|Important key words or phrases.|
|Important concepts or main ideas.|
Zoological Medicine 2008
Reptile Medicine (2008)
Charles Innis, VMD
Cummings School of Veterinary Medicine at Tufts University
1. Learning Objectives and Review
1.1. Learning Objectives
This section on Reptile Medicine will give you a good review of the major husbandry challenges, diseases, and clinical approaches to reptile health issues. Color coded topics indicate learning objectives that the student should become familiar with. Cases will be presented in class to illustrate these topics. At a minimum, you will be expected to be familiar with the following:
Basic husbandry requirements/concerns for captive reptiles
Commonly used reptile anesthetics
Reptile anesthetic monitoring
Important parameters in reptile plasma biochemistry
Nutritional secondary hyperparathyroidism
Vitamin A deficiency
A good review/access to reptile taxonomy can be found at:
2.2. Threats to reptile populations
422 species of reptiles are considered threatened by the IUCN (2007) http://www.redlist.org/
Habitat loss, degradation, and fragmentation
Food, skin, and traditional medicine trade
2.3. Legal issues
Local: mainly focus on "dangerous species"
State: native species, exotic species, pet store laws, breeding permits, etc.
Federal: U.S Endangered Species
Some species may require interstate health certificates for transport due to concerns with exotic diseases (e.g. heartwater disease).
3. Choosing a Pet Reptile: Making the Responsible Choice
Keeping reptiles as pets has always been controversial, and many people believe that they should not be kept at all. However, many of the great contributors to our knowledge of herpetology will testify that keeping reptiles as pets in their childhood or adolescence was a significant factor in their career choice. Furthermore, maintaining a reptile pet may provide a significant, if limited, relationship with the natural world, that may not be otherwise available in today's urban societies. In a properly supervised situation, reptile ownership by children can allow development of important character traits such as personal responsibility, and compassion.
Within the field of reptile keeping, or herpetoculture, several broad categories of reptile keepers exist. The pet owner , in the context of this discussion, is defined as an individual owning a small number of reptiles for personal interest, with no intent of purposeful breeding. In contrast to this is the private reptile breeder , who may own a small number or large number of reptiles, and is in pursuit of successful reproduction of one or more species. Breeders include individuals for whom herpetoculture is a hobby, as well as large scale commercial breeders of animals for the pet trade. A third broad group of herpetoculturists is the academic and scientific reptile keepers, which includes herpetologists, veterinarians, and other professionals that may keep reptiles as research subjects, or to study their biology, disease processes, etc. Finally, the zoological herpetoculturists include reptile keepers and curators keeping animals both for scientific information as well as public education. Ethical issues related to the keeping of an individual species will vary depending on the categorization of the keeper.
For the pet owner, as defined above, several issues must be addressed in selecting a potential species as a pet. First, the keeper must be sure that the species can legally be kept according to local, state, federal, and international law. Laws pertaining to the sale and ownership of pet reptiles vary tremendously among different states and cities. Several states have revised their legislation such that it is no longer determined which species cannot be kept as pets, but which species can be kept as pets. The list of species is revised on a yearly basis to reflect the current global status of the species. Information on the legal status of species at the state level may be obtained from state fish and wildlife departments. Local laws should also be investigated as some cities restrict ownership of certain large species.
Many reptile species have become threatened due to habitat loss and collection for the international food, skin, and pet trade. As such, the pet owner ethically should avoid keeping animals that have been collected from the wild. In addition to ethical concerns , wild caught animals should be avoided as they are less likely to adapt to a captive life style and more likely to be harboring parasites than captive-bred animals. The pet owner should avoid the temptation to keep notoriously difficult or rare species, as well as the temptation to rescue ill animals from pet stores. Keeping such individuals is often very discouraging, and can introduce disease into an otherwise healthy collection.
In selecting a species as a pet, one should investigate those that are being bred in captivity in significant numbers and that have demonstrated longevity in captivity similar to that in their natural environment. Consideration should be given to the adult size of the species, and whether very large specimens can be humanely housed in a given geographic zone. For example, although the African Spur-Thigh Tortoise (Geochelone sulcata) is a friendly, hardy, inexpensive, captive-bred species, it is the third largest tortoise species in the world and cannot be humanely housed as an adult in the home of the average pet owner. It may make a fine pet in an outdoor corral in Arizona, but is impractical indoors in New England. Similar arguments can be made in opposition to keeping green iguanas (Iguana iguana) as pets.
Safety of the keeper's family and the public should be also be considered in choosing a pet reptile. For example, although Burmese Pythons (Python bivittatus) are widely available as inexpensive, generally tractable, captive-bred specimens, the average pet owner probably does not need an eighteen foot long constrictor. There is little that this species offers, other than its thrill value that cannot be appreciated in much smaller, safer species.
A final factor that may influence the choice of species to be kept as a pet is the species dietary and housing requirements. Some keepers have ethical or other personal reasons for not wanting to feed an animal rodents or insects. In that situation, choosing one of the herbivorous species will result in a much more pleasant owner/pet relationship. Also, keeping species that require large water environments, such as aquatic turtles, can be vary labor intensive and may result in keeper reluctance to keep the water adequately clean.
The following list of species includes those that are generally captive bred, and have proven in the author's experience to make good pets. This list is not meant to be all-inclusive, but rather a starting-point for the novice keeper. The keeper should be careful to choose captive-bred animals, as many of these species are available as both wild-caught and captive-bred specimens (e.g. ball python).
Among snakes, good choices are:
Corn snakes ( Elaphe guttata )
Milk snakes and king snakes ( Lampropeltis sp .)
Ball pythons ( Python regius )
Among land tortoises, good choices are:
Redfoot tortoises ( Geochelone carbonaria )
Greek tortoises ( Testudo graeca )
Russian tortoises ( Testudo horsfieldi )
Among water turtles, good choices are:
Painted turtles ( Chrysemys picta )
Reeve’s turtles ( Chinemys reevesi )
New Guinea red-bellied turtles ( Emydura subglobosa )
Among lizards, good choices are:
Bearded dragons ( Pogona vitticeps )
Leopard geckos ( Eublepharis macularius )
Blue-tongue Skinks ( Tiliqua gigas )
Numerous sources for captive-bred reptiles have become available in the past ten years. Locally, reptile specialty pet stores often carry a wide range of healthy captive-bred specimens. In addition, the keeper should investigate classified advertisements in reptile pet magazines. Often, local breeders may be found through these advertisements and may allow the purchaser to handpick their animal. Direct contact with a breeder provides invaluable information on husbandry of the species. Other sources for captive-bred reptiles include numerous regional reptile shows, reptile Internet web sites, and large-scale national reptile breeders. Information on these sources can generally be found in reptile pet-magazines or on the Internet. Keeping reptiles as pets can be a rewarding and fun experience. By properly selecting a species, a specimen, and researching the species needs, the keeper may experience years of enjoyment.
4. Basic Pet Reptile Husbandry and Preventive Medicine
Proper husbandry is critical to the successful maintenance of reptiles in captivity. Strict attention must be paid to environmental temperatures, humidity, light quality, water quality, habitat complexity, and nutrition. Among the thousands of reptile species, husbandry requirements vary extensively. Prospective reptile owners must familiarize themselves with the requirements of the specific species with which they wish to work prior to purchasing the animal.
As ectothermic animals , reptiles must be able to move among various temperature zones to maintain their preferred body temperature. Inadequate temperatures promote poor immune response and poor digestive efficiency, and are a common cause of illness in captive reptiles. As such, heat sources appropriate to the species must be provided. One of the best heat sources for reptiles is simple incandescent lighting . Regular light bulbs in reflector-type fixtures focus heat into certain areas of the environment, simulating the heat derived in the wild from the sun. For most species, this is the most effective and natural way of heating in indoor environments. Temperatures below these lamps must vary with the ecology of the species. For example desert lizards may need basking temperatures of 110F-120F, while some leaf-litter forest species may prefer to be at 70-75F. In addition, some species must be kept very warm even at night while others prefer a night temperature drop. In cases where night temperatures must be high, ceramic radiant heat emitters or heat panels may be installed to provide heat without providing light. Using light emitting heat sources at night may adversely affect the animal's sleep cycle, immune response, and reproductive cycle.
Another source of heat that is useful for some species, particularly snakes, is the thermostatically controlled heat pad . When used properly the heat pads or heat tape are placed under the enclosure and thermostatically set to maintain the correct basking temperature within the enclosure. Such pads are often utilized by gestating female snakes or by snakes that have recently eaten. The pads may also be used to provide a generally increased environmental temperature for tropical terrarium environments. The key to proper use of these pads is that they are arranged and controlled in a way that the animal cannot burn itself. Thermal burns are very common in reptiles exposed to heat sources that are too hot. Hot rocks are synthetic rock-like structures intended to be placed within the enclosure to provide heat. Many veterinarians can testify to the frequency of thermal burns in animals exposed to hot rocks. In light of this, hot rocks are not recommended.
Like the choice of heat source, the choice of enclosure will vary by species. Many small species can be maintained in traditional glass terrarium setups. The enclosure must be escape-proof for the kept species. Larger specimens may need to have custom-built enclosures or large commercially available enclosures. Large aquatic species need large pools such as those used in the aquaculture industry, and generally need some type of powerful filter system to maintain adequate water quality. Arboreal species should have vertically oriented enclosures, while vertical space is of little use to terrestrial species such as tortoises.
Enclosure substrate should be easy to clean and not harmful if ingested. Many types of bedding, including gravel, sand, crushed walnut shells, corn cob, and some bark mulch, are indigestible and often cause intestinal obstructions when they are ingested. Newspaper is a safe and effective substrate for most species . Other safe alternatives include non-frayed artificial turf or carpeting, paper towels, or large size bark mulch. In dry environments, alfalfa pellets such as rabbit food can be used as bedding. Substrates should be spot cleaned daily and replaced when heavily soiled.
Water must be made available as appropriate for the species. Many reptiles will drink water from a shallow bowl. The animal must be able to easily access the bowl without spilling the water. Several species, however, may not drink water from a bowl, preferring a drip or mist system. Green iguanas and true chameleons should be sprayed or misted daily. Spraying may also be required to maintain adequate humidity levels for tropical forest species.
In addition to basking lights, full-spectrum lighting with ultraviolet B wavelengths in thought to be important for many species. While controlled studies exist for only a few species, it is generally recommended to provide UVB light to lizards and chelonians. The best source of UVB light is unfiltered natural sunlight. It is ideal to have an outdoor enclosure for lizards and turtles that can be used during mild weather. In the absence of natural sunlight, fluorescent (e.g. Zoo Med Iguana light) or incandescent (e.g. UVHeat.com) UVB-emitting bulbs should be provided within twelve to eighteen inches of the animal. UVB light is filtered out by glass or plastic.
Dietary requirements of reptiles vary among species. Snakes are carnivorous and most snakes kept as pets will accept rodents as the main diet. Specialized snake species may require fish, lizards, birds, or other hard to obtain prey. These species should be avoided by the pet owner. In all situations, it is safest for snakes to ingest pre-killed items. Live rodents often seriously injure the snake, while the snake may not defend itself. If live rodents must be fed, this must be strictly supervised to avoid injury.
