dogsand cats. Other captive amphibians that should be considered toxic include theEuropean salamander (Salamandra salamandra), the American newt (Notophthalmusviridescens), and some mole salamanders (Ambystoma spp.).Many of the more toxic amphibians exhibit apose-matic coloration and areconspicuous or active by day. Animals that exhibit aposematic or warning colorsrely on a learned response of the potential predator to avoid interaction withthe particular animal or suffer distasteful or noxious stimuli. Some of the com­monlyobserved aposematically colored amphibians include the European salamander (Salamandra salamandra),thered eft phase of the American newt (Notophthalmus viridescens), red salamanders (Pseudotriton spp.), some poisondart frogs (Dendro­batidae), some harlequin frogs (Atelopus spp.), the goldenmantella (Mantella aurantiaca), and the semi­aquaticfire-bellied toads (Bombina spp.). As with some insects and snakes,mimicry in coloration occurs in several "non-toxic" species thatco-occur with more toxic species.Several species of frogs possess unique skin adapta­tions for raisingyoung. The aquatic female Surinam toad (Pipa pipa) carries eggs on herback over several months during which time the eggs invaginate into the skinand undergo direct development into juvenile frogs. Upon hatching the juvenilefrogs swim out of the holes in the skin, ending parental care. Another femaleSouth American frog, the marsupial frog (Gastrotheca spp.), possesses apouch on the dorsum in which eggs hatch into tadpoles (or undergo directdevelopment in some species) and are then released into a suitable aquatic habitat.Skeletal SystemThe skeleton of amphibians is comprised of both an endoskeleton andexoskeleton that is ossified. Exoskeleton is bone formed in the dermis thatfuses with underlying endoskeleton and is most notable in the skull ofamphibians, particularly in frogs and toads. The amphibian skeletal system hasthree func­tions: protection, locomotion, and support for terres­trialexistence. A major adaptation for locomotion on land is the development ofpelvic and pectoral girdles. These are absent in caecilians, but well developedin most salamanders and all frogs. Great variation of the appendicular skeletonexists among species of frogs and toads. In most frogs and some salamanders thehyoid bones are modified to eject the tongue for pre­hension of prey (Figures10.1, 10.2).Amphibians  211Figure 10.1. Skeletal anatomy ofa frog. (Drawing by Scott Stark.)Digestive SystemAll adult amphibians are carnivorous and have a diges­tive tract similarto that of higher carnivorous verte­brates and similar among the three ordersof amphibians. The oral cavity of salamanders and frogs is spacious andgenerally designed for capturing and swallowing whole prey items. A fleshytongue is present in most species. Aquatic salamanders have a primary fish-liketongue and aquatic frogs (Pipidae) have no tongue (Goin et al. 1978). Amphibianteeth are replaced through life when lost (Goin et al. 1978, Duellman and Trueb1994).Prehension of prey may occur by one of several modalities in amphibians:suction, hellbender (Cryptobranchus spp.) and Surinam toad (Pipa pipa); ambushor direct pounce and capture, mole salaman­ders (Ambystoma spp.) and toads (Bufo spp.); luring andcapture, horned frogs (Ceratopbrys spp.); foraging and prehension with tongue, palmsalamanders (Bolitoglossa spp.) and dart frogs (Dendrobates spp.); andscavenging, Amphiuma spp., Siren spp., and aquaticcaecilians (Typhlonectes spp.) (Helfman 1990).The esophagus, stomach, small intestine, and large intestine are similarto those of higher vertebrates. The cloaca is homologous to that of reptiles.The pancreas and gall bladder are present and aid in digestion. The liverserves to convert ammonia into nitrogenous waste products, primarily urea. Inat least one frog species, the Australian gastric brooding frogs, Rheobatracbus spp., the femaleingests the fertilized eggs into the stomach where the eggs hatch into tadpolesand then metamorphose into juvenile frogs. During the brood­ing period alldigestive secretions are stopped in these species (Duellman and Trueb 1994)(Figure 10.3).Respiratory SystemAmphibians exhibit four modalities of respiration: branchial,buccopharyngeal, cutaneous, and pulmonic (Wright 2001c). Adult salamanders usethe four modes of respiration; adult caecilians and frogs do not use thebranchial mode. In most amphibians the left and right lungs are of equal size.Some caecilians have a greatly reduced or absent left lung, as observed insnakes.Branchial or gill respiration is present in free-swimming larvae of allamphibians and in neotenic or aquatic salamanders. Those species with externalgills may exhibit varying degrees of gill development depen­dent uponenvironmental conditions such as dissolved212  Chapter 10Figure 10.2. Salamander skeletal anatomy. (Drawing by Scott Stark.)oxygen. In more stagnant oxygen-deprived environ­ments the gills arelarger to increase oxygen-absorbing surface area. In well-oxygenated water, thegills are typically smaller. Some aquatic species (Sirenidae, Proteidae,Pipidae) may rely more on buccopharyngeal and pulmonic respiration by gulpingair when oxygen content is critically low. Cutaneous respiration is dis­cussedin the Integument section.Buccopharyngeal respiration is primarily driven by air gulping inaquatic species and gular or buccal pumping in terrestrial species. Atmosphericair is pulled in through the nostrils to the nasopharynx and oral cavity bynegative pressure during buccal expan­sion and then driven out by the collapseof the gular skin. Oxygen exchange occurs through the thin-walledbuccopharyngeal capillaries. This pumping action also drives both inspiratoryand expiratory pulmonic res­piration in terrestrial amphibians. Buccopharyngealgas exchange in amphibians is analogous to that ofFigure 10.3. Visceral anatomy ofa frog. (Drawing by Scott Stark.)some freshwater air-gulping fishes such as the electric eel (Electrophoruselectricus) and the lungfishes (Protopterus spp. and Lepidosiren spp.).All terrestrial amphibians, except salamanders of Plethodontidae, whichdo not have lungs, use pul­monic respiration. Amphibian lungs are sac-like,with alveoli most well developed in the Anurans. The lungs of some aquaticamphibians serve as hydrostatic or buoyancy organs in addition to therespiratory func­tion (Wright 2001c).Vocalization is best developed in frogs, but is also observed incaecilians and salamanders of various species. Frogs are the only order ofamphibians in which anatomic vocal structures are well developed and in whichvocalization is known to serve as communication for mating, territorialdefense, and escape from predators (Duellman and Trueb 1994). Vocalization isunique for every species and is also present in aquatic species. Males are themost vocal of the sexes, but females of some species have "distresscalls" which are used when escaping predators or "release calls"to signal males when the female is unre-ceptive during opportunistic breedingcongregations.Excretory SystemThe kidney of amphibians is mesonephric and empties into a urinarybladder. The urinary bladder of someAmphibians  213amphibians may be bilobate. As in reptiles, urine is collected by theWolffian duct (mesonephric duct in amphibians, metanephric duct in reptiles)and then routed to the cloaca and not the urinary bladder. Urine passesretrograde from the cloaca into the urinary bladder (Goin et al. 1978).Nitrogenous wastes of primarily aquatic amphibi­ans are excreted asammonia, whereas many terrestrial amphibians secrete urinary wastes as urea oruric acid. This conversion of ammonia to urea and uric acid conserves water forterrestrial amphibians and reduces the toxicity of ammonia in the blood. Frogsof the genus Phyllomedusa are uricotelic, being able to convert urea to uricacid for excretion (Wright 2001c).Reproductive SystemAmphibians have paired internal gonads that are hor-monally regulated.Collecting ducts (oviducts in female) transport gametes to the cloaca wherethey are expelled from the body. Viviparous species are present in all threeorders and the larvae undergo metamor­phosis in the oviduct of the female andare born as fully functional juveniles. Fat bodies are located adja­cent to thegonads of all amphibians and are presumed to provide nutrient stores fordeveloping gametes. These bodies enlarge during non-breeding season and aregreatly diminished at the end of breeding season.The testes of frogs are collection of seminiferous tubules connected tothe mesonephric ducts by collect­ing ducts. Frogs exhibit the greatestorganizational structure of seminiferous tubules among the amphib­ians. Thetestes (and ovaries) enlarge dramatically in response to breeding season.Copulation is observed in all caecilians but only one species of frog, and fer­tilizationis internal in these species. Fertilization for all other frogs is external.Interestingly, fertilization for all but two families of salamanders(Hynobiidae and Cryptobranchidae) is internal with no copulation. Malesalamanders secrete a jellylike substance in the cloaca that encases the sperm,the spermatophore, and expel this structure during breeding. The female sala­mandercollects the spermatophore in the cloaca and fertilization occurs internally.Fertilization is internal in only a few frogs.The amphibian ovaries are located in proximity to the kidneys as seen inhigher vertebrates. Following ovulation ova are contained within a thinmembrane, the ovisac, which ruptures and releases eggs into the coelom. Eggsare funneled into the ostium of the oviduct by cilia lining the coelomicmesentery and then passed to the cloaca to be expelled into the environ­ment.The lining of the oviduct of viviparous caecilians is consumed by developinglarvae as nourishment during development. In oviparous species the oviductsserve to store or hold eggs until spawning occurs. In salamanders adiverticulum of the dorsal wall of the cloaca forms the spermatheca, whichstores collected sperm to fertilize eggs upon spawning.Amphibians, especially frogs, exhibit tremendous adaptation in parentalcare of developing eggs and larvae. These adaptations are discussed throughoutthe various sections and more specifically in the Behavior section.Cardiovascular SystemThe cardiovascular system is comprised of a three-chambered heart,arteries, veins, and lymphatics. The heart of Siren intermedia and Necturus maculosus contains aninterventricular septum, making a four-chambered heart (Goin et al. 1978). Aswith reptiles, oxygenated and deoxygenated blood mixes minimally in the commonventricle.The three orders of amphibians exhibit great varia­tion in thedevelopment of aortic arch vasculature. A prominent ventral abdominal vein ispresent in amphib­ians as in reptiles. This is the vein of choice for bloodcollection in large frogs or toads. In salamanders not capable of tail autotomy(release of the tail when stressed), blood can be sampled from the ventral tailvein as described for snakes and lizards. Many frogs can also be sampled fromthe ventral lingual plexus in the mouth (see Techniques).Lymphatics and lymphatic circulation is well devel­oped in amphibians.All blood cells and proteins except erythrocytes are found in amphibian lymph.Lymph hearts that beat synchronously and independently of the cardia controllymph circulation. Diagnostic samples may be retrieved lymph sacs, which arefound in various locations of the body. Most notable of these are pairedlymphatic sacs in the skin dorsal and caudal to the pelvis in frogs.Amphibian blood and tissue fluids have a lower osmolality (200 to250mOsm) than mammals (300mOsm) (Wright 2001c). Thus, isotonic fluids used formammals are hypertonic to amphibians and result in dehydration of the amphibianpatient with long-term exposure. Mammalian saline is 0.9% NaCl. A 0.6% NaClsolution is most appropriate for use with amphibians.Nervous SystemThe amphibian nervous system is modified from that of fish with theenlargement of the cerebral hemi­spheres and the development of more complexneural networks in the spinal cord for the innervation pecto­ral and pelviclimbs. A withdrawal response is observed214  Chapter 10in amphibians as a result of trauma such as damage to limbs and toes.Sense OrgansAmphibian eyes, though not as highly adapted as those of reptiles forcomplete terrestrial existence, are greatly modified from the eyes of mostfish. Movable eyelids and lacrimal glands to moisten the eye are among the mostnotable adaptations. The eyelids are not present in amphibian larvae, mostaquatic amphibians, and the neotenic axolotl. A third eyelid or nictitating mem­braneis present in many terrestrial frogs. It is similar to the same membrane ofdogs and cats and its closure is passive, being achieved by contraction of theretrac­tor bulbi muscle followed by withdrawal of the eye into the eye socket.A portion of the levator bulbi muscle actively controls retraction of the thirdeyelid back to its resting position.The amphibian auditory system, while anatomically and physiologicallyinteresting, has relatively little clinical significance. Jacobsons organ, thevomerona­sal organ, is present in amphibians, but is much less developed thanin snakes and lizards. This sense organ is suspected to function in foodrecognition and in plethodontid salamanders (and possibly other genera) isthought to function for pheromone detection during courtship and mating.HUSBANDRYA basic understanding of the life history requirements of the amphibianspecies in question (or extrapolated from a closely related species) is neededto gain a thor­ough history and develop a diagnostic and treatment plan foramphibians. Even among different related species of amphibians, however, theremay be dramatic diversity of environmental needs within a single genus. Thesedifferences are particularly evident among the genera of Dendrobatidae (Dendrobates,Ameerga, Ranitomeya, Excitobates, Phyllobates, Epipedobates) andthegeneraAte/opMsandMtfn£e//tf.TheDendrobatidsare a diverse and geographically widespread group occurring from sea level to2,600 m elevation; some species are terrestrial, some are entirely arboreal;some are 1.5 cm as adults, some are more than 5 cm (Walls 1994). Similarly, theAtelopids have species groups that are termed highland (2,600 to 4,500 m) orlowland (lowland species or vice-versa, the frog will fail to thrive and typicallyperish within days. Similar though less extreme environmental diversity is seenamong Mantella spp. (Staniszewski 1997).Many of the natural history related criteria for evaluating lizards (seeChapter 3) apply to amphibians. The following list highlights the morepertinent infor­mation with which the technician and clinician should befamiliar for a given species:1. Origin of thecaptive patient: Is the patient captive-born or wild-caught? For the morecommon species in captivity, know which of these are more likely caught in thewild or propagated in captivity.2. Preferredmicrohabitat: Is the patient fossorial, ter­restrial, arboreal, aquatic, orsemi-aquatic? What is the preferred air and/or water temperature of thepatient? What is the preferred humidity of the patient?3. Behavior: At whattime of day is the patient active in normal health? Does the patient exhibitseasonal behavioral patterns such as hibernation? Does the patient exhibitcertain defensive postures or behav­iors when stressed or threatened?4. Diet: What is thepatients preferred food in nature and what food items is it known to consumein captivity? What is the preferred size of food item? Is the patient anaggressive feeder that may attack or consume cage mates? At what time of day ornight does the patient feed in habitat? What is the normal feeding behavior ofthe species in question?5. Anatomy andphysiology: What is the anatomy of the normal healthy patient, including sizeor color­ation differences between sexes of a given species? Are certainphysical characteristics seasonally vari­able? Is the patient potentially toxicto cage mates?The diversity of species environmental adaptations necessitates thisknowledge of amphibians even more than among the lizards, snakes, tortoises,and terra­pins. Unfortunately, the majority of amphibian dis­eases progressrapidly or have a narrow window of treatment, making the speed of diagnosis andtreat­ment critical.The greatest progress in successfully maintaining amphibians incaptivity, particularly with the frogs, may be attributed to an understandingof the captive environment for each species. As with many reptiles, successwith captive maintenance and breeding of amphibians has improved dramaticallyin the last ten to fifteen years through the research and experimenta­tion ofzookeepers and private hobbyists.Enclosures and EnvironmentThe four basic generalized amphibian cage designs are arboreal,terrestrial, semi-aquatic, and aquatic. OnAmphibians  215occasion a mix of these designs is appropriate for some animals and eachdesign may be slightly modified to house a particular species. With each ofthese habitats, there may be dramatic variation between species with regard totemperature and humidity in any given envi­ronment. With many species in theirpermanent enclo­sure, effort is made to somewhat reproduce the naturalenvironment to reduce stress and increase adaptability. Once again, havingfundamental natural history knowledge of the patient is essential.The health of the captive amphibian may be directly proportional to the"health" of the terrarium. Certain characteristics apply to allamphibian enclosures. These include security from escape; visual and noisesecurity; refuges for hiding; substrate; and the environ­mental parameters oflighting, temperature, humidity, ventilation, and water quality.Security to prevent escape is of primary importance. The most elaborateclimate-controlled naturalistic enclosure is of no help to the dried outcarcass of an amphibian on the floor of a room. The evolutionary development oflegs has greatly improved the ability for escape by amphibians when compared tofish; some of the most escape-prone amphibians, however, are the leglesscaecilians and the sirens and amphiumas, both of which have reduced limbs. Manyfish enthusiasts can attest to similar escapes with eels, ropefish, lung-fish,and other anguiform fish species. Though many aquatic and semi-aquaticamphibians perish in the dry environment of a climate controlled room, some, ifthey find suitable moist habitat elsewhere in the room, can survive quite welloutside their intended enclosure. Barnett et al. (2001) mentions the placementof "moist oases" along the walls of such rooms to preventdes-sication in case an escape occurs. These may be plastic containers linedwith moistened moss and an adequate opening for entry.Visual, noise, and vibration security is essential for many species.With the exception of the most dominant or aggressive species (Ceratopbrys spp., Pyxicephalus spp., large Bufo spp., large Ranidaespp., some Ambystoma spp., Amphiuma spp.), manyamphibians rely on camouflage or escape as the first defense. Thus, whenthreatened, many frogs attempt escape by jumping. Most enclosures are not ofade­quate size to prevent collision with the cage walls and the collisions maystimulate further escape behavior. Similar evasion may be seen with somesalamanders and many aquatic amphibians, though salamanders typically seekretreats or subterranean refuge. Physical trauma, however, may not be assignificant as the stress created and the resultant maladaptation to a captiveenvironment without adequate cover.Visual security is provided by both internal and external cage design.Painting the external surfaces of the terrarium or applying other externalvisual barriers is helpful to prevent incessant escape attempts through thecage walls and to reduce sudden visual stimulation from movements outside theenclosure. Certain cage ornaments, accessories, and artificial or live plantsare applied inside the cage for refuge and visual security. Clean plastic pots,sections of PVC pipe, the bases of plastic soda bottles, cork bark, sticks orlogs, and rocks are all valuable as refuges. Though less natural, the benefitof plastic refuges is that they are easily cleaned or sterilized for reuse.Cork bark may be auto-claved (if an autoclave is available), though it is notrecommended to use certain detergents, ammonia, or bleach on any natural orporous cage accessories for amphibians. Soaking organic items in clean, freshwater for several hours may be required to remove cleaning agent residues.Dried hardwood leaves are an excellent renewable refuge for salamanders andsmaller frogs. It is also possible to clean these items with diluted bleachsolution prior to use.Understanding the behavior of a species in nature is helpful to propercage design. Many arboreal frogs, for example, will not usesubstrate-interfaced or many horizontally oriented refuges but instead requireverti­cally suspended flat leaves (Agalychnis spp., Hyla spp.) or horizontalbranches (Phyllomedusa spp.) for resting. Similarly, terrestrialsalamanders typically do not benefit from vertically spacious, heavily plantedter-rariums, though the terrestrial cover provided by such plantings may bebeneficial for reducing ground light­ing. Larger terrestrial amphibians such asmarine toads and mole salamanders seem particularly fond of arti­ficial refugesin a terrarium and regularly return to these areas when inactive. Aquaticcaudates such as Cryptobranchus spp. and Necturus spp. occur in fastmoving coldwater streams and require large rocks, logs, or other submergedrefuges to escape the cur­rents. Often these animals also forage for food inthese microhabitats because many food items similarly use the refuges to avoidstrong currents.Certain plants provide ideal refuges for some cau­dates and anurans.Bromeliads are an ideal tropical enclosure plant for smaller hylids, somedendrobatids, and the tropical Bolitoglossa spp. Somebromeliads, however, may have sharp defensive spines that can prove perilous tomany amphibians and their owners. Many smaller aroids (peace lilies, Spathiphyllum spp.) are ideal fortreefrogs. (Gagliardo, personal communi­cation). Large terrestrial amphibiansare best main­tained in terrariums that are sparsely planted or contain largesturdy plants. Marine toads, horned216  Chapter 10frogs, tiger salamanders, and large ranids are quite capable oftrampling and eventually killing all but the sturdiest plants in a terrarium.In similar fashion, larger aquatic amphibians (all aquatics except dwarfaquatic frogs and newts) uproot or damage planted aquatic terrariums in amatter of minutes to hours, though these species typically benefit from copiousfloating or suspended aquatic vegetation.Plants for the terrarium are selected based on utility and aestheticquality. Consideration must be given to the possibility for introduction ofharmful pesticides, fertilizers, detergents, and potential pathogens. Allplants, regardless of their origin, should be cleaned of all soil andthoroughly washed before planting. Furthermore, plants from one establishedamphibian enclosure should never be moved to another amphib­ian enclosure toreduce the risk of parasite or other disease transmission to uninfected orotherwise unex­posed animals. This must be strictly observed for plantsoriginating from any enclosures containing wild-caught amphibians. Avoid usingplants that origi­nate in regions where there are known frog popula­tionsinhabiting or contacting the plants.Basic requirements of an ideal soil-type substrate are a slowlydegradable, well drained, well aerated, slightly moisture retentive soil thatis free of pesticides, fertilizers, or other potentially toxic chemicals. Thesesoils, though all organic, contain many non-traditional components whichinclude horticultural grade char­coal, orchid bark, tree fern or palm trunkfiber, milled sphagnum, and some peat. Generally this substrate is adapted fromepiphytic orchid or tropical pitcher plant (Nepenthes spp.) soil mixesthat are designed to be well drained and aerated (Gagliardo, personal com­munication).The author has maintained several larger well-planted terrariums of dart frogswith these soil mixes for more than years with no soil changing. This soil typeis best used for dart frogs, harlequin toads, mantellas, hylids, and otherarboreal species requiring a well-planted enclosure.The major benefit derived of this soil type is for the maintenance ofplants in the enclosure. An invariable outcome of most peat based or ready-madehouseplant soil mixes in terrariums is rapid decomposition, com­paction, andinadequate aeration. As this process pro­gresses, the roots of plants die andthe plants fail to thrive. Eventually the health of the entire terrariumdeteriorates and animals fail to thrive. The bark/char­coal/peat mix requires alonger time period (two to three years) for decomposition and rarely, if ever,compacts in the terrarium. A disadvantage to the "Nepenthes mix", however,is that it cannot be used for burrowing species of amphibians. The bark, char­coal,and tree fern are all potentially abrasive to amphibian skin. This does notappear to create a problem for most small (but can be irritating to larger frogs and some salamanders.Another soil suitable for substrate is composted leaf litter that isfree of fertilizers, pesticides, or other chemicals. This is particularlyuseful for salamanders and burrowing frogs. Commercially available topsoilpreparations must be used with caution because they may contain chemicaladditives.Proper lighting of a terrarium raises many questions regarding the lightneeds of amphibians. Generally, the specific requirements of ultraviolet light(particu­larly UV-B required for the synthesis of vitamin D3) areunknown for amphibians (Barnett 1996). Histopathology studies of severalPanamanian amphib­ians (Gastrotheca cornuta, Hemiphractus fasciatus) indicate thatmetabolic bone disease occurs in these species (personal observation).Certainly, questions arise regarding the requirements of nocturnal, fosso­rial,or fully aquatic amphibians. For terrariums con­taining live plants, attemptsare made to simulate natural sunlight so that the plants will thrive. Theincidental effects of this lighting scheme on amphibi­ans may be beneficial. Aswith most terrestrial verte­brates some light is required for vision andphotoperiodic behavior.The amphibian owner should attempt to recreate the lighting scheme ofthe amphibian in nature. In general, most terrestrial salamanders and nocturnalfrogs do not require bright lighting and may avoid it altogether. A naturalmethod to reduce lighting on the cage floor is a well-planted terrarium withfull spec­trum lighting. It is not unusual for some nocturnal hylids to rest onleaves or branches that are exposed to full sun during some part of the day(Whites tree-frog, Litoria caerulea; green treefrog, Hyla cinerea). Therefore, suitablebasking sites should be provided for these species. Light fixtures are suitablyplaced above the enclosure, preferably within 46 cm (18 inches) of the cagefloor (Barnett et al. 2001). It is important to note that ultraviolet radiationdoes not penetrate plastic and glass; thus, any lids that may shield the lightshould be replaced with screen. Unfortunately, screen also diffuses thepenetration of UV radiation into an enclosure (author, personal observation).Also, when a full aquarium hood is used as lid and light source for theenclosure, a tight fit is essential to prevent escape of the inhabitants.Commercially available full-spectrum lights for terrariums are availableas fluorescent tube, coiled compact fluorescent, mercury vapor, and compactAmphibians  217halogen. Most, if not all, of the incandescent lights available foraquariums and terrariums do not produce adequate UV-B radiation despitepackaging claims. Additionally, because most incandescent bulbs produce copiousheat, they should be used with caution for amphibian enclosures. Many brands offull-spectrum lights are available for both plants and animals, each with theirown claims of benefits. To date, coiled compact fluorescent, mercury vapor, andcompact halogen lights are the best producers of UV-B radiation.Temperature, humidity, and ventilation for the ter­rarium are allinterrelated and their control and man­agement often dictates cage design morethan any other environmental parameter. As many fish hobby­ists can attest, thelarger the aquarium the easier it is to manage temperature. The same is truefor terrari­ums. This is particularly true for humidity and venti­lation.Surprising to many, amphibians as a group inhabit a wide variety of climatesfrom the equator to the Arctic Circle. Caecilians and salamanders are somewhatless adapted to extreme climates than are frogs. Thus, discussion of the moreextreme tempera­ture and humidity requirements primarily pertain to certainspecies of anurans. Some species of amphibians require seasonal cooling tostimulate ovulation and spermatogenesis for breeding. Knowledge of the spe­cificpatients natural history with regard to environ­mental parameters isessential.Enclosure temperature for many amphibian patients is controlled by roomtemperature. The great majority of amphibians can adapt to normal householdroom temperature of 25 °C to 30 °C (75 °F to 85 °F), though there are someexceptions. Most highland tropical frogs (Atelopus spp. and some Mantella spp.) as well asmost North American salamanders fail to thrive for extended periods attemperatures above 21 °C to 24 °C (70 °F to 75 °F) (Lotters 1996, Staniszewski1997, Obst et al. 1988). The Pacific giant salamander (Dicamptodonensatus), the hellbender (Cryptobran­chus alleganiensis), and the mudpuppy (Necturusmac-ulosus) may all require refrigerated water or air conditioningthroughout the year. Aquatic species such as the Surinam toad {Pipa pipa) and the Africandwarf frog (Hymenochirus spp.) require heated water with protectedsubmersible aquarium heaters.Supplemental heating the terrestrial amphibian enclosure is generallynot required, though some species of frogs and toads benefit from baskinglights or heat sources such as incandescent lights or ceramic heaters. Thesespecies include some toads, monkey frogs (Phyllomedusa spp.), and Whitestreefrogs (Litoria spp.). Most diurnal frogs (Dendrobatids,Atelopids, Mantellids) typically do not require basking areas in theterrarium. Avoid heating enclosures with hot rocks or heating elements withwhich amphibians can make direct contact to prevent dessication and thermalburns.Enclosure humidity and ventilation are somewhat inversely proportional. Thoughother factors such as temperature and amount of water in the enclosurecontribute to humidity, ventilation has the greatest and most rapid effect onincreasing or decreasing humidity. Ideally the amphibian enclosure should bewell venti­lated with appropriate humidity. A partial or full screen terrariumlid or cover is ideal for allowing evap­oration and creating ventilation.Partially occluding the screen lid increases or decreases ventilation andinversely raises or lowers humidity. For large or tall terrariums, smallventilation holes may be drilled in the cage wall and covered with screen toallow ventila­tion of the otherwise stagnant lower reaches of the enclosure. Asmall fan may be placed outside the roof of the enclosure to create cross ventilationfrom these lower air intake ports.Most terrestrial amphibians benefit from a humidity gradient in theterrarium. This gradient is created by shelters in the terrarium, additionalventilation to por­tions of the terrarium, and with basking sites as describedwith lighting. Small depressions, pools, or streams of water may be created inthe terrarium with pond liner or plant watering trays. For small frogs,particularly for dendrobatids and mantellids, it is imperative that even thesmallest water reservoir have multiple escape routes. Many small frogs areincapable of swimming and will drown in even one centimeter of water. Manysalamanders are capable of semi­aquatic life and generally can withstandsubmersion for longer periods. Placement of limbs, plants, raised gravel, orother cage accessories within or around the water ensures the ability forescape. Similarly, the sides of water enclosures for terrestrial amphibiansshould have tapered ramps in all directions for small amphib­ians to escape thewater.Moving water in the enclosure is also helpful to increase both humidityand to a lesser extent ventila­tion. Small waterfalls, humidifiers, orvaporizers may be used for this purpose. Transfer of vaporized air is achievedby connecting an appropriate size PVC pipe from the vaporizer outflow into theenclosure at the desired location. Connecting the vaporizer to an auto­matictimer is helpful to create several periodic Hust­ings per day. Themisting effect in the terrarium can be quite dramatic. Humidifiers andvaporizers must be cleaned weekly to prevent the growth of potential pathogenicorganisms in the water reservoir. Soaking218  Chapter 10with a dilute bleach solution (lfl oz or 30 ml in lqt or 946 ml water)for 15 minutes and then thorough rinsing is sufficient for disinfecting(Barnett et al. 2001).Water for the amphibian enclosure should be free of potential pathogensand all treatment chemicals. Aged tap water (allowed to ventilate in acontainer for twenty-four hours) in many cases is the best water for theterrarium (Barnett et al. 2001). Alternatively, carbon filtered water may beused, though this water treatment may result in developmental abnormalities oftadpoles. Water moving in the terrarium over soil, gravel, or charcoal willgenerally be filtered biologi­cally. Water that is stationary in containersshould be changed as often as possible. Many terrestrial amphib­ians defecatein these water bowls and bacterial or fungal growth in these containers may berapid. Cleaning the water bowls in a dilute bleach solution as described forvaporizer reservoirs is recommended at least weekly.ENCLOSURE DESIGN The Terrestrial EnclosureBy employing the general principles of security and environmentalparameters, design of the amphibian enclosure, based on the species, isrelatively straight­forward and dictated by practicality. With the excep­tionof temporary housing or quarantine, the smallest recommended amphibianenclosure is a 10-gallon aquarium. Though there is no maximum size limit of aterrarium, access for cleaning, visualization, and environmental control mustall be considered.An appropriate substrate is most important for establishing awell-balanced naturalistic arboreal, ter­restrial, or semi-aquatic terrariumand the soil compo­sition is quite variable depending upon the species ofamphibians and plants contained within. The type of soil or gravel, however, isonly one part of establishing a suitable amphibian substrate. Proper design ofthe cage floor-substrate interface is crucial for maintaining a long lastingplanted or naturalistic terrarium. Ideally the soil mix should be elevatedabove the cage floor to allow for water and airflow through the soil and thedevelopment of a moisture gradient within the soil and terrarium.Elevation of the soil above the cage floor is achieved by one of severalmethods. Wright (2001e) uses a standard cage design at National Aquarium inBaltimore (NAIB) by creating a raised platform or false floor of overheadfluorescent light panels (egg crate) cut to fit the tank floor and then raised2 cm above the true cage floor by pilings cut from PVC pipe (Barnett et al.2001). This false floor is then overlaid with window screen or horticulturalshade cloth and then covered by 1 to 2 cm of gravel and then the sheet mossdirectly above the gravel. In one corner of the enclo­sure a 2.5-cm diameterclear plastic tube is placed vertically through the false floor extending tojust below the roof of the cage. This tube allows siphoning of the cage floorwith a separate smaller siphon tube passed to the bottom of the cage. Anoptional but highly recommended bulkhead and spigot may be placed through adrilled hole in the cage floor to allow drainage and replace the siphon tube.The author has used a modified version of this design developed by RonGagliardo at Atlanta Botanical Garden with great success. The egg crate falsefloor is typically inexpensive, but when using standard fish aquariums,prefabricated under-gravel filters (the economy models) are made to fit thesize of the tank and come complete with siphon tubes. One or more of thesesiphon tubes may be used as access for siphon drainage of the cage floor.Additionally, an alternative to the use of aquarium gravel between the filter plateand the soil is to use washed large or medium horticul­tural grade charcoalthat is commonly available for orchids or other special planting mixes. Thebenefits of the charcoal are lighter weight (especially for large enclosures)and the gradual filtration of organic and inorganic compounds from the waterand soil. The benefit of gravel is the large surface area for biologicfiltration that likely also occurs with the charcoal. Charcoal has been used asboth an enclosure base layer and as a component of custom mixed terrarium soilsby the Atlanta Botanical Garden for more than years with no known adverseeffects on various species of frogs.For a planted terrarium a soil depth of at least 5 cm is recommended.Over time some settling of the soil will occur. Plants are added bare root (nosoil on the roots) to the soil mix and lightly watered to settle thesurrounding soil. Generally plants smaller than the eventual desired size areplanted and allowed to grow in the terrarium. Plants in an amphibian terrariumshould never be fertilized. Theoretically, soil decom­position, animal feces,and microbes provide all the nutrients necessary for the growth terrariumplants. It is common that many suitable plants soon outgrow the enclosure andrequire routine trimming.The water level of the terrestrial terrarium is main­tained to achievedesired humidity and fill pools or streams contained within. Plumbing for wateracces­sories may be achieved through drilled holes or siphon tubes through thelid of the terrarium. Water pumps, moving part mechanical devices, andelectrical cordsAmphibians  219should never be inside the terrarium proper. These may be routed throughsealed conduits or contained outside the terrarium entirely. Similarly, outflowsiphon hoses must be fully protected from cage inhab­itants and preferably arelocated beneath the false floor of the enclosure.The Aquatic EnclosureThe aquatic enclosure for many obligate aquatic or facultative aquaticamphibians is somewhat similar to the basic tropical fish or goldfish aquarium.Large aquatic amphibians such as Amphiuma spp., large sirens,and Cryptobranchus spp. are best housed in a 55-gallon or larger aquarium.CryptobranchusandNecturusspp.both require chilled water with very high filtration. These animals should notbe kept in captivity without properly providing for exact water qualityconditions. One requirement for aquatic amphibians is sufficient access to thewater surface to breathe air. Because a majority of aquatic amphibians arerelatively large and somewhat active, all refuges and ornaments must be securein their placement. Aquarium heaters (if required) should be contained within ashroud such as PVC or other durable plastic into which numerous holes or slitsare drilled to allow water movement over the element and proper heatdissipation. This is to prevent the accidental breaking of glass or ceramicheating elements. The lid must be tight fitting and pref­erably latched toprevent escape. With a swimming start, many larger aquatic amphibians arecapable of opening lids to a standard aquarium hood.Some form of water flow is desired for most aquatic amphibians, thoughfrogs such as Pipa spp., Xenopus spp., and Hymenochirus spp. adapt well tostill water. Cleanliness of the terrarium is essential and necessi­tates sometype of filtration system. Under-gravel fil­tration as provided for a fishaquarium is ideal for most aquatic amphibians. Those species requiring highwater flow typically require a canister filter or other high flow rate externalwater pump