Hernias in Dogs and Cats
Hernias are bulges or tears in the body wall that allow body organs and tissue to pass into areas where they do not belong. They are quite similar to sidewall bulges on automobile tires. Some are a minor inconvenience while others are life-threatening conditions. Some are present from birth (congenital) while others are the result of injury. When the hernia’s contents can be pressed back into normal position it is called a reducible hernia. If the contents of the hernia do not receive adequate blood supply it is called a strangulated hernia.
The umbilicus is your pet’s belly button. Congenital umbilical hernias are the most common of all. Since this may be an inherited trait, it is best not to breed pets with this condition. Very few breeders take this advice. Dogs and cats with umbilical hernias have a soft , painless swelling or bulge over their umbilicus. The swelling may come and go depending on the pet’s position and how much it has eaten. Small umbilical hernias contain nothing but a fatty veil called the omentum which normally covers the intestines. Larger umbilical hernias can contain loops of the intestine. Small hernias are not serious and sometimes close spontaneously. In male dogs I repair them when the pet is 12-18 weeks of age. In female pets I spay them through the defect at 5-6 month of age and sew the hernia shut on my way out. Large umbilical hernias can strangulate when a loop of intestine gets pinched off within it. The hernia’s fibrous ring squeezes off blood supply to the strangulated segment of intestine causing cell death and necrosis. This is a life threatening condition. Extremely large hernias are less dangerous then medium size ones. The large ones put no pressure on the intestines. They can be a challenge to close because of a scarcity of available tissue to lap over the defect. Sometimes a sterile synthetic fabric webbing is used as a patch. There is a misconception that cutting the umbilical cord off too close is the cause of this condition. I see more umbilical hernias in purebred dogs and cats than in crosses.
There is an old proverb that genetic defects come in threes. In severe cases of umbilical hernia the pet should be examined for cleft palate and heart abnormalities.
Hernias in the groin commonly occur in female dogs that are pregnant or experiencing bloating or constipation. I occasionally see the problem in male dogs as well. In all cases, tissue that belongs in the rear of the abdominal cavity presses out through a weak area surrounding the femoral artery and nerve. Usually the hernia sac contains nothing but fat. It is reducible back into the abdomen with finger pressure. Under general anesthesia, I carefully dissect out the entire sac with scissors and scalpel down until it resembles a small balloon attached to the thigh Then I carefully replace it into the abdomen. One has to be very cautious in darning the hole shut not to pinch the femoral artery or nerve. It is quite common for a second hernia form later on the unaffected opposite groin so to be safe, I repair both sides. I have seen a few inguinal hernias in immature pekingeses that were too young to become pregnant and the condition occasionally occurs in males. When it does the surgery is the same. Post surgical scaring reinforces and blocks future hernias at the site – I have never had one reoccur.
Perineal hernias occur just lateral to the pet’s anus. I see many more in older dogs than in cats. They are most common in male dogs that have not been castrated. In these pets they may be secondary to an enlarged prostate - but I see them in female dogs as well. Some feel that low muscle mass in the rump area and male hormone predispose to this condition. These hernias can be confused with enlarged or ruptured anal glands. Inherited weakness in the structures that form the ligamentous ring around the anus result also causes this condition. Sometimes only one side is affected but more commonly both sides prolapse (bulge) to some degree. I see this condition most frequently in toy and small breeds. The problem occurs when the pet strains to pass hard stools or when a chronically inflamed anal gland causes straining. It is usually just fat that works its way into the hernia sac but I have seen cases where the bladder was also within the sac. When this occurs the problem becomes a medical emergency because the pet can not urinate. The contents of the sac can be replaced into the abdomen manually or by elevating the dog or cat’s rear legs. The technique for repair of these hernias is similar to femoral hernias. In this case, the difficult part is finding enough tissue surrounding the anus to unite with the pelvic structures. It is a tunneling operation because the pelvic bones prevent good exposure of the surgical site. I use non-absorbable suture to darn these defects closed. These sutures stay in the animal for the rest of its life. One must be very careful not to injure the nerves of the rectum and anus during surgery. The maintenance of sterility during the operation is hard since this is a contaminated area. Pre and post surgical antibiotics prevent infection. Sometimes two or more operations are required before the defect stays completely closed. When I surgically correct the condition I remove the anal sacs as well since they are often the original cause of straining. I also suggest these dogs get plenty of vegetable fiber in their diets.
Although diaphragmatic hernias can be congenital, all the ones I have seen occurred subsequent to car accidents. This problem occurs when pressure within the abdomen suddenly rises, pressing the organs of the abdomen forcefully against the diaphragm and tearing it. This is the most difficult of all hernias to treat. Pets with this condition come into my office gasping for breath. They are reluctant to lie down and become very agitated if their rear legs are elevated. X-rays usually show indistinct areas of the diaphragm at the point of the tear. If the x-rays are not diagnostic I repeat them after giving the pet an oral dose of barium sulfate. The barium outlines the intestine and tells me if it has passed through the tear into the chest cavity. These tears can be any size. They usually occur where the diaphragm attaches to the rib cage. When I do this surgery I must have an assistant breath for the animal. Surgical approach is difficult because the liver and stomach block access to the region of the tear. Once the tear is repaired the dog will resume a normal life.
Scrotal hernias are much more common in horses and humans. I have never encountered one in dogs or cats but I am told that they can occur. Repair of a scrotal hernia would be similar to repair of an inguinal hernia. They would only become life threatening if a loop of intestine or the bladder passed down into the scrotum.
I have never encountered a case of pericardial-peritoneal hernia either. They are quite rare and so are found illustrated in textbooks and professional journals. In this condition, an inherited pathway runs from the pet’s abdomen to the sac that surrounds the heart (the pericardium). Symptoms of the disease are the symptoms of heart failure as the intestines pass into the chest and press on the heart. Repair of such a defect would best be attempted at a large veterinary specialty practice or veterinary school.
Article submitted by: © Ron Hines DVM PhD