Most lizards are also carnivorous, accepting insects, other invertebrates, or rodents depending on the size of the species. There are several omnivorous species [bearded dragons (Pogona sp.), bluetongue skinks (Tiliqua sp.), and Uromastyx sp.], and several herbivorous species [green iguana (Iguana iguana) and Solomon Island prehensile-tailed skink (Corucia zebrata)], that require vegetable matter. Excellent vegetable items include kale, collards, endive, escarole, dandelion, clover, chicory, beet greens, and Swiss chard. These items are chosen to maximize the animal's calcium intake as discussed below.
Chelonians may be carnivorous, omnivorous, or herbivorous. Carnivores may accept earthworms, fish, killed rodents, insects, and commercial foods such as trout pellets. Herbivores require a high fiber, high calcium diet and should be fed greens as listed above as well as fiber sources such as alfalfa pellets, chopped hay, and grass. Omnivores may be offered a mix of the carnivore and herbivore diet. In general, fruits are not tremendously nutritious and should be used as "dessert" in small amounts.
Unless whole rodents or fortified pellets are being consumed, vitamin and mineral supplementation may be needed. In particular, insects and plant matter are often deficient in mineral content. Reptiles that are not supplemented often suffer from calcium deficiency. Supplementation may be done by mixing a powdered calcium supplement with the food items, or by feeding insects a high calcium diet for several days before they are fed to the reptile ( gut loading ). Supplements should be used in moderation as oversupplementation can also occur. Multivitamin supplements in particular are often excessively high in Vitamin A and D and should generally be used only once weekly.
Review Feeds and Feeding syllabus material for more on reptile nutrition.
Proper husbandry and nutrition are the most important aspects of reptile preventive care. However, a number of other practices are recommended. Quarantine of new animals is extremely important. In general, a two to three month quarantine is recommended. Overzealous collecting and overstocking of environments should be avoided. During quarantine, fecal analysis should be performed several times to test for internal parasites. These parasites should be treated and eliminated if possible before release from quarantine. In some situations, further testing such as bloodwork may be recommended.
Finally, annual physical examination by a veterinarian is recommended for all pet reptiles. At the physical exam, the animal's growth and weight are measured, maintenance such as nail trimming and beak trimming is done, stool samples are checked, signs of illness may be detected, and a discussion of modifications of husbandry can occur.
5. Reptile Therapeutics
Several fluids are used commonly, e.g., Normosol R, Plasmalyte, Reptile Ringer’s Solution)
Maintenance fluids can be calculated at 20 ml/kg/day
SQ, ICe, IV, IO, PO are all effective methods for administration - the choice of route depends on severity of illness and logistics of individual animals
Liquid enteral nutrition is often required and can be made up from prepared sources, or natural food items
Ensure, Sustacal, useful for recovery from long-term anorexia, may be mixed with vegetables or fruits for herbivores
Useful preparations include Critical Care Herbivore Diet by Oxbow Hay Co.
Pharyngostomy tubes are useful and may be needed for some chelonians that cannot or will not eat
Force feeding, or assist feeding is often easily performed and effective
6. Reptile Diagnostics
The physical examination should be systematic - consider anatomy and be thorough
(see Turtle Hematology for more)
Coccygeal veins, cardiac stick, cervical and post-occipital sinuses, axillary, jugular, ventral abdominal. Lymph contamination often occurs during blood draw. Lymph contaminated samples will yield inaccurate CBC results but may be used for generally accurate chemistry results (some values not accurate, e.g. lower albumin in lymph than whole blood)
Heparinized sample is recommended to decrease the chance of serum clotting, prevent clotting of cells for the CBC, and provide slightly more volume of plasma for the chemistry profile.
EDTA may cause hemolysis of some reptile samples and is not generally recommended as an anticoagulant. Recent research has shown that this may not apply to some species.
PCV, WBC, differential count, parasites, inclusions
Generally safe to take 0.5 to 1% of the body weight of the animal for a single blood draw
CBC is specific but not sensitive. PCV is useful indicator of anemia and dehydration.
Newer analyzers require as little as 0.1cc of blood or plasma.
BUN (only generally useful in chelonians)
Uric acid (indicates renal function, not always sensitive)
AST, LDH (non-specific locations)
CPK (heart, skeletal muscle)
Ca, PO4 (nutritional and renal status)
Na, K, Cl (as in other species)
Alb, Glob, TP (liver, antigenic stimulation, dehydration, starvation, etc.)
Glucose (no true diabetics, may elevate with hepatic disease, low in sepsis and starvation)
Trig, Cholest (may be high with folliculogenesis)
Bile acids (likely useful indicator of liver disease, needs research)
Mg, Ammonia, Biliverdin, Creatine, protein electrophoresis: may be found to be useful in future
Browse through the Reptile Image folders for examples of reptile radiographs
Lateral, DV, AP are important - always take multiple views
Take a horizontal beam view if at all possible for lateral and AP views
Consider mammography or dental film for small species
GI contrast studies are often indicated - time scale is much longer than in mammals
Iohexol clearance test - a recently described technique for assessing renal competence, usefulness needs to be determined.
7. Anesthetic Techniques in Reptile Medicine
Safe and effective anesthesia is a vital part of successful reptile surgical procedures. In addition, anesthesia or sedation is often required for certain diagnostic or therapeutic procedures such as endoscopy, tracheal wash, or simple blood collection in some species. The last decade has produced a number of important studies of anesthetics, anesthetic monitoring, and anesthetic recovery (see references).
As ectothermic animals, it is essential that reptiles be maintained at their optimum body temperature during anesthesia. This is important not only for proper immune and cardiovascular function, but also allows a more predictable and repeatable response to anesthetics. Safe heat sources include thermostatically controlled heat pads, or radiant heat sources such as incandescent lights or infrared heat emitters. For most species, temperatures of 85 to 95F are acceptable for anesthesia, although this varies significantly among species.
Knowledge of the animal's overall health status will allow a specific anesthetic plan to be determined. The intensity of pre-anesthetic screening will vary depending on the severity of the patient's condition, but the clinician should ideally obtain a CBC, chemistry profile, and survey radiographs before any major surgical procedure. In addition, urinalysis, cultures of lesions, serology for common pathogens, ultrasound, endoscopy, and CT or MRI studies may allow better definition of the patient's problem.
The fluid status of the patient should be evaluated before, during, and after anesthesia. The route of fluid support will vary with the patient's condition, but subcutaneous (SC) or intracoelomic (Ice) fluids are useful in routine situations. For debilitated animals, intraosseus (IO) or intravenous (IV) catheters should be placed. While there is some debate over the 'best' fluid to use in reptiles, many clinicians now prefer to use non-lactated crystalloids such as Normosol-R or Plasmlyte. In most situations, fluids may be administered at a rate of 20ml/kg as a SC or ICe bolus, or at a rate of 1 ml/kg/hr as an IV or IO infusion. These rates are not well defined and are open to clinical judgment. In very debilitated patients, colloids may be needed. Volumes and rates for these products are also not well defined and they should be used judiciously with close monitoring. It appears that Hetastarch and Oxyglobin may be useful, although the author has not used these products in reptiles. If needed, whole blood transfusions may be provided. While no study has yet assessed the efficacy of whole blood transfusions, clinical experience has shown that a transfusion from the same species appears to be safe and effective.
Anesthetic monitoring by an individual trained in the idiosyncrasies of reptile anesthesia is critical to a safe procedure. As such, the clinician should encourage all anesthetists to become familiar with drugs, equipment, and common complications of reptile anesthesia. The first level of monitoring, which is often all that is needed for minor procedures, is visual observation of respiration and systolic pulse. In all species, respiration is generally obvious if present. In snakes, the heartbeat can often be visualized by observing the ventral scales near the end of the first third of the body. In iguanas, the carotid pulse can often be observed just behind the tympanum, or the heartbeat can be seen in the axillary region. The pulse of chelonians is generally not visible.
Electrocardiography has only been defined for a small number of reptile species, and is rarely used by the author. As with other species, the ECG does not provide information on hemodynamic function. It is very common for the reptilian (especially chelonian) heart to continue to beat even after removal from the body during necropsy. Therefore, the presence of a normal ECG rhythm may obviously be misleading! Preferable to the ECG are monitoring devices that provide information on the efficacy of heart function. Doppler blood flow detectors are useful to provide audible evidence of blood flow. Pulse oximetry is also useful in providing a measure of heart rate, and oxygenation status. Normal heart rates will vary among species and conditions, but generally a heart rate between 20 and 60 beats per minute is acceptable. Similarly, oxygenation will vary, and the clinician should be aware that most species are relatively tolerant of hypoxia. As discussed below, hypoxia (compared to mammals) may in fact be beneficial in reptile anesthesia. Oxygen saturation levels over 40% are generally acceptable. Initial studies have validated the accuracy of pulse oximetry in the green iguana.
Local anesthetics may be used for minor surgeries or to facilitate placement of intraosseus catheters. Lidocaine is often used by the author to allow debridement of abscesses.
Injectable sedatives and anesthetics are generally used for minor surgical procedures and for induction of anesthesia prior to inhalant anesthesia. The role of anticholinergics in reptile anesthesia remains unclear, and they are not routinely used by the author. Dissociative agents are useful for many procedures. Ketamine (20-100 mg/kg IM) and Telazol (3-10 mg/kg IM) have both been used safely and effectively for many years for minor surgery as well as induction. In general, lizards and snakes can be treated with the lower end of the dose range for these drugs. If sedation is inadequate, incremental doses up to the maximum dose may be given. Chelonians often require treatment with the high end of the above doses. Prolonged recovery may be seen with high doses of these drugs, but generally recovery occurs within two to twelve hours. Although spontaneous respiration often persists under the effect of these drugs, the patient should be monitored closely and ventilated if apneic.
Propofol (5-15 mg/kg IV or IO) has become a popular reptile anesthetic in the past five years. Benefits of propofol include its rapid onset of action, relatively short residual effect, and cardiovascular-sparing effect. The lower end of the dose may be effective for lizards and snakes, while the higher dose may be needed for chelonians. Drawbacks to the use of propofol include the necessity of IV or IO injection, relatively high cost, short shelf-life, and respiratory depressant effects. Propofol may be used alone to facilitate diagnostic procedures and or as an induction agent for inhalant anesthesia. In snakes, propofol is generally administered by the intracardiac route.
Medetomidine may be useful as an adjunct to other injectable anesthetics. Although one study of its effect on the green iguana reported medetomidine to have little if any effect at high doses, several studies in tortoises have found that medetomidine (25 to 100 micrograms/kg IM or IV) is a useful adjunct to ketamine (5-10 mg/kg IM or IV). By using medetomidine, a low dose of ketamine may be used, thus allowing for a more rapid recovery after reversal with atipamezole. The author has also used medetomidine (50 micrograms/kg IM) as an adjunct to telazol in several chelonian species, when standard doses of telazol provided inadequate restraint.
Neuromuscular blocking agents have been used for restraint of reptiles for non-painful procedures. While these agents have not gained widespread acceptance, succinylcholine and gallamine have been used for procedures such as transport of crocodilians and intubation of chelonians. Preliminary data from Tufts University School of Veterinary Medicine indicates that another neuromuscular blocker, rocuronium (0.4 mg/kg IM), is useful to allow intubation of box turtles (Terrapene carolina ssp.). Initial clinical trials of this drug by the author indicate the drug to be useful in Mediterranean tortoises (Testudo sp.), but less effective at the proposed dose for tortoises of the genus Geochelone. The effect of rocuronium is reversed by neostygmine and glycopyrrolate.
