Ultrasound, Retrograde Urethrography, and Computed Tomography Diagnosis of Urinary Bladder Torsion in a Dog After Resection of a Vaginal Mass.

An 11-year-old female Shih Tzu exhibited dysuria after removal of a large vaginal mass. Abdominal ultrasound revealed bilateral hydronephrosis, hydroureter, and urinary bladder (UB) dilation. The urethral opening was located ventral to the UB, cranial to its normal position. The right ureterovesical junction (UVJ) opened on the ventral aspect of the UB, left of the urethral opening; the left ureter coursed abruptly ventrally at the UB level. Retrograde urethrography confirmed the abnormal position of the urethral opening. Computed tomography demonstrated abnormal positioning of the urethral opening and bilateral UVJs, along with distal ureter rotation. Surgical findings confirmed UB torsion.