Third-degree perineal lacerations and rectovestibular fistulae in cattle: 20 cases (1981-1988).

The case records of 20 cows with either a third-degree perineal laceration or rectovestibular fistula were reviewed to ascertain the signalment, history, treatment, and long-term result of treatment. Fifteen cows, including 10 first-calf cows, had third-degree perineal lacerations that occurred at calving. Surgery was done in 14 of 15 cows; 10 of the 14 (71%) remained fertile. The cow that was not treated surgically was culled after 24 months because of infertility. Five cows had a rectovestibular fistula; 4 of these were treated surgically. The cow that did not have surgery healed by second intention and remained fertile, and 3 of the 4 cows in which surgery was performed were fertile. None of the cows that produced calves after the initial injury suffered a perineal laceration at subsequent calvings. Single-stage surgical repair of third-degree perineal laceration or rectovestibular fistula appeared to have a good prognosis for subsequent fertility in cows.