For long surgical procedures, inhalant anesthesia is necessary. In general, induction of anesthesia with an injectable drug will facilitate intubation. Harmless snakes and some chelonians may be intubated without sedation, but this may be stressful for the patient. Attempts to induce anesthesia by mask or chamber induction may often fail, or take a very long time, due to reptiles' ability to become apneic for long periods. Intubation is relatively easy for most species as the glottis is located rather prominently at the base of the tongue. In some lizards [true chameleons and blue-tongue skinks (Tiliqua sp.)], the glottis may be difficult to locate until the large tongue is pushed ventrally into the buccal cavity. Endotracheal tubes for reptiles should generally be non-cuffed Cole tubes, or may need to be made from urethral or intravenous catheters for very small reptiles.
For reptiles under 3 kg body weight, a non-rebreathing anesthetic circuit should be used. Many reptiles become apneic under inhalant anesthesia and may require intermittent positive pressure ventilation (IPPV) at two to four breaths per minute. Airway pressure should not exceed ten cm of water during manual ventilation.
Because reptilian respiratory drive is stimulated by hypoxia, Diethelm and Mader have suggested that 100% oxygen may not be the best carrier gas for inhalant anesthesia. Their initial studies have shown that recovery time and return to spontaneous ventilation post-operatively may be expedited by using air as a carrier gas . Further investigation of this concept is warranted.
Isoflurane is the accepted inhalant agent of choice for reptiles at this time. Isoflurane is cardiovascular-sparing, has short residual effect, and is readily available. Concentrations of two to five percent may be needed. The newer inhalant agent sevoflurane has been evaluated in the desert tortoise (Gopherus agassizi), and appears to be quite safe and short-acting. The manufacturer of sevoflurane reports it to be useful for mask or chamber induction in reptiles as it has less odor and is less irritating than isoflurane.
Participants in the reptile anesthetic procedure should be aware of the tendency of some reptiles to spontaneously awaken during surgery . This seems to occur most frequently with the green iguana (Iguana iguana). Often, the patient has apparently been at a stable plane of anesthesia for many minutes and is being maintained at relatively high concentrations of inhalant. One possible explanation for this phenomenon is that blood may be shunted away from the lungs, as occurs with the dive reflex in some reptiles, allowing the blood to be less saturated with anesthetic than one would expect. If this should occur, the surgeon should stop and hold the animal as well as possible, while the anesthetist manually ventilates the patient as fast as possible. If available, a third person should hold the patient's mouth tightly closed to prevent extubation. Alternatively, if an intravenous or intraosseus catheter is in place, a bolus of propofol may be given.
Analgesics have not been well studied in reptiles although they are often used clinically. The author has used Ketoprofen (1 mg/kg IM) as a standard post-operative combination for major surgery for several years with good results and no obvious complications. Recent evidence indicates that morphine may be effective for analgesia in bearded dragons and red-eared slider turtles, but not corn snakes. Butorphanol appears to be effective in corn snakes, but not red-eared sliders and bearded dragons. Opiates may cause respiratory depression. Buprenorphine may also be useful in reptiles, but efficacy studies are lacking.
8. General Reptile Surgical Principles
Basic surgical principles can be applied to reptiles, with certain exceptions based on unique anatomy and physiology. Adequate pre-surgical patient evaluation and preparation are essential. As discussed elsewhere in this course, a thorough review of the patient's nutritional status, hydration, temperature, etc. should be performed prior to considering surgery. A thorough plan for anesthesia, analgesia, and anesthetic monitoring should also be developed. Adequate time should be allotted for potential unforeseen complications and anesthetic events.
Sterile surgical preparation of reptile skin can be achieved through standard scrub techniques. Every effort should be made to maintain sterility, as would be done with any mammalian patient. Transparent surgical drapes are useful for very small patients. Common minor surgical procedures include abscess and burn debridement, digit and tail tip amputation, and minor trauma repair. These procedures may often be performed with heavy sedation and local analgesia.
Common major surgical procedures include ovariectomy, salpingectomy, salpingotomy, gastrotomy, cystotomy, full tail amputation, and surgical or endoscopic biopsy. In turtles, surgical access to the coelom can be either via a pre-femoral soft-tissue approach, or transplastron coeliotomy. The latter involves cutting a window in the plastron with a bone saw. This is fairly invasive and slow to heal, and should be avoided if possible.
In most lizards a large ventral midline vein runs along the length of the ventrum. This vessel can be avoided by very careful dissection. However, most surgeons prefer to use a slightly paramedian incision in lizards to avoid the vein. An incision approximately 1-2 cm off midline is generally safe.
In snakes, the coelomic incision is generally made slightly lateral to the ventral midline at the junction of the ventral and lateral scales. This avoids transecting the ventral scales, results in more cosmetic healing, and seems to close more easily than a ventral mid-line approach. In snakes careful consideration and calculation of anatomic landmarks prior to surgery will aid in localization of organs intraoperatively.
Surgical ligation clips, such as Ligaclips or Hemoclips are very useful for reptile surgery, particularly for ovariectomy. These clips allow rapid and precise ligation in very confined surgical areas. Radiosurgery and laser surgery are also becoming popular, and are helpful in cutting and coagulating small vessels. General principles of hemostasis should be followed.
Contamination of the coelom can often be successfully managed via thorough lavage and suction. Medical management for peritonitis should be instituted concurrently.
Reptiles lack enzymes to break down chromic gut suture material. As such, internal absorbable sutures such as PDS, Maxon, or Vicryl, or their equivalents are recommended. Surgical incisions into organs can generally be closed with a simple interrupted pattern. The coelom is generally closed with simple interrupted or continuous pattern through the coelomic membrane and muscle, if it is visible. In some species, this tissue is so thin that it is difficult to close. In general, the holding layer of the reptile coeliotomy closure is the skin. As reptile skin tends to invert, an everting closure pattern such as a horizontal mattress pattern is recommended. Non-absorbable nylon or skin staples are generally used on the skin layer. Skin sutures are generally left in place for 6-8 weeks.
Closure of the chelonian shell is generally accomplished by some combination of wire, screws, and acrylics, at the discretion of the clinician. It is important to prevent acrylic from inhibiting contact of the bone edges. In most cases, surgical incisions are kept dry for several days prior to allowing access to water. Bandages may be used if desired but are not necessary for most routine incisions.
9. Endoscopy in Reptile Medicine
Endoscopy has been used for many years in both human and veterinary medicine. Only recently, however, has endoscopy been used to any extent in reptiles or amphibians. Endoscopy involves the use of a fiberoptic lens system or camera system to visualize the internal structures of the patient. Endoscopy is favored because it is minimally invasive, does not involve large incisions, and can be used to obtain tissue biopsies.
In herpetological medicine, the veterinarian is often faced with a very stoic patient. Reptiles have the ability to appear quite normal externally, while actually being extremely ill internally. As a result, diagnostic testing is often necessary. Blood testing, including cell counts, blood chemistry values, and antibody levels to specific diseases, is often helpful but is equally often unhelpful. It is possible to have a completely normal blood result in a very ill reptile. Similarly, radiographs and ultrasound images are sometimes useful, but only provide an indirect, limited view of organs. Because of these limitations, veterinarians may now favor endoscopy to allow direct visualization and evaluation of reptile and amphibian patients.
There are numerous areas where endoscopy may be useful. Coelioscopy , or internal examination of the coelomic cavity, provides direct view of the liver, lungs, kidneys, heart, spleen, bladder, gastrointestinal tract, pancreas, and gonads. This technique can be used to evaluate these organs for abnormalities including organ enlargement, abscesses, tumors, bleeding, etc. Visualization of the gonads can be used to determine the gender of individuals of sexually monomorphic species or juveniles of dimorphic species. Fieldwork on juvenile desert and Galapagos tortoises, and hellbenders, has demonstrated the utility of endoscopy for gender identification. Endoscopy can also be used in reptiles to look into the trachea and bronchi to evaluate cases of respiratory disease. It can be used to retrieve foreign bodies from the gastrointestinal tract (e.g., coins swallowed by crocodilians). Finally, and perhaps most importantly, endoscopic instruments allow the veterinarian to obtain tissue biopsies of diseased organs. By obtaining biopsies, it may be possible to provide a more precise diagnosis and prognosis than previously available through other diagnostic testing. For example, based on bloodwork an animal may be said to have a liver problem; but with endoscopy, a more definite diagnosis such as a moderate chronic active fungal hepatitis may be made, thus allowing precise treatment for the precise problem.
Several types of endoscopes are useful for reptiles. For chelonians, lizards, and for some procedures in snakes, the rigid 2.7 mm Hopkins telescope is most useful. This telescope system generally is equipped with a sheath to allow introduction of biopsy forceps and endoscopic surgical instruments. Endoscopic scissors are often required to incise through the coelomic membrane or capsule of organs such as the chelonian kidney prior to biopsy. Flexible endoscopes are most useful in snakes for evaluation of the digestive and respiratory tract. To sterilize scopes for coelioscopy, cold sterilization products or gas sterilization may be used. For insufflation, a simple aquarium air pump may be used to provide very gentle pressure. Care must be taken to prevent over-inflation leading to cardiorespiratory depression and severe subcutaneous emphysema.
In general, a small incision (about one cm) must be made in the body wall under general anesthesia. In lizards, the incision for coelioscopy is generally made in the lateral body wall just caudal to the last rib. In chelonians, the incision is made in the center of the pre-femoral fossa. In snakes, the incision is made at the junction of the ventral and lateral scales at a site along the body where the organ of interest is expected to be. The skin incision is generally made with a scalpel, while incision of the coelomic membrane and muscle may be made bluntly with hemostats or sharply with endoscopic scissors.
Veterinarians and herpetoculturists should be aware of the availability of endoscopy and consider seeking a referral veterinarian that can provide this service if other diagnostic options have been unrewarding.
10. Turtle Health Issues
See also Chelonian Medicine.
Nutritional disease of chelonians is common. Most often, nutritional secondary hyperparathyroidism is seen as a result of inadequate dietary calcium, Vitamin D3 and ultraviolet light. The disease is most common in young turtles. Symptoms may include soft shell, pathological fractures, and weakness. If detected early, the disease is reversible by correction of diet and lighting, and calcium and vitamin D3 supplementation. Calcitonin also appears to be helpful in counteracting the effect of parathyroid hormone. General recommendations include treatment with Neocalglucon (calcium glubionate syrup) at 1cc/kg PO SID for several months, and calcitonin (50 IU/kg IM) once weekly for two treatments. Prior to calcitonin treatment, the patient should be on Neocalglucon for one week to prevent fatal hypocalcemia. During treatment, if the patient is eating, it should have its diet improved by adding high calcium food items and a calcium and vitamin D3 supplement. Natural sunlight is provided if possible, or UVB artificial lighting is provided. If the patient is anorexic, it should be syringe fed with a diet appropriate for the species. In stubborn specimens, a pharyngostomy tube may be placed to allow less stressful feeding.
The classic syndrome of Vitamin A deficiency is less common than in past decades. By feeding complete pelleted diets, this problem has been largely eliminated. However, signs of swollen eyes in conjunction with a history of a deficient diet should prompt suspicion. Treatment is generally effective with vitamin A by either the oral or injectable route. The oral route seems to be less likely to cause skin sloughing due to overdose than the injectable route. The clinician should be careful not to diagnose Vitamin A deficiency in an animal that has been on a diet with adequate vitamin A. Often, eye swelling in these specimens is due to bacterial conjunctivitis, sinusitis, or otitis.
