Acute renal failure in an adult cat following oral administration of fosfomycin

Case summary A spayed female mixed breed cat of unknown age (presumably more than 9 years old), weighing 2.9 kg, was presented with a 4 day history of lethargy, anorexia and vomiting following oral administration of calcium fosfomycin (20 mg/kg q12h). A serum biochemical analysis revealed a dramatic increase in the levels of blood urea nitrogen (>140 mg/dl) and creatinine (15.3 mg/dl), and hypercalcaemia (13.1 mg/dl), hyperphosphataemia (13.3 mg/dl) and hyperkalaemia (6.1 mmol/l). The cat was hospitalised and treated with infusion therapy. However, the renal function and clinical signs did not improve with any treatment. The cat was euthanased upon the owner’s request. Histopathological analysis of the kidneys revealed acute tubular necrosis in the cortex. Relevance and novel information The present case report provides, for the first time, clinical and histopathological evidence for acute renal failure induced by oral administration of fosfomycin in an adult cat. It is highly advisable that fosfomycin should not be used in either young or adult cats.