A rectal-vaginal fistula (R-V fistula) is a hole between the rectum and the vagina in mares. During delivery, a foal’s hoof can press up through the vaginal wall and then through the rectal wall. Often this tear continues back through the skin, where the owner seeds a slash between the anus and the vulva. As a result, feces can enter the birth canal, creating a postpartum infection. The injury requires surgery to repair the defect and prevent further uterine infection.