Bacterial diseases are common in chelonians. These infections are often caused by drug-resistant gram negative bacteria . Chelonians commonly develop casseous abscesses of the ear, pneumonia, sepsis, and shell infections. Otitis causes bulging of the tympanic membrane. Treatment of abscesses generally involves debridement of affected tissue, culture of affected tissue, and topical and systemic antibiotics. Septicemia is common in debilitated chelonians and should be treated aggressively. Signs of sepsis may include ecchymoses of the shell, oral petechiae, depression, and anorexia. Infections of the shell may need to be treated by debridement of infected bone, along with topical and systemic antibiotics. Pneumonia is best diagnosed based on symptoms and horizontal beam radiographs demonstrating lung consolidation. As with all ill reptiles, maintenance of proper environmental temperatures is essential.
Mycoplasma agassizii has been identified as the cause of upper respiratory tract disease in several tortoise species. Symptoms generally include rhinitis, sneezing, and dyspnea. The University of Florida currently offers reasonably priced Mycoplasma serology, culture, and PCR to identify affected animals. If detected early, the syndrome can be controlled with antibiotics, although animals may become chronic carriers. Treatment with drugs effective against Mycoplasma, such as chloramphenicol, enrofloxacin, or clarithromycin often results in rapid improvement. Intranasal instillation of a steroid and antibiotic solution (e.g., Gentocin Durafilm) seems to help clinically.
Parasitic diseases of chelonians are common. Both external and internal parasites may be seen. External parasites such as ticks may be removed with forceps. If the tick is thought to have come from outside the U.S., it should be sent to the USDA for exotic disease surveillance. Mites are uncommon in chelonians.
Numerous internal parasites may be pathogenic to chelonians. Both metazoan and protozoan parasites often cause disease of the gastrointestinal tract, liver, and kidney. Specifically, nematodes such as Angusticaecum and protozoans such and Hexamita (a renal parasite found in urine) and Entamoeba may cause significant damage. Treatment of nematodes is generally done with fenbendazole at a range of doses. The author is currently treating at 50 mg/kg PO daily for three days, and repeating in two weeks. If the course is not effective, the drug may be given daily for five to seven days. This schedule of fenbendazole may also eradicate some flagellated protozoans. Alternatively, flagellates may be treated with metronidazole at 20 mg/kg PO EOD for 14 days. Longer courses are indicated based on fecal or urine re-evaluation.
Entamoeba invadens has long been recognized as a significant protozoal pathogen of lizards and snakes. It has been observed that chelonians may be asymptomatic carriers of the organism, acting as vectors for transmission to lizards and snakes. However, a growing body of evidence suggests that Entamoeba may cause significant pathology in chelonians, particularly under conditions of immunosuppression. While some infections remain within the GI tract, Entamoeba may spread to the kidneys or liver resulting in abscess formation. Symptoms of infection generally include watery, bloody, or mucoid diarrhea, anorexia, dehydration, and lethargy. Diagnosis of amoebiasis is generally made by detection of cysts or trophozoites on direct fecal wet mount or fecal floatation, although newer diagnostic modalities such as ELISA testing are being evaluated.
The most commonly reported therapy for reptilian amoebiasis has been metronidazole given orally at relatively high doses and relatively infrequent intervals. Recent pharmacokinetic studies in the green iguana and the yellow rat snake have shown that a metronidazole dose of 20 mg/kg every 48 hours may be more appropriate. Treatment should continue for at least two weeks, although much longer courses may be required. Unfortunately, although metronidazole in considered effective against amoebic trophozoites and is an effective extraintestinal amoebicide, it may be only partly effective or ineffective against amoebic cysts. As a result, combination drug therapy may be needed to completely clear an infection. Iodoquinol or diiodohyroxyquin (Yodoxin, Glenwood Palisades, Tenafly, NJ), has been used to treat amoebiasis in humans, and has been used by Dr. Barbara Bonner (The Turtle Hospital of New England) and the author in several hundred specimens of approximately a dozen species of chelonians. A dose of approximately 50 mg/ kg orally once daily for 21 days has resulted in cessation of cyst shedding (not necessarily proving complete eradication) in the majority of cases. In addition to treatment with amoebicidal drugs, infected patients may also need nutritional support, antibiotics, and antifungal medications. A thorough assessment of the patient must be made, and amoebae treated with consideration of other concurrent disorders. Repeated evaluation of fecal samples over a several month quarantine period is required to ensure eradication.
Viral diseases of chelonians have been reported sporadically, although the frequency is increasing. In particular, herpes virus is being found commonly in European tortoises. The virus generally causes glossitis and stomatitis but has also been found to cause hepatitis and splenitis. Ongoing studies in Britain and the University of Florida are attempting to develop serologic testing for the virus, and determine the efficacy of treatment with acyclovir.
11. Snake Health Issues
Snakes in general are fairly hardy creatures. As a result of their carnivorous diet, most often a diet of whole rodents, snakes are less likely to develop nutritional disorders than many other reptiles. As a result, many of the disorders that are seen are more related to inadequate environmental temperatures and humidity. Bacterial, parasitic, and viral diseases are very common in captive snakes.
The unique process of ecdysis , or skin shedding, in the snake can often be interrupted due to improper environmental parameters. Incomplete shedding, or dysecdysis, commonly occurs in snakes that are kept at low environmental humidity. For proper shedding, snakes should be misted daily or provided with a humid hide box during the shedding process. Retained skin on the body can often be gently peeled off after moistening with water. One area that must be treated with caution, however, is the eye. Snakes do not have movable eyelids, but rather the eye is covered by a transparent scale called the spectacle. The spectacle provides protection to the cornea, preventing abrasion and desiccation. The spectacle is often not shed properly with dysecdysis. Retained spectacles may be gently removed with a cotton swab after moistening with water. Aggressive attempts to remove the spectacle have often resulted in damage to the eye. If the retained spectacle cannot be removed easily, it should be left in place, and shedding husbandry should be corrected before the next shed. Often the spectacle will be properly shed at that time. Retained spectacles seem to be common in snakes infected with the snake mite, Ophionyssus natricis, as discussed below.
Injuries to the skin and underlying muscle may occur due to bites from live prey items. Snakes left unattended with live food in the cage often will not defend themselves if the rodent begins to feed on the snake. Full thickness body wall wounds have been caused by rodents. A second common cause of skin lesions is thermal injury from excessively warm hot rocks, heat pads, or heat lights. Care must be taken to carefully regulate heat sources. Finally, skin lesions may be caused by wet, dirty environments where bacteria or mites may be present.
Snakes that escape from their cage are at risk of succumbing to low environmental temperatures, injuries, and starvation, and pose a potential real or perceived danger to humans. As such, snake enclosures must be escape-proof. Snakes should not be allowed to range freely as human fatalities have occurred from this practice. If nothing else, escaped snakes create bad publicity and may lead to restrictive legislation against keeping reptiles as pets.
Bacterial diseases are common in snakes. The two most common sites of infection are the oral cavity and the respiratory tract. These infections are often caused by drug-resistant gram negative bacteria . Treatment of necrotic stomatitis generally involves debridement of affected tissue, culture of affected tissue, and topical and systemic antibiotics. Respiratory infection may be difficult to treat. The thick, casseous nature of reptile pus, combined with the length of the snake lung and lack of a strong cough reflex (lack of diaphragm), result in a guarded prognosis. Signs of pneumonia in snakes include wheezing, gaping, excessive oral mucous, and coughing. Treatment of pneumonia may consist of tracheal wash and culture, followed by systemic antibiotics, nebulized antibiotics, gravitational therapy (i.e. holding the snake to allow mucous to move anteriorly), coupage, and humidification of the environment. As with all ill reptiles, maintenance of proper environmental temperatures is essential.
Parasitic diseases of snakes are common. Both external and internal parasites may be seen. External parasites such as ticks may be removed with forceps. If the tick is thought to have come from outside the U.S., it should be sent to the USDA for exotic disease surveillance. Mites may be very difficult to eliminate from snakes. As mites have both a parasitic and free living stage, the animal as well as the environment must be treated. To treat for mites, all disposable items from the cage should be eliminated. The snake should be removed from the cage to a simple plastic storage container. While in the container the snake may be sprayed with an ivermectin and water spray (10mg Ivermectin/liter water). At the same time the cage and its furnishing should be sprayed with a pyrethrin based flea and tick spray (e.g. Provent-a-mite ™), then thoroughly washed in hot, soapy water. The cage can then be reset, and the snake returned to the cage. This process may need to be repeated daily for several months to ensure eradication. Snakes parasitized heavily by mites often become anemic and succumb to bacterial infections of the skin, or even septicemia.
Numerous internal parasites may be pathogenic to snakes. Both metazoan and protozoan parasites often cause disease of the gastrointestinal tract. Specifically, nematodes such as Rhabdias and Strongyloides, and protozoans such as Monocercomonas, may cause severe damage. The nematodes may also have stages that migrate through the lung and contribute to pneumonia. Treatment of nematodes is generally done with fenbendazole at a range of doses. The author is currently treating at 50 mg/kg PO daily for three days, and repeating in two weeks. If the course is not effective, the drug may be given daily for five to seven days. This schedule of fenbendazole may also eradicate some flagellated protozoans. Alternatively, flagellates may be treated with metronidazole at 20 mg/kg PO EOD for 14 days. Longer courses are indicated based on fecal re-evaluation. In some cases, feces may not be available and a stomach wash, tracheal wash, or colon wash may need to be done.
Cryptosporidium may be fatal in snakes. The organism generally causes gastric hypertrophy leading to chronic regurgitation and gradual demise. At this time, no routine treatment for cryptosporidium is successful. Initial results indicate that paromomycin and hyperimmune bovine colostrum may be effective, but further study is needed. Current recommendations promote indefinite quarantine or euthanasia of affected snakes and carriers. Cryptosporidium may be detected from feces or stomach wash samples by acid fast stain, or more accurately by IFA testing.
Viral disease of snakes has become well defined in the past decade. Two common viruses, paramyxovirus of viperids, and retrovirus (Inclusion Body Disease) of boas and pythons, have caused significant mortality. The pet owner is more likely to deal with IBD than paramyxovirus since the common IBD host species are more commonly kept as pets. Common symptoms of IBD include chronic pneumonia, regurgitation, and neurologic symptoms such as unusual posture or 'star-gazing'. Unfortunately, this virus is routinely fatal with no simple pre-mortem diagnostic test. The most reliable pre-mortem test is biopsy of the esophageal tonsil, liver, kidney, intestine, and pancreas. Occasionally, inclusion bodies may be seen within erythrocytes on a blood smear. The nature of these inclusions is unclear, but they do seem to be often associated with true infection.
12. Lizard Health Issues
Nutritional disease of lizards is common. Most often, nutritional secondary hyperparathyroidism is seen as a result of inadequate dietary calcium, Vitamin D3 and ultraviolet light. The disease is most common in young lizards.
