A 6-year-old, male castrated domestic short hair cat presented for urethral obstruction. Despite passage of a urinary catheter, urine could not be drained through the catheter, but urine flow was noted around the catheter. Special imaging studies, including ultrasound and fluoroscopy, revealed that the catheter had been passed into an abnormal small bicornuate structure that entered the urethra from dorsally within the pelvic canal. This structure was believed to be a uterus masculinus or remnants of the Mullerian ducts. The anomalous structure was not felt to be related to the cause of the urethral obstruction, but was simply an incidental finding which resulted in difficult catheterization.