Renal Failure in a Female Muskrat

Renal failure syndrome in wild mammals is infrequently reported. Muskrat (Ondatra zibethicus) is a medium-sized rodent known to carry many diseases but rarely exhibiting renal failure. A six-month old female muskrat was submitted to our laboratory for pathological diagnosis, and necropsy revealed severe renal damage with sand-like lithiasis in the ureter, renal calculi, and hydronephrosis. All major organs, including the cerebrum, also showed systemic hemorrhage and calcification which may have been due to uremia induced by renal failure. Histopathologically, necrosis and microcalcification were detected in the renal cortex and the medulla, especially in the proximal convoluted tubules and collecting ducts of the kidney. Significant hyalinization of the glomeruli was also observed, and this suggested chronic nephritis. These findings would support mycotoxic effects, particularly on the kidney. Moreover, infiltration of neutrophils and mononuclear cells was observed in the lung and of plasma cells in the spleen. The definitive cause of the toxic effects in this case of muskrat renal failure could be attributed to contaminated food.