Symptoms may include fibrous osteodystophy of the long bones and mandible, pathological fractures, and hypocalcemic tetany. If detected early, the disease is reversible by correction of diet and lighting, and calcium and vitamin D3 supplementation, Calcitonin also appears to be helpful in counteracting the effect of parathyroid hormone. General recommendations include treatment with calcium glubionate syrup at 1cc/kg PO SID for several months, and calcitonin (50 IU/kg IM) once weekly for two treatments. Prior to calcitonin treatment, the patient should be on Neocalglucon for one week to prevent fatal hypocalcemia. During treatment, if the patient is eating, it should have its diet improved by adding high calcium food items and a calcium and vitamin D3 supplement. Natural sunlight is provided if possible, or UVB artificial lighting is provided. If the patient is anorexic, it should be syringe fed with a diet appropriate for the species. Carnivores may be fed a slurry of canned dog or cat food. The author has recently used Oxbow Critical Care for Herbivores as a syringe feeding diet for herbivorous lizards with good results.
Skin lesions due to thermal injury commonly occur from excessively warm hot rocks, heat pads, or heat lights. Care must be taken to carefully regulate heat sources. In general, incandescent lighting is a preferred heat source for lizards.
Bacterial diseases are common in lizards. These infections are often caused by drug-resistant gram negative bacteria. Green iguanas commonly develop casseous abscesses in the mouth or at other locations on the head. Treatment of abscesses generally involves debridement of affected tissue, culture of affected tissue, and topical and systemic antibiotics. As with all ill reptiles, maintenance of proper environmental temperatures is essential.
Parasitic diseases of lizards are common. Both external and internal parasites may be seen. External parasites such as ticks may be removed with forceps. If the tick is thought to have come from outside the U.S., it should be sent to the USDA for exotic disease surveillance. Mites may be very difficult to eliminate from lizards. As mites have both a parasitic and free living stage, the animal as well as the environment must be treated. To treat for mites, all disposable items from the cage should be eliminated. The lizard should be removed from the cage to a simple plastic storage container. While in the container the lizard may be sprayed with an ivermectin and water spray (10mg Ivermectin/liter water). At the same time the cage and its furnishing should be sprayed with a pyrethrin based flea and tick spray, then thoroughly washed in hot, soapy water. The cage can then be reset, and the lizard returned to the cage. This process may need to be repeated daily for several months to ensure eradication. Lizards heavily parasitized heavily by mites often become anemic and succumb to bacterial infections of the skin, or even septicemia.
Numerous internal parasites may be pathogenic to lizards. Both metazoan and protozoan parasites often cause disease of the gastrointestinal tract. Specifically, nematodes such as pinworms and protozoans such coccidia and trichomonas may cause damage. Trichomonas has been found to cause subcutaneous infection in some gecko species. Treatment of nematodes is generally done with fenbendazole at a range of doses. The author is currently treating at 50 mg/kg PO daily for three days, and repeating in two weeks. If the course is not effective, the drug may be given daily for five to seven days. This schedule of fenbendazole may also eradicate some flagellated protozoans. Alternatively, flagellates may be treated with metronidazole at 20 mg/kg PO EOD for 14 days. Longer courses are indicated based on fecal re-evaluation. In some cases, feces may not be available and a stomach wash, or colon wash may need to be done.
Isospora amphibolori is a coccidian parasite of bearded dragons ( Pogona sp.) that may cause morbidity and mortality in heavily parasitized, young animals. Healthy adults appear to be able to tolerate moderate levels of the parasite. Eradication of the parasite appears to be difficult; however, one recent abstract reported efficacy of ponazuril at 30 mg/kg PO EOD for two treatments. Other clinicians feel that affected juveniles seem to benefit from treatment with trimethoprim/sulfa (30 mg/kg PO) SID for 14 days, or sulfadimethoxine (50mg/kg PO) daily for five days, with repeat treatment if needed.
Cryptosporidium may be fatal in lizards, and is being diagnosed with increasing frequency in geckos. In contrast to snakes, cryptosporidium in lizards generally causes enteritis. At this time, no routine treatment for cryptosporidium is successful. Initial results indicate that paromomycin and hyperimmune bovine colostrum may be effective, but further study is needed. Current recommendations promote indefinite quarantine or euthanasia of affected snakes and carriers.
Cryptosporidium may be detected from feces or stomach wash samples by acid fast stain, or more accurately by IFA testing. There are several reports of cryptosporidium in the ear of green iguanas.
Viral diseases of lizards have not been identified commonly. An adenovirus has been identified in young bearded dragons ( Pogona sp.) and causes high mortality.
Reproductive disorders are common in female lizards. Even in the absence of a male, females may ovulate and produce shelled eggs. Pre-ovulatory stasis occurs when large follicles exist on the ovary but fail to progress or regress. These follicles may begin to decay leading to severe coelomitis. Post-ovulatory stasis may occur if shelled eggs are unable to be oviposited. This may occur due to lack of suitable nest sites, malnutrition, abnormal egg size or shape, or pelvic anomalies. Treatment may consist of provision of suitable nest areas, hormonal induction if shelled eggs are present, or surgical ovariosalpingectomy. Due to the high incidence of such problems in green iguanas, it is reasonable to promote routine spaying of this species at one to two years of age. (See references for more information)
A syndrome of renal failure is being seen commonly in adult green iguanas. The disease is characterized by anorexia, lethargy, and muscle tremors. Blood testing often shows severe hyperphosphatemia and dehydration, with an inversion of the normal Ca:P ratio. Uric acid levels may be very elevated but are often normal. Renal biopsy generally indicates interstitial fibrosis with mineralization or renal gout. Prognosis for these patients is poor, but they may sometimes be stabilized with intraosseus fluid therapy, syringe feeding, calcium supplementation, phosphorus binders, and in some clinicians' opinion, steroids may be helpful.
12.1. Renal failure
Common syndrome in adult middle age to old iguanas
12.1.1. Clinical signs
Anorexia, lethargy, wasting, sometimes seizures or tremors, constipation
Palpate large kidneys
Often hyperphosphatemic , uric acid may be normal
Definitive diagnosis by biopsy
Generally interstitial fibrosis, not reversible
Supportive care: oral fluids syringe feeding, aluminum hydroxide
12.2. Interpreting Iguana Bloodwork
Evaluation of hematology and plasma chemistry values has become a standard part of reptilian diagnostics. Studies documenting normal hematology and plasma chemistry results are becoming more numerous. In addition, several studies have investigated the tissues of origin of diagnostically important enzymes, and one study has assessed normal bone marrow cytology. As our knowledge of reptilian disease syndromes has increased, a number of fairly consistent trends in hematology and plasma biochemical responses to disease have been noted.
Hematology results in reptiles are best determined by evaluation of a heparinized blood sample, as EDTA appears to sometimes lyse reptilian blood cells. Biochemical tests are generally run on heparinized plasma , as reptilian serum will occasionally clot even after separation, and a slightly larger plasma volume than serum volume may be obtained from a given sample. This is important in small patients when sample volume may limit thorough analysis.
A blood volume roughly equal to one half to one percent of the animal's body weight may be collected, although far less than this volume is needed in larger animals. The most widely used venipuncture site in the iguana is the ventral coccygeal vein that runs along the ventral border of the coccygeal vertebrae. The iguana may be positioned in ventral recumbency with the tail hung over the edge of a table, or may be held vertically with the ventral tail facing the phlebotomist. Wrapping the iguana with a towel and placing gentle pressure over the eyes of the iguana may aid in restraint. For iguanas greater than 200 to 300 grams body weight, a 22g, one-inch needle on a 3cc syringe works well. Very large animals may require a 22g, 1 ½ inch needle, while smaller animals may best be approached with a 25g, 5/8-inch needle. The author prefers to heparinize the syringe and needle prior to venipuncture by filling the syringe with heparin and forcibly expelling it repeatedly until a minimum of heparin remains in the syringe.
The syringe and needle is introduced on the ventral midline of the tail ¼ to ¾ of the distance from the cloaca to the tail tip, and may be completely perpendicular to the tail or may be angled up to 30 degrees cranially. Advance the needle until the bone of the vertebral column is contacted. At this point, careful, patient negotiation of the syringe is needed to penetrate the vessel that lies along the ventral spinous processes of the vertebrae. When a flash of blood is seen in the syringe, gentle aspiration should be applied to obtain the sample. If performed properly, this technique should permit 2 to 3 cc of blood to be obtained within ten to twenty seconds. Other venipuncture sites, such as the ventral abdominal vein, the brachial plexus, or the jugular vein may also be used.
Samples should be transferred into heparinized (green top) microtainer tubes immediately after collection. One tube may be submitted as whole blood for hematological analysis, while remaining tubes should be centrifuged immediately. The plasma should be removed to a plain glass or plastic tube for transport to the lab. Delays in separation of plasma from cells may result in artifactually decreased plasma glucose measurement, and increased phosphorus and potassium levels.
The complete blood count generally will include a packed cell volume, total white cell count, and differential white cell count. Comments on cellular morphology and erythrocyte indices may be included. The PCV is run with standard microhematocrit tubes, and the differential cell count is made on a standard Wright's or 'Diff-Quick' stained blood smear. Because reptilian erythrocytes are nucleated, automated cell counters generally provide inaccurate white cell counts, and various manual methods have been developed. The Eosinophil Unopette, Natt Herrick's, ammonium oxalate, and estimated white cell count methods have been shown to provide consistent, although sometimes discordant, results. In general, the chosen method should be the same method by which reference range values have been calculated.
The packed cell volume, as in other species, is a sensitive indicator of anemia, and may be increased in the dehydrated patient. Anemia may be seen with blood loss, malnutrition, chronic disease, hemoparasitic infection, toxicities, or bone marrow infiltrative diseases. Evaluation of erythrocyte morphology may provide evidence for regenerative anemia if significant numbers of immature erythrocytes are seen. These cells are generally rounder, with a more basophilic cytoplasm, and larger nucleus than mature erythrocytes.
Hemoparasites , such as Plasmodium sp., may be found in the extracellular matrix. Intraerythrocytic parasites such as Hemogregarines may be seen within erythrocyte cytoplasm. Other intraerythrocytic inclusions have been noted, and although their significance in iguanas is not completely understood, evidence exists in snakes that these may be associated with viral infection. Artifacts of blood smear preparation and staining must be differentiated from true morphological abnormalities.
The reptilian thrombocyte is nucleated and varies from round to ovoid in shape. It is smaller than the erythrocyte and may be noted in clumps on the blood smear. It may be challenging to differentiate thrombocytes from small lymphocytes. Thrombocyte counts are not generally reported with reptile CBC results, but the cytologist may comment if the numbers appear to be decreased. Disease processes involving thrombocytes have not yet been reported in reptiles.
The white blood cells of the iguana include the heterophil, the eosinophil, the lymphocyte, the monocyte, the basophil, and the azurophil. There has been some inconsistency in terminology over the years, and the monocyte and azurophil may have been considered to be the same cell type. In fact, the term azurophilic monocyte has sometimes been used. It is clear that further research on the origin, nature, and function of these cells is needed.