and/or filter. Most temperate aquatic amphibians require no supplemen­talheating and adapt well to room temperatures during the entire year. Tropicalspecies are likely to require some supplemental heating if room tempera­turesfall below 72 °F to 75 °F.AMPHIBIAN-ENVIRONMENT INTERACTIONSeveral common problems can be avoided in captive amphibians with apractical approach to cage design. First, the substrate and cage accessoriesshould be appropriate so they do not physically injure the animal. Thisincludes even "natural" elements such as plants. Sharp spines oncertain bromeliads or other plants can be lethal to frogs. Certain plants aretoxic to amphib­ians. The toxicity is not necessarily from direct contact, butoccurs secondary to ingestion by food items such as crickets or other insects.This is mostly a concern with the introduction of field-collected insects. Forexample, some plant-sucking insects such as aphids can feed on toxic plants(such as milkweeds, Asclepias spp.) and not become distasteful to thesmaller amphib­ians. In the case of milkweeds, the toxicity usually results indeath of the animal.Substrate ingestion is a major problem for captive amphibians. Thesubstrate should be either too large to ingest or small enough that ingestedparticles are passed through the digestive tract. This may require modifyingthe substrate in a particular enclosure as the amphibian pet grows.Almost paradoxically, water in the terrestrial enclo­sure can result infatalities of some amphibians. Small terrestrial frogs (mantellids,dendrobatids, and atelop-ids) are incapable of swimming or will exhaust veryeasily in water. If a water enclosure is located in the corner of a terrestrialterrarium with no escape pos­sibility against the glass, death of some cageinhabit­ants from drowning is a certainty. Toadequately maintain these species in captivity, standing water is optional orcan be provided in the form of a petri dish or other shallow container.Unfortunately, to success­fully breed both Mantella and Atelopus spp., some form ofmoving or standing water is usually required in the enclosure.Assume that any opening to the outside of the cage will be used forescape. The lid or covering for the enclosure must be tight fitting orcompletely sealed. Even strictly terrestrial frogs are capable of limitedclimbing and jumping to reach the top of the cage. Some salamanders are alsocapable of climbing glass or plastic.AMPHIBIAN-AMPHIBIAN INTERACTIONA common question of many amphibian enthusiasts is "Can differentspecies be housed together?" The safe answer to the question is"No." Nevertheless, with experience and thorough knowledge of thespecies in question, many species that co-occur in nature may be housedcommunally with proper cage design.The ultimate rule of housing multiple species (or even the same speciesfrom different sources) is that220  Chapter 10wild-caught individuals from different sources should never, ever behoused together. Clinically, amphibians (particularly frogs) appear to be morecommonly para­sitized than reptiles, even among captive-born indi­viduals.Exposure of naive animals to certain parasites or bacteria and fungi can resultin disaster for an entire collection. An emerging disease concern forterrestrial amphibian owners is the chytrid (Chytridiomycosis) fungus. Thispathogenic fungus is suspected to be at least one of the causes of worldwidemortality among wild populations of amphibians and it has been iden­tified aswidespread and easily transmitted among captive amphibians (see CommonDisorders) (Berger et al. 1998, Daszak et al. 2000, Morell 1999).Aside from contagious disease is the question of compatibility. For theaverage amphibian owner, large frogs and salamanders (Ceratopbrys,Pyxicepbalus, large Rana, large Bufo, and Ambystoma) are best housedsingly in an enclosure. All large amphibians are typically conditioned to feedon anything that is small enough to fit in their mouth. Ambystomatids in captiv­ityare particularly conditioned to bite anything that touches the flanks, evenanimals larger than they are. The author has witnessed numerous leg amputationsand lacerations of frogs and other salamanders that were temporarily housedwith a tiger salamander of equal size. Frogs such as Ceratobatracbusguentberi, Ceratopbrys, Hemiphractus, Megophrys, and Pyxicep­balus spp. prey on otherfrog species and other verte­brates as a substantial part of their diet andtherefore are generally unsuited for cohabitation with any other amphibians.Toxicity between different species of amphibians is also a concern, evenamong the same family of frogs. Many anecdotal reports exist and the author haswit­nessed that other amphibians (and other Rana spp.) enclosed withwood frogs (Rana sylvatica) die rapidly,leaving only the wood frogs alive (Duellman and Trueb 1994, Mattison 1987). Theexact nature of this sus­pected toxicity is not fully known. It is possiblethat similar toxicity exists between different species of wild-collected dartfrogs, though there is no observed toxicity among captive individuals.QUARANTINEThe role of quarantine for new amphibians in a col­lection cannot beoveremphasized. Segregation of new arrivals is most important for those animalsthat will be introduced into multi-species displays. The quaran­tine procedurefor amphibians, however, is more designed to protect the individual animal fromoccult disease that may manifest itself some time after arrival into the newenclosure.The quarantine enclosure is quite basic. A 10-gallon glass aquarium orplastic sweater box with ventilation holes is ideal for quarantine of mostterrestrial amphib­ians. Larger aquatic amphibians should be maintained in anappropriately sized enclosure. For terrestrial amphibians the cage substrateshould be non-bleached paper towel and possibly a hide box or other dispos­ablecage ornament to provide security. The quaran­tine enclosure should be locatedin a low traffic area of the room where the inhabitants may be monitored foractivity from a distance. If necessary the sides of the enclosure may bepainted or covered with paper to provide visual security. If possible a feedingstation should be provided in the form of a petri dish or shallow dish so thatthe feeding response can be moni­tored. Arboreal frogs and salamanders can bequaran­tined similarly with the addition of horizontal branches for perching.If forced to remain on the cage floor, arboreal frogs may become stressed andfail to acclimate.A fundamental purpose of quarantine is the collec­tion of fecal materialfor analysis. This should be per­formed as soon as the first sample isavailable. Subsequent fecal samples should be examined every three to fivedays, depending on availability, and then rechecked every two weeks following anegative or "clean" sample. A final recheck two months after anegative sample is also advised (Wright and Whitaker 2001c).The quarantine period should be at least thirty days following anegative fecal sample for apparently healthy individuals (Wright and Whitaker2001c). Wild-collected amphibians, despite the status of fecal testing, shouldbe quarantined for sixty days, Under no circumstances should wild-collectedamphibians be introduced into an enclosure with any other animals. Despiteantiparasiticide, antibiotic, and antifungal treatment it is possible for theseindividuals to carry undetected infectious diseases and later transmit them toother naive animals.It is not uncommon to prophylactically treat new amphibian arrivals forgastrointestinal parasites and some cutaneous fungi. Though this practice is nosub­stitute for fecal examination, it can be effective in eliminating orreducing the burden of some infectious diseases. Unfortunately, there is a riskof adverse side effects with this practice. The author has observed the deathof long-term captive imported frogs following deworming with fenbendazole atrecommended doses. The animals were four green and black poison dart frogs, Dendrobatesauratus, which were confirmedAmphibians  221infected with various nematodes including great numbers of lungworms, Rhabdias spp. None of theanimals had exhibited clinical disease and were breed­ing in captivity.Following a single oral treatment with fenbendazole at 100 mg/kg two of thefour frogs imme­diately stopped eating and subsequently died within five days.A third stopped feeding and then resumed feeding and survived. The fourth frogwas not adversely affected. Both surviving frogs continued to shed Rhabdias spp. larvae in thefeces following treatment, yet the numbers of larvae were reduced. The authorhas not observed this phenomenon in other similarly infected Dendrobates spp. or Mantella spp.A common prophylactic antiparasite regimen includes administeringfenbendazole orally at lOOmg/ kg followed by ivermectin topically at 0.2 mg/kg(Wright and Whitaker 2001c). Repeating the treat­ment in three weeks isrecommended, along with rechecking a fecal sample prior to treatment. Theauthor has observed that ivermectin treatment may be fatal is some speciesincluding Central American glass frogs (Centrolenidae) and the lemur leaf frog (Hylomantis lemur).Thefrog deaths were observed in frogs that were infected with Rhabdias spp. Ongoingresearch and personal observations on the treatment of Rhabdias spp. infections inmultiple Central American amphibian species indicates that a complete"cure" or elimination of Rhabidias spp. infection maynot be possible in captive amphibians.Record keeping of feeding and treatments is essen­tial. The clientshould record all observations of activ­ity, feeding response, food itemsconsumed, and other pertinent behavior. Weekly weights are also beneficial forhealthy individuals when this can be performed accurately and in a stress-freemanner.NUTRITIONIf the nutritional needs for amphibians were as simple as tossing a fewcrickets into the enclosure from time to time, they would all be more popularpets. Instead, the nutritional maintenance for many captive amphib­ians is aslabor intensive (or more so) as that of insec­tivorous lizards and thenutritional demands of amphibians are more a consequence of the animals beingsuch generalists rather than being specialists on one food item. The variety offood items consumed in the wild likely results in a tremendously variedvitamin, mineral, amino acid, and fatty acid intake that is not duplicated withcaptive diets. Very little scientific data exists regarding the exact diet andits nutritional com­position for amphibians in the wild. Unfortunately, much islearned about the proper or improper nutri­tion of amphibians throughhistopathology.There is great variability in the feeding preferences of different lifestages of metamorphosed amphibians, and this variability has been observed inthose animals that have been successfully bred over several genera­tions. Forinstance, froglets of the golden mantella (Mantellaaurantiaca) are no more than 8 mm in length at metamorphosis. To a frog this small, even the small­estof domestic fruit flies is too large to eat. These froglets must be raised forseveral weeks on small insects called springtails (order Collembola) until theymay be fed small fruitflies. Adult mantellas, however, are quite ravenous andwill eat crickets that are nearly 20% of their body size.The feeding method of amphibians is also some­what important whenselecting food items. All frogs should be considered food gulpers; aftercapturing the prey item it is swallowed whole with little to no chewing. Incontrast, large salamanders and especially aquatic amphibians (Necturus,Amphiuma, Siren, and Cryptobranchus spp.) all exhibit somechewing motions when feeding. This is especially observed in sirens andamphiumas that may repeatedly move food items in and out of the mouth whilecrushing them. Choosing appropriate food items, or more impor­tantly, avoidingimproper food items for certain species, is important.Another important point to remember regarding most terrestrialamphibians is that they are sight feeders. Generally moving food is preferredover sta­tionary food. Some larger frogs, toads, and salaman­ders may beconditioned to feed on stationary pre-killed or frozen and thawed food items,but this is more the exception than the rule. Thus, when approaching thedilemma of a non-feeding amphibian, always consider the type and size of foodoffered.Perhaps the most important consideration when feeding amphibians is thetiming of feeding. The client must be fully informed of the feeding habits ofthe species in question. Nearly all terrestrial salamanders and many tree frogsare nocturnal and will only feed at night. Many of the larger nocturnal frogsand toads, being opportunists, will feed any time in captivity. The tigersalamander, Ambystoma tigrinum, though noc­turnalin its native habitat, will readily adapt to day­light feeding. Night feeingmay make the monitoring of food consumption difficult with some amphibians. Fornewly established pets, encourage the client to observe the feeding habits witha flashlight or red light illumination if necessary.To compensate for the known vitamin andmineral imbalances in food items and for suspected deficiencies222 Chapter10in amino acids, many hobbyists apply several com­mercially availablevitamin/mineral powders (called dusting) to the food items prior to feeding.The process of dusting food items is discussed in Nutrition of the chapter onlizards. Additionally, food products specifi­cally for the prey items toconsume are designed to enrich the prey item prior to feeding to the amphibianpet. This process is called "gut-loading."Based on known dietary disorders, several basic provisions must be madefor captive amphibians. Calcium and phosphorous (Ca:P) should be provided in aratio of 1:1 to 2:1 to prevent several nutritional diseases (Wright 2001d,Wright and Whitaker 2001a, Donoghue and Langenberg 1996). Additionally, vitaminD3 is supplemented in the diet or produced endogenously by theamphibian when exposed to the appropriate quality and quantity of ultravioletlight. A ratio that is too low in calcium or too high in phos­phorous mayresult in metabolic bone disease (MBD). A ratio too high in calcium or vitaminD3 may con­tribute to hypervitaminosis D and secondary renal failure(Wright and Whitaker 2001b). Powdered sup­plements are available from Rep-Cal(Los Gatos, CA; www.repcal.com)and Nekton (Clearwater, FL; www. nekton.de).Neonatal and young amphibians appear to be most affected by MBD becauseof increased calcium demand by growing bones. The frequency for calcium supple­mentationof these animals is increased compared to that of adults. Neonatal or young,growing amphibi­ans may receive calcium and vitamin D3 supplementa­tiontwice weekly when fed daily and most adult amphibians should receive calciumsupplemented food items once weekly or less often. Larger amphibians fed wholeanimal vertebrate diets such as thawed frozen rats or mice likely do notrequire supplemental calcium in the diet.Aquatic or semi-aquatic amphibians fed diets com­prised solely of fishmay develop thiamine (vitamin Bj) deficiency (Wright and Whitaker 2001b,Donoghue and Langenberg 1996). This disorder is the result of high levels ofthiaminase in the food items that inacti­vates dietary and endogenouslyproduced thiamine in the amphibian. Several susceptible species include aquaticsalamanders, aquatic caecilians, horned frogs (Ceratopbrys spp.), Africanbullfrogs (Pyxicepbalus spp.), and other semi-aquatic frogs.FOOD ITEMSMost clients who maintain breeding colonies or large colonies ofamphibians are required to raise their own food items because the expense ofpurchasing food items can be excessive. The simplest factor dictating thefeeding of captive amphibians is the size of the animal and the size of thefood item. The standard diet for most larger salamanders and frogs is cricketsand the diet of choice for smaller amphibians is fruit flies. Somewild-collected insects such as termites may be available seasonally or throughoutthe year in warmer climates.Domestic or gray crickets (Acheta domestica) of various sizesare the standard diet for most medium to large terrestrial amphibians. Cricketsare commercially available in sizes ranging from 1/16 inch (pinheads) in lengthto 1 inch (adults) from pet shops and mail order from a variety of sources. TheCa:P for crickets is 0.2:2.6 (Donoghue and Langenberg 1996). Periodic dustingof crickets with calcium and vitamin D3 powders is recommended forall amphibians.A variety of specialized cricket diets are available to enrich cricketswith nutrients. The efficacy of these products is debatable. Generations offrogs that have been fed crickets raised on fresh vegetables and fruits such assquash, greens, and oranges have reproduced and lived for five or more yearswith no apparent health abnormalities to themselves or offspring.Another cultured food item for medium to large amphibians is mealworms.The mealworm is actually larvae of the beetle, Tenebrio molitor, which may be culturedeasily in one of several different grain meals supplemented with cut pieces ofapple or vegetable for moisture. Because the adult beetles are required toreproduce for new mealworms, a tight fitting, venti­lated lid is required tomaintain the culture. Mealworms are generally a poor food choice for amphibiansbecause of the hard exoskeleton. Though the softer-bodied, newly molted larvaeare acceptable, the author has witnessed the unexplained deaths of severalfrogs and lizards following the feeding of mealworms. Necropsy on severallizards has revealed peritoneal abscessation that was attributed togastrointestinal perforation from the hard body parts or possibly chewing ofthe larvae. Because mealworms do not provide an improved Ca:P ratio (0.1:1.2)(Donoghue and Langenberg 1996) as compared to crickets, their use as a primaryfood item for most amphibians is not recommended.Similarly, most beetles and other large insects with hard exoskeletonsare not a good food source for amphibians. An exception might be made for largefrogs and especially toads, which may be observed to nearly consume theirweight in beetles while feeding in habitat during summer months. Largeterrestrial salamanders and aquatic amphiumas and sirens areAmphibians  223generally capable of crushing these insects following capture andtherefore may adequately digest them and have minimal risk of gastrointestinalinjury.The flour beetle, Trilobium spp., which is arelative of the larger Tenebrio spp., is a smaller beetle that can safely befed to small frogs. These beetles are approxi­mately 5 mm in length as adultswith comparable small larvae. They are raised and harvested similar to Tenebrio spp., though theadult beetle is fed as com­monly as the larvae.Wingless or flightless fruit flies are the standard diet for smallerfrogs and salamanders, particularly for poison dart frogs, mantellas, harlequinfrogs, and neo­natal amphibians. Two species of flies, Drosophilamelanogaster (the small vestigial or wingless fruit fly) and Drosophila hydei (the largerflightless fruit fly), are commercially available. Fruit flies are easily cul­turedby the client and may be the sole food source for many captive amphibians. Theyare cultured in reus­able canning jars or disposable plastic cups, both ofwhich are sealed with a permeable (but escape-proof) ventilated lid. Fruit flygrowing media is available from Carolina Biological Supply Co. (Burlington, NC;www.carolina.com)or can be made from instant potato flakes, brewers yeast, and a moldinhibitor. Fruit flies are typically dusted with powdered supple­ments as withcrickets.Another small food item that is relished by nearly all amphibians is thetermite. In warmer climates, such as the southeastern U.S. coastal plain,termites can be collected any time of year. There are methods of"cul-turing" termites in the wild that involve burying coffee canspunctured with drain holes in the ground and filling them with rolledcardboard. Unfortunately, the risk of infestation to homes and other woodenstruc­tures is great, so this practice should not be recom­mended to clients.Nevertheless, wild collected termites do not appear to cause harm to captiveamphibians and certain nutrients not otherwise available to these animals maybe provided. Similarly, parasites or other toxins ingested by the termitescould put captive animals at risk for disease.An important but often overlooked food item for small frogs isspringtails or leafhoppers, of the insect order Collembola. These very small(containing soil. They feed on detritus and decaying plant material and can beeasily cultured to feed neo­natal or very small frogs and salamanders. Aplastic container such as a margarine container or plastic shoebox filled withapproximately 1 to 2 inches of potting soil is ideal. The soil is slightlymoistened and a few pinches of fish food flakes are sprinkled on the surface ofthe soil. The springtails may be introduced from a decaying leaf from outdoorsor from a previ­ously existing culture. A method for easily removing thespringtails is to place a small block (10 cm x 5 cm x x cm) of horticulturaltree fern fiber on the soil surface, then remove and gently tap the block toremove springtails when feeding is desired.The only acceptable vertebrate food sources for captive amphibians arefish and thawed frozen pink mice or rats. Large frogs, toads, and salamanderswith conditioned feeding responses usually accept these items when offered byforceps, or in the case of fish when offered in a shallow dish. These largeramphib­ians generally accept other vertebrate prey such as other amphibians,reptiles, large beetles, and grasshop­pers. The client should carefullyconsider the health risk to the amphibian before feeding such items. The riskof parasitism with endoparasites or bacterial or fungal infections is great. Ofparamount concern must be the Chytridiomycosis fungus when offering anyamphibians. This disease is extremely serious for amphibians and should beviewed on the level of the immunodeficiency viruses that affect cats and humanswhen considering prevention.Aquatic amphibians consume a wide variety of food items. Earthworms andfish are the standard diets with other arthropods and some frozen foodsoccasionally accepted. Ideally the food should be cultured or pur­chased ascultured rather than collected from the wild. This reduces the risk ofintroducing infectious diseases into the enclosure.Certain amphibians, particularly several frog species, are specialistsin their feeding choices and may be difficult to feed in captivity. The bizarrecasque-headed tree frogs, Hemiphractus spp., of SouthAmerica and several species of horned frogs, Ceratopbrys spp., are knownfrog-eating specialists (Mattison 1987, Obst et al. 1988). It may be necessaryto feed live frogs to these species while trying to train them to eat variousinvertebrate or vertebrate prey items. Another finicky large frog (8 to 10cm)is the climbing toad, Pedostibes hosei, of southeast Asia.This frog is known to specialize in ants and termites and may not acceptcrickets or other large inverte­brates in captivity (Obst et al. 1988). Thisfrog may be transitioned to a cricket-only diet by feeding smaller sizecrickets or beetles. Among aquatic amphibians the hellbenders, Cryptobranchus spp., as adultstypically feed only on crayfish and must be coaxed to accept other aquatic fooditems if captive.Finally, many clients may be misinformed regarding the feeding ofmanufactured pelleted diets. It is unrea­sonable to expect any terrestrialamphibians to eat224  Chapter 10non-moving prepared foods. It is more likely, though not common, thataquatic amphibians will readily accept these diets. Salamanders and newts, morethan frogs, will adapt to these diets, but they are rarely substitutes for livefoods. Clients should be informed about this fact prior to purchasing amphibianpets. For some the cost of live foods or the time to culture them may not meettheir expectations for proper mainte­nance of amphibian pets. One exception ofnote is the fact that marine toads {Bufo marinus) have been observedand videotaped eating dry dog food from outdoor food bowls in south Florida.So, one can never underestimate the resourcefulness of these animals when itcomes to adaptation.COMMON DISORDERSAmphibian health disorders arise from infectious bac­terial, fungal, andparasitic etiologies to trauma, nutri­tional, and toxic diseases. Severaldiseases such as metabolic bone disease (MBD) and cutaneous bacterial infection(red leg) are well documented in veterinary scientific and popular literature.Many specific infec­tious and metabolic diseases, however, are relativelyunknown.IntegumentAs with snakes and lizards a very common skin disor­der seen in frogs isrostral abrasion. This is particularly common in wild-collected animals, but isjust as pos­sible to develop in any species transported in small containers.The common etiology is trauma from escape attempts through clear plastic lids,screens, or glass enclosures. Prevention of this disorder is enhanced withopaque transport containers and packing of the amphibian with moss or anothersoft substrate to reduce movement within the container.The primary concern with rostral abrasions is sec­ondary infections fromopportunistic or pathogenic bacteria and fungus. If the abrasion is clean andshowing no signs of erosion, then no treatment is indicated. For chronic ormore extensive abrasions in which active erosion of the skin or exposure ofunder­lying bone is present, treatment with topical antibiot­ics, includingophthalmic solutions, is indicated. Gentamicin or triple antibiotic solutionsare applied once or twice daily. Silver sulfadiazine cream is also efficaciousto treat fungal elements in addition to bacteria.Active lesions associated with erosive dermatitis or osteolysis requireaggressive diagnostic and therapeu­tic intervention. Bacterial culture andsensitivity, and cytology if possible, from an impression smear or tissuesample in formalin may be submitted. In addi­tion to topical therapy systemicantibiotics are indi­cated. Enrofloxacin at a dose of 5 to 10 mg/kg PO or TOevery twenty-four hours for seven days (Taylor 2001) is recommended pendingculture results. The client must be vigilant of the patient with regard tohealing of these lesions. Amphibians with substantial rostral abrasions shouldbe maintained in a quarantine enclosure for cleanliness and close observation.Traumatic injuries to limbs are similar to rostral abrasions. Trauma mayoccur secondary to accidents with enclosure lids closing on legs, and bitewounds from cage mates are possible with some species. These wounds typicallyrequire aggressive antibiotic therapy initially rather than just observation.If severe trauma to underlying bone is suspected, amputation is recom­mendedearly in treatment to prevent the development of systemic disease.Bacterial skin infections are common in amphibians and may present asdiscolorations, erosions, abscesses, and ulcerations. Bacterial dermatitis maybe difficult to diagnose on visual inspection alone. Many infec­tions are theresult of immunosuppression from a number of factors including improperhusbandry, inadequate diet, or the stress of shipping. The resultant infectiousagent may arise from the patients environ­ment or from an apparentlyunaffected cage mate.The diagnostic test of choice for any cutaneous lesion is bacterialculture and sensitivity followed by histopathology of affected tissue ifpossible. Pending the response to empiric antibiotic therapy, biopsy may berequired. Unfortunately, the risk of septicemia from a number of bacterialetiologic agents necessitates the initiation of treatment prior to receivingtest results. The commonly referenced "red-leg disease" of frogs isactually the result of hyperemia secondary to septice­mia rather than simplycutaneous disease. If not treated rapidly and appropriately this syndromecarries a poor prognosis for recovery.Systemic enrofloxacin is initiated for seven days for the non-septicemiccutaneous disease. For the septice­mic patient, a water bath of 0.6% saline toachieve hydration is the initial therapy (Taylor 2001). Antibiotic baths withtetracyclines, semisynthetic peni­cillins (SSP), and aminoglycosides may beindicated.Many bacteria are implicated in amphibian skin disease and septicemia. Alarge number of these are Gram-negative rods including the widely reported andwell known Aeromonas spp. and Pseudomonas spp. Mycobacterium spp. are alsoimplicated in various disease syndromes in amphibians, particularly skindisease. Diagnosis is very difficult pre-mortem becauseAmphibians  225the bacteria is difficult to culture. Isolation and neu­tralization ofaffected individuals is recommended because there is no known treatment for Mycobacterium infection.Fungal infections are a concern for amphibians. Most notable among theseis Chytridiomycosis, "chytrid," caused by Batrachochytriumdendrobatidis. The initial clinical sign of this fungal dermatitis isan increased rate of skin shedding with possible associ­ated dermal lesionssuch as pale skin. It is not known how many different species of amphibians aresuscep­tible to this fungus, but confirmed cases of chytrid have been reportedfrom all continents containing amphibians.Patients are diagnosed with chytridiomycosis by presence of the organismin shed skin or in formalin fixed skin. Diagnosed cases or prophylactictreatment of suspected infected animals is performed with a bath ofitraconazole. A 1% itraconazole stock solution in methylcellulose is diluted to0.01% in 0.6% NaCl. Treatment consists of a five-minute bath once daily for tendays (Taylor 2001). Resolution of clinical signs is rapid if treatment isinitiated early.Ectoparasites are uncommon among amphibians and are clinically mostprevalent among toads. Treatment consists of ivermectin at 0.4 mg/kg PO or TOgiven once weekly for at least four weeks (Poynton and Whitaker 2001). Someamphibian species have shown sensitivity to higher doses of ivermectin (2mg/kg) (Poynton and Whitaker 2001, Klingenberg 1993).Finally, a multisystemic disease most notable in the skin is bloating oredema syndrome. This disease process has several possible etiologies, the mostnotable of which is osmotic imbalance secondary to sepsis or toxemia. Otherpossible causes include renal disease or failure, heart disease, metabolic bonedisease, and environmental factors. Cases in which an individual animal isaffected may be challenging to diagnose. For cases in which multiple animals inan enclosure are affected, environmental causes and infectious disease are mostlikely. Prognosis may be fair with a diagnosis and rapid treatment. Often, theinciting cause remains unnoticed for some time prior to the onset of clinicalsigns and the underlying disease progresses beyond the possibility of recovery.Skeletal SystemThough not as common as in lizards, MBD follows the same clinical courseas in reptiles. Juvenile or rapidly growing individuals are most susceptible.The patho­physiology of MBD is discussed in the chapter on lizards. An unknownfactor regarding MBD in amphib­ians is the role of ultraviolet light (UV-B) inthe devel­opment of clinical disease. Because most amphibians are eithernocturnal, fossoreal, or otherwise found in shaded forests it is possible thatoral cholecalciferol (vitamin D3) plays more of a role in calciumabsorption and metabolism than does that of endogenous vitamin D3.However, recent studies of juvenile captive-born Gastrotheca cornutaatthe Atlanta Botanical Garden and El Valle Amphibian Conservation Center,Panama, are highly suggestive that a lack of adequate UV-B radiationcontributes to both clinical signs and histo­pathologic changes consistent withMBD (author, per­sonal observation).An occasional suspected clinical sign of MBD in amphibians isgastrointestinal bloating. If this sign is observed and there is suspicion ofMBD based on history or other physical exam findings, a radiographic studyshould be initiated to confirm the presence of the disease syndrome. Cloacalprolapse may be an addi­tional sign of MBD in juvenile frogs of some species (Hylomantis lemur,Agalychnis callidryas). The dem­onstration of decreased bone densityis diagnostic for MBD, though in severe cases, especially among young, growinganimals, soft pliable bones are highly sugges­tive of MBD. Blood calcium testingis not a reliable method for diagnosing MBD because the blood remainsnormocalcemic until the body stores of calcium are depleted.Treatment of MBD in amphibians is supportive. Oral calcium glubionate ata dose of 1 ml/kg/day (Wright and Whitaker 2001b) and dietary correction isessential. Oral vitamin D3 is recommended to enhance the absorptionof calcium from the gastroin­testinal tract (Wright and Whitaker 2001b,Donoghue and Langenberg 1996). Patients with neurologic disease secondary toMBD may require calcium gluco­nate 10% at 100 mg/kg ICe every four to six hoursuntil signs resolve. Prognosis for the hypocalcemic state of MBD in amphibiansas seen in lizards is poor.A mysterious disease of newly metamorphosed frogs is called spindly legdisease or syndrome. With this abnormality tadpoles develop normal or nearlynormal hind legs, yet the forelimbs either fail to erupt from the skin or areextremely thin and weak, almost as if there were only skin and bone with nomuscle. This syndrome has been reported extensively among dendrobatid frogs.This high rate of occurrence may be due to the fact that these frogs are bredin captivity in such great numbers and therefore the chance for occurrence isgreater. Frogs that metamorphose and leave the water usually fail to eat anddie within days.The potential causes for this syndrome are diet of the tadpole orparents, improper environmental condi­tions (temperature, lighting, etc.),genetics, toxins, and226  Chapter 10possibly chytridiomycosis. Presently a dietary cause is most likelybecause there are several anecdotal reports of dietary variation in clutches oftadpoles from the same parents raised on different foods that may exhibit thedisease. There is no treatment for this disease process.Respiratory SystemClinical respiratory disease is uncommon among amphibians. It is morelikely that respiratory infections in amphibians are under diagnosed ratherthan less frequent than those seen in reptiles. A common respi­ratory pathogenis lungworms {Rhabdias spp.). Though this nematode is diagnosedwith moderate frequency among terrestrial frogs, clinical disease associatedwith the organism is infrequent. It is likely that the migra­tion of larvaethrough host tissues and secondary inva­sion of bacteria with or withoutsepticemia contributes greatly to debilitation of the patient.Rhabdias spp. infection is diagnosed by demon­strating larvae ondirect fecal examination or floata­tion or by cytology of tracheal wash. Patientsexhibiting apparent respiratory distress in association with Rhabdias spp. infection arebest treated with anthel-minthics concurrent with antibiotics such as enrofloxa­cinfor secondary bacterial infection. Those patients that exhibit no activeclinical disease are treated only with anthelminthics such as fenbendazole 100mg/kg PO every fourteen days for three treatments or iver­mectin at 0.2 to 0.4mg/kg PO or TO at the same rate of administration (Poynton and Whitaker 2001).Because the life cycle of this infection (as well as other amphibian nematodalinfections) is direct, isolation and strict hygiene is essential to reducingparasite burdens.Though not an infectious disease, drowning is a common fatal respiratorydisease of captive amphibi­ans. It is mentioned only because it is a disease ofprevention as described in the section on Husbandry. This avoidable diseaseresults in the deaths of many valuable amphibian pets.Digestive SystemAnother rather common though avoidable non-infec­tious disease inamphibians is foreign body obstruc­tion. Typically the result of inappropriatesubstrate or feeding practices, this problem often goes unnoticed for sometime. The primary presenting complaint is anorexia or occasionallyregurgitation. Gravel, soil particles, or rarely invertebrate exoskeleton maycause obstruction. Diagnosis may be presumptive based on history and husbandrypractices or definitive with abdominal palpation and radiographic study.The degree of obstruction, size of patient, and nature of the foreignbody dictate treatment. For organic foreign materials, oral laxatives such aspsyllium and mineral oil may aid in passage of the obstruction. For largeramphibians, surgery may be indicated.Intestinal parasitism is clinically widespread among terrestrialamphibians and somewhat less common among arboreal species. Amphibians areinfected with a wide variety of protozoa and metazoa parasites. It is commonthat routine fecal exams of amphibians reveal these organisms in otherwisehealthy patients. Some protozoans may not be pathogenic and may not requiretreatment. Some protozoan and many metazoan (nem­atodes, trematodes, cestodes)parasites may inhabit amphibian tissues and remain in "balance" withthe host with a competent immune system.The onset of stress and subsequent immunosuppres­sion that results fromtransport, poor diet, or inap­propriate husbandry can rapidly lead toaccelerated reproduction, migration, and infestation of these para­sites.Similarly, the direct life cycle of many parasites only compounds thereinfection rate when the patient is subject to confinement in a terrarium.This is the likely cause for the apparent higher clinical prevalence of theseparasites in terrestrial rather than arboreal species because there is greaterlikelihood for contact with the infective oocysts or larvae.Intestinal parasites are best treated when diagnosed. Nevertheless, theclient must be educated regarding the potential side effects of treatment. Morecommonly there is greater risk of death or debilitation from the hosts immuneresponse to sudden parasite death than from side effects of appropriately dosedmedications. For very valuable animals, treatment of apparently healthy animalsshould be carefully weighed against the potential loss of the patient. Whengroups of animals are to be medicated, treatment of a few animals in the groupis preferable to medicating the entire group at once.The most important factor in breaking the life cycle of direct parasitesis maintenance of the patient in an immaculately clean, well maintainedenclosure. Removal of all feces immediately after passage is imperative.Feeding of the patient should only be per­formed in an enclosure with no fecalcontamination because food items may browse on contaminated sur­faces andreinfect the host. Prophylactic treatment for intestinal parasites is discussedin the Quarantine section of Husbandry.Protozoan parasites present both a diagnostic and treatment challenge.For suspected pathogenic Trichomonas spp. and Entamoeba spp. Infections,Amphibians  227metronidazole is indicated. Dose ranges for adults vary from 10 mg/kg POevery twenty-four hours for seven to ten days for Trichomonas to 100 mg/kg POevery fourteen days for Entamoeba (Poynton and Whitaker 2001). Metronidazolebaths at 250mg to 500mg/L fresh water for six to eight hours once weekly areindicated for larval amphibians (Poynton and Whitaker 2001).Coccidiosis is not uncommon in amphibians, yet its diagnosis iscomplicated by the fact that oocysts are intermittently shed in the feces.Thus, repeated fecal exams over protracted periods are required in some casesfor definitive diagnosis. As seen in mammals, coccidiosis is primarily aclinical disease to the very young, very old, or immunosuppressed animal.Nevertheless, treatment is indicated on diagnosis and consists oftrimethoprim-sulfamethoxazole at 15mg/ kg PO daily for fourteen days (Poyntonand Whitaker 2001). The dosage of TMS in exotic animals is based on thecombined concentration of both the trime­thoprim and sulfa medications.Nematodes are treated as described for lungworms (Rhabdias spp.) in thesection on Respiratory System and Quarantine for prophylactic treatment. It maybe difficult to specifically diagnose each species of nema­tode parasite onfecal exam, though the treatment for each is similar.Trematodes and cestodes have indirect life