Oxytetracycline-associated nephrotoxicosis in feedlot calves

: Renal nephrosis and increased mortality were investigated in feedlot calves that had received excessive doses of oxytetracycline for the treatment of bronchopneumonia. Histopathologic findings included moderate to severe, cortical tubular nephrosis, and suppurative bronchopneumonia. Results of serum and peritoneal fluid analysis were consistent with severe renal disease. Renal toxicosis from the administration of excessive oxytetracycline should be considered a possible side effect in stressed calves with concurrent respiratory disease.