The white cell count in reptiles appears to be less sensitive than its mammalian counterpart, and reptiles with severe infections may have normal white counts. However, the white count does appear to be specific, and an increased white count should prompt a search for infection or inflammation. Generally, increased white counts are the result of heterophilia and, or monocytosis. These responses are commonly seen with bacterial infections, egg yolk peritonitis, gastrointestinal disorders, and chronic renal failure. Basophilia may be noted in response to tissue necrosis. Lymphocytosis may be seen in cases of chronic inflammation or, if severe lymphocytosis is present, may indicate a lymphoproliferative disorder. The eosinophil response in reptiles does not appear to indicate parasitism or allergic reaction as in mammals, and the role of the eosinophil is unclear. Toxic reactions of reptile leucocytes may be difficult to appreciate without considerable experience. Heterophils may appear to have a more basophilic cytoplasm and larger, irregular granules. Lymphocytes and monocytes may become vacuolated.
The plasma biochemical profile generally includes albumin, AST, calcium, chloride, CPK, globulin, glucose, LDH, phosphorus, potassium, sodium, total protein, and uric acid. Cholesterol and triglycerides may also be evaluated.
Evaluation of calcium and phosphorus levels is often useful. In general, the calcium to phosphorus ratio (Ca:P) is 1.1:1 to 2.5:1. These levels are most commonly affected by nutritional secondary hyperparathyroidism, renal disease, or ovarian activity. In young animals on inadequate diets, hypocalcemia and hyperphosphatemia may be noted, with an inversion of the Ca:P. This trend may also be seen with renal disease, generally seen in adult iguanas, and confirmed by further diagnostics. Hyperphosphatemia of renal failure may be severe, and the author has seen levels of up to 60 mg/dl. Mader has reported that the calcium/phosphorus product (Ca X P) is a good indicator of renal disease. When the calcium level (mg/dl) is multiplied by the phosphorus level (mg/dl), a product greater than 70 suggests renal disease. Of course, this must be interpreted in light of other findings. Ovulating females or females suffering from follicular stasis may have very elevated calcium levels with mild to moderate increases in phosphorus levels. In some cases, both follicular stasis and renal failure may be present, and may complicate biochemical interpretation. In such cases further diagnostics are required. In the author's experience, calcium and phosphorus levels generally normalize over several months after ovariectomy in females that do not have abnormal kidney function.
Measurement of BUN and creatinine is generally of little use in evaluating the reptilian kidney. Uric acid levels are generally more helpful, although levels can be normal even with serious renal disease. Elevation of uric acid levels may be seen in some cases of renal disease, gout, or dehydration.
Hypoglycemia may be seen in cases of malnutrition. Hyperglycemia may be associated with hepatic lipidosis or pancreatitis and has also been anecdotally observed in several gravid female iguanas. In these patients, hyperglycemia resolved after ovariosalpingectomy. It is possible that diabetes mellitus occurs in reptiles, although a well-documented case has not been reported.
Hyperproteinemia may be seen in cases of dehydration or due to chronic disease with an elevation of plasma globulins. Hyperalbuminemia may be seen during vittelogenesis. Hypoproteinemia may be seen with malnutrition or protein losing enteropathies (such as intussusception). Protein losing nephropathies have not been well documented.
Electrolyte responses to disease generally follow trends seen in mammalian medicine. Sodium and chloride values often increase in dehydrated patients. Hyperkalemia may be seen with renal disease.
The activities of various tissue and plasma enzymes have recently been evaluated in the green iguana. Low or undetectable levels of ALT, ALKP, GGT, and GMD is found in a variety of tissues, and it is generally concluded that these enzymes have little use in reptilian diagnostics. Moderate AST and LDH activities are found in most tissues; therefore, elevations in either of these enzymes may not be useful in determining the site of tissue damage. CPK activity is generally found only in skeletal or cardiac muscle, and elevations of this enzyme likely represent true damage to these tissues. Elevated CPK levels have been reported in iguanas in renal failure and may be secondary to muscle wasting or muscle tremors from hypocalcemia. Be aware that repeated attempts at venipucture may produce muscle trauma and elevate CPK. High amylase activity is found only in the pancreas, but plasma amylase activities vary widely, and the usefulness of plasma amylase as an indicator of pancreatic disease is questionable.
Cholesterol and triglycerides may be elevated during periods of fat catabolism seen during anorexia or vitellogenesis. This phenomenon has been demonstrated in studies of free-ranging desert tortoises (Gopherus agassizii).
Creatine, a precursor of creatinine has been shown to be elevated in cases of renal failure in the iguana. An assay for this test was briefly available at Colorado State University but has since been discontinued.
Bile acids have been incompletely evaluated in reptiles; however, anecdotal reports suggest that levels greater than 100 micromol per liter may be abnormal. Bilirubin is not a major bile pigment in reptiles and evaluation of plasma bilirubin is generally not recommended. An assay for biliverdin may be useful when it becomes available.
Thyroid hormone levels have not been thoroughly evaluated in the iguana. Cases of hyperthyroidism have been reported in snakes, and have been associated with increased frequency of ecdysis. Hypothyroidism has been documented in tortoises fed large quantities of goitrogenic vegetables.
Heavy metal toxicosis has been rarely reported in reptiles, although its occurrence may be more common than perceived. Iguanas often eat metallic objects, and toxicosis is certainly possible. Louisiana State University has assessed normal levels of copper (1.5 ppm or less), zinc (1.3-2.2 ppm), and lead (10 microgram/dl or less) in a small number (n=12) iguanas. These values may serve as a guide until larger study groups are evaluated.
Further research on reptilian hematology and plasma biochemical evaluation is needed. In particular, studies documenting enzyme responses to organ specific damage should be performed. Evaluation of various isoenzymes of widely distributed enzymes such as LDH and AST may improve their diagnostic utility. Finally, a variety of assays that have not been thoroughly explored must be evaluated. It is likely that further evaluation of bile acids, thyroid function, ionized calcium, magnesium, amylase, biliverdin, protein electrophoresis, and heavy metal levels may provide interesting results.
As in all of veterinary medicine, clinical pathology results of iguanas must be evaluated in light of historical, physical, imaging, and surgical findings. One is often faced with the frustrating circumstance of normal blood values in the face of an obviously ill iguana. Perhaps most importantly, the reptile practitioner should make every effort to document and publish significant or unusual cases that we may all contribute to the advancement of our field.
13. Species profiles of several commonly kept reptiles
Consult species specific literature for more detailed accounts. The information below is intended only as an introduction.
13.1. Green Iguana, Iguana iguana
Tropical, diurnal, arboreal herbivore. Farm raised in Central America.
Requires spacious enclosure, climbing areas
Temps: 90-100F at basking sites, ambient 80-85F daytime, 70-75F night
May prefer to drink when misted
90% leafy greens: dandelion, kale, escarole, chicory, mustard greens, bok choy, etc
10% other vegetables, commercial diets, and fruits
Calcium/vitamin D supplement, multivitamin supplement
13.1.3. Common Problems
Large size, sometimes aggressive
Nutritional secondary hyperparathyroidism (NSHP)
Female repro disorders
GI foreign bodies
13.2. North American Box Turtles Terrapene carolina spp.
Temperate, diurnal, terrestrial omnivore.
Eastern Box turtle
Requires enclosure with large floor surface area,
Basking area, hiding areas
Easily accessed water bowl
Temps: 80-85F daytime, 60-70F night
50% vegetables and fruits, may prefer yellow, orange, red items
50% higher protein sources: low fat dog food, commercial diets, earthworms, chopped mice, insects
13.2.3. Common Problems
Vitamin A deficiency
Overgrown beak and nails
Bot fly larvae
13.3. Red Eared Slider Turtle Trachemys scripta elegans
Temperate, diurnal, aquatic omnivore.
Requires spacious aquatic environment with basking site
Frequent water changes or quality filtration
UVB probably beneficial
Water temps 70-80F, basking site 85-90F
Pelleted turtle or fish diets, earthworms, live fish, insects, leafy greens.
13.3.3. Common Problems
As per box turtles (except bot flies). Also pneumonia.
13.4. Sulcata, Leopard, Testudo Tortoises
Sulcata and Leopard are tropical terrestrial African species.
Most Testudo are temperate to subtropical European, Asian, and North African species.
Note: need interstate permit for movement of Leopard Tortoises due to possible tick/Heartwater threat. See more at APHIS http://www.aphis.usda.gov/lpa/news/2001/07/TORTRULE.HTM on this problem.
Sulcata and Leopard are large species, best kept outdoors
Testudo are moderate size and may be kept indoors or out
Some Testudo hibernate
Need spacious surface area with basking sites and hiding areas
UVB may be beneficial
Temps: daytime 80-90F with basking sites, nighttime 65-75F
Most prefer low humidity
May drink if water available
As per green iguana, also commercial tortoise diets, alfalfa pellets or hay, fresh grazing areas.
13.4.3. Common Problems
13.5. Redfoot, Yellowfoot, Hingeback Tortoises
Tropical, omnivorous, terrestrial, humid savannah and forest species.
Temps 85-90F daytime, 75-80F night
May not bask
High humidity, enjoy soaking in water and misting
80% vegetable based (see green iguana)
10% protein sources: low fat dog food, commercial tortoise diets, earthworms, mice.
13.5.3. Common problems
As per sulcata, etc. above.
13.6. Leopard Gecko
Subtropical, terrestrial, diurnal, insectivore; small, alert, good 'starter' pet.
Basking areas 85-95F daytime, 70-75 night
UVB likely beneficial
Crickets, mealworms, wax worms, cock roaches, etc.
Insects should be dusted with multivitamin/mineral supplement, and 'gut loaded' with cricket diet or high quality dog food.
13.6.3. Common Problems
GI foreign bodies
13.7. Bearded Dragon
Australian, subtropical, terrestrial, diurnal omnivore.
Spacious surface area, hide area, basking area with UVB
Temps: 90-100F daytime, 65-75 night
May brumate in winter
Insects as per geckos, and vegetables as per iguanas.
13.7.3. Common Problems
Coccidiosis, pinworms, flagellates, microsporidiosis - not necessary to tx. coccidia and pinworms in healthy adults.
GI foreign bodies
13.8. Snakes in general
Carnivorous, temperate to tropical, terrestrial to arboreal to fossorial, diurnal or nocturnal.
Tropical species environs as per redfoot/yellowfoot tortoises above
Temperate species as per box turtles above
Heat provided by lighting or heat pads under enclosure
Spacious environs with various hide areas, climbing areas, basking areas
Some like to bury in substrate (take care in choice of substrate, see above)
UVB probably not needed
Consult species specific literature
Most species prefer rodents, ideally pre-killed. Specialized species may eat birds, fish, crayfish.
13.8.3. Common problems
Inclusion body disease (boids)
14. References and Resources
14.1. Professional Organizations
American Association of Zoo Veterinarians http://www.aazv.org/
Association of Reptilian and Amphibian Veterinarians http://www.arav.org/
Center for North American Herpetology http://www.naherpetology.org/nameIntro.asp
Chelonian Research Foundation 168 Goodrich St, Lunenberg, MA 01462. Membership includes the quarterly journal Chelonian Conservation and Biology, the premiere turtle biology publication at this time. Also, members receive discounts on other publications. http://www.chelonian.org/
Reptile Database http://www.reptile-database.org/
Herp and Green Iguana Information Collection http://anapsid.org/ The site all your clients will have already been to!!