cycles in amphibians andinterruption of the vector for reinfec­tion is essential for treatment.Treatment consists of praziquantel at 8 to 14 mg/kg PO every fourteen days forthree or more treatments (Poynton and Whitaker 2001).Excretory SystemThere are no significant renal diseases of amphibians that are notobserved in reptiles, birds, or mammals. Renal disease secondary to toxicosis (medicationsor environmental), mineral imbalances, or gout is possible.Reproductive SystemFailure to lay eggs or "egg binding" is the most commonreproductive disorder of amphibians. Potential causes are categorized asenvironmental, in which certain a suitable oviposition site is not avail­able,unsuitable mate, or other stress that prevents the release of eggs. Othercauses include physical inability to lay eggs that may result fromenvironmental factors. If an egg or eggs becomes lodged in the ostium of theoviduct or within the oviduct proper, all retrograde eggs will be retained.Some cases may require surgery when possible.OphthalmologySuperficial ocular disease in amphibians is commonly associated withskin disease or arises from a common etiology such as bacterial, fungal,protozoal, or viral disease. Cataracts, corneal lipidosis, and glaucoma haveall been diagnosed. Systemic disease or sepsis such as red leg syndrome mayaccount for uveitis in amphibians, as does similar systemic disease in otheranimals. Diagnosis and treatment of ophthalmic dis­eases in amphibians isapproached as in other animals.Corneal lipidosis may be commonly confused with infectious or traumaticinflammatory disease and typi­cally slowly progresses to eventually involve thecornea of one or both eyes. Treatment is supportive and should be directed atreduction of dietary fat or cho­lesterol by altering prey item selection andreducing frequency of feeding (Wright 2009).ToxicityAmphibians are quite sensitive to environmental con­tamination from bothnaturally occurring and syn­thetic toxins. These include ammonia, nitrites,nitrates, excessive salts, chlorine, organophosphates, pyrethrins andpyrethroids, and many solvents used in glues and sealants. It is imperativethat any cleaning compounds used to disinfect enclosures or enclosureaccessories be thoroughly rinsed, soaked, and dried prior to reintro-ductioninto the enclosure. Diana et al. (2001) reports toxicosis among dendrobatidfrogs within enclosures that were misted by a newly constructed system com­posedof PVC pipes. Organic solvents from the pipe cement were found to be the causeof toxicosis. Similar attention must be observed with aquarium glass sealants.Metabolic DisordersHypovitaminosis A is a recently recognized and described disease ofcaptive amphibians (Pessier et al. 2002). This disease progresses in amphibianssimilar to that observed in reptiles with the hallmark histo­pathologic changeof squamous metaplasia. Multiple organ systems may be affected and clinicalsigns may vary widely. Wright (2009) recommends vitamin A treatment for anyclinically ill captive amphibian for which there is no clear diagnosis orclinical sign of disease. Treatment consists of Aquasol A 1 IU vitamin A/g bodyweight once daily for two weeks or until clinical signs resolve (Wright 2009).ZoonosesAmphibians are known to carry several bacteria which are potentiallypathogenic to man and other animals. Though not infectious, certain amphibian228  Chapter 10toxins are potentially dangerous to man and domestic animals.Bacteria such as Listeria monocytogenes, Salmonella spp., and Yersiniaenterocolitica are all reported as isolated from the feces or digestivetracts of some amphibians (Taylor 2001). There is no link to clinical diseasein man from these bacteria arising from amphibians. Care and common sense,however, must be exercised when handling amphibians regarding zoo­noticpotential. Human carelessness is often a contrib­uting factor to zoonoses whenrelated to exotic animals.It is the responsibility of the veterinary clinician and technician toeducate the client regarding proper han­dling of the amphibian pet to reducethe risk of poten­tial exposure. The following are several guidelines thatshould be followed:1. Do not handleamphibians unless absolutely neces­sary. Most (if not all) amphibians show noapparent health or quality of life benefit from human contact. In fact, stressmay be increased as well as tissue trauma that may lead to an increasedincidence of disease to the animal.2. Never handle orclean amphibians, amphibian foods or food containers, or amphibian enclosuresnear a human food preparation area or human sani­tation area such as a kitchensink, kitchen table or countertop, bathroom sink, or bathtub.3. Never allowchildren to handle amphibians without direct adult supervision and make surethat hands are washed immediately after handling.4. Do not allowamphibians to remain loose or uncon-tained in a building intended for humanoccupation, sanitation, or food preparation.Unfortunately, the above suggestions may seem to be common sense, butthe breakthroughs in common sense are always reported in the popular press byrela­tively uneducated media professionals, implicating exotic animals inzoonotic disease. Without the respon­sible education of pet owners there isgreat risk of continued legislation prohibiting private possession of theseanimals.LARVAL AMPHIBIANSTadpoles and larval salamanders face a variety of dis­orders that, forthe most part, are never diagnosed or treated. Under controlled conditions withcaptive breeding the incidence of disease is relatively low, yet many may besusceptible to disease when stressed with substandard environmental conditions.There is tre­mendous variability in natural and cultural conditions of larvalamphibians and some species demand exact­ing environmental parameters, whileother are adapted to what might be considered nearly unsurvivable conditions.For practical purposes all larval caecilians and sala­manders arecarnivorous. Some caeclians are vivipa­rous and consume oviductal secretionswhile developing in the adult female and are then born as juveniles. Forsalamanders, carnivory leads to cannibalism in crowded conditions, particularlyas metamorphosis approaches. It is possible that the survival strategy of somecommunal pond-breeding salamanders depends on this strategy for a few animalsto survive. In con­trast, most frog larvae, tadpoles, are herbivorous. Thereare, however, a few notable exceptions. Though not commonly bred by hobbyistsin captivity, horned frogs (Ceratopbrys spp. and some otherLeptodactylidae) have carnivorous, or more reputedly cannibalistic, tad­poles.Successful rearing of these tadpoles and larvae of other carnivorous speciesnecessitates isolation into individual enclosures for each larva.The most critical husbandry issue for larval amphib­ians is waterquality. Understanding the natural history and reproductive strategy for aparticular species is important for proper care of the tadpoles. Most dartfrogs, for example, lay eggs out of water on leaves, in leaf axils, or on flatsurfaces near the ground. After hatching, the tadpoles are then transferred toa suitable water area that is generally a small plant with water supplied onlyfrom rain. For these species in captivity, elaborate filtration and moving orconstantly filtered water is not essential for survival and metamorphosis. Agedtap water or spring water changed periodically generally yields success.Species that lay eggs above streams or have tadpoles which inhabitmoving water usually require some water oxygenation or filtration for survival.Some of these species, such as many larger Central and South American hylids,feed on particulates suspended in the water and require the water movement tosupply a constant source of food. Many of these species rapidly perish ifmaintained in still or stagnant water.Feeding of larval amphibians, particularly tadpoles, is not difficult inmost cases. An exceptional food for larval herbivorous dendrobatids isspirulina powder (Earthrise Co., Petaluma, CA) that is available from mosthealth food stores. The author has raised many generations of various speciesof dendrobatids and Mantella spp. tadpoles on this diet with absolutelyno developmental abnormalities. Overfeeding must be avoided, however. Waterquality deteriorates rapidly without filtration and death is rapid. Manydendroba­tids and possibly other frog species give parental careAmphibians  229to tadpoles in the form of "feeder eggs." Information on thesespecies is available in many hobbyist texts.Larval salamanders can be problematic in that many species in earlydevelopment require live foods. Daphnia, gammarus (fairy shrimp), and othersmall crustaceans must be cultured or readily available. Wild collection ofthese food items is not recommended, because this is commonly a source forinfection with the trematode Gyrodactylus spp., the body fluke.These microscopic parasites can be rapidly fatal to larvae, and may be theinciting cause of cutaneous ulcers on adults. Treatment may be accomplishedwith dilute salt or formaldehyde baths (1.5 ml of 10% for­malin in 1 literwater for ten minutes) and survivability is good with early diagnosis. Theamphibians undergo­ing treatment must be watched very closely and removed tofreshwater at the first sign of distress in formalin. Dipping the infectedanimals into the treat­ment solution within a net is the most practical methodfor rapid removal.Larval amphibians are subject to bacterial and fungal infections asadults. Treatment is with medi­cated baths rather than by individual dosing.Diagnosis of a specific infection is usually obtained by sacrificing one ormore larvae from a group for bacteriologic or microscopic analysis.HISTORY AND PHYSICAL EXAM HistoryA complete and accurate history of the amphibian patient may be the mostimportant procedure in devel­oping a diagnosis of disease (or health).Unfortunately, amphibian patients are commonly presented moribund or alteredfrom the original onset of clinical signs, making it difficult to diagnose theunderlying etiology based on physical exam. Similarly, the clinician may bepresented with a deceased patient from a group of animals and a diagnosis maybe required to develop a treatment plan for the remaining group of apparentlyhealthy individuals. Additionally, when gaining new clients who own amphibians(and reptiles), much time is spent in phone conversations with clients who arereluctant to bring the patient into the clinic. Though there is littlesubstitute for physical exam of the patient, there is even less substitute fornot having patience with a potential first time client.The first step in obtaining an accurate history is identification of thecorrect scientific name of the patient to at least the genus (andpreferably to species) level. It may be difficult to obtain natural historyinformation based on common or colloquial names.Identification to the subspecies level (many salaman­ders) or thevariety level (many Dendrobatidae) is not important for developing a historyand diagnosis.Establish the origin of the patient; is it captive-born or wild-caughtand imported? This information is par­ticularly important for amphibiansbecause the likeli­hood of acclimation to a captive environment and thepotential pathogens in wild-caught animals must be considered. The client maynot know this history, par­ticularly if the animal was purchased at a pet storeor reptile and amphibian trade show or swap meet. One characteristic ofcaptive-born amphibians includes juvenile age or relatively young animals whenobtained by the client. Imported animals are usually adults because they aremore frequently captured in the wild and more likely to survive shipping. Todaycertain species of frogs are almost exclusively captive-born. Many salamandersand most caecilians are wild-caught.A particularly important question of the client is the medical historyof the patient; has the patient been treated at home prior to or following theclients pos­session of the patient? Has the patient received treat­ment fromanother veterinarian? Home treatment of exotic pets, particularly reptiles andamphibians, is common. Occasionally results are favorable with home treatment,but more commonly the clinical condition fails to respond or deteriorates.All husbandry parameters should be fully investi­gated. Descriptions ofthe enclosure, substrate, acces­sories, cage mates, feeding schedule, andenvironmental conditions of both the enclosure and the room housing theenclosure are important. When multiple individu­als or species of amphibiansare housed together, the client should be questioned regarding the health ofthese animals as well as any quarantine procedures that were performed.The exact nutrition (which food items are con­sumed) of the captiveamphibian is generally not as much of a clinical concern as whether or not thepatient is actually eating. With respect to food items offered, particularlyinsects, it is important to learn the size of insect that is fed and the timingof the feedings. Also, ask the client if the patient is observed to actuallyeat the food items or if the food simply disappears from the cage. Many timesinsects may escape or hide beneath cage ornaments, leading the client tobelieve that the insects were consumed. This is particularly true of nocturnalamphibians. Question the client regarding food supplements such as vitaminmineral powders and frequency of application. For aquatic amphibians it isimportant to know the exact food items offered (live or processed). Manycaptive amphib­230  Chapter 10ians refuse prepared diets such as pellets initially and must be fedlive food.RestraintThe primary consideration when restraining an amphibian is stress on thepatient and the potential health consequences of handling. The patient shouldbe touched or restrained only when absolutely neces­sary. All diagnostic testsor treatments should be pre­pared prior to handling to consolidate proceduresinto the fewest episodes of physical manipulation of the patient. Considerationmust also be given to the safety of the handler. Some species are capable ofproducing toxic skin secretions that are irritating and noxious, but rarelylethal to humans.The following species when known to be wild-col­lected should be handledwith extreme caution: golden poison frog (Phyllobatesterribilis), black-legged poison frog (Phyllobatesbicolor), Colorado River toad (Bufo alvarius), and marine toad (Bufo marinus). It is unlikely thateither of the poison frogs listed will ever be seen in practice as wild caughtindividuals because they are relatively inaccessible for collection andexportation from Colombia, and both species are now widely available ascaptive-born juveniles and adults. Captive-born dart frogs have greatly reducedskin toxins and are generally not toxic to humans (Daly et al. 1994).Nevertheless, an imported Phyllobates terribilis should beconsidered lethal to humans. The toxins of P. bicolor are only 1/50 thestrength of P. terribilis, yet a wild-caughtfrog should be considered dangerous (Walls 1994).The Bufo spp. are a concern not as much for theirdegree of toxicity, which is significant, but for the manner in which the toxinmay be secreted. Both species are capable of ejecting copious amounts of toxinfrom the parotid glands. Reports exist of this toxin spraying six feet or morefrom the animal (Wright and Whitaker 200Id). Entry of the toxin into anunprotected eye can be serious, not just from the standpoint of direct physicalirritation, but also from absorption and systemic effects. All larger Bufo spp. and allwild-caught dart frogs are best handled with powder-free latex gloves.Additionally, protective eyewear is recommended when handling or manipulat­inglarger toad species.When possible, amphibians are best observed in a clear enclosure such asa plastic shoebox, deli cup, plastic bag, or other small enclosure. Handling ofall amphibians is performed with a powder-free exam glove that has beencleaned, rinsed, or moistened with distilled water. Small frogs are bestrestrained with the hind legs extended and held securely between the thumb andindex finger. This frees the head, body, and front legs for examination or treatment,yet adequately prevents jumping or escape attempt. Larger frogs and toads mayrequire support by two hands to the body between the front and hind legs.Medium to large sala­manders are restrained with a delicate grip of the fist,allowing the head to protrude between thumb and index finger and the tailexiting at the little finger. As in lizards, tail autotomy is possible for manyspecies of salamanders. Most adult anguiform amphibians (caecilians, amphiumas,sirens) are nearly impossible to restrain manually and are best examined in anaquarium or chemically restrained (see Anesthesia).Physical ExaminationAs with all exotic animals, the most important physical observations ofthe patient are made without handling. With the exception of some frogs and incontrast to most turtles, lizards, and snakes, the posture of amphibians is notas significant in revealing clinical disease. This is due to the fact that manyspecies are nocturnal and cryptic, preferring to remain inactive or burrowedduring the day. Species in which posture is generally significant are thedendrobatids, atelopids, mantellids, perching hylids such as Phyllomedusa spp., and mostnewts. Activity of the patient may be signifi­cant for some species. During adaytime examination all of the previously mentioned species (with the excep­tionof hylids) should be bright, alert, and responsive. In contrast, nocturnalspecies such as hylids, some toads, ranids, and salamanders are generallyinactive. A common indication of poor health in hylids, typi­cally nocturnal,is activity during daylight hours. Red-eyed treefrogs, for example, generallyrest on the sides of the enclosure with eyelids shut in daylight. Aquaticamphibians, though generally nocturnal, are generally active in the enclosureon presentation. Exceptions may include some aquatic or large semiaquatic frogsthat, by nature, typically are not very active foragers and prefer to wait andambush prey.Observing the feeding response of diurnally active amphibians is apractical method to assess overall health. A failure to respond to the properfood item is generally a sign of illness or stress. Nocturnal or shy animals,however, rarely feed upon observation in day­light hours.With a basic understanding of normal anatomy and body condition of thespecies in question, the visual exam should first focus on body condition. Isthe patient normal weight, underweight, overweight, or bloated? It is importantto remember that some frogs will inflate with air as a defense mechanism andmay appear bloated, but suffer from no abnormal physiol­Amphibians  231ogy. Air inflation is not a physiologic adaptation of salamanders andcaecilians. As with other animals, emaciation does not occur in hours or days,but in weeks or months. Even the smallest frogs have distinct muscle groupsthat reveal weight loss. Poison dart frogs, for example, exhibit emaciationparticularly on the back, scapulas, and pelvis.Observe the cloaca for prolapse. This abnormality may remain unnoticedby the client. Also observe a fresh stool sample. For most terrestrialamphibians the feces are ejected as a pellet and should be somewhat moist anddark brown in color. Abnormalities in color and consistency may be significant.A microscopic fecal exam is essential for all captive-born and importedamphibians.Abnormalities in respiratory effort can be difficult to detect interrestrial amphibians. Normal respiration is driven primarily by buccal orgular pumping rather than by diaphragmatic or intercostal muscle contrac­tion.There is rarely noticeable variation in this rhyth­mic pumping motion, even indiseased animals. Bubbling from the mouth or nostrils in terrestrialamphibians, however, is abnormal and a possible clini­cal sign of respiratorydisease.Abnormality of the integument is one of the more common abnormalphysical findings and a common presenting complaint for diseased amphibians.Understanding the natural history and normal charac­teristics of the integumentfor a given species is essen­tial. Most toads, terrestrial newts, and some treefrogs have relatively dry skin. Many larger tree frogs such as Phyllomedusa spp. and Litoria spp. can producewaxy secretions to prevent dessication. Amphibians slough skin, ecdysis,throughout their lives, and this process should not be confused with disease.Coloration varies widely, particularly in frogs, and with many this colorationis bilaterally symmetric. Even cryptic amphibians exhibit some color andpattern symmetry; therefore, observe closely for abnormalities in sym­metry ofcolor, texture, and morphology. Amphibians typically do not exhibitcolor-changing ability as seen in some lizards, though variation will occurfrom day to night in many hylids. Ulcers, erosions, plaques, and crusts are notnormal. Newly acquired or recently imported frogs are susceptible to rostralabrasions that may rapidly progress into necrotizing ulcerations.Most salamanders and terrestrial frogs have clos-able eyelids and frogspossess a nictitating membrane that is semitransparent. When awake and alertthe amphibian eye should have eyelids open and clear corneas. Iris colorationis variable among amphibians, but is always bilaterally symmetric. As withmammals, unilateral ocular changes are most suggestive of trauma or focal diseaseand bilateral ophthalmic abnormalities are more suggestive of systemic disease.Iris vascula­ture may be apparent in the normal amphibian eye. There is greatvariation in pupil structure from circular to horizontally and verticallyelliptic. An ophthalmo­scope illuminator or slit lamp is helpful for examina­tionof the eye. Commonly used mammalian mydriatics such as atropine andproparacaine are not effective in dilating the amphibian eye. Wright (2001b)recom­mends the combination of D-tubocurarine and benzal-konium chlorideapplied topically for mydriasis (Whitaker 2001).Oral exam requires physical or chemical restraint in most species. Somespecies of frog, Ceratophrys and Hemiphractus spp., are known togape as a defensive tactic, making oral examination possible without restrainton occasion. Similarly, some larger terrestrial salaman­ders (Ambystoma spp., Dicamptodon spp.), particularlythose maintained long term in captivity, may exhibit a conditioned feedingresponse and can be coaxed into biting a soft speculum to examine the mouth.Though it is not recommended as normal practice, these animals, when routinelyhand fed, will bite fingers waved in front of the face. It is unlikely that anyinjury will result to a human from the bite of an ambystomatid salamander.Large frogs (Ceratophrys, Pyxicephalus) and large aquatic salamanders(Amphiuma, Siren, Cryptobranchus) are capable of painful bites to humans. Thesespecies generally require chemical restraint for both physical restraint andoral examination.The clinician and technician should be aware that mandibular bones ofmany small amphibians are easily fractured with improper or forceful techniquesto open the mouth. When properly restrained the mouth of many smalleramphibians may be opened with a variety of apparatus such as plastic cards,laminated paper, coverslips, and small rubber spatulas. Nearly all amphibianswill resist the oral exam if not sedated. Observe for uniformity and symmetryin shape and coloration of the oral mucosa and the tongue. Occasionallyparasites such as flukes and leeches may be observed attached to the oralmucosa.Palpation is easily accomplished for larger amphib­ians, but shouldgenerally be avoided in smaller species to prevent iatrogenic trauma. Internalorgans of the smallest species may be evaluated by transillumination of thepatient through a clear plastic container. This process is ineffective forlarge or dark pigmented patients. The heart, liver, spleen, gonads, and somevasculature may be observed in this manner. Palpation of larger species mayreveal abnormalities such as foreign bodies and calculi, though normalstructures may be difficult to assess or identify.232  Chapter 10The heartbeat may be visible as pulsations of the skin in the region ofthe xiphoid on the ventral thorax in some amphibians. Similarly, in some frogs,pulsation of the lymphatic hearts is occasionally observed lateral to theurostyle. Cardiac auscultation is possible in larger amphibians, though theclinical significance of this procedure during wellness exams is question.RADIOLOGYAs with reptiles, radiology is valuable in the diagnosis of someamphibian disease. This imaging is particu­larly useful for the diagnosis ofskeletal disorders, urinary tract calculi, tissue mineralization, pulmonarydisease, gastrointestinal foreign bodies, and other gas­trointestinal diseasewith the aid of contrast materials. Unless abnormality is present, it isgenerally not pos­sible to clearly differentiate coelomic cavity structuresradiographically in amphibians.Techniques for radiographic exposure are similar to those described forreptiles. Because of the small size of most amphibians, a table-top exposurewith detail cassettes yields the best quality image. Generally, an exposuresetting consistent with the lowest mamma­lian extremity setting is sufficient,though with smaller patients overexposure is still possible. For techniciansafety the use of a collimator to achieve the smallest exposure field isessential. With this technique, multi­ple exposures are possible on a singlecassette.Restraint of the amphibian patient during radiology is a hands-offaffair. Many frogs will sit briefly directly on the cassette for exposure. Forthose that are reluc­tant to remain still, placement of the patient in aplastic bag facilitates restraint and manipulation for proper exposure (Stetter2001a). When possible, a lateral and dorsoventral exposure should be made ofevery patient imaged. This typically requires the movement of the radiographicbeam into a horizontal beam projection as the patient sits on the tabletop orplatform.Contrast studies are easily performed in amphibi­ans. Barium sulfate isthe contrast medium of choice and is given orally via a rubber catheter orfeeding tube. The dosage varies greatly based on the size of amphibian. A rangeof 10 to 15 ml/kg PO is generally sufficient, though the technician shouldapproximate the volume of the calculated dose to the patients body size andadjust accordingly. Percloacal barium admin­istration is also performed forsuspected colonic foreign bodies, strictures, or other disease. Great care mustbe used when manipulating catheters with these tissues to prevent iatrogenictrauma.ANESTHESIA AND SURGERY AnesthesiaAnesthesia for amphibians is useful for physical exami­nation ofaggressive or reluctantly restrained patients, certain diagnostic and therapeuticprocedures, and surgery. Reports exist for the use of injectable anes­theticsin amphibians, though current consensus regards these medications asimpractical and ineffec­tive for safe chemical restraint. The anesthetic ofchoice for amphibians is tricaine methanesulfonate (MS-222, tricaine, FINQUEL,Argent Chemical Laboratories, Redmond, WA) (Wright 2001f). It is a whitecrystal­line powder that may be mixed with water to anesthe­tize fish andamphibians. Amphibians are immersed in a bath of tricaine methanesulfonateuntil anesthesia is achieved and then maintained in fresh water for theparticular procedure to be performed. For longer pro­cedures, the patient maybe immersed in a 50% dilu­tion of the original induction solution or intubatedand maintained on isoflurane.Preparation of tricaine solution requires dissolving the powder intoclean distilled water. The standard solution is 0.1% concentration: lg MS-222in 1 liter distilled water. Because tricaine is quite acidic, the solution mustbe buffered to a pH of 7 to 7.4, which is the physiologic range of amphibiantissue. This is accomplished with either sodium biphosphate (Na2HP04)or sodium bicarbonate (Na2C03). Wright (2001f) reportsthe use of 34 to 50 ml of a 0.5 M Na2HP04 solution to the1 liter stock solution of MS-222. Stetter (2001b) applies Na2C03powder (common baking soda) to the stock solution until no more dis­solves,yielding the preferred pH range. Ideally pH should be tested with a pH meter.Tricaine is not stable in water when exposed to light. Therefore, unlessmultiple anesthesia episodes are planned, it should be mixed only in thequantity desired for a single anesthetic episode. Generally a 1-liter solutionis adequate. All dissolved tricaine should be discarded after use and notreused for other patients.Amphibians are induced in a bath of 1 g/L tricaine methanesulfonate in asuitable induction chamber that may be a plastic bag or orher sealable plasticcontainer. Induction time may vary, but usually thirty minutes exposureachieves surgical anesthesia (Wright 2001f; Stetter 2001b). Loss of therighting reflex and lack of voluntary movement is indication of adequate induc­tion.Loss of the withdrawal or deep pain reflex indi­cates surgical anesthesia.The patient is then transferred out of the induction chamber onto atreatment pan or receptacle and main­Amphibians  233rained in clean fresh distilled water or a 50% dilution of tricaine(0.05%) for the duration of the procedure (Wright 2001f). The patientsnostrils and mouth must be maintained above the water level to prevent aspira­tion.At this time, for longer surgical procedures, large amphibians may be intubatedand maintained on oxygen (with or without isoflurane) with intermittentpositive pressure ventilation (IPPV). Continued expo­sure to the 0.05% tricainebath maintains adequate anesthesia in the absence of isoflurane.The patient should be monitored for heartbeat throughout the anestheticprocedure. Respiration is reduced or nearly absent and oxygenation of the tric­ainebath with oxygen is recommended to enhance oxygen absorption through the skin.The patient is recovered from tricaine anesthesia in clean distilled water,making sure that the nostrils and mouth are not under water to preventaspiration. The recovery period may range from thirty to sixty minutes.An additional anesthetic protocol is the topical application of liquidisoflurane. A mixture of 3cc liquid isoflurane with 1.5 cc water and 3.5 ccKY-Jelly is made in a 10-cc syringe and shaken. The resulting liquid is thenapplied to the back of the patient at a dose of 0.025 cc to 0.035 cc/g bodyweight. The lower dose is applied to frogs and salamanders and the higher doseis for toads. The patient is induced in a sealed container over five to fifteenminutes. Following induc­tion the remaining gel is wiped from the skin andanesthesia will last for forty-five to eighty minutes.SurgeryThough surgical procedures on amphibians are not routine, severalpathologic conditions may require sur­gical treatment. Celiotomy, mass removal,and limb amputation are the most commonly performed procedures. Otherprocedures include enucleation and orthopedic surgery. All invasive surgicalproce­dures are performed with general anesthesia using tricaine or isoflurane.Pre- and post-surgical admini­stration of antibiotics are recommended forinvasive procedures.The amphibian skin is prepped using 0.2% chlorhex-idine (Wright 2001f)or 0.2% chloroxylenol diluted to 0.75% with water. Isopropyl alcohol and iodinecom­pounds are potentially toxic to amphibians and should be avoided. Thesurgical prep should have as long a contact time as possible prior to surgery,preferably ten minutes. The surgical site should be moistened with saline priorto draping and surgery. Depending on the procedure, draping may not beperformed. For celiotomy, sterile clear plastic drape is applied. Peripheral tothe plastic drape a sterile cloth drape may be used to maintain a sterile fieldfor surgical instruments.As with lizards, a paramedian ventral midline inci­sion is recommendedto avoid the large ventral abdom­inal vein that lies on the ventral serosalsurface of the coelomic cavity. Closure of surgical incisions is accom­plishedwith non-absorbable monofilament sutures of appropriate size.TECHNIQUES VenipunctureBlood collection in amphibians can be a challenge, yet in some species,with proper technique and anatomical knowledge, the task is routine. Prior tosampling the skin should be prepped with diluted 2% chlorhexidine or 2%chloroxylenol at a 1:40 dilution (Wright 2001f). Alcohol should not be usedbecause of irrita­tion and dessication to the patient. Sampling fromsalamanders is performed from the ventral tail vein as described for snakes andlizards. A 1-cc or smaller syringe with a 25- or 27-gauge needle is ideal formost amphibians and the sample is preserved in lithium heparin.Phlebotomy in frogs and toads is performed from a variety of locations.In larger frogs and toads the ventral abdominal vein is the best choice forboth quality and quantity of the blood sample. Sampling from this vein isperformed in the same manner as described for lizards. (Figures 10.4, 10.5).Because the lymphatic system of amphibians courses parallel to the bloodvessels, it is not uncommon to collect lymphatic fluids with peripheral blood.Other sites of blood col­lection that are generally accessible in large frogsinclude the femoral vein and the lingual vein located on the ventral surface ofthe tongue. The volume of blood collected should be no more than 1% of thepatients body weight or 0.5% from a debilitated patient (Wright 2001f).CeliocentesisThis technique is performed to analyze fluid retained in the coelomiccavity of amphibians. It may be both diagnostic and therapeutic. Fluid mayaccumulate in the coelom secondary to cardiac, renal, hepatic, or other osmoticimbalances. Similar to phlebotomy, a 25- or 27-gauge needle on a 1- to 3-ccsyringe is ideal. The sample site is prepped with a 1:40 dilution of 2%chlorhexidine or chloroxylenol. The preferred collec­tion site is from the midlateral flank or mid ventral coelomic cavity. The syringe should fill withfluid on gentle aspiration and forceful aspiration should be234  Chapter 10Sub-Lingual VeinFemoral VeinFigure 10.4. Venipuncture sites in a frog. (Drawing by Scott Stark.)avoided to prevent damage to delicate internal organs. Fluid may besmeared immediately or submitted in lithium heparin for cellular and chemicalanalysis.Fecal ExaminationFecal exam is one diagnostic test that can be performed in allterrestrial amphibians and nearly all aquatic amphibians with relative ease.Collection of feces is facilitated particularly well during quarantine. Theamphibian is maintained on paper towel in a clean cage such as a plasticshoebox or storage container that is adequately ventilated and a sample iscollected.The sample should be examined directly in 0.9% saline and by fecalfloatation with standard commer­cially available fecal floatation solutions.Common parasite ova include nematodes, trematodes, coccidia, variousprotozoans, and lungworm larvae (see Parasitology).Amphibians  235Figure 10.5. Venipuncture ofthe midabdominal vein {ventral abdominal vein) in a frog. (Photo courtesy of Dr. Stephen J. Hernandez-Divers,University of Georgia.)Cloacal WashCloacal wash is performed in larger amphibians (>5cm) to collectfecal material for microscopic analy­sis when a fresh stool sample isunavailable for analy­sis. A lubricated semi-rigid plastic or rubber catheterattached to a 1-ml syringe is gently inserted into the cloaca and isotonicsaline (0.6%) is infused from and retrieved into the syringe. The fluid volumemay be between 0.5 and 1 ml and not all fluid will be retrieved. A portion ofthe sample is then viewed with a micro­scope for pathogens. For smalleramphibians (Examination of fecal samples is recommended for these species.Transtracheal WashThe techniques for tracheal wash are identical to those in othervertebrates. The patient must be anesthetized (see Anesthesia and Surgery) anddelicate handling of the tissues and apparatus must be performed. A steriletomcat or small gauge mammalian intravenous cath­eter may be inserted into theglottis in the floor of the mouth. Depending on patient size, 0.25 to 0.5 ccsterile isotonic (0.6%) saline is infused and gently retrieved.The sample may then be smeared and stained for microscopic analysis.Skin Scrape and Impression SmearThese processes are designed to identify fungal, bacte­rial, andprotozoal elements to the skin or wounds on the skin. An impression smear isperformed when tissue is damaged or ulcerated and a scraping will only createfurther trauma. Shed skins are particularly helpful for microscopic analysisand may be fixed in formalin for histopathologic staining to identify certainbacterial and fungal pathogens. A skin scraping is per­formed with the edge ofa coverslip and wetmount examination.Assist FeedingAssist feeding is required for amphibians that are dis­eased and unableor unwilling to voluntarily feed. It is important that the owner understandthat this proce­dure may be stressful on the patient and debilitated patientsmay not survive repeated handling; neverthe­less, this may also be a lifesaving procedure designed to return the patient to a normal feeding response.Wright and Whitaker (2001d) list the standard meta­bolic rates (SMR) forcaecilians, salamanders, and frogs at temperatures ranging from 5 °C to 25 °Cand they recommend that caloric intake for diseased animals should exceed theSMR by 50% on a daily basis.An ideal feeding formula for amphibians is Clinical Care Feline Liquid(Pet-Ag, Elgin, IL), which provides 0.92kcal/ml and has a well balancedprotein-to-fat-to-carbohydrate ratio for amphibians (Wright 2001d). This liquidproduct is easy to administer through a small bore tube and provides nutrientsand calories evenly in suspension. The patients normal food items are provideddaily under observation to assess for a return to normal feeding. Forcefeedings are not made daily to reduce handling. Instead, the calculated dailydose may be multiplied by the number of days between feedings (three, five,etc.) and the total dose for those days is administered at one time. Wright andWhitaker recommend that the volume of feeding should not exceed 10% of thepatients body weight in a twenty-four hour period.The feeding procedure is accomplished in a matter similar to that ofreptiles. A red rubber catheter, intra­venous catheter, tomcat catheter, orball tipped feeding needle is passed into the stomach and the food prepa­rationis infused. The technician should be aware that the stomach of most amphibians(especially frogs) is relatively proximal in the coelom; thus, passage of thetube no more than one-third to one-half of the patients body length (excludingthe tail) is recommended.An alternative to Clinical Care Liquid is a mashed or ground mixture ofinvertebrates such as fruit flies or crickets administered in the same manner.The author has had great success with anorectic dart frogs using this techniqueon an every seventy-two hours basis. Several patients have required two weeksor more of assist feeding before feeding voluntarily.236  Chapter 10Therapeutic AdministrationAmphibians present fewer problems than one may expect with medications.The semipermeable skin enables the clinician to apply some medications topi­cally(TO) for systemic absorption, a technique not applicable to reptiles.Additionally, medicated baths may be used to treat both cutaneous and systemicdiseases. Oral (PO) administration is possible and standard for somemedications such as deworming agents and antibiotics. Finally, injections maybe given intramuscularly (IM) or intracoelomically (ICe) in large amphibians orsubcutaneously (SC) in frogs and some salamanders. Intravenous (IV)administration is rare and difficult at best in all but the largest amphib­ians.Physical restraint of the patient is required for all but the topical route oftherapeutic administration.The application of injectable medications in a topical manner is verypractical for amphibians with perme­able skin. This method likely results inlower percuta­neous absorption rates in toads or in species that produce a waxyskin coating. Antibiotics such as enro­floxacin and ivermectin have beenapplied topically with great success for