Dysuria caused by a partially obstructing urethral membrane in a female dog

A 3.5-year-old spayed female Labrador Retriever was examined for dysuria of unknown duration.

Urogenital examination revealed a recessed vulva and a persistent hymen. The hymen was broken down digitally. Results of urinalysis at the referral examination were unremarkable, and no clinically relevant abnormalities were detected on clinicopathologic analysis of blood and serum samples or cytologic evaluation of a vaginal smear. After clinical signs persisted, retrograde contrast vaginourethrocystography was performed; results were considered normal. During uroendoscopic examination, a translucent membranous structure was detected that partially obstructed the urethral lumen near the junction of the urethra and bladder.

Passage of the endoscope into the urinary bladder ruptured the membranous structure. The dog recovered from the procedure uneventfully and was treated with colchicine (0.03 mg/kg [0.014 mg/lb], PO, q 24 h for 14 days). One month later, the owner reported resolution of clinical signs. Fourteen months later, the patient was evaluated for recurrence of dysuria of several months' duration. Uroendoscopic examination revealed a membranous structure similar to that originally detected; this tissue was also ruptured during endoscopy. The patient was discharged and the owner was instructed to administer colchicine at the same dosage. Recurrence of dysuria was reported again 10 months following the second procedure.

To the authors' knowledge, this type of membranous urethral obstruction has not been previously described in a dog. Administration of colchicine did not prevent recurrence, but potential effects of drug administration on time to recurrence could not be evaluated.