International Reptile Conservation Foundation http://www.ircf.org/
Kingsnake - the internet portal for reptile and amphibian enthusiasts http://www.kingsnake.com/
National Turtle and Tortoise Society PO Box 9806 Phoenix, AZ 85068-9806
New York Turtle and Tortoise Society 163 Rotterdam Ave Suite 365 New York, NY 10023 http://www.nytts.org/
Partners in Amphibian and Reptile Conservation http://www.parcplace.org/
San Diego Turtle and Tortoise Society. PO Box 519 Imperial Beach CA 91933-0519 http://www.sdturtle.org/
Society for the Study of Amphibians and Reptiles http://www.ssarherps.org
Turtle Survival Alliance http://www.turtlesurvival.org/
Veterinary Information Network: http://vin.com/
Zoological Education Network - Exotic DVM Magazine http://www.exoticdvm.com/
14.3. Herp Supplies
Bush Herpetological Supply PO Box 539, Neodesha, KS 66757 http://www.bushherp.com/
Vision Herpetological 7453 Deering Ave Canoga Park, CA 91303 http://www.kingsnake.com/visionherp/
Matrix Vivarium Systems, Kingston, MA
Glades Herp Fort Meyers, FL http://www.gherp.com/
Oxbow Hay Co.http://www.oxbowhay.com/
Pro-Vent-a-MiteTM Spray http://www.pro-products.com/
Antech Diagnostics . Toll-free number: 888-397-8378 http://www.antechdiagnostics.com/ Large national lab, request Schiller or Kincaid for pathology.
Avian & Exotic Animal Clinical Pathology Labs . 1701 Inglewood Ave., Suite #106. Redondo Beach, CA, 90278. Tel. (800) 350-1122. http://www.avianexoticlab.com/
Avian and Wildlife Laboratory, University of Miami, Division of Comparative Pathology , 1550 NW 10th Ave., Rm.105, Miami, FL 33136. Tel. (800)-596-7390
Pathology (352) 392-4700 x4500
Chelonian herpesvirus (352) 392-4700 x5775
Mycoplasma (352) 392-4700 x3979
Tick ID - Ms. Petey Simmons, 4602 Catalina Lane, Bonita Springs, FL 34134.
Idexx Laboratories http://www.idexx.com/ Large national lab offers exotics services.
Northwest ZooPath .18210 Waverly Dr., Snohomish, WA 98296-4815. Tel. (360) 669-6003. http://www.zoopath.com : Excellent histopathology.
Zoo/Exotic Pathology Service . 2825 KOVR Drive, West Sacramento, CA 95605.Tel. (800) 457-7981 http://www.zooexotic.com : Excellent histopathology.
Zoogen, Inc . 1756 Picasso Ave., Davis CA 95616. Tel. (800) 995-2473. DNA sexing for green iguanas. http://www.zoogen.biz/
Mader, Douglas M. Reptile Medicine and Surgery, 2nd rev. ed. W.B. Saunders Co. Philadelphia, 2006.
Biology of the Reptilia . Edited by Gans, various publishers. A technical series of texts mainly for academic herpetologists. Invaluable physiology and anatomy.
Boyer, T. 1998. Essentials of Reptiles: a Guide for Practitioners . AAHA Press
Diseases of Reptiles by Reichenbach-Klinke and Elkan. Academic Press 1965. Old but great detailed pathology.
Frye. F. (ed.) 1991. Biomedical and Surgical Aspects of Captive Reptile Husbandry . Krieger Publishing. Malabar, FL.
Jacobson, E. 2003. Biology, Medicine and Surgery of the Green Iguana . Krieger Publishing. Malabar, FL..
Jacobson ER. 2007. Infectious Diseases and Pathology of Captive Reptiles . CRC Press.
Advanced Vivarium Systems series. Lakeside, CA. Excellent, inexpensive, species specific handbooks for husbandry.
Klingenberg, Roger. Understanding Reptile Parasites . Published by AVS. Good intro info.
Self-assessment Color Review of Reptiles and Amphibians by Frye and Williams. Iowa State University Press. 1995. Case based presentations of common and uncommon problems.
Snake Keeping: Proven Techniques Everyone Can Use by Barry Nielsen. Excellent general husbandry info. Published by Best Pets PO Box 200, North Billerica, MA 01862.
McArthur, Stuart, Roger Wilkinson, and Jean Meyer. Medicine and Surgery of Tortoises and Turtles. Blackwell Publishers, 2004.
Practical Encyclopedia of Keeping and Breeding Tortoises and Freshwater Turtles , by Andy Highfield, 1996. Carapace Press, London. The best chelonian husbandry reference.
Bacterial Diseases of Reptiles , by Ross and Marzec, 1984. Institute for Herpetological Research. Stanford, CA.
Kingsnakes and Milksnakes by Markel, 1990. TFH Publication, USA.
The Care of Reptiles and Amphibians in Captivity by Chris Mattison, 1983, Blandford Press, London.
Encyclopedia of Turtles by Pritchard 1979, TFH, USA. Along with Ernst and Barbour provides the best taxonomy and description of species. Not a husbandry text.
Breeding Terrarium Animals by Zimmerman, 1986.. TFH, USA. Good general info.
Captive Maintenance and Conservation of Amphibians and Reptiles , Murphy et al (eds), 1994. SSAR.
Amphibians and Reptiles of Connecticut and Adjacent Regions. Klemens, 1993. DEP Maps and Publications, Hartford. Excellent.
Completely illustrated Atlas of Reptiles and Amphibians for the terrarium. Obst et al (eds). 1988 TFH.
Pythons of the World . Barker and Barker. 1994.
Rat Snakes - the hobbyists guide to elaphe and kin. Staszko and Walls. 1994.
The Reproductive Husbandry of Pythons and Boas. Ross and Marczek. Institute for Herp Research. Stanford, CA.
Turtles of the World. Ernst and Barbour. Smithsonian Press. 1989.
Iguana iguana. Guide to Successful Captive Care. Frye and Townsend. 1995. Krieger Publishing.
Veterinary Clinics of North America - Exotic Animal Medicine series . WB Saunders Co, Philadelphia, PA.
Ross, RA and G Marzec. Bacterial Diseases of Reptiles . Institute for Herpetological Research. Stanford, CA., 1984.
Abram, R. 1992. ivermectin as a spray for treatment of snake mites. Bull ARAV 2.1
Allen,M. et al. 1988. The effect of three light treatments on growth in the green iguana. Proc AAZV
Anderson, N., Wack, R., Calloway, L., and Hetherington, T. 1999 Cardiopulmonary effects and efficacy of propofol as an anesthetic in brown tree snakes, Boiga irregularis. Bull. Assoc. Reptile and Amphibian Veterinarians ;9(2).
Backues, K. et al.1994. Ovariectomy for treatment of follicular stasis in lizards. J Zoo Wild Med 25(1).
Bagatto, et al. 1997.Tricaine Methane Sulfonate (MS222) anesthesia in spiny and Florida soft-shell turtles. 7.2.
Bennet, R.A., 1991. A review of anesthesia and chemical restraint in reptiles. J Zoo Wild Med 22(3).
Bennett, R. Avery, et al. Cardiopulmonary and anesthetic effects of propofol administered inraosseously to green iguanas. JAVMA , V. 212 (1), 1998, pp. 93-98.
Benson, Keith G., J. Paul-Murphy, and P. MacWilliams. Effects of hemoloysis on plasma electrolyte and chemistry values in the common green iguana (Iguana iguana). J Zoo Wild Med, 30 (3), 1999: 413-415.
Benson, Keith G., and L. Forrest. Characterization of the renal portal system of the common green iguana (Iguana iguana) by digital subtraction imaging. JAWM , 30 (2), 1999: 235-241.
Bernard, J. 1995. An illuminating discussion of vitamin D, UV radiation and reptiles. Proc ARAV.
Bernard, J. et al. 1991. The response of vitamin D deficient iguanas to artificial ultraviolet light. Proc AAZV .
Berry, K.H., D. Brown, M. Brown, E. Jacobson, J. Jarchow, J. Johnson, L. Richey, L. Wendland, and R. Nathan. 2002. Reptilian mycoplasmal infections. J. Herp. Med. Surg . 12(3): 8-20.
Bonner, B.B. 2000. Chelonian therapeutics. Pp. 257-332, in The Veterinary Clinics of North America Exotic Animal Practice : Therapeutics, (S.A. Fronefield, ed.). Philadelphia, PA: W.B. Saunders Company. 3(1):1-370.
Boyer, T. 1992. Clinical anesthesia of reptiles. Bull ARAV 2.2
Boyer, T. et al. 1996. Clinicopathologic findings of 12 cases of renal failure in Iguana iguana. Proc ARAV .
Brown, D.R., I.M. Schumacher, et al. Application of diagnostic tests for mycoplasmal infections of desert and gopher tortoises, with management recommendations. Chelonian Conservation and Biology , 4(2): 249-262.
Burridge, M et al 2002. Evaluation of safety and efficacy of acaricides for control of the African tortoise tick on leopard tortoises. J Zoo Wild Med 33(1):52-57.
Burridge, Michael J. Significance and control of exotic ticks on imported reptiles. Proceedings of the Association of Reptilian and Amphibian Veterinarians , 2000: 121-122. Also paper in Florida Entomologist 85 (1), 2002.
Chittick EJ, et al. 2002. Medetomidine, ketamine, ans sevoflurane for anestheisa of injured loggerhead sea turtles: 13 cases (1996-2000). JAVMA 221(7): 1019-1025.
Cranfield and Graczyk. 1995. An update on ophidian cryptosporidiosis. Proc AAZV .
Cranfield, M. 1996. Adenovirus in the bearded dragon. Proc ARAV .
Crawshaw, et al. 1996. Comparison of plasma biochemical values in blood and blood lymph mixtures from red-eared sliders. Bull ARAV 6.2.
Dennis, Patricia M., and Heard, Darryl J. Cardiopulmonary effects of a medetomidine-ketamine combination adminsitered intravenously in gopher tortoises. JAVMA , v. 220 (10), 2002: 1516-1519.
Di Bello, A, C Valastro, F Staffieri. Surgical approach to the coelomic cavity through the axillary and inguinal regions in sea turtles, JAVMA , v. 228 (6), 2006 :922-925.
Diethelm, G., and Mader, D. The effect of FIO2 on post anesthetic recovery times in the green iguana. Proc ARAV 1999.
Divers, S. 1996. The use of propofol in reptile anesthesia. Proc ARAV .
Divers, S. et al. 1993. Dystocia (egg-binding) in reptiles. Brit Herp Soc Bull 45.
Divers, S. Reptile endoscopy. Proceedings NAVC 2000.
Donoghue, S. 1996. Veterinary nutritional management of reptiles and amphibians. JAVMA , 208 (11), 1996: 1816-1820.
Franke, J. and T.M. Telecky. 2001. Reptiles as Pets: An Examination of the Trade in Live Reptiles in the United States. Humane Society of the United States. Washington, D.C.
Garner, M.M., C. Gardiner, M. Linn, T.S. McNamara, B. Raphael, N.P. Lung, D. Kleinpeter, T.M. Norton, and E. Jacobson. 1998. Seven new cases of intranuclear coccidiosis in tortoises: an emerging disease? Proc AAZV/AAWV : 71-73.
Gehrmann, W. 1987. UV irradiances of various lamps used in animal husbandry. Zoo Bio 6:117-127
Gehrmann, W. et al. 1991. Early growth and bone mineralization of the iguanid lizard, Sceloporus occidentalis in captivity: is vitamin D3 supplementation or UVB irradiation necessary? Zoo Bio 10:409-416.
