Snake Gout
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Gout is a metabolic disease where there is a precipitation of urate crystals in tissue. There are two types of gout in animals.
- In primary gout there is an overproduction of uric acid related to a innate metabolic problem.
- In secondary gout acquired disease interferes with the uric acid metabolism. Terrestrial reptiles are predisposed to secondary gout since nitrogenous waste is excreted as uric acid.
In snakes kidney disease often leads to the development of the visceral form of gout.
Examination
History may show poor husbandry including limited access to water. Snakes often present as anorexic and lethargic. Often if kidney disease is involved there is a palpable lump in the caudal third.
Diagnosis
The diagnosis of gout may be suspected on history and physical examination. Biochemistry may indicate a hyperuricaemia. Sometimes radiography is useful if calcium is deposited with the urate crystals. Biopsy of any lumps may be useful. A definite diagnosis is the demonstration of tophi in diseased tissue.
Therapy
Supportive treatment especially aimed at rehydration may be useful but gout carries a poor prognosis. Previously allopurinol (a xanthine oxidase inhibitor that decreases formation of uric acid) has been recommended as a treatment of hyperuricaemia in reptiles and birds but in fact appears to be of little use. Other drugs such as uricases (enzymes involved in the degradation of uric acid to allantoin) may be more useful.
Prevention
Any bouts of dehydration will predispose to the development of gout so good husbandry is important in prevention (as always!). Veterinarians should ensure adequate hydration of reptiles prior to any drug therapy especially the use of nephrotoxic drugs.