A four-year-old, intact, female Anatolian Shepherd dog was presented with a three-day vaginal prolapse and anuria. She was lethargic, dehydrated, tachycardic, and blood analysis showed leukocytosis and azotemia. Ultrasonographic examination demonstrated that the urinary bladder was located in the prolapsed vaginal tissue. Ultrasound-guided cystocentesis was performed to empty the obstructed bladder and intravenous fluid therapy was instituted. When the dog was deemed cardiovascularly stable, a caudal midline celiotomy incision was made. Through gentle retraction of the uterus, the colon descendens and the bladder were placed back to their normal positions. After resolution of the cervical invagination, the cervix was pexied to the abdominal wall to prevent recurrence and ovariohysterectomy was performed. The dog made an uneventful recovery and had normal urination at the one month follow-up. Chronic vaginal prolapse can be complicated by a retroflexed urinary bladder with urethral obstruction leading to life-threatening azotemia. Ultrasonography of the prolapsed tissues contributes greatly to early diagnosis of complicated cases.