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Nutritional Diseases
Longterm maintenance of most amphibians requires live food. While most adult terrestrial and aquatic amphibians feed on invertebrates, including earthworms, bloodworms, black worms, white worms, tubifex worms, springtails, fruit flies, fly larvae, mealworms, and crickets, some amphibians feed on vertebrates and require live minnows, guppies, goldfish, or neonatal mice or rats. Vitamin and mineral supplements are necessary to prevent nutritional disease. These are commonly administered by “gut loading” insects using commercially available diets high in calcium or by coating insects with powdered multiple-vitamin preparations that include vitamin D3 and calcium (also known as “dusting”).
Metabolic bone disease is frequently seen in amphibians consuming nonsupplemented invertebrates. With the exception of earthworms, most invertebrates used as food have an inverse calcium:phosphorus ratio. This results in mandibular deformity, long bone fracture, scoliosis, and eventually tetany and bloating. Diagnosis is made radiographically by finding thinning cortices of long bones, mandibular and hyoid bone deformities, pathologic fractures, and in severe cases, GI gas. Treatment includes correcting the diet and administering calcium glubionate 1 mL/kg, PO, sid for 30 days. Full-spectrum lighting with biologically active ultraviolet-B light should be provided. Vitamin D3 can also be administered in severe cases.
Thiamine deficiency is seen in amphibians fed frozen fish containing thiaminase. Clinical signs include tremors, seizures, and opisthotonos. Initial treatment is the administration of thiamine at 25–100 mg/kg IM or intracoelomic, followed by thiamine 25 mg/kg body wt, PO, with each meal. Thiamine deficiency can be prevented by routinely supplementing diets with 250 mg thiamine/kg of fish fed.
Obesity is a disease. Overfeeding is the primary cause of obesity, as many amphibian species will continue to consume prey as long as it is available and without regard for their energy needs. The oversized fat bodies may be palpated within the coelomic cavity; however, in females, ultrasound may be necessary to differentiate enlarged fat bodies from egg masses. Treatment for active species includes enlarging the size of the enclosure to allow increased activity. Maintaining the amphibian at the upper end of its POTZ will accelerate metabolic rate and increase caloric use. Lastly, a reduction in caloric intake may be used to control weight.
Neoplasia
Spontaneous neoplasia occurs in most organ systems but is rare except when caused by pollutants or an infectious agent, such as the virally induced Lucké renal carcinoma that affects populations of northern leopard frogs (see above) or epidermal papillomata in the Japanese firebelly newt. With increasing longevity in captivity and better healthcare, it is likely that more cases of neoplasia will be identified.
Trauma
Traumatic injuries are common in captive amphibians and include lacerations, bone fractures, internal bleeding, desiccation, and the loss of digits, limbs, or tail. Rapid assessment followed by supportive care is required for a successful outcome. Desiccation is common in amphibians that escape their enclosure or do not receive proper care. For smaller amphibians (<30 g) most fractures can be managed conservatively with cage rest. The use of external or internal fixation with larger amphibians may be beneficial. Pain management must be considered in traumatic cases. The presence of opioid receptors suggests using opioids may be beneficial (buprenorphine, 0.02 mg/kg, IM, SC, or PO). NSAID may also be used (meloxicam, 0.2 mg/kg) and appear to provide pain relief.
Last full review/revision July 2011 by Brent R. Whitaker, MS, DVM
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