Diagnosis and successful medical management of a renal corticomedullary abscess in a dog.

A 10-year-old spayed female mixed-breed dog was brought to the Ohio State University Veterinary Medical Center because of a suspected mass located to the right kidney. The mass was diagnosed by abdominal ultrasound following a recurrent lower urinary tract infection. Abdominal computed tomography revealed 2 isoattenuating, peripherally hypoattenuating, and centrally non-contrast-enhancing nodules in the right kidney; the larger one measured 1.9 cm. Initial attempts at fine-needle aspiration were unsuccessful. The dog was returned and the mass was aspirated using ultrasound guidance under heavy sedation. Cytology confirmed the presence of septic inflammation, consistent with a renal corticomedullary abscess. The dog was administered oral enrofloxacin (15 mg/kg, q24h) after diagnosis. Ultrasound guidance was used 2 wk later, under general anesthesia, to achieve percutaneous drainage of ~0.25 mL of fluid and instillation of 5.7 mg (0.25 mL) of enrofloxacin into the abscess capsule. Two weeks after percutaneous drainage, ultrasound examination showed complete resolution of the renal corticomedullary abscess. Urine culture confirmed resolution of the urinary tract infection. To the authors' knowledge, kidney-sparing medical management has never been successfully reported in a dog with a renal corticomedullary abscess. Key clinical message: Renal corticomedullary abscesses occur infrequently in dogs. Medical management is feasible and can result in complete resolution of clinical signs and imaging abnormalities.