Hydrocolpos in a mixed-breed dog: a case report.

A 3.5-year-old, 5.2-kg mixed-breed dog was presented with persistent stranguria after being neutered due to dystocia 6 months ago. Plain abdominal radiographs revealed an intrapelvic soft-tissue attenuating mass that displaced the urinary bladder cranially and constricted the descending colon. Abdominal ultrasonography yielded inconclusive results. Computed tomography revealed the mass as a tubular, hypodense structure compressing the urethra and the descending colon. This finding was defined as hydrocolpos induced by an imperforate hymen, segmental vaginal aplasia, or a vestibulovaginal disorder. Vaginoscopy revealed vaginal atresia and a stem-shaped mass obscuring the ostium urethrae externum. Retrograde cystography showed a significantly dilated urethra behind the obscured ostium urethrae externum. A pedunculated mass (polyp) was suspected to hinder the urinary outflow. A minimal invasive resection of the polyp and widening of the urethra were performed. Normal micturition was observed for 2 months. In the 9th week, the patient returned with tenesmus. An invasive procedure involving episiotomy, evacuation of the hydrocolpos, and creation of a stoma between the mucous membrane of the hydrocolpos and the vaginal mucosa led to permanent resolution of the clinical signs. Only a few case reports exist regarding congenital hydrocolpos. As the history indicates, a traumatic origin is considered likely; therefore, we assume that this is the first case report of secondary, trauma-induced vaginal atresia, and the resulting hydrocolpos.