An umbilical hernia is a condition in which abdominal contents (fat, intestines, etc.) protrude past the abdominal wall at the location where the umbilical cord was attached to the fetus. Congenital umbilical hernias are more common in puppies than in kittens.

The umbilicus, or belly button, is where the umbilical cord attaches when the puppy or kitten is in the womb. The umbilical cord carries nutrition and oxygen from the mother to the fetus, and waste products and carbon dioxide from the fetus to the mother. Normally, after the puppy or kitten is born, the cord breaks, and the connection at the umbilicus closes up.

An umbilical hernia occurs when the hole doesn’t close correctly. When this happens, skin is the only barrier between the abdominal organs and the environment.

Umbilical hernias are diagnosed on physical examination.

Small hernias do not usually cause any problems, and are often left untreated.

Large hernias should be repaired surgically, because there is a risk that the abdominal contents inside the hernia sac could become damaged or strangulated. Strangulation of intestinal loops can cause blood flow restriction to the intestine, intestinal blockage, etc. Strangulated hernias can become life-threatening; signs can include a large, warm hernia sac; vomiting; abdominal pain; lack of appetite; and depression. Radiography or ultrasonography may be necessary to help diagnose a strangulated hernia.

As long as the hernia isn’t causing problems for the puppy/kitten, the herniorrhaphy (hernioplasty, hernia repair surgery) can be delayed until the scheduled ovariohysterectomy or neuter. However, if strangulation occurs, the surgery becomes an emergency procedure.

The exact cause of congenital umbilical hernias is unknown, but it is generally thought to be a hereditary condition.