various bacterial and parasiticdiseases. Baths with medications such as gentamicin, nitrofurazone,itraconazole, sulfamethazine, mettroni-dazole, and other medications have shownsuccess and safety in combating various diseases.Oral administration is possible in nearly all sizes of amphibians and isthe preferred route of treatment when possible to achieve maximum systemicabsorp­tion. This route is contraindicated in those species that are refractoryto handling or physical manipulation. Metal feeding tubes or rubber cathetersare used in large animals and microliter pipettes are used for small patients.Dilution of the commercially available prepa­rations or compounding ofmedications is required for smaller amphibians. Dosing for most oralmedications is daily or less often depending on the drug.Injections are possible in amphibians, but carry moderate risk of traumato muscles or internal organs and may result in chemical trauma or excessivepain and disability at the injection site. Many injectable medications appliedorally in amphibians show good systemic absorption. This is particularly trueof enro­floxacin that may be otherwise irritating to amphibian skin and maycause skin irritation, discoloration, or sloughing from topical administrationor injection. The intracoelomic route is preferred for fluid adminis­tration incritically ill or dehydrated amphibians. The method of injection is similar tothat of celiocentesis.A considerable benefit to choosing the topical route for medicating thepatient is allowing the client to treat at home for non-critical cases. Allother routes of administration require hospitalization or repeated visits tothe clinic for treatment by the technician or clinician. Medications should bedispensed in indi­vidual syringes with the appropriate amount for each dosedrawn up and ready to apply. This negates the possibility of inappropriatedosing by the client. The client should return the used syringes for disposalat the end of the treatment period to allow both a recheck of the patient andto assess compliance of therapeutic administration.An important fact regarding amphibian disease is that pharmaceuticalsare not required to treat or cure every disease. It cannot be overemphasizedthat dis­eases resulting from improper husbandry comprise a substantialpercentage of presenting complaints with amphibians and reptiles. The numberone consider­ation when choosing pharmaceuticals for disease man­agement isside effects. Though it may be difficult for the client to appreciate thatenvironmental manipula­tion alone can correct improper health, it is even moredifficult to understand further debilitation caused by unnecessary treatment.EUTHANASIAInvariably treatments fail to gain response or patients are toodebilitated to withstand treatment and the client elects euthanasia. Amphibiansand reptiles can pose some problems with euthanasia in that the heart maycontinue to beat for some time after neurologic incapacitation or death hasoccurred.Reducing patient suffering and pain and client dis­comfort with theeuthanasia process may be difficult. If possible the patient may be sedatedwith one of several anesthetic agents prior to administering eutha­nasiainjections. Ketamine at a dose of 100 mg/kg IM or telazol(tiletamine-zolazepam) at a dose of 10mg/ kg IM (Wright 2001f) is sufficient toachieve sedation for euthanasia. The clinician and technician should understandthat both of these injections are likely to cause pain and discomfort to thepatient at the injec­tion site. Alternatively, tricaine (MS-222) may be used asa pre-euthanasia sedative or if overdosed as a eutha­nasia solution (Wright andWhitaker 2001b).Administration of a barbiturate euthanasia solution such aspentobarbital at a dose of 100 mg/kg intracar­diac (if possible) results ininstant death. Alternatively, the injection may be given intracoelomically orintra-cranially through the foramen magnum, though cardiac death may bedelayed.If histopathology is required of the patient, then minimizing trauma tovital organs is essential. In thisAmphibians  237case, an overdose of tricaine given intracoelomically or immersion ofthe sedated patient in 20% ethanol will result in death (Wright and Whitaker200Id). Most importantly, clients should be informed of the euthanasiaalternatives and fully understand the pro­cedure to be performed if they wishto be present during the euthanasia process.REFERENCESBarnett SL. 1996. The Husbandry of Poison-Dart Frogs (Family Dendrobatidae).Proceed.Assoc. Amphibian and Rept. Veterinarians, 1-6.Barnett SL, et al. 2001. Amphibian Husbandry and Housing. In: AmphibianMedicine and Captive Husbandry. Edited by Wright KM, Whitaker BR. Malabar, FL:Krieger Publishing Co.Berger L, et al. 1998. Chytridiomycosis Causes Amphibian MortalityAssociated with Population Declines in the Rain Forests of Australia andCentral America. Proc. Nat Acad. Sci. 95: 9031-9036.Daly JW, et al. 1994. Dietary Source for Skin Alkaloids of Poison Frogs(Dendrobatidae)? Journal of Chemical Ecology 20 (4): 943-98.Daszak P, et al. 2000. Emerging Infectious Diseases of Wildlife—Threats to Biodiversity and Human Health. Am Assoc. for theAdvancement of Science 287: 443-449. de Vosjoli P. 1996. Care andBreeding of Popular Tree Frogs. Santee,CA: Advanced Vivarium Systems, Inc. Diana SG, et al. 2001. ClinicalToxicology. In: Amphibian Medicineand Captive Husbandry. Edited by Wright KM, Whitaker BR.Malabar, FL: Krieger Publishing Co. Donoghue S, Langenberg J. 1996.Special Topics: Nutrition. In:Reptile Medicine and Surgery. Edited by Mader DR. Philadelphia:W.B. Saunders Co. Duellman WE, Trueb L. 1994. Biology of Amphibians.Baltimore:Johns Hopkins University Press. Gagliardo R. Atlanta Botanical Garden.Personal communication. Goin CJ, Goin OB, Zug GR. 1978. Introduction toHerpetology,3rd ed. New York: W.H. Freeman and Co. Helfman GS. 1990. Mode Selectionand Mode Switching in ForagingAnimals. Advances in the Study of Behavior 19: 249.Klingenberg RJ. 1993. Understanding Reptile Parasites. Lakeside,CA: Advanced Vivarium Systems. Lotters S. 1996. The Neotropical ToadGenus Atelopus. Koln,Germany: M. Vences and F. Glaw Verlags GbR. Mattison C. 1987. Frogs andToads of the World. New York: Factson File Publications. Morell V. 1999. Are Pathogens Felling Frogs? Science 284:728-731.Obst FJ, et al. 1988. The Completely Illustrated Atlas of Reptiles andAmphibians for the Terrarium. Neptune City, NJ: TFH.Pessier AP, Roberts DR, Linn M, et al. 2002. "Short tongue syn­drome",lingual squamous Metaplasia and suspected hypovita­minosis A in captive Wyomingtoads. Proceedings, Association of Reptilian and AmphibianVeterinarians, pp 151-153.Petranka JW. 1998. Salamanders of the United States and Canada.Washington, DC: Smithsonian Institution Press. Poynton SL, Whitaker BR.2001. Protozoa and Metazoa InfectingAmphibians. In: Amphibian Medicine and Captive Husbandry.Edited by Wright KM, Whitaker BR. Malabar, FL: KriegerPublishing Co.Stebbins RC. 1985. Peterson Field Guide to Western Reptiles andAmphibians. Boston: Houghton Mifflin Co. Stetter MD. 2001a. Diagnostic Imaging of Amphibians. In:Amphibian Medicine and Captive Husbandry. Edited by WrightKM, Whitaker BR. Malabar, FL: Krieger Publishing Co. Stetter MD. 2001b.Fish and Amphibian Anesthesia. VeterinaryClinics of North America: Exotic Animal Practice. 4(1): 69-82.Taylor SK. 2001. Mycoses. In: Amphibian Medicine and CaptiveHusbandry. Edited by Wright KM, Whitaker BR. Malabar, FL:Krieger Publishing Co. Walls JG. 1994. Jewels of the Rain Forest—PoisonDart Frogs ofthe World. Neptune City, NJ: TFH Publications. Whitaker BR. 2001. TheAmphibian Eye. In: Amphibian Medicineand Captive Husbandry. Edited by Wright KM, Whitaker BR.Malabar, FL: Krieger Publishing Co. Wright KM. 2001a. AmphibianHematology. In: AmphibianMedicine and Captive Husbandry. Edited by Wright KM,Whitaker BR. Malabar, FL: Krieger Publishing Co. Wright KM. 2001b.Anatomy for the Clinician. In: AmphibianMedicine and Captive Husbandry. Edited by Wright KM,Whitaker BR. Malabar, FL: Krieger Publishing Co. Wright KM. 2001c.Applied Physiology. In: Amphibian Medicineand Captive Husbandry. Edited by Wright KM, Whitaker BR.Malabar, FL: Krieger Publishing Co. Wright KM. 2001d. Diets for CaptiveAmphibians. In: AmphibianMedicine and Captive Husbandry. Edited by Wright KM,Whitaker BR. Malabar, FL: Krieger Publishing Co. Wright KM. 2001e.Evolution of the Amphibia. In: AmphibianMedicine and Captive Husbandry. Edited by Wright KM,Whitaker BR. Malabar, FL: Krieger Publishing Co. Wright KM. 2001f.Surgical Techniques. In: Amphibian Medicineand Captive Husbandry. Edited by Wright KM, Whitaker BR.Malabar, FL: Krieger Publishing Co. Wright KM. 2001g. Taxonomy ofAmphibians Kept in Captivity.In: Amphibian Medicine and Captive Husbandry. Edited byWright KM, Whitaker BR. Malabar, FL: Krieger Publishing Co.pp. 3-14.Wright KM, Whitaker BR. 2001a. Nutritional Disorders. In: AmphibianMedicine and Captive Husbandry. Edited by Wright KM, Whitaker BR. Malabar, FL:Krieger Publishing Co.Wright KM, Whitaker BR. 2001b. Pharmacotherapeutics. In: AmphibianMedicine and Captive Husbandry. Edited by Wright KM, Whitaker BR. Malabar, FL:Krieger Publishing Co.Wright KM, Whitaker BR. 2001c. Quarantine. In: Amphibian Medicine andCaptive Husbandry. Edited by Wright KM, Whitaker BR. Malabar, FL: KriegerPublishing Co.Wright KM, Whitaker BR. 2001d. Restraint Techniques and Euthanasia. In:Amphibian Medicine and Captive Husbandry. Edited by Wright KM, Whitaker BR.Malabar, FL: Krieger Publishing Co.Wright KM. 2009. Three things you must know to see amphibians. Proceedings of theNorth American Veterinary Conference (23). Gainesville, FL, 1822-1825.Section 5 MammalsCHAPTER ELEVENFerretsJames R. McClearen, Julie Mays, and Tarah HadleyINTRODUCTIONThe art of veterinary medicine has extended into many families ofcreatures. Among small mammals, also known as "pocket pets," theferret has become one of the more popular pets in todays society. Although thepractice of medicine in ferrets is still viewed as being different from thetraditional feline and canine prac­tice, the same techniques that are used insmall animal practice may be easily applied to small mammal prac­tice. It isimportant for the veterinary team to recog­nize that there are similarities anddifferences in the application of these techniques compared to small animalpractice. Other novel medical approaches may also be used to provide solutionsto problems.The domesticated ferret found in the United States is commerciallyraised for the pet industry and medical research. It is conjectured thatdomesticated ferrets arrived in North America as pets from early Englishsettlers more than 300 years ago. They are most likely a domesticated varietyof the European ferret (Mustela putorius furo). The black-footedferret [Mustela nigripes) is an indigenousspecies of the southwestern United States. There are strict fish and wildliferegula­tions that vary from state to state regarding the pos­session of theseanimals. Veterinary facilities, which often serve as the first point of contactfor the pet-owning public, must be acutely aware of these requirements.ANATOMYConformationThe ferret has an elongated body that allows it to enter small areas andholes for to pursue prey. This feature provides challenges for both owner andveterinary staff in caging and handling. Remember: wherever the head goes sofollows the rest of the body. The males are larger than females and theirweight fluctuations vary according to season, similar to dogs and cats (Hillyerand Quesenberry 1997).Skin and Hair CoatThere are three naturally occurring coat color patterns. Sable is themost commonly observed but albino and cinnamon are also seen. The sable ferret,known also as "fitch," has been reported as a cross between theEuropean polecat and ferret. They typically have black-tipped guard hair, acream undercoat, black feet and tail, and a black mask. In the United States,enthu­siasts have developed more than thirty color combina­tions, includingsilver, chocolate, panda, and Siamese.One of the first observations that handlers of ferrets notice about thisanimal is that there is a distinct odor. This odor is primarily from oil glandsand not from the anal glands, as many people tend to think. The odor may becomemore obvious when the ferrets are excited or during breeding season. There arenumerous commercial bathing products that help to make these creatures more"house friendly." Descenting at a young age is a popular procedureperformed at breed­ing farms but unfortunately it has limited effects inpreventing the odor.Ferrets have no sweat glands in their skin. As a result, the veterinarystaff must be aware of the pos­sibility of hyperthermia.SkeletalThe vertebral formula for the ferret is C7, T15, L5 (6), S3, Cdl8(Hillyer and Quesenberry 1997). The ana­tomical considerations of interestinclude a small sternum and thoracic inlet, nonretractable claws, and aJ-shaped os penis. Skeletal anatomy is depicted in Figure 11.1.Digestive TractThe ferret has thirty deciduous teeth and thirty-four permanent teeth.The permanent teeth erupt between fifty and seventy-four days. The upper teethare as follows: six incisors, two canine, six premolars, and241242  Chapter 11two molars. The bottom arcade has six incisors, two canine, sixpremolars, and four molars (Fox 1998).Ferrets have five pairs of salivary glands. Care must be taken not toconfuse the mandibular salivary gland with the lymph nodes in that area. Thestomach of the ferret is simple and can expand to accommodate large amounts offood (Figure 11.2). The small intestine is short in length and has an averagetransit time of three to four hours (Fox 1998).Heart and LungsThe heart lies approximately between the sixth and eighth ribs. Incomparison to other mammals such as cats and dogs, the location of the heart inferrets is relatively more caudal than expected for auscultation. The lungsconsist of six lobes. The left lung has two lobes and the right has four (Fox1998).SpleenThe ferret spleen varies greatly in size, depending on the animals ageand state of health. When enlarged, the spleen extends in a diagonal fashionfrom the upper left to the lower right quadrant of the abdominal cavity. Anenlarged spleen tends to be a very distinct finding during physical examination(Hillyer and Quesenberry 1997).Urogenital TractThe right kidney is cranial to the left kidney and is covered by thecaudate lobe of the liver. The bladder holds approximately lOcc of urine. Inthe male the prostate is found at the base of the bladder.Gender is easily determined in males, which have a ventral abdominalpreputial opening similar to dogs.Figure 11.2. Ferret visceral anatomy. (Drawing by Scott Stark.)Ferrets  243In females the urogenital opening has the appearance of a small slit(Figure 11.3). During estrus, the vulva becomes enlarged. The natural breedingseason is from March to August.BFigure 11.3. (A) Male reproductive anatomy. (B) Female reproductiveanatomy. (Drawings by Scott Stark.)Fertility in both genders depends on the photope­riod. Females are seasonallypolyestrous and induced ovulators. Ovulation occurs thirty to forty hours aftercopulation. Gestation typically lasts forty-one to forty-two days. Iffertilization does not occur, pseudopreg-nancy often occurs and that will lastforty-one to forty-three days. If these females are not bred, a largepercentage of these individuals will remain in estrus with the potential fordeveloping bone marrow sup­pression secondary to elevated estrogen levels(Hillyer and Quesenberry 1997).Adrenal GlandsBoth adrenal glands lie in the fatty tissue anterior to the cranial poleof the kidneys. The left gland is located medial to the kidney and isapproximately 6 to 8 mm in length. The right adrenal gland is more dorsal thanthe left. It is covered by the caudate lobe of the liver and is attached to thecaudal vena cava. It is larger than the left with an overall length of 8 to 11mm. This knowledge is important when assessment of adrenal gland disease isattempted either surgically or ultrasonographically.Biological and Reproductive Data Table 11.1 providesbasic biological and reproductive data necessary for proper examination of aferret or answering common client questions.BEHAVIORFerrets are active little animals and the trouble that they can get intois limited only by the size of their head. The adult males are called hobs,intact females are called jills, spayed females are sprites, and juveniles arecalled kits. The ferret has been and still is used for hunting, biomedicalresearch, and most recently as a pet. The domesticated ferret does not fearhumans or unfamiliar environments unlike its counterpart, the European polecat(Fox 1998). In pairs they constantly play fight, expelling sounds from a lowgrowl to a high-pitched scream when challenged or in pain. They continuouslyroll and bite their opponent on the face and feet, with their favorite spotbeing the nape of the neck.Many times in the heat of play with humans or companions, ferrets backup across the room chatter­ing and hissing at the same time. They are attractedto quick movements, an instinct developed primarily for hunting prey. Theireyesight is only good up to short distances and they depend upon theirexcellent sense of smell and acute hearing to help them maneuver in244  Chapter 11Table 11.1. Physiologic values for domestic ferrets.Adult weightMaleFemale Life spanSexual maturityGestation period Normal weight atbirth Eyes and ears openWeaning age Rectal temperatureAverage blood volumeHeart rate Urine volume1-2 kg 600-950g5-8 years average in the United States. Some may reach 12 years of age4-8 months of age (usually reached in first spring after birth)41-42 days8-1 Og21-37 days of age (usually30-35 days) 6-8 weeks 37.8°C-40°C(100°F-104°F) Mature male, 60 mL;Mature female, 40 mL 180-250 beats per minute 26-28 mL/24 hoursSource: Hillyer and Quesenberry (1997).their environment. Due to their sense of smell, ferrets constantly keeptheir noses close to the ground. This predisposes them to loud sneezing, whichoften alerts their owners as to their location. Ferrets are active about 25% to30% of the day and asleep the remain­ing 70% to 75% (Hillyer and Quesenberry1997).HUSBANDRYThe word "ferret" means to search out something, to ferret itout, or to find something. This is a pet ferrets whole existence and anextremely important factor in providing a safe and an environmentally richhabitat for these animals. Assume that ferrets can go any­where. The limitinghole diameter for escape is usually less than 1 inch; anything over that theycan easily explore. Cages in the home setting and the veterinary hospital mustreflect this attitude. All potential open­ings to the outside such as heatingand air conditioning vents and tubing, dryer vents, doors, and windows are allpossible routes of escape.Ferrets do not fare well outdoors because of their domestication. Insidethe house, reclining and other furniture, bedding, appliances, and electricalcords offer potential injury and even death as a possibility. Owners must beacutely aware of the dangers of inges­tion of household items such asinsulation for wiring and pipes, packing material, rubber bands, soft rubbermaterial for shoes, or other pet toys. These latter items are particularlydangerous because ferrets seem to have an affinity for materials made out ofrubber. Gastrointestinal obstruction is a common problem seen in young ferrets.Caging should be of adequate size with minimum dimensions of 24 inches x24 inches x 18 inches (Hillyer and Quesenberry 1997). Ideal caging shouldprovide multiple levels and a hiding or den area, suf­ficient area for a litterbox, and space for food and water. However, some owners may also set aside anentire room as living quarters for their ferrets. Food bowls should be made ofa nontoxic product and safe water bottles are available commercially. Litterpans in a household setting may consist of a small plastic litter box similarto cat pans but may require lowering one side of the pan for entry. In aveterinary hospital, small, low cardboard boxes are useful with debilitated orpostsurgery animals. They are also conveniently disposable.Toys should be "ferret" approved; hard, nonchip-ping rubberballs, metal toys that make noise, and "ferret" jungle gyms made ofPVC pipes provide good entertainment.NUTRITIONThe domestic ferret, European polecat, and black-footed ferret arepredatory animals that feed primarily on small mammals and birds. Earlyferreters fed their animals bread or corn meal soaked with milk. They survivedon this diet as long as it was supplemented with fresh meat.Most ranch ferrets are fed commercial pelleted foods. Initially, minkdiets were fed but they lacked important nutritional components due to theirprotein base of fish (Bell 1999).The ferret is an obligate carnivore with a very short intestinal tract.Compared to a cat, the ferret has relatively about one-half the intestinallength. They are spontaneous secretors of hydrochloric acid, like humans andunlike dogs, cats, and many other preda­tors. These animals often hide food invarious locations in their environment for future consumption. Because of theinefficiency of the ferrets digestive tract, ferret diets must be high inprotein and fat and low in fiber. Traditional ferret diets include 30% to 40%protein and 15% to 30% fat. The type of diet depends on the ferrets healthstatus and life stage, such as if they are growing kits or lactating jills(Bell 1999).Ferrets  245It is important to feed a high-quality domestic ferret food in dry form.Dry food is preferred over moist due to the health benefit for the mouth,teeth, and gums. Young kits require some moistening of the kibble foods untilthey get their adult teeth. At about ten weeks of age they should begin tohandle dry kibble. There are numerous commercial foods available either frompet stores, veterinary clinics, or the Internet. If food availability isdifficult, a high quality dry kitten food may be substituted. Some ferret foodmanufactur­ers also have senior diets available.Supplements may be warranted in some situations, such as medicalproblems, surgery recovery, or cold environmental conditions. Products such asLinatone (Lambert Kay) and Nutrical (Evsco Pharmaceuticals; Division of IGIInc.) are available through veterinary offices. A common over-the-counterproduct, Ferretone (8-in-l Pet Products), is also a good choice. Snacks andtreats should be held to a minimum because ferrets will over indulge on theirfavorite foods and run the long-term risk of malnutrition. Commercial meat orliver snacks for cats or ferrets are acceptable, and an occasional raisin mayadd a little variety to a ferrets diet. In some medical conditions, such asinsulinoma, treats or supplements that are high in sugar may need to be avoidedexcept at the direction of a veterinarian.Water should be fresh and available at all times.COMMON AND ZOONOTIC DISEASESInfluenza (orthomyxovirus) is the only documented zoonotic disease offerrets. In most cases the transmis-sibility from humans to ferrets is muchhigher than ferrets to humans. Owners should be aware of that risk to theirpets when they have upper respiratory problems. Other potential zoonoticdiseases include leptospirosis, listeriosis, salmonellosis,campylobacte-riosis, tuberculosis, and rabies. There are no known cases oftransmission of rabies to humans from ferrets. Cryptosporidiosis has thepotential of transmissibility to immunosuppressed individuals (Hillyer andQuesen berry 1997).Many disease syndromes are found in ferrets. Upper-respiratoryinfections are common with ferrets as well as with their owners. Caninedistemper is occa­sionally found manifesting itself in various forms. Earlysigns include mucopurulent ocular nasal dis­charge, crusty facial and eyelidlesions, and hyperkera­tosis of the footpads. In some individuals there is anorange color change to the skin. These animals are often anorexic, and inadvanced cases may show central nervous signs such as ataxia, torticollis, andnystagmus.Intestinal obstructions are very common in young inquisitive ferrets.These individuals present with or without vomiting, they may have diarrhea,they are lethargic, and in most situations there is a palpable abdominal mass.Bruxism, which is when a ferret gnashes its teeth from side to side and mayfroth at the mouth, is a common sign of pain.Epizootic catarrhal enteritis (ECE) or green slime disease is adebilitating disease of young and old ferrets. ECE is usually brought into thehouse via intro­duction of a new young ferret. It is a highly contagiousdisease of ferrets characterized by profuse green diar­rhea, dehydration,anorexia, and progressive wasting.Tumors present themselves in many ways with ferrets. The most commontumors involve the adrenal gland (Figure 11.4). These tumors may be benign ormalignant. Adrenal gland disease most often presents as a dermatologicalconcern. Hair loss on the tail, bilateral hair loss along the abdomen, andvulvar enlargement in spayed females are consistent findings with adrenal glandinvolvement. Adrenal tumors can also cause behavior change and generalizedmuscle wasting. Secondary complications of the disease found in male ferretsinvolve the prostate in the form of prostatic hyperplasia or cysts and theycommonlyFigure 11.4. Adrenal gland disease in a ferret. (Photo courtesy of Dr. Sam Rivera.)246  Chapter 11present with dysuria. Bacterial or fungal bladder infec­tions can be asequela to prostatic disease in males with adrenal disease. This problem may beextremely chal­lenging to treat.Lymphoma is found in the ferret in numerous forms. It may involve thelymph nodes, spleen, liver, intestines, kidneys, lung, and bone marrow.Squamous cell, mast cell, basal cell, and sebaceous gland tumors are the mostcommon tumors of the skin.Insulinoma, a type of pancreatic cancer, is very challenging to manage.Ferrets present very weak and sometimes with seizures. Due to the excessiveinsulin produced by this pancreatic tumor, blood glucose levels in affectedferrets are very low. These animals often present with significant weight loss,dehydration, moderate to severe depression, anorexia, or in a coma­tose state.Renal cysts are found in many ferrets and often are only coincidentalfindings.Ectoparasites such as fleas, ear mites, sarcoptic mites, and ticks arecommon in ferrets and are easily treated. Endoparasites are uncommon butcoccidia and giardiasis are occasionally found. There is some geographicprevalence to ringworm (mycotic) in some individuals.Posterior weakness is a frequent observation in sick or debilitatedferrets. This is also a common sign seen in hypoglycemic animals.Myofaciitis is a new emerging disease that has been documented in atleast a dozen ferrets. This disease is characterized by severe inflammation ofmuscles and surrounding fascia. Ferrets with this condition tend to be young(six to eighteen months of age) and have multiple clinical signs includingpain, high fever, a reluctance to move, diarrhea, vomiting, and anorexia.Individuals also develop a neutrophilic leukocytosis. None of these symptomstypically respond to antibiot­ics or anti-inflammatories. The cause of thisdisease, which is rapidly progressive and fatal, is unknown (Garner 2007).HISTORY AND PHYSICAL EXAMINATIONThe procedure for taking a history and performing a physical examinationon ferrets should follow routine small animal veterinary protocol. Questionsshould include: Has your ferret been coughing, sneezing, vom­iting, or havingdiarrhea? Has there been any discharge from the eyes, nose, or any other bodyorifice? What is your pets diet and how is its appetite? Does your ferretdrink water excessively, have increased urina­tion, or is it straining tourinate? Is your ferret active and alert?Physical examination should also be consistent. Begin at the facialregion and work caudally. Make sure that all areas are searched. Look fordischarge from the eyes, nose, or ears. Examine the ears for masses or signs ofmites. Remember, dirty ears do not necessarily need to be cleaned. A certainamount of discharge is normal and is present for protection. Are the eyesuniform in appearance and are there any signs of cataracts? Are all adult teethpresent or are there remaining deciduous teeth? Does the rest of the oralcavity appear normal? Gingivitis and tartar are common findings in the oralcavity that should be noted if present. Often the best way to evalu­ate theoral cavity is by gently scruffing the nape of the neck and waiting for theferrets characteristic yawn reflex.Are there any signs of lymph node enlargement? Heart and lung fields areevaluated in the same respect as with other small animals with one slightchange. Due to the more caudal location of the heart, ausculta­tion of theheart in ferrets typically occurs at the caudal chest area as opposed to themid chest area. Are the lung sounds normal and is there any indication of aheart murmur? Does the animal appear normal and of good conformation? Muscleand skeletal systems should be symmetric and show no sign of dysfunction. Dothe limbs move in a normal manner? How is the appearance of the skin and haircoat? Canine distem­per may cause crusty lesions on the skin or an orange colorchange. Hydration is also measured by skin turgor. Always be aware of masses ofthe skin and subcutaneous tissue.Abdominal palpation is best accomplished by ele­vating the ferret abovethe examination table by the nape of the neck or by gently holding it aroundthe neck. Most of these individuals accommodate the examination without toomuch struggle. Keep in mind that the spleen in many ferrets may be enlargedwith no other indication of disease or illness. Examination of the prepuce andpenile region in the male and vulvar area of the female is important to lookfor infection or any indication of endocrine problems.For neurologic problems consider the overall behavior of the ferret. Isit aware, alert, and curious, or does it appear to be stargazing andunconcerned with its surroundings? Is the ferret having trouble standing?Ferrets with evidence of neurologic disor­ders, depending on the clinicalsigns, may have a life-threatening illness that requires immediate medicalintervention.Ferrets  247PREVENTIVE MEDICINEThe primary focus for preventive care in ferrets should be centered onannual or bi-annual physical examina­tion. An early vaccination program isimperative in young ferrets. These individuals should be vaccinated at six toeight weeks, ten to twelve weeks, and thirteen to fourteen weeks for distemper(Purevax Ferret Distemper; Merial, Inc., Athens, GA). Rabies vaccination isstrongly recommended in environments with risk of infection and may also berequired by law in individual states or municipalities. A rabies vaccine(Imrab3, Rhone Merieux Inc., Athens, GA) may be given as early as three monthsof age. Both canine distemper and rabies boosters are given yearly along with aphysical examination.Despite the creation of safer ferret vaccines, vaccine reactions stillcommonly occur in some ferrets. Vaccine reactions seen include lethargy,depression, seizures, and cardiac arrhythmias. Veterinary hospitals haveadopted various protocols for dealing with newly vac­cinated ferrets. Somehospitals monitor these ferrets at least thirty minutes after vaccination.Other hospitals may provide premedication with an antihistamine prior tovaccination. Whatever the protocol, be aware that vaccine reactions have beenknown to occur at least twenty-four hours post vaccination. Owners should bealerted to the clinical signs and take appro­priate measures to seek veterinarycare should these signs appear after discharge from the hospital.Heartworm disease is found in ferrets. Prevention of heartworm diseasemay be accomplished by off-label use of Heartgard 68 |Xg (Heartgard-30,Merck Agvet Division, Rahway, NJ). Give one-fourth tablet once monthly. Theremainder of the tablet should be dis­carded because the remaining preparationwill deterio­rate. A liquid ivermectin preparation may also be used by mixing0.3 ml of injectable ivermectin (Ivomec 1% injection for cattle, Merck AgvetDivision, Rathway, NJ) in 28 ml (loz) of propylene glycol. Administer 0.2 ml/kgPO (0.02 mg/kg) once per month. This prepa­ration is light sensitive and shouldbe stored in a light-blocking container. The expiration date is two years aslong as the time period falls within the expiration date of the stock bottle (Hillyerand Quesenberry 1997).Internal parasites are not commonly seen in ferrets; however, an annualfecal examination is strongly recommended.RESTRAINTAs with any animal, proper restraint involves the humane handling of thepatient with consideration forFigure 11.5. Ferret restraint using the scruffing method. (Photocourtesy of Dr. Sam Rivera.)the safety of the assistant. Although ferrets are usually activecreatures, they are easily managed in the clinic setting. Young ferrets andoccasionally adults that are less frequently handled may have a tendency tonip. Some of these individuals may latch onto a finger and require a gentleextraction.The preferred methods for injections and examina­tion are scruffing theneck or forming a ring around the neck using the index finger and thumb (Figure11.5). The rear legs and rear quarters are firmly pulled caudally but not atfull extension. Another method involves wrapping the ferret in a towel"burrito" style (Figure 11.6). This is very effective for jugularveni­puncture. Many ferrets may be vaccinated or treated without any physicalrestraint other than using a treat as a distraction.A few individuals may require restraint with light sedation prior to theperformance of any procedures. Chamber or mask induction with gas anesthesia isusually all that is needed. Besides the risks of anesthe­sia, minor changes mayoccur in the results from blood drawn in the anesthetized patient. Theadvantages are that procedures may be performed quickly and with less stressand struggling on the part of the patient and handler.RADIOLOGY AND ULTRASOUNDAs with many small animals, it is difficult to radio­graph a partwithout radiographing the whole indi­248  Chapter 11Figure 11.6. Ferret restraint using a towel. (Photo courtesy of Dr. Sam Rivera.)vidual. Obviously, one should measure the body part of interest and setthe machine according to the thick­ness and the machines technique chart.Small mammal technique charts must be tailored to each clinics equipment.Contrast radiography is employed as a diagnostic tool in ferrets. The mostcommon use is in gastrointestinal studies. The protocol, though similar to thecat, should keep in mind the fast gastrointestinal transit time of the ferret.Ultrasound studies are easily performed and readily tolerated by ferretswith only light restraint. Whole body scans are performed, often with specialattention to the stomach, pancreas, lymph nodes, liver, kidneys, adrenalglands, and bladder, and the prostate in males.ANESTHESIA AND SURGERYInhalation anesthesia is the recommended product for induction offerrets. Isoflurane is the most common product in use. Sevoflurane has morerecently been used and lacks the irritating taste of isoflurane. The maindisadvantage is the cost of sevoflurane. Intubation may be a challenge withferrets but is similar to that of cats. The technique may require the use of astylet. Gas anesthesia is then continued for the duration of the procedure. Useof a forced-air patient warming system (Bair Hugger, Arizant, Eden Prairie, MN)helps to prevent hypothermia. Pulse oximeters, respiratory monitors, andcardiac monitors work well with ferrets.Analgesia is an important element in the recovery of postsurgical ferretpatients. Butorphanol (0.1 to 0.5 mg/ kg IM or SC every twelve hours) iseffective in ferrets.Common procedures in ferrets include gastroto-mies, enterotomies,adrenalectomies, cystotomies, partial pancreatectomies, lymph node biopsies,and mass excisions of the dermis. Most orchiectomies and ovariohysterectomiesare performed at the breeding farms prior to entry of the ferret into the petpopula­tion. Every state has its own regulations regarding breeding, spaying,and neutering. Hepatic and splenic biopsies are employed as diagnostic toolsand may be performed surgically or through the use of ultrasound-guided biopsyforceps. Ferrets often have enlarged spleens that may or may not be the originof disease. Many orthopedic problems common in dogs and cats are not found inthe ferret. However, fractures and dislocations do occur in pet ferrets.PARASITOLOGYFecal examinations are routinely performed in young ferrets and in ferretspresenting with clinical signs of illness. Intestinal parasites are uncommoncompared to dogs and cats. Coccidiosis (Isospora spp.), when found,occurs in young animals. The oocysts are shed between six and sixteen weeks ofage and can be dem­onstrated in fecal examination. The Isospora spp. that affectscats and dogs may cross-infect ferrets.Giardiasis may be seen in ferrets housed in pet store settings.Cryptosporidiosis is a common finding in young ferrets and may persist inimmunosuppressed individuals for months. No treatment exists in ferrets and onemust keep in mind the zoonotic potential in the immunocompromised humanpopulation.Ear mites often produce a persistent brown-red aural discharge withoutclinical significance. These parasites also cross-infect dogs and cats. Earswabs are the key to diagnosis.Heartworm disease (Dirofilaria immitis) occurs in ferrets,especially in endemic areas. Heartworm pre­vention is unapproved butrecommended.Flea infestation (Ctenocephalides spp.) is a common findingin ferrets housed with dogs and cats. Flea control methods for cats,particularly Advantage (Bayer, Shawnee Mission, KS) and Revolution (Pfizer, NewYork, NY), have been used but are not approved. These topical medications areusually applied in smaller doses (Hillyer and Quesenberry 1997).URINALYSISCollection is achieved by one of three methods. Gentle expression,catheterization, and cystocentesis have allFerrets  249 > Table 11.2. Urinalysis normals for ferrets. Color Clear to yellow Specific gravity 1.015-1.055 Ph 6.0-7.5 Protein 0-1 Glucose 0-Trace Ketones Negative Bilirubin Negative Occult blood Negative WBC 0-5 RBC 0-3 Casts Occasional Crystals Occasional Epithelial cells 0-Few Bacteria Negative Urine volume (ml/24 hr) 8-140 ml (Mean 26-28 ml)Source: Antech Diagnostics.been successfully used. Catheterization is difficult in both males andfemales due to the small size of the urethra and the anatomically challengingos penis. There are manufacturers that produce specialized equipment for thesepurposes (Cook Veterinary Products, Queensland, Australia). However, size 3.5French red rubber catheters have been successfully used to catheterize maleferrets.Due to the activity of the animal, cystocentesis may be best performedunder anesthesia using a 25-gauge needle attached to a 1-cc or 3-cc syringe.Care should be taken to avoid using a large needle because it may lacerate thebladder.Urine dipstick, specific gravity, and sedimentation are used forstandard analyses. Urinalysis normals are presented in Table 11.2. Urineculture should be performed in cases of suspected kidney or bladder infection,preferably using a sample obtained via cys­tocentesis or sterilecatheterization.EMERGENCY AND CRITICAL CAREThe normal life span of a ferret is five to seven years. In anemergency, as with any animal, a history and physical examination are crucialin determining the magnitude of the situation. Insulinoma, adrenal glanddisease, and cardiomyopathy occur most often in older ferrets. Mediastinallymphosarcoma, diarrhea, or foreign body ingestion are found commonly in emer­genciesof young animals. Infectious diseases affect ferrets of any age and are aconsideration in an envi­ronmental setting in which people have respiratoryillness or where new ferrets have been introduced.Ill ferrets require minimal handling. Young and old ferrets aresusceptible to green slime disease (epizootic catarrhal enteritis). Vaccinereactions were more common with previous vaccine protocols but have improvedwith the introduction of the new ferret dis­temper