A minor surgical procedure commonly performed on broodmares to prevent aspiration of air and contaminants into the vagina. After repeated pregnancies the abdominal muscles may become stretched and slack. The abdominal contents fall downwards within the abdomen, including the uterus which in turn pulls the vulva forward and down where it is prone to soiling by faecal material and to aspirating air when the horse breathes. This can predispose to uterine infections (metritis) and is a common cause of infertility in older mares.
The solution is to surgically remove a narrow strip of skin from each side of the upper part of the edge of the vulval lips and suture the two exposed raw edges together when they will fuse within a few days, reducing the size of the vulval aperture by around 2/3rds. The operation is performed under local anaesthesia and complications are rare. The joined section of the vulva is opened with scissors just prior to foaling.