The pathology of nephrotoxicity of gentamicin in snakes. A model for reptilian gout.

Two gopher snakes (Pitophis melanoleucus catenifer) each were given 5 mg/kg body weight gentamicin every 72 hours (group 1); two snakes each were given 5 mg/kg/day (group 2). Doses for both groups were given over a 2-week period. After the second week, the dose for one snake in each group was increased to 50 mg/kg/day for 2 more weeks and then discontinued. Weekly renal biopsies taken from snakes in group 1 showed no abnormalities by light microscopy during and at the completion of the experiment. Snakes in group 2 had cloudy swelling of the proximal tubules at 2 and 4 weeks after the gentamicin was administered. Snakes given the high dose of gentamicin had hydropic degeneration of the proximal tubules 2 weeks after the dose was raised to 50 mg/kg/day. This progressed to tubular necrosis 1 week after the gentamicin was discontinued. These snakes (high dose) also developed visceral gout, apparently as the result of the extensive tubular necrosis. Tophi were in the pericardium, serosal membranes and parenchyma of the kidneys, liver, spleen and lungs.