vaccine (Purevax FerretDistemper, Merial, Inc., Athens, GA).Standard methods of restraint for ferrets include wrapping the ferret ina towel or grasping the nape of the neck. TPR, physical examination, andhistory are important to establish a good baseline.Hospitalization of critical ferrets requires a quiet,temperature-controlled cage with oxygen capabilities.Anorexic ferrets are at risk due to hypoglycemia or hepatic lipidosis.The gums of the lethargic ferret may be rubbed with supplements containing highlevels of sugar to provide an immediate energy boost to the ferret until otherlife-saving measures may be per­formed. Later on, force-feeding A/D Diet(Hills Pet Nutrition, Inc., Topeka, KS), Eukanuba Recovery Diet (Proctor andGamble, Cincinnati, OH), or Critical Care Diet for Carnivores (Oxbow, Murdock,NE) via syringe or tongue depressor provides good nutritional support. Otherpreparations are available or can be formulated in the hospital.Basic diagnostic tests include a blood chemistry, hematology, and fecalexamination. A blood glucose can be performed on a human glucometer or bloodchemistry analyzer, or with less accuracy using a blood glucose stick. Theblood chemistry analyzer offers the best accuracy providing the blood samplehas been properly processed. The primary venipuncture site in ferrets is thejugular vein with the saphenous and cephalic veins serving as secondary sites.Catheter placement is intravenously either in the lateral saphenous orcephalic veins. Jugular catheter­ization can be used but is not tolerated wellby ferrets. They often become depressed due to the required ban­daging aroundthe neck. Cut downs of the jugular and cephalic veins in severely dehydratedferrets may be a consideration. Sometimes the vascular system of the dehydratedpatient may require re-hydration with fluids delivered via the subcutaneousroute hours prior to attempted placement of IV or IO catheters.Intraosseous catheter placement can be performed in the humerus, femur,or tibia; the femoral placement is best. This procedure is best done underanesthesia. Anesthesia may not be a safe option in animals that are severelydebilitated. This procedure is painful and may require local block of the periosteumand sur­rounding soft tissue.250  Chapter 11The fluid administration requirement for ferrets is 70 ml/kg/day.Dehydration and losses are the same as in other small animals. With criticalanimals it is important to use the IV or IO route. Use of an IV pump designedfor small mammals is recommended.Medications are administered via IV or IO cathe­ters, IM injection inthe quadriceps, and oral routes. Oral preparations are accepted best in liquidform because pill medication is difficult to administer in ferrets. Oralmedications may be made more palatable with special flavorings that encouragebetter compli­ance from the patient.Cystocentesis may require sedation due to the thin wall of the bladderand the potential for laceration. Ultrasound-guided centesis is also aconsideration.Urethral catheterization requires anesthesia in all patients regardlessof condition. Locating the urethral opening is a challenge in both males andfemales. Male ferrets present more often in an emergency situation due tourethral obstruction from prostatic disease sec­ondary to adrenal glandproblems or cystic calculi (Orcutt 1998).SEX DETERMINATIONSex determination is not as difficult as in many small mammals. Adultsare similar to the dog. Neonate males have a urogenital opening on the ventralabdomen. Female ferrets have a narrow anogenital distance (Fox 1998, 106)(Figure 11.3).TECHNIQUESUrine Collection (Sterile)Cystocentesis: Use a small syringe attached to a 25-gauge needle.Palpate the bladder in the caudal abdomen or use an ultrasound-guidedtechnique.Urinary catheterization: Use a 3.5 French red rubber or other specialtycatheter, nasolacrimal cannula or small gauge needle, water-based lubricant,sterile gloves, hemostats, forced-air warming blanket, and gas anesthesia.Males: The male anatomy is complicated by the J-shaped os penis and thesmall diameter penile urethra.a. Prepare suppliesand anesthetize the patient.b. Estimate the lengthof the catheter from the center of the urinary bladder to the urethralentrance.c. Position the ferretinto ventral recumbency and retract the prepuce.d. Use thenasolacrimal cannula or a blunt-tipped needle as a stylet, and insert thelubricated tip of the cannula or catheter into the urethra orifice. Keep inmind that the orifice is not directly at the tip of the penis but ventral tothe end of the penis. There is often a small flap of penile tissue that must beelevated to access the urethral opening.e. Advance thecatheter until urine begins to flow.Females:a. Prepare suppliesand anesthetize the patient.b. Place the animal inventral recumbency with ele­vated hind quarters.c. Aseptically preparethe vulva and perivulvar area.d. Locate the urethralopening using a vaginal specu­lum or otoscopic cone.e. View the urethralopening on the ventral floor of the vaginal vestibule, approximately 1cm cranialto the clitoral fossa (Quesenberry and Carpenter 2004).f. Insert the catheterand advance until urine flow is achieved.Collect voided sample from examination table or empty litter box: Manyferrets will urinate and defe­cate after their temperature is taken.TPRThe same procedure employed with the dog and cat is used in the ferret.Medication AdministrationInjectable medications and fluid administration require properrestraint.IV sites: Normally given via IV cathetera. Jugular veinb. Cephalic veinc. Lateral saphenousveinIM sites:a. Quadricepsb. Lumbodorsalsc. Tricepsd. Semitendinosus andsemimembranosus. Use caution to avoid the sciatic nerve.Subcutaneous sites: Can be given in a fold of skin anywhere along thedorsum.Per os: Administered by tilting the head back and placing the syringethrough the side of the mouth orFerrets  251placing the syringe in side of the mouth while ferret is standing.Venipuncture (Figure 11.7) Jugular vein:a. Sternal recumbencywith one hand pulling the front legs off the table and the other pulling thehead back.b. Using a towel, wrapthe ferret tightly with only the animals head exposed. With the animal indorsal recumbency the ferrets head is flexed dorsally toward the personresponsible for drawing the blood sample. The assistant should apply light pres­The Caudal Artery.Figure 11.7. Venipuncture sites. (Drawing by Scottsure to the vein on either side of the manubrium and the sample is drawnfrom the jugular vein, c. The ferret may be positioned similar to a cat for ajugular venipuncture. The head is elevated dorsally, the front legs areextended downward, and blood is drawn with the needle approaching the samedirection as the head.Cephalic vein:a. Use normalrestraint using the scruff of the neck.b. Extend the foreleg.c. Hold off the vein.d. Draw the sampleusing a 25- or 22-gauge needle.The Jugular Vein.The Cephalic Vein.■■)252  Chapter 11Saphenous vein:a. Used as a lastresort.b. The technique isthe same as for the cephalic vein.Cranial vena cava: This site has become more and more popular asveterinary personnel become comfort­able with its use. The risk of cardiacpuncture is low due to the length of the vena cava and caudal thoracicplacement of the heart along with the proper use of short needles and properplacement. Sedation or anes­thesia may be required unless the patient is calmand adequately restrained. Practice with an anesthetized ferret can aid inmastery of this venipuncture (Lennox 2009).a. The ferret isrestrained in dorsal recumbency with its neck extended. Alternatively, it canbe wrapped in a towel.b. Choose a one-halfinch needle of 25- or 27-gauge.c. Insert the needlein the area to the right or left of the manubrium of the sternum at a slightangle, aiming it toward the opposite hip.d. Advance the needlewhile applying negative pres­sure. Deep penetration is not necessary becausethe vessel is fairly close to the surface at the cranial aspect of the sternum.e. Look for a flash.Once one is obtained, blood should be obtained with ease. If no blood is seen,redirect­ing the needle may be necessary or the needle may go through thevessel.f. Use of thistechnique is strongly recommended only by experienced veterinary team members.IV Catheter PlacementSites: Include jugular, saphenous, and cephalic veins (Figure 11.8).Technique:a. Materials required:24- or 26-gauge IV catheter, clippers and surgical preparation supplies, tape,flush, tourniquet if needed.b. Prepare the siteusing aseptic technique.c. Apply a tourniquetas needed.d. Use a 22-gaugeneedle to penetrate the skin lateral to the vein in the area where the catheterwill enter just prior to entering the vein. In general, ferret skin isdifficult to penetrate.e. Visualize the vein,insert the needle, and advance the catheter until blood enters the hub of theneedle.f. When the catheteris properly seated in the vein and blood is flowing freely from the catheter,flush the catheter thoroughly with about 0.2 to 0.3 ml hepa­Figure 11.8. Cephalic catheter placement. (Photo courtesy of Dr. Sam Rivera.)rinized saline and replace the cap. Remember that a smaller amount offlush will be used to accom­modate the smaller patient.g. A small drop ofsurgical glue may be placed at the catheter-skin junction. Tape the catheter inplace, taking care not to apply too much pressure to the skin and resultingconstriction of the vein.h. Connect the IV lineto the patient using a minidrip set and/or an IV pump with the potential tocali­brate fluid rates for smaller patients.Intraosseous Catheter Placement Sites: Include humerus, tibia, and femur(Figure 11.9). Technique:a. The femur is thebest site that causes the least restriction in movement.b. Use 20- or 22-gaugecatheters. A stylet or larger needle may be used to create a pilot hole, orentry point, for the catheter.c. General anesthesiais recommended except in debili­tated individuals. Local anesthetic blocks maybe used for the surrounding soft tissue and periosteum.EnemaMaterials needed: Small rubber urinary catheter, water-based lubricant,enema solution (warm soapy water), syringe. Technique:a. Insert thelubricated tip of the rubber urinary cath­eter into the rectum of therestrained animal,b. Attach the syringefull of enema solution to the end of the catheter and gently flush the colonusing constant steady pressure.Ferrets  253Figure 11.9. IO catheter location. (Drawing by Scott Stark.)c. Remove the catheter and cleanse the surrounding skin.Bandage and Wound CareThe same procedures used on other small animals may be used withferrets. A separate small mammal bandage box with ready-to-go materials may beused. The materials should include small-scale items, such as small scissorsand one-half inch tape or materials cut to scale from larger diameter supplies.Blood TransfusionBlood transfusions may be used if a local donor system is in place. Manyfacilities that see large numbers of ferrets may keep healthy donor ferrets onsite in case a transfusion is needed. Other ferrets may be privately owned andavailable as needed on an emer­gency basis.Donor ferrets, similar to their canine and feline counterparts, requireregular screening for disease through physical examination, baseline blood workevaluation, fecal examination, assessment of adrenal hormone levels, and possiblyradiographic and ultra­sonographic examination. These ferrets also need pre­ventivemedical care, including heartworm prevention, regular deworming, andvaccination for rabies and canine distemper viruses.The amount of blood available for transfusion is based upon body weight.The compatibility of donor and recipient ferrets should be determined accordingto previously described methods in canine and feline practice. The donor ferretshould be sedated with gas anesthesia to avoid any struggling and to provide acomplication-free needle stick, which will prevent contamination of the samplewith disruptive clotting factors. The transfusion recipient may receive theblood sample via fluid pump. Prior to transfusion, necessary premedication withanti-hista-mines may be performed to minimize transfusion reactions.The donor ferret should be kept warm, receive replacement fluids and,depending upon the amount of blood removed, will then be designated asunavailable for transfusions for a period of time as determined by theveterinary facility.EuthanasiaEuthanasia is best performed by sedating the patient using chamber ormask induction with gas anesthesia. As an alternate method, telazol(0.2cc/101bIM) may also be used. After the ferret has been sedated, the euthanasiasolution can be administrated via the IV or intracardiac routes.REFERENCESBell JA. 1999. Ferret nutrition. Veterinary Clinics of North America.Exotic Animal Practice, Critical Care, January, 169-192.Fox JG. 1998. Biology and Diseases of the Ferret. 2nd ed.Philadelphia: Lea and Febiger. 5-106. Garner MM, Ramsell K, SchoemakerNJ, Sidor IF, NordhausenRW, et al. 2007. Myofasciitis in the ferret. Vet Pathol 44(1):25-38.Hillyer EV, Quesenberry KE. 1997. Ferrets, Rabbits, and Rodents,Clinical Medicine and Surgery. Philadelphia: W.B. Saunders Company. 4-70.Lennox AM. 2009. Proceedings of the North American VeterinaryConference, 1867-1870. Orcutt CJ. 1998. The Veterinary Clinics of NorthAmerica. ExoticAnimal Practice, Critical Care, September, 99-126. Quesenberry KE, CarpenterJW. 2004. Ferrets, Rabbits, andRodents, Clinical Medicine and Surgery. St. Louis: W.B. SaundersCompany. 21-22.CHAPTER TWELVERabbitsDouglas K. Taylor, Vanessa Lee, Deborah Mook, and Michael J. HuerkampINTRODUCTIONThe domestic rabbit (Oryctolagus cuniculus) is a lago-morph ofthe family Leporidae that descended from wild rabbits found originally in thearea of modern day Spain. Cottontail rabbits are related, but in the genus Sylvilagus. The earlydomestication of the rabbit began in western Europe and northwestern Africa inthe first century B.C. By the mid-1600s, rabbits were raised all over Europefor meat and fur and were in the course of dissemination all over the world viasailing vessels that stocked them as a source of meat supply. Female rabbitsare called "does," males are "bucks," and neo­nates aretermed "kits." Those rabbits raised for food are termed"fryers."Rabbits are attractive as pets because they are quiet, gentle, and relativelyodor-free, they rarely bite, and they can be trained to use a litter box. Theygenerally enjoy good health if kept under sanitary conditions; receive adequatewater and nutrition; and are pro­tected from predators, environmental extremes,drafts, and trauma. Today in the United States, in addition to being kept aspets, rabbits are exhibited for showing, used in scientific research, and usedfor food and fur production. Depending upon the locale and nature of theveterinary practice one could be presented with rabbits from any of thesegeneral areas of use.BEHAVIORRabbits are a generally timid and often submissive prey species with apropensity for chewing and gnawing. If given the space and socialopportunities, they will chase, jump, gambol, rear, bat at objects, gnaw, andexplore (Bayne 2003). Episodes of cavort­ing and exploration tend to beintermittent and inter­spersed with longer periods of huddling or restingagainst a wall or surface. Overall, rabbits are generally quiet, not particularlyplayful with humans and tend to urinate and defecate in a chosen area, whichfacili­tates litter box training. If caged, those of a timid nature retreat tothe back of the enclosure when approached and may thump a hind foot-the latteris a general warning or alarm call. Aggressive rabbits may growl or grunt,charge, flail with the front feet, and attempt to bite. Biting is fairly rare,but rabbits may scratch, especially with the powerful rear limbs. They scentmark by rubbing the chin on objects and they enjoy chewing on wire, wood,cardboard, paper, hay, or other materials they encounter. Sexually intactrabbits of either gender, but particularly males, may fight, and this should betaken into account in counsel­ing owners toward neutering or recommending indi­vidualhousing. Compatible groups of does, particularly if formed in small clusterswhile young, can be main­tained for lengthy periods of time (Bayne 2003).Sexually intact, mature rabbits of either gender may also spray urine and markterritory (Stein and Walshaw 1996).Abnormal and stereotypic behaviors that might be elicited during theacquisition of a history include cage bar chewing, excessive fur plucking,psychogenic water consumption, head swaying or weaving, head pressing,obsession with pawing or digging at the cage floor or food hopper, rapidcircling, or sitting with the head lowered (Bayne 2003). Although not backed byany scientific evidence, stereotypies and abnormal behav­iors are most likelyto be disproportionately high in rabbits kept singly and confined to hutches ascom­pared to those that are more free-roaming in the home. As such, the rabbithutch should be designed and outfitted to encourage species-typical behaviorand enhance the well-being of the inhabitant.In confined conditions, enrichment devices have been documented todecrease the incidence of undesir­able behaviors and increase overall activityof rabbits (Bayne 2003, Johnson et al. 2003). The devices that have been usedmost successfully to encourage the species-typical nudging, playing, andinvestigative behaviors of rabbits are chew-resistant plastic toys and balls,Nylabone® products, sections of PVC tubing,255256  Chapter 12metallic washers suspended from chains, stainless-steel rabbit rattleson spring clips, and hay and other food items specially formulated for rabbits(Bayne 2003, Johnson et al. 2003).Mating of rabbits should be supervised because does may be aggressivetoward bucks. A buck will circle a receptive doe and then quickly mount andcopulate. Mating is an amusing ritual to observe as the post-coital male swoonsoff of the back of the doe. Kits are born in a nest that the doe makes fromhair plucked from the dewlap and other materials that it may scavenge from thecage or environment. The kits are born hairless and blind, an attribute thatdifferenti­ates rabbits from hares, which are born furred and with open eyes. Adoe typically nurses the kits only once per day. Lactation peaks at three weekspostpar­tum. The kits start eating solid food at two weeks of age andcecotrophy commences about a week later. Weaning should be done at five to sixweeks.ANATOMY AND PHYSIOLOGYRabbits have a number of distinguishing morphophys-iologic attributesthat make them interesting and differentiate them from more traditional pets.For example, rabbits importantly use cecal bacterial fer­mentation in digestion,cannot vomit, have a narrow pylorus, and engage in cecotrophy. In some part dueto the latter three characteristics, they rarely have an empty stomach. Theyhave large, accessible veins and arteries in the ears, facilitating fluidadministration, intravenous injection of therapeutic agents, blood-gasanalysis, and direct blood pressure measurement. The ears, in addition to highvascularization, serve in sound gathering and heat dissipation and are highlysensitive and fragile. Consequently, rabbits should never be restrained orcarried by the ears.Rabbits have a high muscle-to-bone ratio. While 13% of the body weightis comprised of bone in the cat, only 8% is bone in the rabbit (Harkness andWagner 1989). Because they are engulfed in large muscle masses, the long bonesand lumbar spine are particularly at risk of fracture or luxation,respectively. For rabbits used as pets and in research, this is an unfortunatecharacteristic that can be attributed to a heritage of development for maximalmeat production. Three in five rabbits will have atropinesterase in the serum,which rapidly hydrolyzes atropine, essentially rendering the agentunpredictable to worthless in effect. Like cats, rabbits are prone tolaryngospasm and may be a challenge to intubate owing to the com­bination of asmall glottis, narrow oropharynx, rela­tively large and fleshy tongue, andother anatomic factors. The skeletal anatomy of the rabbit is shown in Figure12.1.The predominant white blood cells are lymphocytes and heterophils, therabbit equivalent of a neutrophil (Color Plate 12.1), which may be mistaken foran eosinophil because of the presence of numerous small intracytoplasmiceosinophilic granules. Unlike cats and dogs, lymphocytes are generally morecommon than granulocytic cells (heterophils). Basophils (2% to 7%) are morecommon in rabbits than other species (Harkness and Wagner 1989). Reticulatedred blood cells may also be encountered more frequently in rabbits than in dogsor cats.Clinical chemistry values observed in rabbits are not remarkable ascompared to dogs and cats with the exception of serum amylase and calciumlevels.PelvisFigure 12.1. Rabbit skeletal anatomy.Rabbits  257Plate 12.1. Rabbit blood smear showing heterophil. (Photo courtesy of Dondrae Coble.) (See also colorCalcium is absorbed from the gut efficiently at a high rate.Consequently, blood levels relate directly to dietary levels, often resultingin a dietary nonpatho­genic hypercalcemia. Rabbits on high calcium diets mayhave blood levels meeting or exceeding 15mg/dL. Calcium is cleared from theblood by the kidney and excreted in the urine. Most other species excretecalcium primarily in the bile (Cheeke 1987). Rabbits are susceptible toarteriosclerosis as a consequence of dietary calcium imbalance or vitamin Dexcess. Serum amylase values are considerably lower than those found in dogsand cats (McLaughlin and Fish 1994). Blood gas values of normal rabbits andtheir interpre­tation are essentially identical to other species.Reproductively, does have a duplex uterus with each uterine horn havingits own cervix and eight to ten mammary glands. Does can rebreed withintwenty-four hours of parturition, termed "kindling" in the parlanceof rabbit users, and produce up to eleven litters per year. Kits may showgrowth rates of up to 35 to 40 grams per day. Like cats, ovulation in rabbitsis coitus-induced. Unlike cats, the receptive does are not likely to driveowners to distraction, but intact bucks, especially those that are house pets,regularly mount seemingly everything in sight, and not uncom­monly the ownersslippered foot after sitting down in the evening to relax. The inguinal canalsremain open for the life of the buck and the testicles may inter­changeably befound in the scrotum or retracted into the abdomen. Herniation of otherintraabdominal organs is prevented by large fat depots immediately covering thecanals (Swindle and Shealy 1996). Figure 12.2 shows rabbit visceral anatomy.The rabbit is most interesting and unique from the perspective ofdigestion. It is a nonruminant herbivore dietarily preferring the tender,succulent parts of plants. The teeth are open-rooted and grow continu­ously.The normal dental formula is 12/1, CO/0, PM 3/0, and M3/3, and is unique becausethe upper dental arcade includes two sets of incisors with a small, sec­ondarypair, the peg teeth, situated immediately to the lingual side of the largerlabial pair. The single pair of lower incisors occludes with the uppersecondary inci­sors. The void between the incisors and premolars that is devoidof canine teeth is called the diastema (Figure 12.3). The incisors may grow ata rate of up to 1cm/ month.Rabbits have a glandular stomach that functions essentially as a storageorgan. The cardiac sphincter has tone to the degree that true vomiting isprevented. The stomach is never empty and even after a twenty-four-hour fastwill typically be more than half full (Griffiths and Davies 1963). The stomachof the adult rabbit is noteworthy for having a gastric pH that is significantlylower than that of other species (Cheeke 1987). This renders the uppergastrointestinal tract sterile, serving partly to protect against the oralroute of inoculation by pathogens. The gastric pH is higher in sucklings, permittingbacterial colonization of the hindgut by cecotroph-oral inoculation from adultsin the population. Unfortunately, it also provides a window of opportunity forentry of bacterial gastro­intestinal pathogens, particularly at or around thetime of weaning.The small intestine, similar to most species, is the major site of acidneutralization, protein and carbohy­drate digestion, fat emulsification, andabsorption of many nutrients. Rabbits are hindgut fermenters, similar to thehorse, with digestion characterized by selective excretion of fiber, cecalfermentation, and reingestion of cecal contents. The spacious cecum, comprisingabout 40% of the total gastrointestinal capacity, is a site of constantperistalsis with mixing and remixing of its contents and where an intricate anddelicate relationship exists between nutrients, the microflora, and motility.It is the primary site of bacterial fermen­tative digestion and waterabsorption. The anaerobic flora important in cecal fermentation are comprisedof Bacteroides and other species (Cheeke 1987, Davies and Davies2003).Fermentation of carbohydrates results in the pro­duction of volatilefatty acids, in a process similar to that of rumination, which are absorbedthrough the cecal wall and used as a source of energy (Cheeke 1987). The colon,characterized anatomically by serial sacculations (termed haustrae), contractsand moves258  Chapter 12Figure 12.2. Rabbit visceral anatomy.Figure 12.3. Rabbit dentition.fluid and small digestible particles back into the cecum and propelslarge pieces of fiber distally where they are formed into the excreted hardpellets that are typically observed in litter boxes and fecal pans.At intervals, the cecum contracts and the fluid, protein, and vitamin-richcecal contents are expelled into the colon, formed into small, soft balls,covered with mucin, consumed directly from the anus, and swallowed whole by therabbit (Davies and Davies 2003). This process is known as cecotrophy and itserves to recycle vitamins, amino acids, volatile fatty acids, and digestedbacteria to the upper GI tract for absorption or further digestion as needed(Davies and Davies 2003). The unique separation of the nutritive products ofcecal fermentation and fecal waste allow­ing for the reingestion and absorptionof bacteria and their by-products in the small intestine results in moreefficient use of forage proteins than rumination. It is enabled by the fususcoli, a muscular thickening at the termination of the transverse colonexclusive to lagomorphs that regulates contractions that separateRabbits  259Figure 12.4. Rabbit GI tract.digestible from indigestible material (Davies and Davies 2003).Morphologically, the cecotrophs appear as clumps of smaller, soft, moistfecal pellets that glisten from their gelatinous coat. This mucus-like membraneserves to protect the cecotrophs, and fermentative commen­sals containedtherein, from the gastric pH. Cecotrophs are also called "nightfeces" or "soft feces." As a general rule, cecotrophy generallyfollows about four hours after consumption of a meal (Davies and Davies 2003).While wire caging has no effect upon cecotro­phy given the consumption of the cecotrophsdirectly from the anus, the act can be prevented through the application of anElizabethan collar.Anatomically, the rabbit gastrointestinal tract is also unique withrespect to the presence of a lymphoid mass, the sacculus rotundus, at the terminationof the ileum into the cecum. Lymphoid tissue is also found in the appendix atthe cecal tip (Figure 12.4).BIOLOGIC AND REPRODUCTIVE DATAIn the interpretation of laboratory tests, one should ideally rely upona normal reference range for the species provided by the diagnostic laboratorythat has conducted the test(s). When such values are not pro­vided by thelaboratory, the ranges in the tables that follow can be used as anapproximation of what can be expected in the normal healthy rabbit (Tables 12.1,12.2, 12.3). However, one should appreciate that "normal values" maybe influenced by laboratory variation, sample collection technique (e.g. extentof restraint), type of anesthesia (Gonzales et al. 2005), hemolysis,post-collection sample handling (e.g. refrig­eration), time to centrifugation,centrifugation charac­teristics, breed and age of the subject, and otherfactors. The numeric data provided in the tables below are normal valuesobtained from research populations of rabbits that were of fairly uniformgenotype and age and maintained under standard conditions. They are presentedas the normal distribution about the mean of a healthy population of rabbits.Presentation of values in this format merits several comments. First, someparameters may not have a Gaussian distribution and a normal distribution maynot apply. Second, 5% of normal, healthy animals have values that lie outsideand at the extremes of the normal range. The interpre­tation of laboratorydata, as in any other circumstance with any other species, should take intoaccount for interpretation the history, findings from a physical examination,and results of any other diagnostic tests.HUSBANDRYRabbits can be housed either indoors or outdoors, the latter withappropriate shelter from the elements. Rabbits can be litter box trained and,for this reason, make suitable indoor pets, but their proclivity for gnawing isa drawback. Furniture, carpets, window dressings, toys, electrical cords, andshoes provide numerous indoor targets for gnawing. Wherever they are housed itis critical to protect rabbits from drafts, temperature extremes, predators,flying insects, and environmental intoxicants. Rabbits are cold-weathertolerant and are best kept at temperatures of 55°F to260Chapter 12Table 12.1. Hematology and blood coagulation values.NormalParameter distribution Reference72°F or slightly below and 30% to 70% relative humidity (Patton 199A). Rabbits can be housed out­doors if protectedfrom cold below 40°F in the winter and excessive heat in the summer.Protection from cold, drafts, and moisture in winter can be accomplishedby providing a covered nesting > Table 12.2. Clinical chemistry values.   Normal   Parameter distribution Reference AST (U/L) 0-30 Yu et al. 1979 ALT (U/L) 0-60 Yu et al. 1979 GGT (U/L) 0-8 Hewitt et al.     1989 SAP (U/L) 0-139 Hewitt et al.     1989 CPK (U/L) Hewitt et al.     1989 BUN (mg/dL) 9-22 Hewitt et al.     1989 Creatinine (mg/dL) 0.6-1.5 Hewitt et al.     1989 Glucose (mg/dL) 86-137 Hewitt et al.     1989 Amylase (U/L) 270-700 Yu et al. 1979 Total bilirubin 0.4-9.2 Yu et al. 1979 (mg/dL)     Sodium (mEq/L) 138-150 Gillett 1994 Chloride (mEq/L) 92-120 Gillett 1994 Calcium (mg/dL) 6-15 Yu et al. 1979     Hewitt et al.     1989     Gillett 1994 Phosphorus (mg/dL) 3-5 Yu et al. 1979 Potassium (mEq/L) 3.5-7 Gillett 1994 Total protein (g/dL) 5.3-7.6 Yu et al. 1979 Albumin (g/dL) 3.1-4.7 Yu et al. 1979 box containing straw, shavings, or other insulative bedding. In hotweather, generally temperatures above 85°F, rabbits require shade and plenty ofcool water. Heat stress is a significant risk at this temperature and above. Inextreme heat, consideration should be given to moving the hutch to a breezygarage or patio with a fan. Moving the rabbit indoors to an air conditionedarea may be too much of an acute environmental stressor and such drasticactions on the part of an owner should be discouraged.Plans for rabbit hutches and nesting boxes can be obtained fromlibraries, extension agents, or feed com­panies. Assembled cages suitable forrabbits often can be obtained from pet stores. At a minimum, rabbits confinedto cages should be given sufficient floor space to stretch out to full lengthwith sufficient head room to permit sitting on the haunches. Hardware cloth of1.25- x 2.5 cm-grid is suitable for flooring, but the animal should have accessto other surfaces as well because wire flooring can predispose the rabbit to > Total WBC (10 V) 4.6-13.2 Wolford et al.     1986 Heterophils (%) Wolford et al.     1986 Lymphocytes (%) >50% Wolford et al.     1986 Monocytes (%) 0-3% Wolford et al.     1986 Eosinophils (%) 0-2% Wolford et al.     1986 Basophils (%) 0-7% Wolford et al.     1986 Platelets (103/ul) 300-700 Wolford et al.     1986 PCV (%) 33-45 Wolford et al.     1986 RBC (106/ul) 5.5-7.5 Wolford et al.     1986 Hemoglobin (g/dL) 11-15 Wolford et al.     1986 MCV (fl) 56-66 Wolford et al.     1986 MCHC (%) 32-36 Wolford et al.     1986 MCH (pg) 19-22 Wolford et al.     1986 Reticulocytes (%) Wolford et al.     1986 Bleeding time 0.8-2 Livio et al. (minutes)   1988 Clotting time 1.1-5.5 Livio et al. (minutes)   1988 OSPT (seconds) 7.9-17.9 Gentry 1982 APTT (seconds) 19.5-22.5 Gentry 1982 Prothrombin time 6.9-8.1 Lee and (seconds)   Clement     1990 Thrombin time 5.7-14.1 Lee and (seconds)   Clement     1990 Rabbits  261Table 12.3. Normative and reproductive values.Normal > Parameter distribution Reference Life span (years) 5-7 (15 Gillett 1994   maximum)   Gestation (days) 31-32 Gillett 1994 Litter size (kits 4-10 Gillett 1994 born)     Weaning age 5-6 Gillett 1994 (weeks)     Rectal temperature 101-104 Gillett 1994 (°F)     Heart rate (bpm) 200-300 Gillett 1994 Respiratory rate 30-60 Gillett 1994 (bpm)     Blood pressure, 90-130 Gillett 1994 systolic (torr)1     Blood pressure, 80-90 Gillett 1994 diastolic (torr)1     Food intake (g/kg/ 50 Harkness and day)   Wagner     1989 Water intake (ml/kg/ 100 Harkness and day)   Wagner 1989^lood pressure values are given for instrumented conscious rabbits withcentral arterial catheters. Values average 10 torr less if the centralauricular artery is used (Edwards et al. 1959).pododermatitis. Wire flooring should be cleaned regu­larly to removesuspended hair and feces. Sexually mature rabbits, whether male or female,should be individually housed, known to be compatible, or closely monitoredbecause they may attack one another. Attempts at environmental enrichmentshould focus on providing hiding places, material for chewing (card­board,paper), or nutritional supplements such as hay.NUTRITIONRabbits should be fed a rationed amount of pellets supplemented withfree choice hay and small amounts of fresh foods. Rabbits should be fed andwill readily eat extruded pelleted diets specially formulated for theirspecies. These can be found in feed mills and major pet stores. Pelleted dietsshould be stored at 72°F or lower and used within three to six months of themilling date (PMI Nutrition International 1998). Pelleted diets arenutritionally complete and typically contain 14% to 18% crude protein, 40% to50% carbohydrate, 2% to 4% fat, 10% to 22% crude fiber, and appropriatevitamins and minerals in the proper balance. Indigestible fiber, althoughdiscriminately excreted and not an important source of nutrients, is importantin digestion; normal health; and the preven­tion of fur pulling, gastrictrichobezoars, enteritis, mucoid enteropathy, and other gastrointestinal mala­dies(Cheeke 1987). Fiber stimulates ceco-colonic motility promoting the peristalticactivity critical to the hindgut fermentative process. Without sufficient longparticle length (>0.5 mm) fiber, hypomotility is induced, floral alterationsoccur, the digestive process grinds to a halt, and disease may be induced(Davies, et al. 2003). For growth, 10% to 15% dietary fiber is optimal, whileless than 10% predisposes to GI disease. Adult rabbits should be kept onrations containing 15% to 22% fiber.The pelleted diet should be supplemented with hay because thisindigestible fiber helps maintain a healthy weight, gut motility, and dentalhealth. Timothy and alfalfa hay are available in many pet stores, but alfalfahas high calcium content and so should not be given to rabbits predisposed tourinary sludge.Fresh greens and vegetables can also be given in small quantities.Suitable greens include cabbage, cau­liflower leaves, broccoli leaves, kale,turnip greens, and mustard greens. Other greens, such as sunflower leaves,carrot tops, or green bean vines, can also be offered. There is little to noinformation on the effect of herbs on rabbit nutrition or health and theyshould be used with caution. Overfeeding of fresh greens predisposes to starchoverload, cecal pH extremes, and enteric diseases. In addition, to preventgastroenteritis, it is important not to feed spoiled foods or those discardedin the trash at restaurants or groceries.Another option is to permit grazing on clover or dandelions undersupervised conditions in a fenced, covered enclosure in the yard. This shouldonly be done in areas where fertilizers, herbicides, and pesti­cides have notbeen used. This practice also carries some risk of exposure to parasite oocystsshed by wild rabbits other forms of wildlife, dogs, cats, and other species.Grazing on forages other than clover or dan­delions is not recommended. Forexample, crown vetch contains glycosides that may be toxic and Bermuda grasses,kudzu, and birdsfoot trefoil have low feeding value (Cheeke 1987).Some rabbits may relish human breakfast cereal products, such asshredded wheat biscuits or grain cereals, as a treat. Fruits, whole grains,fat-based treats, and high carbohydrate supplements should be avoided (Davieset al. 2003). It is not necessary, and262  Chapter 12may actually be harmful in some cases, to supplement a proper pelleteddiet with minerals.As a rule of thumb, a rabbit generally consume 5% of its body weight indry feed and 10% in water. Rabbits kept as pets or used in research typicallyare limit fed pelleted diets, while those grown for food production or that arelactating are fed ad libitum. Peak food consumption in ad libitum fed rabbits isbiphasic, occurring in the interval from late afternoon to approximatelymidnight and again shortly after dawn (Davies and Davies 2003). Limit orcontrolled feeding is done by feeding 50% to 75% of the ad libitum consumption onceper day and is important in preventing obesity and urolithiasis and otherwiseopti­mizing health.For a medium-sized rabbit (4- to 6-kg adult), limit feeding is done byproviding 120 to 180g pelleted diet /day. This translates to 3 to 4oz or about2/3 cup. Administration of the ration by limit feeding encour­ages dailyobservation of the pet and prompt detection of anorexia as a tip-off to anunderlying health problem. Pregnant does should be fed 175 to 225 g/ day and atparturition they should be gradually increased over a few days to ad libitumfeeding. Limit feeding is especially important at weaning during the dietarytransition from milk-based diet to plant-based food when there may not besufficient brush border enzymes in the gut to digest plant carbohydrates andprotective maternal antibodies are waning. Limit feeding of weanlings protectsthem from osmotic over­load, pH extremes, and enteric disease. Weanlings ofmedium-sized breeds should be given 60g/kg/day up to a maximum of 120 to180g/day.Rabbit kits are entirely dependent upon milk until ten days of age andthen they progressively begin to consume solid foods and maternal-origincecotrophs up until weaning at around four weeks of age (Davies and Davies2003). Kits typically nurse once daily with ingested milk forming a semi-solidcurd protected in the stomach by an antimicrobial fatty acid product formed bythe action of the kits digestive enzymes on the milk; this is called"stomach oil" or "milk oil" (Davies and Davies 2003). Thiscurd gradually passes into the intestine over the time between feedings (Daviesand Davies 2003). Rabbits fed on milk substi­tutes or milk from another speciesfail to develop the protective fatty acid products and are devoid of colos-tralantibody, making them susceptible to bacterial enteric infections (Davies andDavies 2003).Water should be given free choice and is generally consumed at twice thefeed intake quantity or about 100 120ml/kg/day. Water consumption varies withfactors such as environmental temperature, diet com­position, and health (e.g.lactation). Lactating does consume water up to 90% equivalent of their bodyweight daily (Harkness and Wagner 1989).COMMON AND ZOONOTIC DISEASESThe medical management of rabbits can generally be accomplished bymeeting a few basic goals. The tenets of preventive care are good nutrition andsanitation combined with protection from predators, drafts, envi­ronmentalextremes, environmental