Reptile Disease Conditions Related to Nutrition and Husbandry Thomas N. Tully, Jr., DVM, MS, DABVP (Avian), DECZM (Avian) Louisiana State University School of Veterinary Medicine Baton Rouge, Louisiana Parasites Endoparasties are a common finding in reptiles and amphibians. The same groups of endoparasites commonly identified in domestic species are also routinely identified in reptiles and amphibians, including protozoa, nematodes, trematodes and cestodes. Most reptiles treated at veterinary hospitals are imported and should be considered to have parasites until proven otherwise. A fecal examination can be performed to identify any parasites so that an appropriate treatment can be initiated. A fecal saline direct smear and a fecal flotation should be performed on all fecal samples. The direct smear will enable the reviewer to identify bacteria and protozoa, while the fecal float is used to identify larger parasite ova (e.g. Roundworms). A fecal examination should always be repeated in 2 and 4 weeks to determine if the animal is really negative as shedding can be transient Imported reptiles routinely have ectoparasites, such as mites, ticks and leeches. These parasites survive by ingesting blood meals from their host. Heavily parasitized juvenile animals can develop a life-threatening anemia. Many of these ectoparasites also serve as vectors for other diseases, including bacterial and possibly viral infections. The diagnosis of an ectoparasite infestation can be made during a thorough physical examination. Mites are the smallest of the ectoparasites (1-2mm) and can be easily over-looked. The mite can be found anywhere on the reptile host, although they tend to accumulate around the eyes, mouth and gular fold. A cotton-tip application soaked in mineral oil can be used to remove a mite to confirm the diagnosis. Common Diseases The majority of the diseases encountered in pet reptile and amphibian medicine are directly related to inappropriate husbandry. Animals maintained under inappropriate temperatures, provided inadequate diets and housing conditions, are at an increased risk of developing disease. Nutritional diseases Secondary Nutritional hyperparathyroidism The most common nutritional disease reported in reptiles is secondary nutritional hyperparathyroidism (SNH). Secondary nutritional hyperparathyroidism occurs as a result of a calcium deficient diet, phosphorus rich diet, and/or vitamin D 3 deficiency. The parathyroid glands are activated and release parathormone, which mobilizes calcium from the skeleton for the animal to meet its daily needs.
A thorough history will often guide a veterinarian in the diagnosis of this disease. Animals suffering from SNH are often young, fast growing animals or adult reproductively active females maintained at an inappropriate ETR (reduced metabolism), offered a calcium deficient diet, excessive phosphorus diet, and/or not exposed to ultraviolet B wavelength light (synthesis of vitamin D3). On physical examination the animal often has muscle tremors and fasiculations, swollen mandibles and long bones (fibrous osteodystrophy), and may suffer from seizures. Medical management includes supplemental calcium and vitamin D therapy, fluids to rehydrate animals, enteral support to maintain energy demands, and treatment of secondary problems, such as splinting pathologic fractures. Hypovitaminosis A Chelonia offered inappropriate diets often develop hypovitaminosis A. Animals presenting with hypovitaminosis A are often young fast growing animal or long term wild caught specimens maintained at inappropriate temperatures and offered a restricted vitamin A deficient diet. On physical examination the animals will often have unilateral or bilateral blepharoedema (swelling of the eyelids), a nasal and ocular discharge, diarrhea, pneumonia, aural abscesses and hyperkeratosis. Recommended treatment for hypovitaminosis A is supplementation with vitamin A (500-1,500 IU.kg every 10 days for 1-4 treatments). Over supplementation of vitamin A can lead to iatrogenic hypervitaminosis A. Hypervitaminosis A leads to skin sloughing and can be lifethreatening. Gout Gout results from the deposition of monosodium urate crystals into the viscera (visceral gout) or joints (articular gout) as a result of the body synthesizing too much uric acid (e.g. high protein diets),dehydration, or renal impairment. Generally, these animals are reported to be in good health, but become acutely depressed and lethargic. A review of husbandry practices will often reveal that these animals have been offered an inappropriate diet or not provided sufficient access to a water source. On physical examination these animals are clinically dehydrated, have poor muscling condition and are in overall poor condition. Reptiles and amphibians with gout often have a hyperuricemia, however animals with gout can have normal plasma uric acid levels. Abscesses Abscesses are a common finding in animals managed under inappropriate conditions. Abscesses are often the result of an infectious origin (e.g. bacterial infection), foreign body, or parasite. Abscesses in reptiles and amphibians can be found anywhere on the body and are commonly located on the toes and tail, and in the oral cavity. Abscesses are often firm, well circumscribed lesions. Successful management of reptile or amphibian abscesses requires incision and curettage. A local anesthetic line or ring block using lidocaine should be performed prior to making the incision. A microbiological sample should be collected for culture and sensitivity once the incision is made. Husbandry Related Problems Thermal burns- Reptiles will often seek heat to maintain their core body temperature. If
