Logic and wisdom should tell us that umbilical hernias are hereditary. That a dog that had an umbilical hernia as a puppy should never be bred, Logic and wisdom however, does not distinguish between a “true hernia” where there is an actual defect in the body wall, and a “delayed closure” which is simply where a bit of fatty tissue slips out of the area before the umbilical cord closes. There is no evidence at all that the “delayed closure” hernias are hereditary.
A “true hernia” is hereditary. They will generally have a thick cartilage edge with an irregular, circular shape. They may extend from up into the diaphragm, thus causing a communication between the chest cavity and the abdominal cavity.
The term “delayed closures” completely describes the condition. There is a small area in the abdominal wall, where the vessels of the umbilical cord exits the body of the fetus to deliver nutrition and oxygen from the placenta. After birth, these vessels begin to close and shrink up. There is left behind a small area in the middle of the abdomen of the where the vessels formerly escaped the body. The nature of this structure is a straight slit in the middle of the abdomen, lined with normal connective tissue. Oxygen is obtained through the umbilical cord from the placenta, where the mother’s blood stream exchanges carbon dioxide and oxygen with the baby’s circulation. This is normal development for these holes to be present and close over a period of time after birth.
A combination of fatty tissues called Omentum is a slippery, thin sheet of tissue which is present in the abdomen. It provides several services to the organs in the abdomen. It has blood vessels traveling through it to the intestines. Its’ surface produces a serous fluid which lubricates the organs and makes it possible for them to slide against each other without rubbing or causing friction. It also carries lymph nodes for the abdomen and is a major unit for fat storage. It partially contains the abdominal organs, mainly the small intestines and supports them in a kind of protective bag. As a puppy puts on weight, it’s possible for a bit of this thin, slippery, fatty tissue to protrude through the umbilical slit. As the normal process of closing of the umbilical cord proceeds, it is possible for a bit of tissue to become trapped. The only danger here is whether it is solely fatty tissue that is escaping or if the defect is large enough for a small loop of intestine to escape from the abdomen as well.
It is necessary with either condition to “reduce” the fatty tissue escaping at least once a day. Turn the puppy on it’s back, and gently massage the protrusion or small bubble until it slides back into the abdomen. This lowers the risk of a loop of small intestine becoming strangulated in the protruding tissue. If the “hernia” is a closure defect, the normal process of closing will continue and at some point a small amount of fatty tissue may be trapped inside the bubble outside the essentially closed body wall. This is viewed by most people as “hernia”. If the dog is a year old, has a small bubble or belly button and it cannot be reduced, it has been there since it was just a baby and the dog is healthy and well, it is obvious that the bubble or protrusion does NOT contain any of the small intestine. While the puppy is younger it may not be clear as to whether or not there is intestine involved The tiny hole with a small bubble of fatty tissue does NOT require surgery. Slightly larger holes should be closed to make sure no intestine becomes strangulated during the normal process of closure. A delayed closure can never close completely if the fat remains protruding, What happens is that the abdominal wall closes tightly around the fatty tissue, trapping it outside of the body in a firm bubble. These tiny bubbles can be fixed at the time or spay or neuter, but it not usually necessary as they are of no risk to the puppy.
“True” umbilical hernias will make no progress in changing at all. They must always be surgically repaired and these dogs should never be bred. Delayed closures are NOT hereditary. A dog with a delayed closure can be bred and the condition will not be carried on in the line.
The trick is you must know what you have. Most veterinarians don’t or won’t make any kind of a conclusion or try to differentiate between the two different conditions. Your vet may or may not be of any help to you with this, Breeders with years of experience often know the difference immediately,
“True hernias” are rare. Most have never seen one unless they are breeding a line that produces them. In these cases, they see hernias all them time and a breeder with any common sense will stop breeding that line.
A responsible breeder will alert the new owner to the hernia and advise them of the proper care, and if the delayed closure is not closed at the time of spay or neuter, the breeder will pay the difference in cost of having the “hernia” fixed.