Umbilical Hernias in Foals

Within the uterus of a pregnant mare, the umbilical cord connects the fetus to the placenta so that nutrients and oxygen can be supplied to the growing foal. When the foal is born, the umbilical cord breaks, and the opening through which its blood vessels entered the foal’s abdomen usually contracts.

In some cases, such as when the cord is pulled sharply or is too tough to break normally, the tissues around the opening may be stretched or torn so that it does not close completely. In other cases, genetics or a defect in muscle development can allow the hole to stay open. When the opening doesn’t close properly, a bulge can form in the skin at the site where the cord was attached. This bulge is a hernia that contains a small section of intestine and peritoneum, the tissue sac that encloses the horse’s intestines. As well as being unsightly, an umbilical hernia creates the risk of a loop of intestine becoming trapped and having its blood flow compromised, leading to tissue death and often the death of the foal as well.

A veterinarian can assess the size of a hernia and make a judgment as to whether treatment is needed. There are several options for dealing with an umbilical hernia. A common treatment is to anesthetize the foal, roll it onto its back so that any abdominal contents can be gently pushed back into the abdomen, and then apply a clamp or elastic ring to the skin around the hernia. The clamp will hold the opening together, allowing scar tissue to seal the hole. The foal can usually continue to be turned out with its mother. Within a week to ten days, the clamped skin will fall off as the tissue is deprived of circulation. This hernia repair method has few risks, but to minimize the chance of infection, veterinarians may suggest waiting until cooler fall weather reduces the fly population before treating the hernia.

The danger of intestinal entrapment is sometimes greater with larger hernias, and surgical repair in these cases is done without waiting for the season to change. Healing is usually uncomplicated and most affected foals have no long-term defects.