Gross, T. et al. 1992. Control of oviposition in reptiles and amphibians. Proc AAZV .
Harr, Kendal E. et al. Morphologic and cytochemical characteristics of blood cells and hematologic and plasma biochemical reference reanges in green iguanas. JAVMA 218 (6), 2001: 915-921.
Harvey-Clark, C. 1993. Midazolam fails to sedate painted turtles. Bull ARAV 3.1
Heaton-Jones, T. et al. 1994. Characterization of the ECG of the American alligator. J Zoo Wild Med 25(1)
Heaton-Jones,t et al. 2002. Evaluation of medetomidine-ketamine anesthesia and atipamezole reversal in American alligators. JZWM 33(1): 36-44.
Holz, P. and Holz, R. 1995. Electrocardiography in anethetized red-eared sliders. Res Vet Sci 58:67-69.
Holz, P., et al. 1994. The reptilian renal portal system and its effect on drug kinetics. Proc AAZV/ARAV .
Holz, Peter, et al. The Anatomy and perfusion of the renal portal system in the red-eared slider (Trachemys scripta elegans). Journal of Zoo and Wildlife Medicine , Vol. 28 (4), 1997, pp. 378-385.
Holz, Peter, et al. The Effect of the renal portal system on pharmacokinetic parameters in the red-eared slider (Trachemys scripta elegans). Journal of Zoo and Wildlife Medicine , Vol. 28 (4), 1997, pp. 386-393.
Innis, C. 1996. Treatment with propranolol and PGF2a stimulates nesting behavior but not oviposition in a gravid green iguana. Bull ARAV 6.2.
Innis, Charles J., Coelioscopic-assisted prefemoral oophorectomy in chelonians, JAVMA , April 1, 2007, Vol. 230, No. 7, pp. 1049-1052.
Innis C, Garner M, Johnson A, Wellehan J, Tabaka C, Marschang R, Nordhausen R, Jacobson ER. 2007. Antemortem diagnosis and characterization of nasal intranuclear coccidiosis in tortoises. Journal of Veterinary Diagnostic Investigation 19:660-667.
Innis C, Tlusty M, Merigo C, Weber ES. 2007. Metabolic and respiratory status of cold-stunned Kemp's ridley sea turtles. J Comp Physiol B 177: 623-630.
Innis C, Tlusty M, Wunn D. 2007. Hematologic and plasma biochemical analysis of northern red-bellied cooters: J Zoo Wild Med. 38(3).
Innis C, Young D, Papich M. 2007. Pharmacokinetics of metronidazole in the red-eared slider turtle after single intracoelomic injection: J Vet Pharm Ther 30:168-171.
Jacobson, E. 1994. Causes of mortality and diseases in tortoises. J Zoo Wild Med 25(1)
Jacobson, Elliott R. Implications of infectious diseases for captive propagation and introduction programs of threatened/endangered reptiles. Journal of Zoo and Wildlife Medicine , V. 24 (3), 1993, pp. 245-255.
Jacobson, E.R., J.L. Behler, et al. 1999. Health assessment of chelonians and release into the wild. Pp. 232-242, in Zoo and Wild Animal Medicine: Current Therapy , (M.E. Fowler, ed.). Philadelphia, PA: W.B. Saunders Company. 4: 1-747.
Jacobson, E., Rostal, D., Lance, V., Flanagan, J., Hill, L.W., and Novoa, SL. Temperature dependent sex determination in chelonians and studies with neonate captive hatched and reared Hood Island Galapagos tortoises, Geochelone nigra hoodensis. Proc ARAV 1999.
Jacobson, E.R., J. Schumacher, S.R. Telford, E.C. Greiner, C.D. Buergely, and C.H. Gardiner. 1994. Intranuclear coccidiosis in radiated tortoises (Geochelone radiata). JZWM 25(1):95-102.
Jacobson, E.R., E. Greiner, S. Terrell, and M. Garner. 1999. Intranuclear coccidiosis of tortoises. Proc ARAV : 85-86.
Klingenberg, R. 1992. A comparison of fenbendazole and ivermectin for the removal of nematode parasites in ball pythons. Bull ARAV 2.2
Klingenberg, R. et al. 1996. Safety and efficacy of fenbendazole in green iguanas. Proc ARAV: 115.
Laing, Christopher J., Trube, Angelika, Shea, Glenn M., Fraser, David R. The requirement for natural sunlight to prevent vitamin D deficiency in iguanian lizards . Journal of Zoo and Wildlife Medicine 32, 2001: 342-348.
Lloyd, M. 1990. Reptilian dystocias review - causes, prevention, management and comments on the synthetic hormone vasotocin. Proc AAZV .
Lloyd, M. 1996. Chlorhexidine toxicosis in a pair of red-bellied short neck turtles, Emydura subglobosa. Bull ARAV 6.4.
Lloyd, Mark, and Pat Morris. Chelonian venipuncture techniques. Bulletin of the ARAV , 9 (10), 1999: 26-29.
Lloyd, Mark, and Patrick J. Morris. Phlebotomy techniques in snakes. Bulletin of the ARAV , 9 (4), 1999: 30-32.
Lock, B., Heard, D., and Dennis, P. Preliminary evaluation of medetomidine/ketamine combinations for immobilization and reversal with atipamezole in three tortoise species. Bull ARAV 1998;8(4).
MacLean R et al. 2008. Propofol anesthesia in loggerhead sea turtles. J Wildlife Diseases 44(1):143-150.
Mader, D. 1993. Use of calcitonin in green iguanas with metabolic bone disease. Bull ARAV 3.1
Mader, D. 1995. Pulse oximetry as a tool for monitoring reptile patients. Proc ARAV .
Marschang, R.E., and T.H. Ruemenapf. 2002. Virus "X": characterizing a new viral pathogen of tortoises. Proc ARAV : 101-102.
Mayer J, Knoll J, Innis C, Mitchell M.2005. Characterizing the hematologic and plasma chemistry profiles of captive Chinese water dragons, Physignathus concincinus. J Herp Med Surg. 15(3).
McCracken, H. 1991. The topographical anatomy of snakes and its clinical application: a preliminary report. Proc AAZV .
Micinilio, J. 1996. Ivermectin for treatment of pentastomids in a tokay gecko. Bull ARAV 6.2.
Miller, H. 1994. Trichomoniasis associated with ocular and subcutaneous lesions in geckos. Proc AAZV/ARAV .
Millichamp, N.1990. Ocular disease in captive amphibians and reptiles. Proc AAZV .
Mitchell, M.A. 2002. Diagnosis and management of reptile orthopedic injuries. Pp. 97-114, in The Veterinary Clinics of North America Exotic Animal Practice: Therapeutics , (T.N. Tully, ed.). Philadelphia, PA: W.B. Saunders Company. 5(1):1-221.
Moon, P. et al. 1996. Anesthetic and post-anesthetic management of sea turtles. JAVMA 208.5.
Mosley CAE, Dyson D, Smith DA. 2003. Minimum alveolar concentration of isoflurane in green iguanas and the effect of butorphanol on minmum alveolar concentration. JAVMA 222(11): 1559- 1564.
Mosley CAE, Dyson D, Smith DA. 2003. The cardiac anesthetic index of isoflurane in green iguanas JAVMA 222(11): 1565-1568.
Nathan, R. 1996. Treatment with ovicentesis, PGE2 and PGF2a to aid oviposition in a spotted python. Bull ARAV 6.4.
Norton, T. Effect of medetomidine/ketamine anesthesia in the gopher tortoise (Gopherus polyphemus). Proc ARAV 1998.
Norton, T., Loomis, M. Natural history, captive husbandry and medicine, and field laparoscopy for sex determination in the hellbender, Cryptobranchus alleganienesis. Proc ARAV 1999 .
Origgi FC, Romero CH, Bloom DC, et al.: 2004, Experimental transmission of a herpesvirus in Greek tortoises (Testudo graeca). Vet Pathol 41:50–61
Origgi, F., E.R. Jacobson, C.H. Romero, and P.A. Klein. 2001. Tortoise herpesvirus and stomatitis-rhinitis in tortoises. Proc ARAV : 101-102.
Orosz, S. et al. 1992. Follicle aspiration for treatment of pre-ovulatory egg-binding in a green iguana. J Small Exotic An Med 1.4. Follow-up letter to editor from S. Barten 2.1, 1992.
Raiti, P. 1995. Veterinary care of the common kingsnake. Bull ARAV 5.1
Ramsay, E. et al. Tissue and serum enzyme activities in the yellow rat snake, AJVR , vol. 56 (4), 1995, pp. 423-428.
Rand, A. et al. 1990. The diet of a generalized folivore (Iguana iguana) in Panama. J. Herp . 24.2
Robeck, T. et al. 1990. Ultrasound imaging of reproductive organs and eggs in Galapagos tortoises. Zoo Bio . 9:349-359.
Rooney, M., Levine, G., Gaynor, J., Macdonald, E, and Wimsatt, J. Sevoflurane anesthesia in desert tortoises (Gopherus agassizi). Journal of Zoo and Wildlife Medicine 1999;30(1).
Rostal, D., Grumbles, J., Lance, V., Spotila, J. Non-lethal sexing techniques for hatchling and immature desert tortoises (Gopherus agassizii). Herp Monographs 1994;8:103-116.
Schildger, B. Endoscopic examination of the urogenital tract of reptiles. Proc ARAV/AAZV 1994.
Schumacher, J. et al. 1992. Effect of ketamine on cardiopulmonary function in snakes. Proc AAZV
Schumacher, J. et al. Inclusion body disease in boid snakes. Journal of Zoo and Wildlife Medicine , V. 25 (4), 1994, pp. 511-524.
Shaw, N. 1996. Echocardiographic anatomy and scanning technique of the Burmese python. Proc ARAV .
Sladky K et al. 2008. Analgesic efficacy of butorphanol and morphine in bearded dragons and corn snakes. JAVMA 233(2):267
Sleeman JM, Gaynor J. 2000. Sedative and cardiopulmonary effects of medetomidine and reversal with atipamezole in Desert tortoises (Gopherus agassizii). Journal of Zoo and Wildlife Medicine 31(1): 28-35.
Solano M, Innis C, Smith C, Merigo C, Weber ES . 2008. Scintigraphic and Radiographic Evaluation of Appendicular Skeletal Lesions in Eight Cold-Stunned Kemp’s Ridley Sea Turtles. Vet Radiol Ultrasound 49(4): 388-394.
Stahl, Scott J. General husbandry and captive propagation of bearded dragons, Pagona vitticeps . Bulletin of ARAV , 9 (4), 1999: 12-17.
Wagner, Robert A. and Randy Wetzel. Tissue and plasma enzyme activities in juvenile green iguanas. AJVR , V. 60 (2), 1999, pp. 201-203.
Werner, Dagmar, I. and Tracy J. .Miller. Artificial nests for female green iguanas. Herp Rev . 15(2), 1984, pp. 57-58.
Wozniak, E. et al. 1996. The biology of reptilian hepatozoan species and their potential influence on the health status of captive reptiles. Bull ARAV 6.3.
Wright, K. 1992. Use of oral allopurinal and saline dialysis in the management of hyperuricemia in a Chilean tortoise. Bull ARAV 2.1.
Wright, K. 1997. Ivermectin for treatment of pentastomids in the Standing's day gecko. Bull ARAV 7.1.