Gentamicin-induced nephrotoxicosis in lambs

Lambs injected with gentamicin sulphate remained bright and continued to eat, but their plasma creatinine and urinary microprotein concentrations and activities of alkaline phosphatase, gamma glutamyltransferase, leucine aminopeptidase, and N-acetyl-beta-glucosaminidase were significantly increased. Urinary creatinine and specific gravity were significantly decreased. The kidneys of lambs killed shortly after the last treatment with gentamicin were pale and oedematous and microscopic changes included marked tubular necrosis and dilation. Mild tubular dilation was the only lesion in lambs killed later. Reduced enzyme activity was observed histochemically in cells of the convoluted tubules. The lambs showed little clinical evidence of gentamicin toxicity, but the urinary enzyme activity and protein content were sensitive and reliable markers of renal injury, in agreement with the pathological findings. The lesions were different from those reported in naturally occurring tubular nephrosis of lambs.