intoxicants, and trauma.Rabbits commercially reared are often raised in pole barns and, for themost part, are free of infectious agents. Pasteurella-iiee flocks are notuncommon, but most sources have some problems with coccidiosis,encephalitozoonosis, and, on occasion, internal and/or external parasites. NewZealand white and Dutch belted rabbits are often available as specificpathogen-free animals from rabbitries. Other outbred stocks or domestic breedsare generally not pathogen-free and typically are colonized by Pasteurellamultocida. Rabbits obtained from pet stores, unless the vendor canmake a specific claim otherwise, should be assumed to be Pasteurella-mitcttd.Clientsconsidering the pur­chase of a rabbit should be counseled to obtain it from asource with a Pasteurella-iree colony or to obtaina kit at weaning or as close to weaning as possible. This is arguably the bestadvice, from a preventive medicine standpoint, that can be given to a clientdesiring a pet rabbit.In private practice, a domestic or wild rabbit is most likely to beencountered in the clinic for interventional purposes rather than preventivemedicine. There are no effective vaccines for specific rabbit diseases avail­ablein the U.S., for example, and, other than neutering over-sexed males orperforming ovariectomies on females, there is little in the way of preventivemedical procedures that a rabbit owner may seek proactively. However, clientsthat otherwise own dogs or cats may seek the advice of a clinic in providingproper care for their rabbits. Knowing a little bit about rabbits may not onlybe good for the occasional rabbit patient, but it may also be valuable inmaintaining business.The most common presentations of rabbits to a veterinary clinic are forabscesses, malocclusion, elec­tive surgical procedures such asovariohysterectomy and orchiectomy, and possibly nail trimming. Rabbits alsomay experience respiratory, gastrointestinal, or integumentary illnesses, aswell as neoplasia. The rabbit diseases of greatest clinical importance aregrouped into those affecting the respiratory, digestive,Rabbits  263and integumentary systems and by infectious, inher­ited, ortraumatic/environmental etiology.Respiratory Infectious DiseasesBacterial upper respiratory tract disease in rabbits is commonlyreferred to as "snuffles," and is character­ized by sneezing,mucopurulent nasal discharge, and conjunctivitis. This syndrome is the mostcommon infectious illness in pet rabbits, and the usual etiologic agent is thebacterium Pasteurella multocida. The organism ispart of the normal nasal flora of cats, as well, but the serotypes that causedisease in rabbits differ from those in cats. Other bacteria have beenidentified in cases of rabbit snuffles, including Bordetellabronchiseptica and Staphylococcal species, but their importance to thepathogenesis is unknown and may be trivial (Deeb and DiGiacomo 2000). Inrabbitries and/or pet stores where Pasteurella is enzo­otic, up to90% to 100% of adult rabbits are infected. Inapparent carriers of Pasteurella occur frequently,and subclinical infections localized to the nasal pas­sages or tympanic bullaeare common. On the other side of the clinical spectrum, the bacterium may causea chronic, progressive, incurable, potentially fatal, multi-systemic disease,starting with the upper respira­tory tract. Most commonly, the syndromepresents with frequent sneezing or mucopurulent nasal dis­charge (Langan et al.2000).Pasteurella may be transmitted from rabbit to rabbit by directcontact, close contact aerosol, or, less fre­quently, venereal routes. The roleof fomites in trans­mission is unclear. Pasteurella multocida is harbored in thenasal cavity and/or tympanic bullae where it may remain localized. Harborage inthese areas protects the bacterium from antibodies and adminis­teredantibiotics. The organism is capable of dissemina­tion from the nasal passagesto other parts of the body, leading to a constellation of clinicalmanifestations including conjunctivitis, skin abscesses, inner ear infec­tion,pyometra, orchitis, pneumonia, or septicemia.In a rabbits with suppurative clinical signs, diagno­sis ofpasteurellosis can easily be confirmed by bacte­rial culture. When septicemicPasteurellosis is suspected, the organism should be recoverable from the blood.Asymptomatic carriers may prove more difficult to diagnose, because even deepnasal swabs may not iden­tify all organisms. When carriers are suspected, deepnasal swabs may be attempted under anesthesia/seda­tion, for both culture andpolymerase chain reaction amplification, using an alginate swab. Alternatively,the serum can be assessed for antibodies against Pasteurella multocidathatmay be suggestive of expo­sure and infection (Sanchez et al. 2004).There are no effective vaccines, commercially avail­able or otherwise,to prevent pasteurellosis or control its clinical signs, although there havebeen many attempts at generating them. Veterinary care is primar­ily supportiveand symptomatic, and may be dissatisfy­ing for all parties. Antibiotics, suchas marbofloxacin (Rougier et al. 2006), sulfas, chloramphenicol, tetra­cyclines,or enrofloxacin, may be given for a month or more and result in improvement ofclinical signs, but it is difficult to eliminate the organism. Upon comple­tionof a course of therapy, symptoms may recrudesce and worsen over time.Consequently, for the most severe cases, antibiotics may simply buy time for anowner to come to terms with the prospect of euthana­sia. Less severe cases mayimprove and stabilize, but animals may remain carriers. Supportive caredelivered by a veterinary technician is symptom-directed and may includeregular cleaning of obstructed nares, flushing of the nasolacrimal duct incases of severe conjunctivitis, nebulization or vaporizer treatments, andexcision or incision/drainage of abscesses.The proportion of rabbits with pasteurellosis increases as rabbits age.By adulthood, 90% or so of animals from a rabbitry with enzootic infectionbecome colonized. Preweanling rabbits have a low rate of infection and earlyweaning can be used as a tool to obtain Pasteurella-free animals. Additionally,treat­ment of pregnant does prior to kindling and through lactation withantibiotics such as furazolidone, oxytet-racycline, or sulfaquinoxaline in thediet or drinking water suppresses the bacterium and promotes the weaning ofpathogen-free kits.Diseases of the DigestiveSystemRabbits, particularly weanlings and young kits, are commonly subject todiarrheal disease. Infectious agents that play an important part in thegastrointes­tinal illnesses of rabbits include coccidia; rotaviruses andcoronaviruses; and the bacterial agents E. coli, Lawsonia, and Clostridium. Diet plays a vitalrole in maintaining gastrointestinal health, and the provision of a high fiberdiet will in many cases be preventative or ameliorative.Coccidiosis, caused by enteric or hepatotrophic species of the genus Eimeria, is a major diseaseproblem in young rabbits. Infection can be subclinical or mild, but clinicaldisease is characterized by fulminant diarrhea, and occurs in juveniles,especially recent weanlings, kept under poor conditions or stressed bytransportation. Unlike enteric coccidial species, Eimeria stiedae parasitizes theliver and bile duct. Infection is often subclinical, but in young rabbits theagent may cause fatal hepatic failure characterized by264  Chapter 12icterus, hepatomegaly, elevated hepatic enzymes, wasting, and anorexia.The transmission of coccidia in rabbits is by the fecal-oral route and thediagnosis is made by fecal examination for oocysts or at necropsy.Administration of sulfa drugs, ivermectin, and/or toltrazuril are treatmentoptions (Cam et al. 2008). Because oocysts require a day or more to sporulateat room temperature, the ingestion of night feces is not considered to play arole in the dissemination of disease, and aggressive sanitation is an effectivemeans of control. If housing and fomites are not cleaned effectively, oocystsremaining in the environment may be a source of reinfection for months. VitaminE defi­ciency may potentiate coccidiosis.Rotavirus is enzootic in many rabbitries where it is of mildpathogenicity. It destroys enterocytes that syn­thesize disaccharidases,consequently causing diarrhea due to maldigestion. Infection may be fatal inyoung kits that are not protected by maternal antibodies under epizooticconditions. As with enteric viral dis­eases of other species, treatment isdirected at sup­portive care.Coronaviruses have been found in association with diarrhea in youngrabbits. One survey of commercial rabbitries in North America showed aprevalence of antibodies detected by serology to be as much as 40% (Deeb et al.1993). Definitive diagnosis requires dem­onstration of coronaviral particles ingut contents by electron microscopy. Thus, diagnosis of pet rabbits isunlikely, and treatment remains directed at supportive care.Clostridial enterotoxemia is caused primarily by Clostridiumspiroforme. This Gram-positive, anaerobic bacterium is not normallya part of the gastrointestinal flora or is suppressed to a very low andnonpathogenic level in healthy adults. The normal gut microflora is protective,and its disruption appears to be required for colonization by C. spiroforme. Changes caused byweaning, following environmental stress, or by disrup­tion of the normal florathrough concurrent infection or the use of antibiotics with anaerobic andGram-positive spectra can be predisposing factors. Antibiotics that have beenincriminated in the disease include clindamy­cin, lincomycin, ampicllin,penicillin, metronidazole, and erythromycin. These antibiotics should be usedclinically with caution, with the informed consent of the client, and not on aherd-wide basis.Clinical signs include anorexia, wasting, and diar­rhea, and are usuallythe result of enterotoxins which damage normal gut function. The disease issuspected based on a combination of signalment (the condition usually occurs inyoung rabbits) and a history of recent change in environment and clinicalsigns. Gram stains of gut contents may show typical coiled bacteria. Anaerobicculture can positively identify the organism, and several methods exist toassay for the enterotoxin. Treatment consists of a combination of nursing care,fluid therapy, antibiotics, and increasing the fiber content of the diet,aiming toward a normalization of the gut microflora. The importance of sanitation,for removal of spores from the environment, should be stressed to the client.Tyzzers disease is caused by Clostridium piliforme, a Gram-negativeobligate intracellular bacterium with vegetative and spore forms. Likecoccidiosis, it causes disease most commonly in recent weanlings, especially inthe face of crowding, poor sanitation, or deprivation of food or water. Naturalinfection is thought to be by ingestion of spore-contaminated food or bedding.The spores are hardy and can persist in the environment for years. Mortalitycan be acute and high. The diag­nosis can be difficult to establish and isoften made using special stains (silver) of specimens obtained at necropsy.Serologic assays exist for the agent, but suffer from non-specific cross-reactivityleading to false positives.Enteropathogenic strains of E. coli are also impor­tantpathogens of young rabbits. The bacterium is normally found as part of thecommensal flora, but proliferates in the cecum in disease-causing yellowdiarrhea and leads to high mortality within forty-eight hours (Wales et al.2005). Sucklings within two to eight days of birth and weaned kits less thanthree months of age are most at risk. The organism can be identified byculture, and characterization of the isolate assists in predicting itsvirulence. Good sanitation, fluid therapy, body temperature maintenance, andantibiotics are important in treatment.Lawsonia intracellular is is the cause of proliferative enteropathyand typically afflicts young rabbits. Although infection is characterized by aone- to two-week course of diarrhea, depression, and dehydration, it is rarelyfatal. The organism is difficult to culture; histopathology or moleculardiagnostic assays are usually necessary (Horiuchi et al. 2008). Severely diar-rheicrabbits require fluid therapy and body tempera­ture management.There are few helminth parasites of clinical impor­tance in domesticrabbits. The rabbit pinworm, Passalurus ambiguus, is not contagiousfor humans and is largely nonpathogenic. It is found in the cecum and largeintestine of wild rabbits and occasionally domestic or laboratory rabbits. Thelife cycle is direct and infection is acquired by ingestion. The diagnosis maybe made by demonstration of oocysts by fecal floatation examination techniquesor observation ofRabbits  265expelled adult nematodes on the feces. The eggs (43 um x 103 um,flattened on one side) are laid in embryonated, infective form. Commonanthelmintic agents used in dogs and cats, such as ivermectin, fen­bendazole,and pyrantel pamoate, have high efficacy in rabbits (Carpenter et al. 2001,Curtis and Brooks 1990, Duwel and Brech 1981).Mucoid enteropathy syndrome is a mucoid diar­rheal disease of graveprognosis that is particularly severe in weanling rabbits. The pathogenesisremains largely conjectural, but dietary factors have been implicated.Commercial rabbit feed is high energy and low in fiber, and rabbits on lowfiber diets have lower acetate levels. This fatty acid is thought to be a com­ponentof the protection offered by the normal gut environment. When levels are low,microorganisms may proliferate, further altering the fermentative microflora.The imbalance, in the presence of as yet unidentified microorganisms,progresses to profuse, mucoid diarrhea (Percy and Barthold 2007). Affectedrabbits are thin with a hunched posture, anorectic, dehydrated, hypothermic,and mildly bloated. Dietary change and other stressors, such as painfulinjections, overheating, or inadvertent water deprivation (includ­ingexcessively warm, yet plentiful, water in the summer months), may alsopredispose to disease. Treatment is generally unsuccessful with the case fatal­ityrate approaching 100%. This is clearly a disease in which an ounce ofprevention is worth a pound of cure. Mucoid enteropathy can be prevented byfeeding high fiber rations and restricting the pelleted diet to 60g/kg bodyweight.Gastric stasis syndrome may occur in rabbits of all ages, and generallypresents as an anorectic rabbit with decreased or no fecal production, butotherwise appears normal. It may be possible to palpate a doughy mass (thestomach) in the cranial abdomen, but abdominal palpation may also be normal.Gut stasis can be caused by environmental changes, stress (includ­ingpostoperative stress), or excessive amounts of a high energy, low fiber diet.The gut contents may or may not be predominantly composed of hair, and thepresumptive diagnosis of trichobezoar may occasion­ally be made more rapidlythan is warranted. Due to gastric hypomotility, the stomach contents, whetherhair or ingesta, become dehydrated and difficult to pass. Treatment consists ofrehydrating the contents of the stomach, maintaining hydration of the animal,and stimulating motility. The rabbits should be force-fed liquids and/or fruitand vegetable purees (e.g. baby food). The use of pineapple juice for thebromelin has been advocated as a method for breaking down the mass. The juicemay well work, but the mechanism of action is more likely to be based on thehydration of the mass than a chemical decomposition. If necessary, the rabbitshould be administered subcutaneous or intravenous fluids. Provided there areno signs of impaction, metoclopramide for three to five days should assist inrestoring normal gastrointestinal motility.Additionally, it is important to appreciate that healthy rabbitscommonly harbor gastric trichobe­zoars without pathologic effect. Slaughterchecks of 208 healthy rabbits in one study, for example, showed that 23% had trichobezoars(Leary et al. 1984). In the same study, infusion of rabbit stomachs with latexcausing a large space-occupying mass had no effect on the immediate orlong-term health of the rabbits. Consequently, trichobezoars can be incidentalfindings in rabbits and should not be considered to be patho­logic until provenotherwise.Integumentary Infectious DiseasesThe most important integumentary disease of rabbits is ear miteinfestation by the ectoparasite Psoroptes cuniculi (Figure 12.5). Thecondition, most properly called otoacariasis, may be referred to as ear mangeor ear canker by rabbit keepers. Exudate and inflamma­tion in the ear canal canbe extensive and the mites may also parasitize periauricular areas, includingthe face and neck. Transmission of the parasite is direct from rabbit to rabbitand the life cycle requires twenty-one days for completion. Tens of thousandsof mites may be found on a single animal (Bowman et al. 1992). Mites cansurvive off of the host for weeks at a time (Hess 2004). Infestation causespruritus, head shaking, stress, and competition for nutrients. The ears may bepainful to touch and, in advanced cases, are heavily encrusted with exudate.The mites are large enough toFigure 12.5. Ear mite infestation.266  Chapter 12be seen with the unaided eye, but the diagnosis usually is made byotoscope examination of the large adults (males, 431 to 547 um x 322 to 462 um;females, 403 to 749 um x 351 x 499 um) in the aural canal or micro­scopicobservation of mites from exudate swabbed from the ear.Treatment is with ivermectin by SC injection every two weeks for a totalof three treatments, and aggres­sive environmental sanitation (Curtis andBrooks 1990, Wright and Riner 1984). Although the antipara­sitic agentsselamectin and moxidectin are not labeled for rabbits, both have been used toeradicate Psoroptes cuniculi without ill effects(McTier et al. 2003, Wagner and Wendlberger, 2000). Alternative methods fortreatment, including topically applied ivermectin and oils, have been advocated(Fichi et al. 2007) and may be effective, but thorough environmental sanitationis still required and cases treated thusly should be closely monitored.Venereal spirochetosis is caused by a spirochete bacterium, Treponema paraluiscuniculi. The disease is known by a number of synonyms includingtrepo-nemiasis, cuniculosis, vent disease, and rabbit syphilis. Transmissionmay be horizontal by the venereal (coitus) or extragenital (facial-genitalcontact) routes. Fomite inoculation is also a possibility. In contrast to manyother infectious diseases of rabbits, young rabbits are relatively resistant toinfection, but inci­dence increases with time in a breeding program. Followinginfectious contact, organisms localize and proliferate at mucocutaneousjunctions, causing ery­thema and edema of prepuce, vulva, scrotum, perineum, oranus. The nose, eyelids, lips, and extremities can also be affected. Thelesions become vesicular; exude serum; and then become dry, scaly, and crusty.In the natural course of the disease, lesions persist for at least one to three monthsand often for five months or so (Delong and Manning 1994). During the course ofinfection, the bacterium then colonizes regional lymph nodes where it remainseven after lesions fade. Overt clinical disease is then precipitated by stress.Venereal spirochetosis may be confused with and should be dif­ferentiated fromtraumatic or chemical dermatitis, localized nontreponemal bacterial pyoderma(e.g. "hutchburn"), dermatophytes, and ectoparasites. The diagnosisof treponemiasis is by history, physical examination, and in vitro tests such asdarkfield microscopy and various serologic assays.Penicillins, given for periods ranging from five to twenty-eight days,are the treatment of choice. A less intensive penicillin regimen involvingweekly injections for a total of three treatments has also been advocated(Delong and Manning 1994). Lesions generally resolve and the organism will beeliminated within three weeks of the start of treatment.Ulcerative pododermatitis presents as decubital ulcers, typically on theplantar surfaces of the hind feet (Figure 12.6). Superficial ulcers and scabsmay prog­ress, without intervention, to abscesses or granulomas, and furtherprogression could lead to osteomyelitis or sepsis. The lesions arepressure-induced and predis­posed commonly by a genetically-related decrease inhair density on the feet. Poor sanitation, excessive environmental moisture,foot stomping, large adult size, and wire-bottomed caging all may be contribu­toryfactors. Treatment consists of debriding and cleaning the site, and topicalapplication of antibiotic creams with bandaging and rebandaging for weeks at atime.Other interventions should include improving sani­tation and changingthe flooring from wire to flat metal slatted flooring or solid flooring withuse of a litter box. The latter, however, may become soiled and aggravateproblems. When rabbits must be kept on wire the strategic placement of a flat,solid resting board in an area of the cage preferred for rest and away fromareas used for urination/defecation may be helpful. Successful treatment islengthy and the condi­tion often recrudesces, particularly if housing condi­tionsare not changed. Staphylococcus aureus is the mostfrequently identified associated organism (Percy and Barthold 2007).Moist dermatitis (blue fur disease) may be seen in the perineal areasubsequent to urine or diarrhea scald, known colloquially as "hutchburn," or around the face, neck, or dewlap as a consequence of malocclu­sionor continual moistening of the fur by drinking from a water bowl. The latterpresentation may be called "slobbers" by fanciers and breeders. TheinitialFigure 12.6. Pododermatitis.Rabbits  267physical insult may lead to secondary bacterial derma­titis caused bythe bacterium Pseudomonas aerugi­nosa, which originatesfrom feces or fecal-contaminated drinking water. Pseudomonas species elaborate ablue-green pigment that discolors the affected area. Rabbits so afflicted areoften described as having blue fur. The treatment is by correcting theinitiating cause, drying the environment, clipping fur in the area of anylesions, and treating the lesions with astringents and topical or systemic gentamicin.The condition is prevented by good sanitation, controlling obesity, and notoffering water from bowls or crocks.Necrobacillosis (Schmorls disease) is a syndrome that most commonlyrefers to dermatitis of the face and neck area caused by excessive salivation,usually due to malocclusion or other dental disease. Skin lesions may be foundelsewhere on the body, however, and infection is typically associated withfilthy condi­tions or skin trauma. The microorganism generally associated withthis condition is the Gram-negative anaerobic bacterium, Fusobacteriumnecrophorum. This bacterium is a normal inhabitant of the gastroin­testinaltract and causes ulceration and necrosis of the skin when inoculated into it.Fecal contamination from cecotrophy may be a source of oral inoculation. Thediagnosis is made by a combination of clinical signs and anaerobic bacterialculture. Treatment consists of debriding wounds and applying topicalantibiotics. Systemic drugs with an anaerobic spectrum such as penicillins,cephalosporins, or chloramphenicol may be used in severe cases. Prevention isachieved by main­taining a high level of sanitation, providing dental carewhere indicated, and eliminating sources of trauma such as coarse feed or sharpedges in cages.Fly strike is not uncommon in rabbits housed out­doors. Larvae of Cuterebra species can befound in the subcutis, causing 1- to 3-cm swellings, each housing a singlelarva and each having a breathing hole. Larvae should be surgically removedcarefully, so as not to damage them, because crushed larvae can cause ananaphylactic reaction. Maggots of non-Cuterebral species may befound anywhere on the body, but have a predilection for the perineal skin foldsof aged or obese rabbits. For all fly species, the treatment is to remove thelarvae and clean the wound site under sedation, provide antibiotics and fluidtherapy, and administer ivermectin for two doses at two-week inter­vals.Preventive strategies consist of fly control mea­sures including screeningoutdoor pens.Mastitis can occur in lactating does, and also is possible independentof lactation. The offending bac­teria are typically Staphylococcusaureus, streptococci, or Pasteurella (Pare et al. 2004).Treatment consists of antibiotics, warm compresses, fluid therapy, and, whereindicated, incision and drainage.Other Infectious DiseasesCerebral larval migrans and fatal central nervous system disease may beseen in rabbits that acquire aberrant infections with Baylisascaris species. Diseasemay occur where raccoons or skunks contaminate stored feed or hay, gain accessto barns or cages housing rabbits and defecate from the cage top into theinterior of the cage, or where pet rabbits have grazed contaminated forage orbeen housed on con­taminated hay (Deeb and Digiacomo 1994, Jensen et al. 1983,Kazacos and Kazacos, 1983). Signs of infec­tion include progressivetorticollis, ataxia, tremors, and falling (Deeb and Digiacomo 1994). Thediagnosis is based on clinical signs and histopathology, but fresh minced braincan be placed in a Baermann apparatus to separate the larvae for specificidentification. The condition is untreatable. Rabbits are a dead-end host forthis disease and cannot pass it on to humans.There are a number of other infectious diseases of rabbits that are notlikely to be encountered in pet rabbits, but are worth mentioning. Obeliscoides cunic­uli,therabbit stomach worm, is common in wild rabbits and may be found in laboratoryrabbits that are fed contaminated feed or grazed on contaminated forages. It isa trichostrongyle, embedding in the gastric mucosa with a direct life cyclewith shedding for sixty-one to 118 days (Jenkins 2004). Staphylococci may causesepticemia, suppurative disease (including cuta­neous abscesses or mastitis),and conjunctivitis. It is most severe and common in young or distressedanimals. Rabbit hemorrhagic disease (RHD) is caused by a calicivirus andtargets rabbits after weaning. The disease is acute and highly fatal, showingfew clinical signs. The virus usually presents as an explosive out­break withhigh mortality in rabbitries, with rabbits succumbing to a severe andwidespread intravascular coagulopathy (Xu and Chen 1989, Percy and Barthold2007). Slaughter and disinfection are standard proce­dures in rabbitries whereoutbreaks have occurred. Rabbits are also susceptible to toxoplasmosis (Lelandet al. 1992) and may be an accidental host for the canine heartworm (Narama etal. 1982) and other dirofilarial species if housed outdoors.Inherited DiseasesBuphthalmia (glaucoma, ox eye) is not uncommon in New Zealand whiterabbits and is due to inadequate drainage of aqueous humor from the anteriorchamber (Tesluk et al. 1982). It occurs unilaterally or bilaterally and isusually detectable by the time the rabbit is three268  Chapter 12to five months old. Buphthalmia in rabbits is charac­terized bymegaloglobus, increased intraocular pres­sure, and increased corneal diameter.The condition is generally not painful, at least in the early stages, but maycause blindness. Medical treatment with anti-glaucomatous agents generally isnot successful. Consequently, affected rabbits should be monitored regularlyfor pain or distress. Clients should be cau­tioned not to breed affectedrabbits.Splay leg, a developmental musculoskeletal disor­der, is seen in youngrabbits; the rear limbs splay and will not bear weight (Cohen 1969, Deeb andCarpenter 2004). The condition varies in severity, with relatively mild casesshowing only clumsiness when ambulating, to severe cases, which are completelyparalyzed. In the latter cases, euthanasia is warranted. As is the case withmost inherited disorders, clients should be cau­tioned not to breed affectedrabbits.Depending upon the breed and genotype, rabbits may be afflicted by anynumber of other genetic and metabolic diseases including epilepsy,hydrocephalus, arteriosclerosis, cataracts, Pelger-Huet anomaly, cleft palate,lymphosarcoma, and hypertension (Lindsey and Fox 1994). Arteriosclerosis is apolygenic or familial trait that can be seen in all breeds, with calci­fiedvessels visible on radiographs. Clinical signs are vague and may includegeneral malaise, lethargy, and weight loss. Hydrocephalus is often associatedwith dwarfism and brachygnathia, although vitamin A defi­ciency in pregnantdoes will produce identical clinical signs in offspring (Cohen 1969, Lindseyand Fox 1994).Skeletal, Traumatic, and Environmental DiseasesMalocclusion of the incisors (mandibular progna­thism, walrus teeth, andbuck teeth) may be inherited due to the shortening of the maxillary skullrelative to the mandible of normal length with the lower incisors extendingcranial to the upper incisors and growing into the mouth. Malocclusion may alsobe caused from tooth loss due to trauma. More commonly, malocclu­sion resultsfrom high-energy diets causing excessive tooth growth and resulting in teeththat are not worn down adequately (Crossley and Aiken 2004). Uncontrolledgrowth of the incisors or "spikes" which develop as a result ofincomplete or inadequate wearing of teeth leads to functional anorexia andwasting with variable drooling and oral lesions. The treatment for malocclusionis periodic tooth trimming with an appropriate power dental bur or extraction.The owner should be counseled against breeding the animal when the cause issuspected to be genetic.Traumatic vertebral subluxation or fractures may occur secondary to strugglingagainst restraint, improper handling or sudden jumping, or startling a cagedrabbit. Injury is predisposed by the high muscle-to-bone ratio in rabbits. Thelumbosacral joint acts as a fulcrum for the hind limbs with subluxation or frac­turegenerally occurring at L7 or the caudal vertebrae. Diagnosis is made byclinical signs (i.e. posterior paresis or paralysis, loss of pain sensation,urinary retention, and fecal incontinence), palpation, and/or radiography.Sequellae include decubital sores and perineal dermatitis from urine scald,along with uremia from urine retention. To treat, provide shock doses ofmethylprednisolone sodium succinate if the injury is acute. Long-term prognosisdepends on the degree of injury, with mildly injured rabbits responding to acourse of treatment including bladder expression and anti-inflammatory drugs.Severely injured rabbits are likely incurable and may require euthanasia.Pregnancy toxemia is uncommon, but may be seen especially in Dutch orPolish breeds. It is most common in pregnant does in the last week ofpregnancy, but a similar metabolic toxemia may also be seen in pseudo-pregnant,postparturient, or obese does. Obesity and fasting are considered to bepredisposing factors, and there is some evidence that hereditary factors play arole. There is often hepatic fatty infiltration and necro­sis.Clinically-affected animals are depressed and have acetone breath, dyspnea, anddecreased urine produc­tion. Abortion, incoordination, convulsions, and comamay precede death. Death without premonitory signs can be a presentation.Treatment with lactated Ringers or 5% dextrose, steroids, and empiric use ofcalcium gluconate is recommended, but is rarely successful. Prevention isaccomplished by providing an adequate nutritional plane, including ahigh-energy diet late in gestation balanced with obesity prevention.NeoplasiaRetrospective assessments of tumor incidence in rabbits are confoundedby the fact that case reports and his­torical surveys have been largely derivedfrom colonies of research animals in which rabbits, for the most part, rarelylive longer than one to two years (Weisbroth 1994). While tumor incidenceincreases with age, there is no comprehensive tumor incidence information foraging rabbits.Uterine adenocarcinoma is the most common neo­plasm of female rabbitswith a high incidence in the Dutch, Californian, and New Zealand white breeds.The incidence is less than 5% in does under two years of age, but in certainpopulations it may affect 80% of does over five years of age (Percy andBartholdRabbits  2692007). Clinical signs include vulvar bleeding, anemia, and a palpableabdominal mass. The prevention and attempted treatment of the disease is byovariohyster­ectomy (OHE). Unless does are to be bred, OHE is recommendeduniversally. In young rabbits, the most common neoplasm is lymphosarcoma.Unlike other species, in which lymphoid organs are the most common sites ofinvolvement, in rabbits it is the kidney and gastric mucosa (Percy and Barthold2007). Interstitial cell tumors and seminomas have been reported in malerabbits (Weisbroth 1994). Other neo­plasms that have been reported with somefrequency in rabbits include embryonal nephroma, leiomyoma/ leiosarcoma,lymphosarcoma, cutaneous papilloma, and mammary adenocarcinoma (Weisbroth1994).Zoonotic DiseasesDomestic rabbits harbor few zoonoses of any signifi­cance, withdermatophytosis ("ringworm") arguably the most important. Trichophytonmentagrophytes is most common, but Microsporum canis and other speciesmay cause infection (Bergdall and Dysko 1994, Vogtsberger et al. 1986). Typicalred, raised lesions are usually found around the head and ears, and diagnosiscan be made from a skin scraping placed in dermato­phyte test medium or clearedwith 10% KOH. There is a demonstrated association with marginal husbandrypractices, poor nutrition, environmental or internal stress factors,overcrowding, excessive heat and/or humidity, genetics, ectoparasites, extremesof youth or old age, and pregnancy. Direct contact or fomite trans­missions arenot uncommon and rabbits may be asymptomatic carriers (Lopez-Martinez et al.1984). The disease is readily transmissible to humans. Individual animals canbe isolated and treated with griseofulvin (orally or topically in DMSO) ortopical povidone iodine (Bergdall and Dysko 1994).Salmonellosis, often presenting as a peracute fatal disease subsequentto a stressor (e.g., anesthesia, envi­ronmental extremes), has been reported inrabbits. The diagnosis is based on culture and identification of the organismfrom blood, bile, feces, lymph nodes, or affected organs. Treatment isineffective in eliminating the carrier state and, due to the public healthrisks, infected animals should be euthanized.Rabies virus has been identified in pet rabbits in New York state,serving as a reminder that any pet animal with access to the outdoors requiresadequate protection. There are currently no rabies vaccines available for petrabbits.Yersinia pseudotuberculosis is acquired by ingestion and causesemaciation and swollen lymph nodes with variable incidence of septicemia ordiarrhea. Listeria monocytogenes causes acute,sporadic disease in many species. In rabbits, it most commonly causes septice­mia,abortion, and fatality of pregnant does.Encephalitozoonosis, caused by the protozoan Encephalitozooncuniculi, has a tropism for the brain, kidney, and eyes, and maycause neurologic signs, pri­marily head tilt, in rabbits. It may also infectimmuno­compromised humans, with diarrhea, renal disease, andkeratoconjunctivitis associated with encephalitozoono­sis in AIDS patients.Encephalitozoonosis may be found in up to 30% of asymptomatic rabbits incertain colo­nies, and a survey of neurologic pet rabbits revealed 69% to beseropositive (Harcourt-Brown and Holloway 2003). In cases in whichencephalitozoonosis is sus­pected, definitive diagnosis is difficult because ithas historically relied on visualization of lesions in brain tissue or PCR ofthe same. Thus, antemortem diagnosis is based on clinical signs and serology,although a recent report cites positive PCRs obtained from liquefied lensmaterial in cases of uveitis and lens rupture (Kunzel et al. 2008). Infectionis acquired by ingestion, usually of food contaminated with infected urine, ornasal inocu­lation. Little scientific evidence is available regarding treatmentof rabbits for encephalitozoonosis, although albendazole and corticosteroidshave anecdotally resulted in improvement in some cases (Harcourt-Brown andHolloway 2003), and fenbendazole has been shown to resolve others (Suter et al.2001).Certain ectoparasites, such as the fur mite Cheyletiellaparasitovorax, and burrowing sarcoptid mites may be transmissible fromrabbits to humans. Of lesser importance are diseases such as leptospirosis,tularemia, and endoparasitism. Francisella tularensis, the etiologic agentof tularemia, rarely infects domestic lagomorphs, but may cause acute, febriledisease. It is noteworthy that exposure to wild rabbits is associated with thevast majority of human cases. Zoonoses gen­erally can be prevented by wearinggloves and long-sleeved clinical garments when handling rabbits andhand-washing upon the removal of gloves.TAKING A HISTORYThe basic fundamentals of the history for rabbits are similar to thosefor other animals, and are summarized in Table 12.4. As with other species, thefirst informa­tion to document should be the signalment. Certain rabbit breedsmay be predisposed to particular dis­eases, so breed is an important componentof the sig­nalment, as it would be for dogs. There are currently forty-sevenbreeds in the United States recognized by the American Rabbit BreedersAssociation (ARBA),270Chapter 12Table 12.4 History questions for rabbit owners.TopicQuestionsCommentsSignalment  Age SexNeutered status BreedAcquisition  Location (pet store, breeder, etc.)When the animal was acquiredHousing Cage typeFlooring substrate Exercise amount/frequency Frequency of cage cleaningEnvironment  Other animals in the houseIndoors/outdoors Potential environmental hazardsDiet Types of food: hay,pellets, fresh foodsAmount offered and eatenAnimal Changes in feces orurineChanges in appetite or diet preferences Changes in behavior Coughing,sneezing, or nasal discharge Any medications, including herbal and nutritionalsupplementsOwners may not be correct about the sex of the rabbit and educationmight be necessary.The age when the animal was neutered may also be relevant.How many owners the animal has had may beimportant for behavioral problems. If the animals have wire bottomcages, ask aboutaccess to areas away from the wire. Amount of time per day or weekavailable out of thecage for exercise is important. Newly acquired rabbits or wild animalsmay be asource of infectious disease. Rabbits may like to chew objects whenroaming thehouse.Make sure to ask about treats and if the pellets are just pellets orhave other items (corn, seed, etc.).If there are changes in appetite/drinking, ask about any environmentalchanges such as a new diet, stressful situation, or new water or fooddispensers.ranging in size from 1kg dwarf/small breeds to 5 to 8 kg or greatergiant breeds. Many of these breeds can have multiple colors called "varieties."Rabbit breeds are made distinctive by a combination of body size and shape, earcarriage, and pelt coloration. If the ears "flop" down alongside thehead, rather than stand erect, the breed is of the lop-eared variety. Some non-showgrade lops may have one or both ears "heli­copter" by projectinghorizontally. Many rabbits presenting to a veterinary practice, particularly ifacquired from a pet store, are not purebreds or do not meet the breedstandards. However, some breeds are commonly seen, such as the Dutch, Hollandlop, Mini-lop and Rex (Table 12.5). The best method to become familiarized withrabbit breed is to visit the ARBA web site at: http://www.arba.net.The realities of rabbit medicine are such that most are presented to aclinic for intervention for a clinical problem and there are few presentationsfor wellness exams, which requires a detailed history about both the routinecare of the animal and the presenting com­plaint. To obtain accurate information,it is important to be non-judgmental and carefully ask questions because ownersmay be reluctant to admit what they do not perceive as the "correct"answer. The diet is perhaps the most significant question for many rabbitowners. This requires specifically asking not only what is offered, but whatthe animal actually eats. Unfortunately, many commercial rabbit pellets