33rd Annual Scientific Meeting proceedings

Case history and clinical findings

A 4-year-old American miniature horse mare was referred because of chronic urinary incontinence refractory to medical management. Physical examination revealed constant urine dribbling and severe urine scalding of the hind limbs. Abdominal ultrasonographic examination showed a nondistended urinary bladder and no abnormalities of the kidneys. Vaginoscopy revealed a severe urovagina. During vaginoscopy and cystoscopy, a vesicovaginal fistula (VVF) with continuous urinary leakage into the vagina was observed. Both uretericorifices could be identified directly abaxial to the fistula without abnormalities.

Treatment and outcome

A surgical approach from the vagina described by Latzko et al. (1913) was used for the fistula repair under general anesthesia with the mare positioned in ventral recumbency. The mucosa at the fistula edge was incised and the combined vaginal and vesicular wall was separated by careful dissection. Subsequently, the vaginal shelf was apposed with a single layer continuous Lembert pattern. Postoperatively, the urinary incontinence was significantly reduced, and endoscopy revealed complete closure of the fistula. However, the urinary incontinence increased again during the following 8 weeks, and cystoscopy revealed a 2 mm fistula at the edge of the previous repair. This was reconstructed using the same approach as described above, in the standing sedated mare.

Clinical relevance

To the authors’ knowledge, VVFs in horses have not been previously described and represent a differential diagnosis for persistent urinary incontinence and recurrent urinary tract infections in mares. The surgical repair through a vaginal approach is feasible, yet fistula formation can occur.