an animal is placed in an enclosure that has an exposed light bulb, heating pad, or heat rock as its only source of heat, the animal may remain on the device and develop severe life-threatening burns. In severe burn cases, an animal can lose significant amounts of fluids through the burn sites and should be provided supplemental fluids. Wound management should follow standard mammalian protocols. The wound should be irrigated with an isotonic saline solution and a non-irritating cleansing solution. Topical anti-microbials may be applied to prevent wound contamination. Topical creams or ointments should be applied in a thin coat over the wound, as excessive application can result in anaerobic conditions. Silvadene cream is an excellent anti-microbial cream that can be applied to thermal injuries. Application of a wet-to-dry bandage can be used to reduce wound contamination and encourage wound healing. The bandage should be changed daily until the wound begins to dry, and then as needed until the granulation tissue is considered adequate. It is important to remember that bandages that include the body wall should not be too restrictive and impede respiration. Animals with severe burns should be placed on antimicrobials. Prey bites Reptiles and amphibians only hunt food when they are hungry. Many prey items, including rodents and insects, will attack the predator if left unattended. Owners should be educated as to the dangers of feeding live prey and directed only offer their pet prekilled food items. Dysecdysis Reptiles shed the outer epidermal layer of their skin as they grow. In juvenile animals shedding (ecdysis) occurs regularly and slows as the animal matures. Shedding of the skin is a routine and necessary behavior that all reptiles experience, however patterns of shedding differ between species. Chelonia and lizards routinely shed their skin in pieces, whereas snakes shed their skin in one long piece. Most of the problems associated with shedding (dysecdysis) are reported in snakes, although dysecdysis can occur in all reptiles. Causes of dysecdysis in reptiles have been associated with low environmental humidity and temperature, ectoparasites, traumatic wounds, systemic disease, mishandling, and a lack of an adequate surface to assist with shedding. 1 Treatment for dysecdysis should include correcting any environmental and medical problems and soaking the animal in a warm (82-84 o F) water bath. After soaking, a soft, cotton towel can be used to gently wipe the animal down and remove any excess shed. Do not pull at skin that is not ready to come off because you may damage the underlying skin. Clients should be made aware of the importance of checking that the spectacles or eye caps are removed after every shed. Retained spectacles can develop into sub-spectacular abscesses, which can lead to the loss of the eye if not managed appropriately. More Reptile Diseases Adenoviruses have been described in lizards, snakes, and crocodilians. This virus has been associated with high morbidity and mortality in reptile collections. Transmission of the virus is by the direct route (fecal-oral). Affected animals may present for anorexia, weight loss, limb paresis, diarrhea and opisthotonous. Concurrent
dependovirus and coccidial infections have also been observed in neonatal bearded dragons. Biopsies of the liver, stomach, esophagus, and kidney may be taken to confirm diagnosis (ante-mortem). There is no effective treatment for adenoviral infections, although supportive care (e.g., fluids, enterals, antibiotics) may be useful in stemming the secondary effects of the disease. The incidence of herpesvirus infections in chelonians has been on the rise since originally being isolated from sea turtles in 1975. Herpesvirus infections have been identified in freshwater, marine, and terrestrial species of chelonians. Transmission of the herpesvirus is believed to be via the horizontal route, although it has been suggested that a vertical route of transmission is also possible. Affected animals may present with rhinitis, conjunctivitis, necrotizing stomatitis, enteritis, pneumonia, and neurological disease. Affected animals should be provided appropriate supportive care (e.g., fluids, enterals, and antibiotics). Acyclovir has been used with some success by reducing viral replication. A retrovirus is considered to be the etiologic agent for inclusion body disease. This disease primarily affects snakes in the family Boidae (e.g. boas and pythons). The method of transmission of this virus is unknown, but it is suspected that snake mites (Ophionyssus natricis) may play a role. Affected boa constrictors present with chronic regurgitation, but may develop neurologic signs, including loss of righting reflex, tremors, and disorientation, as the disease progresses. Affected pythons develop severe neurologic signs, similar to those described for the boas, and progressively decline in health. Animals typically succumb to this disease as a result of secondary infections and starvation. Diagnosis can be made ante mortem from surgical biopsies and post-mortem from histopathologic examination. There is no effective treatment for this virus. Affected animals should be euthanized to prevent the spread of the virus to other snakes. Mycoplasmosis is a bacterial infection that has been associated with severe disease in chelonians and alligators. Affected animals may present with nasal and ocular discharge, conjunctivitis, palpebral edema and pneumonia. There are several diagnostic tests available to confirm mycoplasmosis in reptiles, including culture, an ELISA, and PCR. Microbiologic culture can be used to confirm an infection, but it is difficult and time consuming. Currently, the combination of the ELISA and PCR assays provides the highest degree of sensitivity. Treatment may be attempted using tetracyclines and flouroquinolones. Mycoplasmosis has been associated with declines in native tortoise populations in the United States and treatment of wild specimens is not recommended.
Cryptosporidiosis is a protozoal parasite with a monogenous life cycle. This parasite has been associated with severe disease in snake collections for years. More recently, this non-species specific parasite has been associated with an increased incidence of clinical disease in lizards and chelonians. Affected animals may present with a history of regurgitation, weight loss, and foul smelling stools. Diagnosis may be attempted by gastric lavage, cloacal wash, biopsy, and serology. Unlike other apicomplexa protozoa, Cryptosporidium serpentis is not self-limiting. Attempts to treat the parasite with anti-coccidial drugs have proven ineffective. More recent research evaluating hyperimmune bovine colostrums has been promising. Culling effected animals from collections is strongly recommended. REFERENCES 1. Tully TN, Mitchell MA. A Technician s Guide to Exotic Animal Care. Lakewood, CO, AAHA Press, 2001, pp 35-80