Surgical repair of rectovaginal fistulae in mares: Twelve cases (1983-1991).

The case records of 12 mares at the Ontario and Atlantic Veterinary Colleges were reviewed to evaluate the success rates of surgical techniques used to repair rectovaginal fistulae. A modified horizontal perineal technique was used in eight mares; it was unsuccessful in one mare, but the fistula was subsequently successfully repaired using the same technique. One rectovaginal fistula that was converted to a third-degree perineal laceration was successfully repaired on the third attempt, using the suture principles of the modified horizontal perineal technique. A modified transvaginal technique was used in three mares, in two of which it failed; their fistulae were subsequently converted to third-degree perineal lacerations and repaired using a one-stage closure. We conclude that the modified horizontal perineal technique is a one-stage procedure that is technically easy to perform, results in less tension on the suture lines, and is effective in modifying poor vulvar conformation.