There's a Hole in My Pet: The Hernia



Written by: Dr. Chip Coombs

One of the most common issues facing both dogs and cats is a defect called a hernia. Many owners will be all too familiar with this problem, as they are quite common among people. A hernia, in its simplest terms, is essentially a ring-like defect resulting from a hole or tear through muscle layers. The cause could be a defect that occurred at birth, the result of trauma, or in some cases, there was normally a ring-like opening that already existed, but over the years with muscle weakness got bigger allowing a hernia to occur.

An Umbilical Hernia

Undoubtedly the commonest hernia affecting our pets would be the umbilical hernia. The “belly-button” of the pet is definitely an “outie”. At birth, the umbilical cord can be torn too close to the puppy or kitten’s abdominal wall causing a hole or defect within the muscle layers. From the outside, this small protuberance or button is often quite visible, as it usually contains a small amount of body fat that has become trapped between the skin and the inner muscle layers. In other cases, the button may come and go, if the ring or hole is large enough to allow the fat to slip in and out of the abdominal cavity. In the situation where the fat will or can be manipulated to return to the abdominal cavity, the hernia is referred to as being “reducible”.

Umbilical hernias are quite common, so at what point does one become concerned about them? There is no rule of thumb, but if the hernia is reducible, the concern is that later in life, if fat can make its way through this ring like defect, perhaps some important organ like intestine could as well. Once inside this ring, the blood supply to the intestine could be compromised and then trouble starts. The usual solution is to act preventively when a dog is spayed or neutered the umbilical hernia is repaired at the same time to avoid the risk of potential future problems. With females, it is easy, as the spay incision is essentially where the hernia is located, so the incision is simply made a little longer. With males, a separate incision needs to be made in the abdominal wall over the hernia to repair it. Not all umbilical hernias need repairing, especially if they are not reducible. When your veterinarian exams your pet, they will advise what the best options are.

A Diaphragmatic Hernia

If your pet is in an accident, one of the serious issues that could result is a hernia. Although less common, the hernia could occur in the abdominal wall with abdominal contents now sitting just underneath the skin. This type of a hernia is easily detected and when your pet is stable, it can readily be repaired. The more common type of a hernia resulting from significant trauma, like a fall or being hit by a car, is a diaphragmatic hernia. These can be very serious. Separating the chest cavity from the abdominal cavity in all mammals is a thin muscle layer called the diaphragm. Its primary purpose is to separate the organs in the chest from those in the abdomen, allowing the lungs to inflate when the chest expands and compressing the lungs when the chest contracts – in other words, it allows normal uninterrupted breathing to take place. Sometimes after significant trauma, a tear will occur in the diaphragm muscle allowing abdominal organs to press into the chest cavity which can seriously compromise the pets breathing. In dogs, this type of a hernia is very serious and must be corrected as soon as it is safe to do so, and with cats, it’s equally important. However, every veterinarian at some point in their practice career has X-rayed a cat, only to see an old diaphragmatic hernia from a past accident and the owners had no idea. (Probably a stray that was adopted out). Clearly, one of its nine lives were used to survive that situation without corrective surgery.

A pet can also suffer from an uncommon type of a hernia through the diaphragm that does not usually result from trauma, rather it is a congenital defect that allows contents of the abdomen to press through a naturally occurring ring of fibrous tissue which allows the esophagus to pass through the diaphragm – so-called hiatal hernia.

An Inguinal Hernia

Another relatively common hernia found in our furry friends is called an inguinal hernia. In the groin, there naturally occurs a small ring of fibrous tissue that is just wide enough to allow the passage of blood vessels, thin muscles and nerves to exit the abdominal cavity to supply the hind legs. In males, at birth, the testicles also pass through this ring to set up residence in the scrotum. When a hernia occurs, abdominal contents (often fat, intestines, bladder or uterus) end up passing through this ring and bulging up under the skin in the groin (true inguinal hernia), or in males, the contents end up in the scrotum (a scrotal hernia). A pet could be born with this defect, but it is most common as an acquired hernia in intact female dogs that are either pregnant or in heat. It appears that there is a genetic component to this in some of the toy breeds, the shar-pei, golden retrievers, cockers and other breeds. Again, these hernias need to be dealt with surgically to prevent serious complications should an organ become entrapped and its blood supply compromised.

A Perineal Hernia

The last relatively common hernia to mention occurs in older, intact male dogs (>90%). It results from a tear in the pelvic musculature allowing abdominal contents (usually fat, but potentially the bladder) to migrate down and end up bunched up near the anus. In a dog with long hair, this might not be so obvious to an owner, but they might notice straining while their dog is defecating. When examined by their veterinarian, the hernia would be detected and surgery recommended.

Although some hernias are far more serious than other others, most of them do require surgical correction and not always under ideal conditions. One has no control over the congenital types or the influence from genetics, but as owners, we can help prevent some of the hernia occurrences by neutering our pets at a younger age and making sure we keep them as safe as possible from traumatic accidents.