Small Umbilical Hernias Usually Pose No Serious Threat to Health

They can be repaired during spaying and neutering for cosmetic reasons
Hernias are breaks in a cavity or body wall that allow organs or tissues to protrude. They can occur because of a muscle defect or a tear in the lining of body cavities known as the peritoneum. Hernias are labeled by location — umbilical, inguinal (groin area) or scrotal. They're also classified as to whether they are "reducible," meaning the tissue in the hernia can easily be pushed back in-side the body wall.
In the case of an umbilical hernia, the ring the umbilicus — the navel — passes through fails to close completely after birth. The umbilical blood vessels provide nutrients for the puppies in utero. Normally, the blood vessels close and atrophy after birth and the connective tissue opening closes. When the closure is delayed or doesn't happen, this results in a con-genital hernia, one present at birth. Umbilical hernias can also occur secondarily to trauma or a surgical problem, but those causes are rare.
"The vast majority of umbilical hernias in dogs appear as small bumps on the midline of the belly, similar to a human 'outie' bellybutton," said surgical specialist John Berg, DVM, chair of the Department of Clinical Sciences at the Cummings School of Veterinary Medicine at Tufts University. "These hernias usually contain a small amount of fat and are not at all life threatening. They can be repaired for cosmetic reasons at the same time the dog is spayed or neutered."

Size Varies
Hernias may be as small as the end of your little finger or as large as a quarter or more in size. The skin over the area appears normal. Although a rarity, large hernias that encompass a loop or two of intestines could lead to a medical emergency. Once the intestines fall through the opening, they could twist or become strangulated. This could cut off the blood supply and lead to dead or damaged tissue.
"If your dog has a large hernia, your veterinarian may advise you to have it repaired sooner rather than later," said Dr. Berg.
Most dogs with umbilical hernias aren't in immediate danger. Certainly if your dog's hernia becomes more swollen, red or painful to the touch, you need to contact your veterinarian right away. Repair surgery is usually straightforward, with the veterinarian bringing tissues together to close over the opening.
Now, why doesn't that umbilical ring close as it should? One theory is that excess traction on the cord during the puppy's birth damages the tissues. Another theory is that, if the mother chews the umbilical cord off too close to the body wall or the person assisting at whelping cuts the cord off too short, the ring won't close properly.
In large animals such as cattle, it's proven that umbilical hernias are a genetic defect, and this is most likely the cause in dogs, too. It's probably a recessive genetic trait, possibly with modifier genes, so that not all dogs with the genetic material for the problem will develop hernias. More female than male dogs are affected, but both sexes and virtually any breed or mixed breed may have the problem.
Umbilical hernias are seen with some frequency in Airedales, Basenjis, Pekingese, Pointers, Weimaraners, Bernese Mountain Dogs and Shih Tzus. Despite the probable genetic connection, dogs with umbilical hernias and those who have had umbilical hernias repaired are eligible to participate in American Kennel Club conformation shows. Ideally, dogs with umbilical hernias should not he bred.

FROM: CUMMINGS SCHOOL OF VETERINARY MEDICINE AT TUFTS UNIVERSITY