An umbilical hernia is the protrusion of abdominal contents beneath the skin at the navel (umbilicus). The umbilicus is the healed scar (“belly button”) in the mid-abdominal area. It marks the opening through which the prenatal blood vessels and other fetal structures pass before birth. After the umbilical cord is cut at birth, the opening rapidly closes. Occasionally, however, it does not close completely, and an opening in the abdominal wall remains.

The danger of a hernia is the potential entrapment of intestines through this opening. If the hernia interferes with the blood supply to the trapped bowel, passage of food through the bowel is blocked. The strangulated tissue dies and releases toxins that may kill the animal.