aremixed with unhealthy items such as corn and seeds, and rabbits may selectivelyeat high carbohydrate and high fat items, leading to obesity or gut stasis(Harcourt-Brown 2002). Pellets can also be composed of different types of haythat may have different nutri­ent values.After questions about husbandry, the general ques­tions about the rabbitare similar to those for other animals. Decreased appetite/anorexia is one ofthe most common presenting complaints for rabbits, but this can indicate a widevariety of diseases. Respiratory, dental, dermatological, and gastrointestinalproblems are common issues for rabbits presenting to the veteri­narian.Sometimes rabbits, especially unspayed adult females, may present because ofincreased aggression. The etiology for aggression can vary from hormonal,normal exploratory behavior, overzealous grooming, pain, deafness, and eveninfectious diseases, so these are all important aspects of the history toaddress in addition to the standard questions (Harcourt-Brown 2002).Rabbits  271Table 12.5. Common purebred rabbit breeds. > Breed Size range (lbs) Color and markings Other characteristics Californian 8-10.5 White with colored nose, ears, tail, and feet Compact body type and pink eyes Checkered giant >11 White with colored nose, ears, eye-rings, cheek spots, a stripe down length of spine, and a pair of spots on each side of body Hare-like posture Dutch 3.5-5.5 White forequarters and thorax with ears, cheeks, and back half of body colored Short, blocky, compact body type Himalayan 4-5 White with colored nose, ears, feet, and tail Small and slender body type with a long, pointed head, erect ears, and pink eyes Holland lop Variable Short, blocky, compact body type Rex 7.5-10.5 Variable Short and upright fur Mini-lop 4.5-6.5 Variable Short, blocky, compact body type New Zealand white 9-12 Albino Compact body type PHYSICAL EXAMINATION AND PREVENTIVE MEDICINEAs with cats, clients should be advised to bring the rabbit to theclinic concealed in a secure carrier in which the rabbit should remain until inthe exam room. A normal rabbit typically rests compactly on all four limbs withits mouth closed and regular twitching of the nostrils. A rabbit presentingwith severe pain will show a hunched posture and immobility and may grind itsteeth. Those in acute pain or distress, espe­cially upon handling, may emit ahaunting, high pitched cry. Many an amiable rabbit will become aggressive if inchronic pain or distress.An appreciation of the normal protrusion of the eyes is necessary torecognize buphthalmia or exoph-thalmia. The eyes may protrude more in somebreeds, males during breeding season, and when fearful (Harcourt-Brown 2002).Rabbits may not menace because of their natural tendency to freeze, so thisresponse is not an adequate test for vision (Vernau et al. 2007). Ocularexaminations can be done as for other species, but keep in mind the caveat thatatropine may be unreliable or ineffective as a mydriatic owing to the presenceof serum atropinesterase in many rabbits. There should be no ocular or nasaldischarge. Periocular depilation or discharge may suggest con­junctivitis ordacryocystitis/nasolacrimal duct obstruc­tion that can occur with bacterialinfections or malocclusion. Dacryocystitis is usually secondary to dentaldisease, particularly of the incisors. Conjunctivitis can be associated withprimary bacterial infections, environmental irritants, or eyelid abnormalities,or it can be secondary to dacryocystitis or an upper respira­tory infection(Harcourt-Brown 2002). Conjunctivitis in combination with nasal discharge iscommonly caused by Pasteurella multocida. Throughout theexamination be mindful of sneezing or evidence of obstructed breathing that maysuggest pasteurellosis. Rabbits are fastidious groomers; therefore, the eyesand nose may be dry while the inside of the front paws has evidence ofdischarge that has been groomed away.The ears should be examined for crusts or discharge that may indicatebacterial or mite infections. Lop-eared rabbits in particular are prone toaccumulations of exudate in the ear canals. The scrotum of mature males and theinternal pinnae of the ears are the only hairless areas on a normal rabbit.Alopecia should be noted, but small areas of alopecia can occur normally aspart of the molting process in some breeds. Mature females can have a largefold of skin over the throat called a dewlap, which is particularly prone toderma­titis in animals that drink from water bowls or have excessive salivasecondary to dental disease. Older cas­trated males can develop skin folds aswell, so do not confuse these with a females dewlap.The hair should be examined for evidence of para­sites, especially onthe dorsum, such as fleas or272  Chapter 12Cheyletiella. If the rabbit spends time outside, look carefullythrough the hair for signs of maggot infesta­tions or Cuterebra larvae. Cuterebra larvae cause cysticstructure or fistulas, and usually the small breathing hole is the onlysuperficial indication of their presence. Skin turgor is the best assessmentfor hydra­tion, and rabbits do not tend to develop appreciably sunken eyes.When dehydrated, the skin can become wrinkled and the hairless skin on thescrotum of the males or the inguinal skin in females/neutered males is the bestplace to assess skin tenting.Gentle palpation of the trunk should show the ver­tebrae and ribs to bedetectable, but not pronounced. The abdominal organs, such as the stomach,kidneys, and spleen, can be easily palpated. With respect to vital signs, theheart rate (130 to 325 beats per minute) and respiratory rate (thirty to sixtybreaths per minute) are more rapid than other more commonly encounteredspecies. Temperature is not usually taken during the exam unless the animal iscritical, but the body tem­perature of the domestic rabbit is significantlyhigher than that found in other species. The normal range is 101°F to 104°F(Harkness and Wagner 1989). Animal and human tympanic thermometers aresometimes used, but these produce more variable readings and may read lowerthan rectal temperatures, although implantable microchip transponders correlatewell with rectal temperature (Chen and White 2006). Ausculted airway soundsshould be short, regular, and rapid in progression with obviously drybronchovesic-ular sounds. Auscultation of gut sounds may be helpful if therabbit has a decreased appetite, but keep in mind that gut sounds are notalways present, even in healthy animals.As described in the restraint section, cradle or lift the animal to lookat the ventrum. The chain of mammary glands of intact does should be palpatedfor evidence of mastitis. Not only lactating or pseudopreg-nant does aresusceptible to this condition, but also non-gravid females with uterinehyperplasia or adeno­carcinoma (Mullen, 2000). The urinary and genital openingsare located immediately below the anus (Figures 12.7,12.8). The testes descendat about twelve weeks of age in the buck, but, due to the open inguinal canals,may be present in the scrotum or retracted partly into the abdomen. Thetesticles can be gently manipulated from the inguinal canals into the scrotumfor palpation by applying mild pressure in the cranial inguinal area. Look forany signs of crusts in the genital region suggestive of ectopic ear mites orsyphi­lis. Rabbits have inguinal glands, which are folds of skin by the analorifice that normally have a brown, foul smelling deposit. At this time, alsolook at feet forFigure 12.7. Sex determination ofa female rabbit. (Courtesy of DondraeCoble.)Figure 12.8. Sex determination ofa male rabbit. (Courtesy of DondraeCoble.)length of nails and evidence of pododermatitis. Obese or mature,potentially arthritic animals may have urine scald or the presence of a fecalimpaction in the fur and perineal skin folds because of their inability togroom themselves.The oral exam is usually the least appreciated part of the physical, soit is often saved for last. A non­invasive indicator of dental disease may besaliva stain­ing around the mouth. The incisors can be easily viewed for lengthand symmetry by retracting the lips. Dwarf rabbits in particular are prone tocongenital incisor malocclusion (Figure 12.9). The molars are difficult toexamine without sedation, except in the hands of experienced and skillfulindividuals. An oto-scopic cone, commonly used for examining dog ears,Rabbits  273Figure 12.9. Malocclusion.or stainless steel nasal speculum with an attached light source can beused to aid visualization in an awake and appropriately restrained patient.Although person­nel can become quite adept at this technique, it is not asubstitute for an anesthetized exam if intraoral disease is suspected.There are no vaccines or monthly prophylactic dewormers standardlyrecommended for pet rabbits in the United States. Owners should bring theirrabbits for a wellness check when they are first obtained and for annual examsthereafter with blood work and screening tests as recommended by theveterinarian. Fecal exams may also be recommended, especially in new rabbits orthose housed outdoors. The best pre­ventive health measure is to spay femalerabbits at about five months of age, depending on the breed, to eliminate thepotential for uterine adenocarcinoma. Neutering both males and femalesdecreases the chance of aggressive behaviors. Remember that males should beseparated from intact females for about four weeks after neutering, becausethey can maintain fertile sperm during this time period.RESTRAINTRabbits are at significant risk of injury from improper handling due totheir general timidity and musculosk­eletal conformation. Something seeminglyas innocu­ous as permitting a rabbit to leap from ones arms into a cage mayresult in a vertebral luxation or fracture, especially of the caudal lumbarvertebrae. Additionally, if rabbits are improperly restrained, they may inflictpainful scratches to a handler from the claws on their powerful rear limbs.The safest way to transport a rabbit is in a small carrier suitable fora cat, but this is not always practi­Figure 12.10. Restraint for transport. (Courtesy of Vanessa Lee.)cal. One appropriate method of restraint is to grasp the scruff of theneck with one hand and support the body and hindquarters with the other arm.While in this position, use the scruff to tuck the head of the rabbit into thecrook of the elbow of the arm, which is used to support the body weight (Figure12.10). This will conceal the rabbits eyes and make it less likely to becomestartled. Never handle a rabbit by the ears or allow its back feet to dangle.When returning a rabbit to its cage, carrier, or setting it on a surface, suchas an examination table, do not allow it to leap or hop from the arms becausethis a common time for back injuries. If possible, place the rabbit down rearend first, especially when placing it back in the cage. This way, the rabbit isless likely to kick from your arms, which predisposes it to back injury.Alternatively, continue to grasp the scruff of the neck with one hand andsupport the hindquarters with the other and place it on the surface with therabbits head concealed in the elbow throughout the process. It will bedisinclined to jump and instead often will simply turn away from the handler.Remember that even a seemingly immo­bilized rabbit can kick its back legs andobtain a back injury.For examination, rabbits should be placed on an examination table andnever left unattended due to the risk that they may jump off of the table. Abathmat or large towel can help the animal have traction and feel secure sothat it is less likely to kick while trying to gain its footing. Whenrestraining a rabbit, stand facing the flank of the patient while placing onehand gently over the thorax and the other upon the hind­quarters, with thepurpose of maintaining the position of the rabbit should it attempt to make a suddenand274  Chapter 12dangerous jump forward. If alone, the hindquarters can be braced againstthe restrainers abdomen. With one hand on the thorax, the other can be usedfor the physical exam. Most rabbits, providing they are not agitated, will sitquietly in a compact posture, occa­sionally raising the head to look about orsniff. Examining the ventrum and genital region is very important but can bedifficult to do safely, and is easiest done with an assistant. Some animals willbecome immobile when placed in dorsal recumbency, which can be advantageous forthe exam, but realize that some argue that the animal is "freezing"because of undue stress (Harcourt-Brown 2002, Mader 2004). One technique is tocradle the rabbit in one arm with each foot securely held with each hand. Somerabbits may be too large or unruly to safely do this, so they can be lifted,allowing them to rest the rear legs on the table for observation.An oral exam requires two people if the animal is not sedated. It iseasiest to wrap the animal in a towel and tuck the back end into therestrainers abdomen (Figure 12.11). Place each arm along the flanks torestrain the body, leaving the hands free to restrain the head and neck area.The restrainer should be careful not to occlude nasal passages because rabbitsare obli­gate nasal breathers and will not breathe through their mouth, eventhough is it open during the exam. Chemical restraint with inhalants (oftenisoflurane or sevoflurane) or injectable anesthetics are useful forradiography, thorough oral exam, or collection of laboratory samples. Foradministration of oral medica­tions or assisted feeding, the rabbit can besimilarly wrapped in a towel and either restrained on a table or in therestrainers lap. While holding the head with one hand, use the other to insertthe syringe or pill giver into the commissure of the mouth at the proximity ofFigure 12.11. Restraint using a towel. (Courtesy of Vanessa Lee.)the diastema and administer the agent. Restraint for specific proceduresis further described in "Clinical Techniques."RADIOLOGYThe common indications for radiography include con­firmation orevaluation of dental disease, vertebral luxation, limb fracture, respiratorydisease, and gastro­intestinal diseases or other intraabdominal disease such asuterine adenocarcinoma. Positioning for radiogra­phy is often facilitated bythe use of sedation or general anesthesia. Otherwise, it is not possible tostretch the rabbit and properly position it for lateral or ventro­dorsal viewswithout risking serious injury to the animal or movement during the exposure,which may degrade the quality of the image. The DV view, rather than the VD, ispreferred in rabbits because it minimizes the risk of torso rotation along itssagittal axis, enhances spino-sternal alignment, and does not impairrespiration. In general, and because of the relatively rapid respiratory rate,short exposure times (0.017 second) are most desirable (Morgan and Silverman1984).If the practice encounters a significant number of lapine patients, itis most advantageous to develop a technique chart for the various anatomicstructures given the capacity of the X-ray generator, the film speed commonlyavailable, and the qualities of the intensifying screen. An alternative is touse a feline technique chart, but to shorten the exposure time, compensate withincrease mA, and, given the less dense bones, reduce the KVp to preserveresolution. Without a custom technique chart, a good starting point for rabbitsis to use a focal film distance of 40 inches and an intensifying screen. For athoracic expo­sure, use 60 kilovolts, 300 milliamperes, and an expo­sure timeof 0.008 second for an 8-cm thick chest (Morgan and Silverman 1984). For asimilarly thick abdomen, increase the exposure time to 0.034 second, reduce themA to 100, and reduce kVp to 58 (Morgan and Silverman 1984).Dental radiographs should include lateral, DV/VD, and two lateraloblique skull films; rostral and intra­oral views may also be helpful (Capelloand Gracis 2005). Obliques are used to thoroughly evaluate the tooth roots, andare obtained by placing the animal laterally and rotating the side of the mouththat is facing upward dorsally approximately 10 to 20 degrees.Mammography films and high quality dental radio­graphic units obtain thebest images, but standard radiographic machines are adequate for most diagnos­ticpurposes. Be very careful when positioning aRabbits  275Figure 12.12. Lateral radiograph. (Courtesy of Ryan Cheek.)Figure 12.13. VD radiograph. (Courtesy ofRyan Cheek.)sedated animal for radiographs, especially a rostral view, becauseflexing the neck can obstruct the airway. The neck should always be extendedwhenever possi­ble (Figures 12.12, 12.13).ANESTHESIARabbits may present an anesthetic challenge to veteri­narians orveterinary technicians unfamiliar or inexpe­rienced with them. However, becausevirtually all drugs, equipment, and resources necessary for safe and humaneanesthesia of rabbits are available in most veterinary clinics, this does notneed to be the case. The rumors regarding rabbit anesthesia, for example, thatrabbits are difficult to intubate, can be overcome by a veterinary technicianwho is knowledgeable and balances caution with confidence. In any event, it isimportant to keep the rabbit calm and isolated from perceived threats such asnoisy dogs. A frightened rabbit can be so permeated with catecholamines thatanesthesia can be adversely affected (Jenkins 2000).PreanesthesiaAs with other companion animals, obtaining a thor­ough history and apreanesthetic physical examination are important in detecting underlyingmedical condi­tions, such as rabbit pasteurellosis, that may compli­cateanesthesia. For rabbits, the nares should be examined for rhinorrhea suggestiveof bacterial respi­ratory disease, the thorax should be carefully auscul­tatedfor evidence of cardiac or pulmonary disease, and the rectal temperature shouldbe determined. Once admitted to the clinic, rabbits should be kept inescape-proof cages in a quiet area.Rabbits have high metabolic energy requirements and are unable to vomit;therefore, the need for pre­operative fasting is a topic of debate. Mature,non-obese rabbits may be fasted for twelve hours to decrease the amount ofingesta in the cecum and stomach that may result in anesthetic overdosages dueto overestimating the real body weight. In addition, rabbits breathe primarilyby diaphragmatic movement, so fasting to decrease stomach volume will enhancerespiration during anesthesia. However, this may have variable effect due tocecotrophy and given that rabbits will drink water to excess when fasted (Chew1965). Fasting may also cause mild metabolic acidosis or postoperativegastrointestinal disturbances (Flecknell et al. 2007). Short preoperativefasting periods between two hours (Jenkins 2000) and up to four hours (Heard2004) are recommended. Fasting in excess of twelve hours is contraindicatedbecause it may promote hypo­glycemia and more severe metabolic acidosis and, inyoung rabbits or adults of small breeds, fasting for more than a few hours mayinduce the same condi­tions. Fasting of obese, pregnant, or postparturientrabbits is contraindicated because it may predispose to ketosis and livernecrosis.Preanesthetic medications are not typically used, with the exception ofanticholinergic drugs, because single injection anesthesia techniques have beendevel­oped that minimize the handling stress and eliminate the discomfortassociated with multiple injections. A sedative or tranquilizing preanestheticagent should be used if, in the opinion of the anesthetist, the animal wouldbenefit from such agents. Serum and tissue atro­276  Chapter 12pinesterases found in many rabbits render the anticho­linergic agentatropine sulfate of unpredictable efficacy. In the presence of atropinesterase,atropine must be given in high doses (1 to 2 mg/kg) with redosing every ten tofifteen minutes (Lipman et al. 1997). Therefore, 0.01 to 0.02 mg/kgsubcutaneous (SC) administration of glycopyrrolate, a quaternary ammonium para­sympatholytic,should be administered to reduce salivary and bronchial secretions and preventvagal bradycardia.Types of Anesthetic AgentsUsed in RabbitsFor practical purposes, anesthetics used in rabbits can be divided intoinjectable and inhalation agents. Historically, injectable drugs have beenpopularly used for anesthesia of rabbits because they are inexpensive, requireno specialized equipment as do inhalant agents, and are typically safe andeffective. However, disad­vantages attendant to anesthesia by injection includethe lack of precision in anesthetic depth control, pro­longed recovery time,and physiologic changes such as hypotension, hypoxemia, and acid-base disordersassociated with some agents. For uncomplicated pro­cedures involving healthyanimals, these drawbacks may not be of consequence, but when used in illanimals, some injectable agents carry unacceptable risk of untoward events.Ketamine HC1 is the anesthetic agent most com­monly used in rabbits, butas a sole agent, it does not provide sufficient analgesia or muscle relaxationfor surgical purposes at any dose. For minimally invasive diagnostic proceduresrequiring immobilization (i.e. radiography); surgical procedures of moderateinten­sity (i.e. wound suturing, tissue biopsies) lasting less than thirty toforty-five minutes; or anesthesia permit­ting preparation of a surgical field,placement of intra­vascular catheters, and intubation for subsequentadministration of gas anesthetics, ketamine is most commonly combined withxylazine HC1 or medetomi­dine and given intramuscularly as a single injectioninto the cranial muscles of the thigh or the lumbar epaxial musculature. Theketamine dose is 35 to 45 mg/ kg with xylazine (5 mg/kg) given IM or IV, and 15to 25 mg/kg with medetomidine (0.5 mg/kg) (Flecknell 1996, Flecknell et al.2007, Orr et al. 2005)) given SQ. It is worth noting that some question theeffectiveness of SQ administration, but it continues to be adminis­teredcommonly in this way. The combination of xyla­zine and ketamine alone may beunreliable in inducing and/or maintaining an adequate anesthetic plane for anappreciable period of time and will not provide adequate analgesia forprocedures with intense sympa­thetic stimulation such as laparotomy andthoracot­omy; therefore, the use of ketamine combined with medetomidine isgaining favor. Additionally, ketamine/ medetomidine has been shown to maintaincardiovas­cular parameters more effectively than ketamine/xyla-zine whenadministered IM (Difilippo et al. 2004). While there are choices for the routeof administration for ketamine/medetomidine, it has been shown that SQadministration causes less discomfort for the patient (Williams and Wyatt2007).Anesthesia with either combination is fully induced within ten tofifteen minutes and typically lasts twenty-five to forty-five minutes, buttotal time unconscious may be up to two hours (Flecknell 1996). Whenket-amine/xylazine must be used, 0.1 mg/kg butorphanol tartrate or, lessideally, 0.75 mg/kg acepromazine maleate, can be given to augment musclerelaxation and analgesia. These triple combination regimens provide anesthesialasting sixty to ninety minutes. Acepromazine should be used with caution inill animals, however, because it may further contribute to hypotension,bradycardia, and respiratory depression. If it is necessary to further extendanesthesia, incre­mental doses of one half the original ketamine dose can begiven.Telazol (Aveco Co. Inc., Fort Dodge, IA), tiletamine combined withzolazepam, has been shown to be neph­rotoxic for rabbits at doses of 7.5 mg/kgand its use is contraindicated (Brammer et al. 1991, Doerning et al. 1992). Itis possible that the reported toxic effects of telazol are breed-specific andthere are those who advocate its use. This being the case, the authors rec­ommendjudicious use of this anesthetic agent, should it be chosen.If for some reason, such as debilitation or disposi­tion, injection isnot feasible, the intranasal route is an option for administration of inductionagents (Robertson and Eberhart 1994). The onset of effect is generally rapid(less than three minutes) and the dura­tion of effect may be thirty minutes ormore. Midazolam alone for sedation and xylazine-ketamine for low gradeanesthesia can be given effectively by this route (Robertson and Eberhart,1994).For procedures anticipated to last one to four hours, when inhalationanesthesia is unavailable, and the patient is healthy, administration of aconstant infu­sion of xylazine and ketamine can be done. Over com­parableperiods of time, anesthesia by controlled infusion provides stable anesthesiawith a decreased total anesthetic drug requirement and reduced recov­ery timeas compared to anesthetics given periodically by multiple bolus (Wyatt et al.1989). Rabbits to be anesthetized by intravenous infusion are first givenxylazine (5 mg/kg) and ketamine (35mg/kg) by intra­Rabbits  277muscular injection to induce anesthesia. Following placement of anindwelling catheter in a lateral ear vein, as described elsewhere, a constantinfusion of xylazine (0.04mg/kg/minute) and ketamine (0.4mg/ kg/minute) can begiven in 0.9% saline. A working infusion solution is made by adding 4 ml ofketamine HC1 (lOOmg/ml) and 2 ml of xylazine (20mg/ml) to 94ml 0.9% saline. Theinfusion solution is given at a rate of 6 ml/kg/hour to maintain anesthesia.This method of anesthesia should be done with an infusion pump or preciselycontrolled use of a mini-drip (60 drops/ml) and vital signs should be monitoredclosely.The use of inhalation anesthesia is feasible in rabbits and oftenpreferred for procedures lasting two or more hours because it is precise,rapidly adjustable, and safe and effective. In addition, postoperative recoveryis more rapid and less complicated than with injectable anesthetics. An AyresT-piece or other non-rebreath-ing circuit is most appropriate for rabbitinhalational anesthesia (Flecknell 1996). For anesthetic induction, anintravenous injection of propofol (1.5 mg/kg slowly to effect) or an SC or IMinjection of xylazine and ketamine are preferred.The use of ultra-short-acting thiobarbiturates is not recommended due totheir narrow margin of safety, slow elimination in obese animals, and resultantrespi­ratory depression or fatal apnea that can occur if intu­bation is notperformed in a timely manner. Induction using a mask or induction chamber isnot recom­mended because of the high incidence of struggling, distressvocalization, and breath-holding (Flecknell 1996, Hedenqvist et al. 2001). Thistechnique is com­monly used in practice, however, and can be done without harmto the patient with proper restraint (Figure 12.14).The anatomy of the rabbit oropharynx makes endo­tracheal intubationchallenging (Tran et al. 2001). The oral cavity is long and narrow, themandible has a limited range of abduction, and entry into the oral cavity ispartially occluded by the large incisors and cheek teeth. The tongue protrudesdorsally; the epi­glottis is relatively large, U-shaped, soft, and flexible;and the larynx slopes ventrally. Just beyond the epi­glottis is a deep sagittalniche, bordered on both sagit­tal recesses by the friable hamuli epiglottiwhich are easily damaged. Additionally, laryngeal tone and the propensity tolaryngospasm are high. All of these factors combine to obscure visualizationand access to the glottis and make endotracheal intubation of the rabbitchallenging.These challenging anatomic features aside, rabbits can be reliably andeasily intubated by an experiencedFigure 12.14. Inhalation anesthesia using a face mask.technician. Prior to intubation, diazepam or mid­azolam can be given IVto effect if additional relax­ation is necessary. Intubation should be donewith a transparent, cuffed (e.g. Murphy), 14-cm long, 3- to 4-mm internaldiameter endotracheal (ET) tube for rabbits weighing 3 to 6 kg or an uncuffed1- to 2.5-mm endotracheal tube for rabbits weighing less than 3 kg. The key tointubation by direct visualization is to bring the mouth, larynx, and tracheainto linear alignment by positioning the rabbit in dorsal recumbency andhyperextending the head. One way this can be achieved is by placing a rolledtowel under the cervical spine or permitting the head to overhang a table edge.The tongue should be retracted laterally through one of the diastema, thebilateral spaces between the incisors and premolars, to prevent laceration onthe incisors and an inverted laryngoscope with a #1 Miller blade should beinserted into the contralateral diastema and main­tained either between theincisors in alignment with the midline or lateral to the incisors at a slightangle to the sagittal plane of the body. Gentle pressure should be directedventrally with the blade tip while slight rostrodorsal traction is placed onthe head until the epiglottis and arytenoid cartilages are seen.To assist in intubation a metal dowel or cotton-tipped applicator usedas a stylet to prevent bending of the tube can be employed. If a 3-mm or largerinternal diameter ET tube is used, intubation can be done using thepolypropylene guide technique (Gilroy278  Chapter 121981). A 56-cm, 8 French polypropylene catheter should be passed throughthe endotracheal tube lumen from the connector to the distal end until theblunt catheter tip extends 15 to 20 cm past the bevel. Under directvisualization using a laryngoscope, the tip of the catheter should becautiously advanced through the diastema, past the vocal folds, and into thetrachea. Once the guide is in the trachea, the laryngoscope can be removed andthe ET tube advanced as a sheath over the stationary catheter into the trachea.Following intubation, the stylet or guide should be immediately removed and theET tube secured. Alternative intuba­tion aids are described in the literature,including otoscopes (Heard 2004) as well as endoscopes (Tran et al. 2001).If preferred, intubation can be performed blindly. After induction, therabbit should be placed in sternal recumbency with the head extended dorsallysuch that the alignment of mouth, larynx, and trachea is perpen­dicular to thetable surface. An endotracheal tube should then be advanced to the proximalaspect of the larynx. This can be confirmed by visualizing the fogging of thetube interior with every exhalation and listening for respiratory soundsthrough the endotra­cheal tube. The position of the tube should be adjusteduntil the sounds are at maximal intensity. At this point, the endotracheal tubeshould be gently advanced into the trachea. If breaths are shallow, it issometimes helpful to have an assistant administer gentle chest compressions andto advance the tube timed with the release of a compression (inhalation). Acough reflex often confirms correct insertion. A capnograph can also help toconfirm proximity of the tube tip at the oropharynx. This blind techniquecarries a risk of trauma and should be abandoned in favor of direct observationif intubation is not successful after several gentle attempts.Regardless of the intubation technique, intubation should never beforced, because the trachea, tracheal bifurcation, and tissues of theoropharynx are easily damaged and the vagus nerve may be stimulated. Correctplacement in the trachea should be further confirmed by visualizing therespiration-associated condensation of water vapor on the internal surface ofthe endotracheal tube, by auscultation in conjunction with manual respirationusing an Ambu bag, or cap-nography. Mechanical ventilation should not be doneuntil intubation is confirmed, because overzealous ven­tilation into thestomach can lead to acute dilatation and rupture.There is no consensus on the use of topical anesthet­ics to enhanceintubation. While spraying of the pharynx, larynx, and trachea will reduce therisk of laryngospasm and enhance passage of the tube, it also suppresses theconvenient forward motion of the glottis during swallowing that may enhanceintuba­tion. If a topical anesthetic is desired, lidocaine 10% oral sprayshould be judiciously misted on the glottis to prevent laryngospasm andfacilitate intubation. Topical benzocaine should not be used, because it maycause methemoglobinemia.An alternative to endotracheal intubation to main­tain a patent airwayduring inhalation anesthesia is the use of a laryngeal mask airway (LMA). Theprinciple advantage that the LMA can offer over an ET tube is that it requiresless technical skill to place, which is highly beneficial for those with littleexperience or in cases of emergency. LMAs have been used in human pediatricpatients for many years and their use in rabbits has been recently described(Kazakos et al. 2007, Smith et al. 2004). These reports indicate that LMAs size1 to 1.5 perform the best. One problem with the use of LMAs is the possibleinability to com­pletely protect the airway from gastric contents; however, ina species with the inability to vomit such as the rabbit, this should not be aconcern.Once intubated, the rabbit should be connected to a gas anesthesiamachine with a closed breathing circuit for ventilation with a mechanicalrespirator at a rate of thirty to forty breaths per minute and a tidal volumeof 11 to 15 ml/kg. The inspiration-to-expira­tion ratio should be 1:2 or 1:3and airway pressures should not be permitted to exceed 20 cm H20because barotrauma will occur at higher pressure (Reuter et al. 2005). Gas flowrate of 200 ml/kg is sufficient (Heard 2004). If mechanical ventilation is notavailable, spon­taneous ventilation should be accommodated with a semi-closedpediatric breathing circuit. Spontaneous respirations should be regular anddeep and occur at a rate of fifteen or more breaths per minute. The anes­thetistshould be cognizant of the risk of apnea in this circumstance and be preparedto evaluate the depth of anesthesia and assist ventilations.Anesthesia should be maintained with 2% to 3% isoflurane in 100% oxygen.This requirement for rela­tively high isoflurane concentration in rabbits isdue partly to their tendency to take shallow breaths com­pared to otherspecies, although intubation and mechanical ventilation can reduce therequirement. Although not routinely done because combination anestheticregimens can allow for the reduction of gas concentration needed to maintainanesthesia, yohim­bine or atipamezole can be given shortly after gas anesthesiais commenced to reverse the hypotensive effects of xylazine or medetomidine ifthose agents were used at induction.Rabbits  279Perioperative ConsiderationsWhile anesthetized, rabbits should have bland oph­thalmic ointmentplaced in the eyes to prevent expo­sure keratitis. The maintenance ofnormothermia from induction through recovery is very important and can beaccomplished through the use of circulating water blankets such as the Gaymar-T(Gaymar, Orchard Park, NY) or hot air blankets such as the Bair Hugger (ArizantHealthcare, Eden Prairie, MN)(Sikoski, Young, and Lockard 2007). An intravenouscatheter should be placed for administration of parenteral fluids. Becausefasting generally induces mild meta­bolic acidosis, warmed lactated Ringerssolution, pro­viding the kidneys are functioning normally, or half-strengthsaline-dextrose solutions with sodium bicarbonate supplementation are mostideal for fluid administration in surgery. These should be given at a rate of10 to 20 ml/kg/hour via a 60-drop/ml intrave­nous fluid administration set. Ifit is desirable to gain arterial access for blood-gas analysis or bloodpressure monitoring, a 22-gauge catheter can be placed in the central auricularartery and secured with a heparin-lock (for blood gases) or connected to atransducer (for continuous arterial pressure monitoring).Anesthesia MonitoringBecause controlled ventilation may increase mean intra­thoracicpressure, decrease venous return, compromise cardiac output, and causehypotension, blood and airway pressure should be monitored. The systolic/diastolic arterial pressure of an anesthetized rabbit is approximately 95/75(Huerkamp 1995). As a rule, arte­rial pressures should not be permitted todecrease below 80/60. Intubated animals undergoing lengthy proce­dures shouldhave cuffed tubes deflated, rotated, and reinflated hourly because there isevidence suggesting injury can occur during prolonged procedures (Phaneuf etal. 2006), while those that are not intubated should be positioned to maintainan open airway. Alterations in heart rate and blood pressure are the mostreliable indicators of anesthetic depth with changes of 20% or more frombaseline usually mandating modifications in management to ensure an adequateplane of anesthesia. The monitoring of heart rate and rhythm can be done withan esophageal stethoscope or electrocardiography. In addition to direct blood pressuremonitoring via the central auricular artery, indirect monitoring can beattempted with cuffs placed on a limb. Capnography (end tidal C02determination), blood-gas analysis, and pulse oximetry are useful in evaluatingthe adequacy of ventilation. Ventilation-perfusion efficiency can also beassessed through observation of mucous membrane color and capillary refilltime.Where sophisticated cardiovascular monitoring is not practical, reflexassessment is the most accurate determinant of adequate anesthesia depth.Traditional reflexes used in the monitoring of rabbit anesthesia includerighting, palpebral, corneal, pedal withdrawal, and pinna reflex. The pinnareflex is the most accurate measure of depth of anesthesia followed by pedalwith­drawal, corneal, and palpebral reflexes, in that order. Corneal reflex maybe preserved until very deep levels of anesthesia are reached. Muscle tone, jawtone, and purposeful movements in response to surgical stimuli may also be usedas indicators of anesthesia depth. When reflex assessment is used as the soledeterminant of anesthetic depth, more than one reflex should be monitored toensure adequate anesthesia. At a minimum, anesthetic depth should be monitoredtem­porally by constantly assessing reflexes, cardiac rate and rhythm, andrespiratory rate.AnalgesiaRabbits experiencing pain often exhibit changes in appetite, reducedgrooming, reduced activity, and teeth grinding (bruxism), and monitoring forsuch behavior can help the technician effectively manage pain (Kohn et al.2007). As a general rule, analgesics should be first administered before theanimal is fully recovered from anesthesia, but stable, and should be continuedfor the next forty-eight to seventy-two hours. Rabbits may self-mutilate areasthat are painful or irritating and if self-mutilation is a concern, a 12-inchElizabethan collar can be used in conjunction with administration ofanalgesics. Be aware that rabbits typically tolerate these collars very poorlyand long-term maintenance will prevent cecotrophy, which could lead to Bvitamin and other nutritional deficiencies.There are essentially two classes of drugs available for painmanagement, nonsteroidal anti-inflammatory drugs (NSAID) and opioids. Often,analgesia is most effectively provided by using these agents in combina­tion.NSAIDs inhibit the production of chemical medi­ators such as prostaglandinsthat activate peripheral nociceptors and are sufficiently potent to treat muscu­loskeletal,incisional, and acute, mild visceral pain. There are several effective NSAIDsfrom which to choose, but the authors prefer newer, more specific inhibitors ofcyclooxygenase 2 activity such as meloxi­cam, a drug which can be given orallyor injected subcutaneously once per day at 0.3 or 0.2 mg/kg respectively. Thesenewer NSAIDs are often as effec­tive as some opioids for the control of pain.Opioid agents act by binding to specific receptors in different parts ofthe nervous system. Those most280  Chapter 12commonly used are buprenorphine, butorphanol, fen-tanyl, morphine,meperidine, and oxymorphone; all are controlled substances. Opioids aretypically used in their injectable form, but fentanyl is also available as adermal patch, which is advantageous because it abrogates the need to handle thepatient for drug administration. A 25ug/hour fentanyl patch can be used andshould be applied before or at the time of the painful procedure (Foley et al.2001). Because twenty-four hours is required for dermal fentanyl to reachtherapeutic levels, administration of an additional agent such as an NSAIDduring