Management of nephrolithiasis by pyelotomy and pyeloscopy in an Asian small-clawed otter (Aonyx cinereus).

A captive adult sexually intact female Asian small-clawed otter (Aonyx cinereus) was evaluated because of diarrhea and signs of abdominal discomfort on arrival at the quarantine area of a zoological park.

Radiographic and ultrasonographic examinations revealed the presence of a large nephrolith in the left kidney. Mild nephrolithiasis was detected in the right kidney. Results of hematologic and serum biochemical analyses were within references intervals. Intravenous pyelography was used for functional assessment of the urinary system and revealed normal renal excretory function bilaterally.Unilateral (left-sided) pyelotomy was selected as a treatment option to preserve maximal functional renal tissue. Pyeloscopy was successfully used for detection of some small nephroliths that were not removed by repeated flushing of the renal pelvis. Surgical treatment of the right kidney was not considered necessary. The otter recovered fully from anesthesia and surgery. Renal function was considered normal when assessed at 3 and 7 days and at 1 and 12 months after surgery.To the authors' knowledge, pyelonephrotomy in otters has not been reported and may be considered as a potential surgical solution for nephrolithiasis. Pyeloscopy allowed the identification of small uroliths that were not removed by repeated flushing of the left renal pelvis following removal of the large nephroliths.