that time period and beyond if necessary should be considered.Opioid agonist-antagonists, such as butorphanol, or buprenorphine, haverelatively long half-lives and offer the advantage of attenuating or ablatingvisceral pain while minimizing the undesirable respiratory and cardiovascularside effects compared to morphine and meperidine. Buprenorphine can be given byinjection every six to twelve hours to rabbits (0.01 to 0.05 mg/ kg IM, SC).Anecdotally, the authors have observed frequent cases of postoperative anorexiaand ileus in rabbits given intensive treatment with buprenorphine injections.In these cases, appetite return was associ­ated with discontinuance ofanalgesic treatment. Buprenorphine given at the high range of recom­mendedlevels in rats has been shown to cause anorexia and weight loss (Jablonski etal. 2001). Others have also questioned the efficacy of buprenorphine in rabbits(Wixson 1994).Immediate Post-anesthetic CareFollowing completion of surgery under inhalation anesthesia, recovery israpid and rabbits typically are conscious and regain the righting reflex withintwenty to thirty minutes. The most likely causes of delayed or complicated recoveryfrom general anesthesia are hypothermia and anesthetic overdosage followed bycomplications related to lengthy procedures or a pre­senting medical conditionsuch as hypoglycemia and dehydration. Anesthetic agents impair central andperipheral thermoregulatory mechanisms and rabbits are prone to radiative andconductive heat losses because of their relatively high body surface area tobody weight ratio. Because the pharmacokinetics of anesthetic metabolism arepartially temperature depen­dent, maintaining body temperature is critical torecovery from anesthesia. Ideally, recovering animals should be kept in anescape-proof incubator on a clean, dry towel or blanket. The use of anincubator permits careful control of the ambient temperature and enablessupplemental oxygen administration. Recovery should not be done on metalflooring or in suspended wire cages because heat loss will be accelerated.If an incubator is not available, supplemental heating can be providedwith a water-circulated heating pad or a heat lamp judiciously placed outsideof the cage. It is important to remember that rabbits are gnawing species that,left unattended following recovery, may mutilate heating pads or wiring. Theambient temperature in the recovery area should be 29°C to 32°C. Thetemperature of the animal and the recovery area should be monitored asregularly as for dogs and cats.Animals slow to recover from anesthesia should be turned every thirty tosixty minutes to prevent hypo­static lung congestion and should be givenwarmed, parenteral fluids to compensate for metabolic needs and for lossesduring surgery. Extubation should be done only when chewing begins or coughingis elicited. If not done beforehand, yohimbine or atipamezole can be given toreverse the effects of xylazine and medeto­midine. Where reversal is notpossible, respiratory depression can be treated with 2 to 5 mg/kg doxapramgiven SC or IV every fifteen minutes.COMMON SURGICAL PROCEDURESThe duties of a veterinary technician supporting a sur­gical procedurefor a rabbit are identical to those duties for other species, with the focus onpreoperative preparation of the surgical patient and intraoperative support ofthe procedure, including anesthesia man­agement. The surgeon and operating roomattendants should prepare and dress as for procedures done on other petspecies. Sterile instruments and draping should be used. When post-op care isexpected to be extensive, a nasogastric tube can be placed to permit feeding ofliquid diets and evacuation of any gastric gas (Mullen 2000). Rabbits with ahistory of pasteurel­losis should be started on a preoperative course ofantibiotics for a duration (days) sufficient to suppress any clinicalmanifestations or prevent septicemia (one to two hours pre-operatively IV).As would be customary in any species, the fur at the surgical siteshould be clipped and the skin should be decontaminated with alcohol anddisinfectants. Rabbits have thick hair coats and thin skin, which rendersclipping of the hair from a surgical site more time-consuming and puts apremium on clipper blade sharpness. It is critical that sharp, spare blades beavailable and that all clipper blades be properly cleaned and restored afteruse. The rabbit skin easily lacerates or tears in cases in which clipping isdone hurriedly orRabbits  281carelessly or where dull clipper blades are used. The technician shouldconcentrate on keeping the skin taut in front of the clipper blade and the headof the blade flat against the skin. The best skin preparation comes from usinga combination of no. 10 and no. 40 blades to prepare the skin. This is an areawhere patience and careful attention to detail are most important. In fact,gentle handling of the skin perioperatively and all tissues intraoperatively iscritical in reducing the inci­dence of postoperative automutilation ofincisions for which rabbits are notorious. Some people choose to wear a maskwhile shaving a rabbit to preclude float­ing hair from entering their mouth ornose.The surgical procedures most commonly performed in rabbits include spay,castration, drainage of abscesses, cutaneous mass excision, and exploratorylaparotomy. Enucleation, perineal dermatoplasty in cases of relent­less urinescald, cystotomy, large bowel, and renal sur­gical procedures have also beendescribed in rabbits (Mullen 2000, Jenkins 2004). Castration and ovario­hysterectomy(OVH) are often done for the same reasons that these procedures are done indogs and cats. Castration should be recommended to clients as a measure forbucks housed indoors to prevent urine spraying and mounting, reduce aggressiontoward other rabbits and owners, and eliminate the risk of testicular cancer.OVH is recommended as a preventive measure for group-housing and uterinediseases such as uterine adenocarcinoma. Both procedures are performed with thepatient in dorsal recumbency. The surgical approaches for these two proceduresare similar to those used for dogs and cats, with castration commonly done bythe scrotal approach (Jenkins 2000), prescrotal approach, or abdominal midlineincisions for crytorchi-dism (Swindle and Shealy 1996). The OVH requires astandard, mid-line abdominal approach, and surgical site preparation shouldreflect this. It is important to express the urinary bladder during preparationfor an OVH to avoid complications during surgery.A variety of other surgical procedures can be safely performed inrabbits, and the preparation of the surgi­cal site varies by location andsurgeon preferences. Cystotomy is indicated for urolithiasis. Although thebladder wall is thin, which may be discouraging to some surgeons, it holdssuture well (Mullen 2000) and can be closed in a single layer (Swindle andShealy 1996). Most rabbits with urolithiasis are overweightand probably overconsuming calcium (Mullen 2000); therefore, the post-operativeinstructions given to the owner should include an exhortation to limit feed andnot provide mineral supplementation. Exploratory laparotomy is required incases of gastrointestinal obstruction from trichobezoars, other foreign bodies,or space-occupying lesions. Enucleation may be neces­sary for ocular trauma,severe buphthalmia, or retro­bulbar abscess. The retrobulbar venous sinus isextensive and there is a risk of severe and difficult-to-control hemorrhage(Mullen 2000). It is important to have considerable sterile methylcellulose onhand to pack the ocular defect. Likewise, bulla osteotomy for drainage ofmiddle ear infections, such as for pasteu­rellosis, is fraught with risks ofpost-operative pain and drainage complications (Swindle and Shealy 1996) and isa procedure probably best referred to a specialty surgical practice.Absorbable polymer suture materials, such as monofilament polyglyconate,are preferred by many for internal use, due to their minimally reactive nature.Because they are not exposed and are less likely to be chewed, subcuticularsutures are preferred for skin closure. Generally, sutures in sizes appropriatefor cats (3-0, 4-0, and 5-0) are most appropriate for rabbits. Cyanoacrylatetissue adhesives also provide satisfac­tory closure, as long as they are usedin clean, dry, incisions. Wound clips are a viable alternative and areadvocated by some for skin closure. Regardless of which material is used forskin closure, it is important to keep in mind the proclivity of rabbits forchewing at their wound closure materials and monitor animals closely during thewound healing period.Following acute recovery from anesthesia, the most reliable indicator ofpost-operative well-being, includ­ing the effectiveness of analgesia, is thedaily assess­ment of body weight and food and water consumption. Becauserabbits are prone to hypoglycemia because of high metabolic rates and, injuvenile animals, limited fat reserves, a nutritious pelleted diet should bepro­vided as soon after surgery as feasible. Inappetant animals can be offeredsupplements such as hay, other supplements, or treats as described under"Nutrition," or herbivore liquid dietary products. In some cases, thestress associated with surgery will cause pH changes in the cecum that resultin alterations of commensal and fermentative bacteria. When chronic anorexiaand ileus that is nonresponsive to treatments described above is the result,specific bacteriotherapy, as described in the "Critical Care"section, may be useful in recolonizing the gastrointestinal tract.PARASITOLOGYThe most important diagnostic tools used in the diag­nosis of parasitismin rabbits are essentially the same as for dogs and cats. These comprise thefecal floata­tion examination, fur exam, skin scraping, and exami­282  Chapter 12nation of the ear canals. With respect to skin scrapings, bear in mindthat the skin of rabbits is thin relative to dogs and cats and may lacerateeasily. The examina­tion of the ear canals should be done using an oto­scope.This is sufficient in many cases to diagnose aural acariasis caused by Psoroptes cuniculi.Themites are easily seen with low magnification crawling in the beam of lightemitted from the otoscope. The diag­nosis can be confirmed, and mitesdemonstrated for the owner, by swabbing exudate from the canal with acotton-tipped applicator and mineral oil and examining it under a microscope.For rabbits housed outdoors, one important consideration is that flies areattracted to rabbit droppings and owners may confuse the recently hatched flylarvae with parasites.URINALYSISThe urine pH ranges from 6 to 8.2 with alkaline urine (pH > 8)generally associated with good health and acidic pH with anorexia or fasting.The normal range of urine specific gravity is 1.003 to 1.036 with 1.015representing the normal mean in a healthy population of rabbits (McLaughlin andFish 1994). The urine typically is turbid due to calcium carbonate excretionand is also pigmented ranging from light yellow to orange to variouscombinations of red with brown. Certain porphyrin pigments in the urine maycause a reddish appearance and elicit concerns of hematuria (Garibaldi et al.1987). Consequently, any suspected cases of hematuria in the rabbit should beconfirmed by complete urinalysis. The most likely causes of hematuria are fromuterine adenocarcinoma, uterine polyps, uterine hyperplasia, abortion,urolithiasisis, cystitis, septicemia, DIC, and certain renal diseases.The urine should be free of protein, casts, blood, glucose, ketones, andbilirubin. An occasional white blood cell per high-powered field in an examinationof the sediment is within the realm of normal. The urine output ranges from 20to 350 ml/kg/day and is influ­enced by many factors related to the diet,animal, and environment (McLaughlin and Fish 1994). Ammonium magnesiumphosphate (struvite) and calcium carbon­ate are the two most common uroliths ofrabbits (Bergdall and Dysko 1994). Struvite uroliths are usually theconsequence of urinary tract infection. Calcium carbonate uroliths mayprecipitate and form uroliths when the urinary pH exceeds 8.5 (Leek 1988).Infection, inadequate water intake, genetic predisposi­tion, metabolicdisturbances, and nutritional imbal­ances enhance the development ofurolithiasis.CLINICAL TECHNIQUES Blood CollectionBlood is most often obtained from the ear arteries or veins or jugularor saphenous vein, and may also be collected from the cephalic (Figures 12.15,12.16). Blood collection from the ear vessels carries a risk of hematoma orbruising that may be unacceptable to an owner. It also has a small risk of thrombosisand sub­sequent sloughing of the skin, which is more likely in breeds withsmall ears or if the artery is used (Mader 2004, Harcourt-Brown 2002). Thepreferred location depends on the techniques developed by the phleboto-mist.Rabbit blood can clot quickly, so heparinizing the syringe and needle may behelpful.The auricular artery is central, while the veins are found along themargins of the ear (Color Plate 12.2). The hair may be shaved and a warm towelmay be applied to help dilate the vessel. A topical anesthetic, such as EMLAcream or lidocaine cream, can be used in an awake animal to reduce headshaking. These agents may reduce the restraint that is required, but keep inmind the time it takes for the creams to have an effect (Flecknell et al.1990). The size of the needle depends on the size of the vessel, and generallya 22- to 27-gauge needle is used. The needle is inserted into the vessel and ifthe vessel is large enough may be aspirated with a syringe. For small breeds,suction from a syringe may collapse the vessel and so blood can be collected asit drips from the needle hub. Upon removal of the needle, it is necessary toapply pressure for three to five minutes if using the artery and monitorthereafter for ten to fifteen minutes recrudescence of bleeding; less time maybe needed if using a vein.The lateral saphenous is easily accessible in an appropriatelyrestrained rabbit. The restrainer should hold the animal wrapped in a towel inhis lap and hold off the back leg just below the stifle. The vein is seen whereit crosses from medial to lateral, usually in the area of the middle third ofthe lateral tibia. Sometimes the vessel can be visualized with just alcohol,but often shaving is required. A butterfly catheter attached to a syringe isoften the easiest way to obtain blood.The jugular can be used in some cooperative awake patients, but thistechnique may require sedation. If the animal is sedated, place it in dorsalrecumbency and shave the neck area. If the animal is awake, it can berestrained in the same way as a cat for jugular venipuncture. The rabbit iswrapped in a towel and held at the edge of the table. One hand is used to holdthe head up and the other restrains the front legs. Venipuncture from thecephalic is difficult, particularly in small breeds.Rabbits  283THE CENTRAL ARTERY AND MARGINAL VEINFigure 12.15. Venipuncture sites.THE LATERAL SAPHENOUSTHE JUGULARFigure 12.16. Blood sampling using the central auricular artery with abutterfly catheter. (Courtesy of RyanCheek.)Placing a CatheterThe marginal ear veins and cephalic are the easiest and most frequentlyused to place an intravenous catheter. As with venipuncture, catheterization ofthe ear vessels carries a small risk of necrosis, so the cephalic is often used(Mader 2004, Harcourt-Brown 2002). The saphenous can also be used for venousaccess, and the central ear artery can be used if arterial access is neededPlate 12.2. Marginal lateral ear vein on the left and the prominentcentral auricular artery. (Photo courtesy ofRyan Cheek.) (See also color plates)284  Chapter 12for direct blood pressure measurement or periodic blood-gas analysis insurgery. For any catheter, an E-collar may be used to prevent the animalremoving it, but should be avoided in cooperative animals. E-collars can bestressful and prevent the animal from engaging in cecotrophy, so they are notideal for long-term use.The principles of preparation are the same as for other species, but theanimal may require sedation for vasodilation and to enhance cooperation. Aswith venipuncture, EMLA cream may facilitate placement of the catheter in anawake patient. A 24-gauge cath­eter is appropriate for most rabbits, but a22-gauge may be used in large vessels of some large rabbits. Occlude the vesselby compressing proximal to the location of the catheter. After puncture of thevessel wall, the catheter should be advanced over the stylet and into thevessel lumen. The thin walls of the vessel make it easy to visualize thethreading of the catheter into the lumen of the vein to the hub. Due to therela­tive small volume of blood in the vein and the low venous blood pressure,it is unlikely to obtain a back-flow of blood into the catheter flange or hub.If in doubt, a small quantity of saline can be injected via the catheter forobservation of the telltale blanching of the vessel with infused fluid. For theear, a roll of four to five gauze 4x4sponges should be placed in the concave pinna and then the catheter securedusing tape in a butterfly application and a circumferential wrap of tape overthe roll of gauze in the ear. The IV line should also be secured with acircumferential wrap of tape. The principles of fluid therapy are identical tothose for other species. See Figure 12.17 for illustra­tions relating toplacing an IV catheter.Intraosseous infusion is indicated when intravenous access is notpossible or difficult and a delay in access may affect survival. The commonlocations for cath­eterization are the humerus, tibial crest, and femur. A 20-to 22-gauge spinal needle that is about half the length of the bone isappropriate for most situations. If a spinal needle is not available, use anappropriately sized hypodermic needle. If the hypodermic needle plugs, athinner, sterile Kirschner wire can be used as a plunger to push bone cortexfrom the needle lumen (Anderson 1995). The procedure is done using a similarapproach and equipment as for cats and can be done in kits as small as 200grams, although poten­tial risk to active growth plates must be considered injuvenile animals (Bielski et al. 1993, Harcourt-Brown 2002).Preparation of the area should follow strict aseptic technique becauseof the risk of osteomyelitis, and if it is necessary in an emergency situationin a consciousIISIP^»*■* mBCFigure 12.17. (A) Initial insertion ofthe catheter in the vein; note the "flash." (B) The catheter isseated into the vein and the cap has been applied. (C) A tongue depressor wasadded for additional support.Rabbits  285animal, a local anesthetic such as lidocaine can be used. The humerusmay be the easiest location for placement, where the needle is inserted throughthe greater trochanter (Harcourt-Brown 2002). For the tibial crest, the needleshould be inserted at the medial aspect of the proximal tibia of the flexedstifle at an angle of about 30 degrees (Anderson 1995, Bielski et al. 1993,Otto and Crowe 1992). Because of the curved cortex of the tibia, it may bedifficult to keep the needle in the medullary cavity and instead go into thecortex. The femur can be difficult because of the well devel­oped trochantericfossa, and the catheter often needs to pass through three layers of corticalbone. Although placement of the catheter may be more difficult in the rear leg,some rabbits may be less inclined to disturb a catheter that is not by the face(Jenkins 2004).For any location, the needle should be advanced in a distal directionaway from the physis until there is a dramatic reduction of resistance,indicating penetra­tion of the marrow cavity, and one aspirates slightly toobtain marrow to confirm that the needle is in the desired location. Once inthe marrow cavity at the desired depth, the needle should be sutured to theskin and protected and further immobilized with a sterile wrap and bulkybandage. Any drug, agent, or fluid that can be safely given intravenously canbe given by the intraosseous route. The maximal rate of infusion is about 10ml/minute by this route (Anderson 1995).Bandaging and Wound CareThe principles of bandaging and wound care are essen­tially the same forrabbits as they are for other species. Ulcerative pododermatitis is one of themost frequent indications for bandages, and these bandages are gen­erallywell-tolerated by the rabbits being treated. Bandages of the feet shouldrelieve pressure on the affected area, such as with a doughnut bandage. Thebandages should extend above the hock and be secured at the proximal aspectwith loosely wrapped adhesive tape extending from the bandage to the fur, sothat the bandage is not kicked off.Rabbit skin is very thin, so bandages must be changed frequently andcarefully observed for signs of urine contamination, irritation, constriction,or slip­page. Tight or contaminated bandages can themselves cause dermatitisand even tear the skin. As opposed to dogs, dermatitis should not be treatedwith ointments containing steroids because rabbits are particularly sensitiveto their side effects, including adrenocortical suppression, delayed woundhealing, and immunosup­pression (Graham 2004). If topical antibiotics are used,make sure the animals cannot ingest the oint­ment because of their sensitivityto some antibiotics.Urine CollectionUrine may be collected from rabbits into a clean cage pan, bycatheterization as for cats, by cystocentesis, or from anesthetized rabbits byexpression. The bladder wall is thin and susceptible to trauma or puncture;therefore, cystocentesis, manual expression, or cathe­terization should be donewith care. If doing cystocen­tesis, use a small needle appropriate for thepatient (23 to 25 gauge).Administration of Medication IntravenousInjectionThe marginal ear veins are the easiest to access for IV injection, butthe cephalic and saphenous can also be used. The technique is the same asdescribed for veni­puncture. Typically volumes of up to 5 ml can be given bybolus by this route (Flecknell 1987). Be careful not to inject into the centralauricular artery, which may be fatal (OMalley 2005).Per OsRabbits may accept oral medications when mixed with small amounts ofpreferred food items, such as bananas or bread. Rabbits can be difficult topill, but may accept palatable medications when placed through the diastema asfar back in the mouth as possible. A pill "gun," as used in cats, maybe useful for this proce­dure. Alternatively, the pill should be crushed andgiven in suspension. Suspensions or liquid medications may be eaten from thesyringe if palatable, and rabbits usually like sweet formulations such as juiceor fruit baby foods. Otherwise, the rabbit can be restrained as previouslydescribed and volumes should be limited to less than about 5 ml of liquid. Insome cases it may be tempting to give drugs via the drinking water; however,this is imprecise. Depending on their level of consump­tion, the palatabilityof the liquid, and stability of the drug, animals may be overdosed orunderdosed.Subcutaneous InjectionThe methodology for a subcutaneous injection is the same as for otherspecies with the interscapular region preferred. A 21- to 25-gauge needleshould be inserted under the lifted loose skin over the scapulae and paral­lelwith the underlying muscle. Volumes of 10 to 20 ml/ kg can be given by thisroute (Harcourt-Brown 2002).Intraperitoneal InjectionThis route is rarely used in rabbits, but should be considered inneonates or moribund, hypothermic animals in which vasoconstriction may bepronounced and there is a need to rapidly attempt fluid therapy or286  Chapter 12administer medications. For intraperitoneal injection, the rabbitideally should be held on its back with the head slightly lower than thehindquarters to allow the stomach and intestines to fall cranially. However, ifdorsal recumbency is at all resisted, the animal can be positioned on its sideor in ventral recumbency. A second individual should insert a 21- to 25-gauge needleat a 45 degree angle through the skin and abdominal wall slightly to the rightand just caudal to the umbilicus. Aspirate before injecting to reduce thechance of injecting into an organ. For fluid therapy or injection of a volumeof material in excess of a few milliliters and to prevent accidental lacerationof the internal organs, a catheter can be inserted and the stylet immediatelyremoved after puncture of the abdominal wall. Volumes of up to 100 ml of warmedfluids can be given to a 4- to 5-kg rabbit by the IP route (Flecknell 1987).Intramuscular InjectionThe restraint for injection is similar to that for exami­nation,remembering to always hold the hindquarters and keep the rabbit from jumpingforward with the other hand. If alone, the animal should be held with the flankagainst the restrainers side/abdomen and the head tucked into the elbow of thedominant arm, with the dominant arm wrapped around the exposed flank of theanimal and the hand curled around and restrain­ing the hindquarters. The freehand is then used for the injection. Fractious rabbits may need two people forinjection or to be wrapped in a towel. Lumbar muscles (cranial to the pelvis)or the cranial aspects of the rear leg (quadriceps) are the sites of choice toavoid damage to the sciatic nerve (Mader 2004). Aspirate to confirm that bloodis not obtained before injecting. Any volume greater than 0.5 ml/kg should bedivided and given in two sites.Teeth TrimmingConventional dog nail trimmers should not be used for trimming theincisors because of the risk of complica­tions, including longitudinalfissures, periodontal abscesses, and damage to the germinal tissue (Gorrel1996, Malley 1996). Nail trimmers can also leave sharp edges that may laceratethe tongue, cheek, or lips. Ideally, the teeth should be reduced using highspeed dental equipment with a water-cooling system (Capello and Gracis 2005).Alternatively, a Dremel® tool (Dremel, Racine, WI) can be used, but these havea lower speed and increased torque that increases the chance of thermal damageto tissues. These procedures generally require sedation, although rarelyveterinary personnel may be able trim the incisors in a conscious animal. Thisshould be done, however, with great caution and the obvious consent of the owner.Specialized equipment is available that significantly aids rodent and rabbitdentistry (Cappello and Gracis 2005), but readily available items can also beuseful, such as a tongue depressor or the barrel of a syringe through thediastema to serve as a gag to open the mouth slightly and as a backstop whentrimming the incisors. Extraction is also an option for severely affectedteeth, but is much more difficult for cheek teeth than incisors. Rabbits canactually do very well with all of their incisors extracted by using their lipsfor prehension. In cases of malocclusion, teeth trimming may need to berepeated every six to eight weeks for the lifetime of the animal (Swindle andShealy 1996).Nail TrimmingNail trimming can be done with any conventional nail trimmer used fordogs or cats. The quick is generally easy to visualize, and overly aggressivetrimming causing bleeding should be managed as for dogs and cats. Owners can betaught to trim the nails of their pets because nails may grow long with rapidityin sedentary animals. Similar to dogs, declawing should not be done in rabbitsunless medically necessary for a particular digit. Unlike cats, rabbits use thelast phalanx for weight bearing and traction, and removal can lead to abnormalweight distribution and foot injuries. Excessive scratching should be dealtwith by behavior management and frequent nail trims.Assisted FeedingNutritional support is important for rabbits that are anorexic because,like cats, they are predisposed to hepatic lipidosis. Critical care dietsspecifically for her­bivores are available (Critical Care, Oxbow Animal Health,Murdock, NE), but ground-up pellets can be used as well. Many rabbits can besyringe fed by restraining the animal with a towel and gently placing acatheter tip syringe in the diastema as previously described. Rabbits that donot readily accept food from a syringe may be tube fed.Restraint for tube feeding is similar to that used for oral examination.A second person should place an oral speculum behind the incisors, in thediastema. Select a tube that should be larger than the trachea and premeasureto the last rib on the left side and mark the tube. Once the tube is passed,proper placement can be confirmed by aspirating stomach contents or injecting 5to 10 ml of air through the tube while aus­cultating the stomach for thetelltale sounds of bub­bling fluid or turbulent airflow. The tube should beeasy to pass, and if the rabbits struggles excessively theRabbits  287procedure should be stopped. The animal may need to be sedated for thisprocedure.If a suitable mouth gag is not present on the prem­ises, a gag can bemade by taping two tongue depres­sors (0.75 inch width) in flat alignment withmedical adhesive tape. A hole should be bored through the center of the tapedtongue depressors, using a scissors tip or other sufficiently sharp instrument,of such size to permit passage of the stomach tube. An alternative is to removethe plunger from a syringe, bore a hole through the cylinder walls, and use theempty barrel as a gag. Mouth gags for rabbits should be of sufficient height ordiameter to prohibit occlusion of the incisors and sectioning or damage to thetube. Tongue depres­sors that are 0.75 inches wide or the barrel of a 10-mlsyringe are generally sufficient as gags for rabbits 4 to 6 kg in weight.Although of arguable value given the confounding effects of thebactericidal low gastric pH, force-feeding may be attempted for transfaunationin cases of cecal dysbiosis. This procedure is accomplished by outfitting ahealthy donor rabbit with an Elizabethan collar overnight to preventcecotrophy. The collected ceco­trophs should be mixed and suspended in warmed(37°C), nonbacteriostatic saline and strained through gauze prior toadministration with a stomach tube. A volume of 40 to 60 ml of this suspensioncan be safely given to a 4- to 5-kg rabbit using a 12 French, 16-inch SovereignFeeding Tube (Kendall Co., Mansfield, MA).If a permanent tube is needed, nasogastric tubes can be placed using atechnique similar to that used in cats. The disadvantage of nasogastric tubesis that solutions designed for nutritional support of rabbits will clog a tubethis small. Although it is common to use human nutrition products such asEnsure for rabbits, these are not ideal for herbivores. Solutions available forherbivorous reptiles will pass through these tubes, although no solution willbe able to provide appropri­ate insoluble fiber because it would clog the tube(Paul-Murphy 2007). Surgical placement of pharyngostomy and gastrotomy tubeshave also been described (Smith et al. 1997, Rogers et al. 1988).SEX DETERMINATIONGender determination in rabbits is similar to that in cats with theexception that does also show sexual dimorphism by virtue of a pendulous foldof skin at the caudal mandibulocervical region. This redundant skin is termedthe "dewlap." The vulva in does is located directly below the anus(Figure 12.7). The ensheathed penis of the buck is also located directly belowthe anus, similar to cats, and it has an obvious scrotum with palpable testes(Figure 12.8). However, due to open inguinal canals the testes may migrate backand forth from the scrotum to the abdomen.EMERGENCY AND CRITICAL CAREEmergency and critical care are action-oriented and immediate with thegoals of interventions being to stabilize the rabbit and afford the opportunityto then pursue the diagnosis of the primary problem. There may be any number ofpresentations requiring critical care, including gastrointestinal disorders,trauma, environmental exposure (hypothermia, hyperthermia), intoxications,respiratory distress, neurologic symp­toms, and urinary obstruction. Identicalpresentation directed interventions constitute the tenets of care includingfluid therapy, body temperature mainte­nance, oxygen administration, andcontrol of hemor­rhage. If in shock, rabbits rarely present in a compensatorystage as may be seen in dogs and birds, and instead usually have signs ofdecompensation such as hypothermia, bradycardia, hypotension, pale mucousmembranes, and prolonged capillary refill time (Lichtenberger 2007). Rabbitsare obligate nasal breathers, so a rabbit that is open mouth breathing is insevere respiratory distress. Acute respiratory distress can occur withbacterial infections of nasal passages, bacterial pneumonia, trauma, or cardiacdisease (Paul-Murphy 2007).If CPR is required, immediate action is directed at the "ABCs" of emergency care as in other species: Airway, Breathing, andCirculation. An airway should be established with either intubation or atracheos­tomy tube and the animal placed on oxygen. If an airway cannot beestablished, high flow oxygen with tight-fitting mask can be used at a rate oftwenty to thirty breaths/minute, but monitor the animal for signs of bloat(Lichtenberger 2007). Chest compressions at a rate of at least eightytimes/minute and medications are used to address circulatory issues, butremember that some rabbits have serum atropinesterases so atro­pine is not thepreferred anticholinergic if one is indicated.More advanced care and monitoring includes intra­venous fluids, ECG,blood-gas analysis, end tidal C02 measurements, and temperature. Theuse of corticoste­roids in shock therapy is controversial in dogs and cats andnot recommended for rabbits (Lichtenberger 2007). The treatment may also needto include address­288  Chapter 12ing metabolic disturbances that may be the cause or consequence of theshock.In addition to shock, hypothermia is a risk in suck­lings, rabbitshoused outdoors in winter, and those recovering from anesthesia, especially ifroom-temper­ature fluids were administered. Therapy centers on slowly warmingthe animal and restoring circulation with warm, isotonic fluids in conjunctionwith an external heat source such as warm water bottles, water-circulatedheating pads, or a Bair-Hugger. The goal in treating hypothermia, as it is withother species, is to raise the body temperature slowly. Otherwise, in theory,the cure may be worse than the disease. A rapid rise in body temperaturewithout control may increase brain metabolic demands above that which can beprovided and expose the heart, liver, and lungs to cold, acidotic blood fromthe periphery. Overzealous body warming also could result in hyperthermia.Failure to restore fluids in any hypothermic animal can result in acute tubularnecrosis. Hypoxemia should be consid­ered as a possible complication in downerand hypo­thermic animals, and animals may require oxygen delivered via a facemask.Hypoglycemia is generally a risk in neonatal or small breed animalseither on an inadequate nutri­tional plane or recovering from surgery. Highmeta­bolic energy demands and low depot fat reservoirs coupled withpostoperative anorexia make these animals particularly at risk. It could be acompanion to hypothermia. In a pinch, however, response to glucose therapy canbe used as a diagnostic tool. Acute hypoglycemia should be treated as for otherspecies by intravenous or oral bolus of 50% dextrose (e.g. 2ml/ kg). Parenteraladministration of glucose is preferred because excessive administration of oralcarbohydrates may create conditions that upset the enteric microflora andpredispose to cecal dysbiosis. For those animals that are both hypoglycemic andhypothermic, intrave­nous glucose provides fuel to the brain during re warming.Hyperthermia is associated with rectal temperatures higher than 104°F.Rabbits are prone to hyperthermia if housed outdoors because they cannot sweator effec­tively pant. It may also be caused iatrogenically by overzealousrewarming during anesthetic recovery or can be associated with certain toxicoses.The treat­ment, as for other species, is to cool the rabbit slowly.Hyperthermia can be treated with room-temperature intravenous fluids and tepidwater, especially on the ears. Animals need to be monitored for kidney failureand other metabolic abnormalities.Rabbits may present with a variety of gastrointesti­nal emergencies,such as ileus, diarrhea, gastric dila­tion, and obstruction. Ileus and diarrheacan both lead to life-threatening enterotoxemia and dehydration. Ileus is morecommon than diarrhea, and is a common problem given the intricate, complex anddelicate interrelationship between diet, other environmental factors, thecommensal, fermentative microflora, and gut motility in rabbits of all ages.Diarrhea can also occur due to these factors or associated with otherconditions, such as infection or antibiotic administration.Fluids and nutritional support are the most impor­tant aspect oftreatment for these animals. Even if there is no appreciable fluid loss becauserabbits cannot vomit and diarrhea is not observed, colonic hypomotil­ity leadsto decreased water absorption and dehydra­tion (OMalley 2005). Cecotrophscontain high levels of vitamins B and K, so supplementation of B vitamins inparticular should be considered for animals that are unable or unwilling to eattheir night feces. Additional treatment may include analgesics, motilityagents, anti­biotics, anthelmintics, anti-ulcer medications, or other agents asindicated. For diarrhea, transfaunation with cecotrophs collected from ahealthy donor rabbit to re-establish the enteric flora may be considered. Itshould be noted that yogurt and many commercial probiotics have not been shownto be effective in floral reconstitution for rabbits (Myers 2007).Gastric dilation is rare, but must be excluded in an anorexic rabbit,because the animal may need to be decompressed and prokinetic agents may becontrain­dicated. Gastric dilation can occur secondary to small intestinalobstruction because of the inability to vomit, leading to fluid and gasaccumulation in the stomach. This must be differentiated from gut stasis basedon radiographs. Initial treatment includes passage of a stomach tube todecompress and fluid therapy, with subsequent decisions regarding whethersurgery is nec­essary (Harcourt-Brown 2007).Traumatic presentations may include fractured limbs, traumatic vertebralluxation or fractures, and fight-related lacerations, including those of thescrotum. Limb fractures should be stabilized by splint­ing if possible, butoften this is difficult and surgery may be indicated. Radiography should bedone to characterize the fracture and permit the development of a plan forreduction and stabilization. Unfortunately, vertebral injuries are rarelycurable and often eutha­nasia is the most humane option. Rabbits presentingacutely for vertebral injury should be radiographed to confirm the diagnosisand should be kept clean, padded to retard the development of decubital ulcers,and provided fluid and dietary therapy as needed. Spinal surgery is notcommonly done in rabbits, but a referralRabbits  289center can be contacted to determine if someone is capable of performingthis procedure. For especially-dedicated and competent owners, the use of cartshas been described for paraplegic rabbits (Boydell 2000).Trauma to the scrotum or testes may require surgi­cal castration.Steroids for trauma should be used with caution in rabbits because they aresensitive to their side effects (Paul-Murphy 2007).The principles of treatment for toxin exposure are also similar to thosefor cats and dogs, with some notable exceptions. Emetics such as apomorphineare ineffective for the physiologic reasons mentioned. It may also be necessaryto apply an E-collar for seventy-two hours to keep rabbits from eatingcecotrophs that may still contain the toxic substance. Therapy should involvefluid administration, gastric lavage, bathing, and activated charcoal asindicated, depending on the substance and route of intoxication. Toxicoses havebeen associated with a variety of chemicals, pesticides/ rodenticides,antibiotics, tiletamine, and various household plants (Johnston 2008). Althoughrabbits are resistant to many plant toxins such as ragwort, nightshade,comfrey, and laburnum, they are sensitive to anatoxins that m