Common Hernias In Dogs And Cats

Umbilical, Inguinal, Perineal And Diaphragmatic Hernias And What Needs To Be Done

Ron Hines DVM PhD

What Are Common Hernias In Dogs And Cats?

Hernias are bulges and tears in your pet’s body wall or organs that allow tissue to pass into areas where they do not belong.

Hernias are quite similar to sidewall bulges on an automobile tire. In both situations, a supportive barrier has been damage enough to loose its ability to retain contents. Some hernias are minor inconvenience while others can be life-threatening conditions. Some hernias are present from birth (congenital hernias) while others are the result of injury or perhaps a surgical incision that failed to completely close. When the hernia’s contents can be pressed back into normal position it is called a reducible hernia. With time, hernias often form a tough fibrous ring around their edge. In those situations the contents of the hernia sac sometimes become “trapped” in the pocket or sac and can no longer be manually replaced. If the contents of hernias do not receive adequate blood supply in those situations they are called a strangulated hernias. Those are an emergency situation. They also occur when organs such as the bladder “flip over” within the hernia space and can no longer empty. 

Umbilical Hernias:

The umbilicus is your dog or  cat’s belly button or navel. The source of nutrients and oxygen while still in the womb. Congenital umbilical hernias are the most common of all the hernias that veterinarians encounter. Since this problem might be an inherited trait, many feel that it is wise not to breed pets born with this condition. Very few dog or cat breeders take that advice.

Dogs and cats with umbilical hernias have a soft , painless swelling, bulge or bubble over the point where their belly button indentation or scar should be. The swelling may come and go depending on the pet’s position and how much it has eaten. You might be able to push it back in with your finger.

Small umbilical hernias contain nothing but a portion of the fatty veil we all have in our abdomens called an omentum . It normally drapes over the intestines like a veil. When pets become obese, their omentum fills with fat and enlarges. So you might notice your dog or cats umbilical hernia enlarge if your pet becomes chubby.

Small umbilical hernias are not a serious problem. They sometimes close by themselves as your young pet matures. In male dogs and cats, I repair these hernias when the dog or cat is about 18 weeks of age – old enough to make the general anesthesia required for the surgery safe. In female pets I often spay them right through the defect – dogs at 8-12 months – female cats that have any chance of becoming pregnant when they reach 5 pounds. Then I sew the hernia closed on my way out. Veterinarians differ in their preferred timing for hernia surgery. There is a common misconception that cutting the umbilical cord off too close to the body is the cause of this condition. Since genetics can play a part in susceptibility to umbilical hernias, veterinarians tend to encounter them more purebred dogs and cats than in pets that resulted from crossbreeding or random breeding.

As I mentioned earlier, larger umbilical hernias can strangulate body organs (cut off their supply of vital oxygen, blood and nutrients) such as when a loop of intestine or portion of another body organ, gets pinched off or twisted within it. In these cases, the hernia’s fibrous ring squeezes off the blood supply to the strangulated segment of intestine causing cell death and necrosis. As the damaged tissue within the hernia swells with trapped edema fluid , it is squeezed even tighter. This is a life threatening emergency condition. If it is noticed when your regular veterinary clinic is not open, it cannot wait until morning. 

Very large body wall hernias can less immediate danger then medium size ones. The large ones put no pressure on the intestines and portions of other body organs that may be inside them. But large hernias can be a challenge for your veterinarian to close because of a scarcity of available extra tissue to lap over the defect. When hernias do not have sufficient body wall tissue to overlap and sew together soundly, synthetic fabric webbing can be used in dogs and cats just as is in humans. 

There is an old doctor’s proverb that genetic defects sometimes arrive in 3’s. So when your dog or cat has a major umbilical hernia, ask your veterinarian to examine your pet for other defects such as cleft palate,  liver shunts and heart abnormalities. Just as many birth defects occur in puppies and kittens as in human babies. You can read about some of the more common ones here

Inguinal And Femoral Hernias:

Hernias in the groin commonly occur in female dogs that are pregnant with large litters or experiencing bloating or constipation. Vets 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, this sac can be carefully dissect out with scissors and scalpel until it resembles a small balloon attached to the thigh Then it can be carefully replace it into the abdomen. One has to be very cautious when 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, both sides should be carefully checked and any weakness reinforced. Veterinarians occasionally see inguinal hernias in immature pekingeses and other small breeds – too young to be due to the increased abdominal pressure of pregnancy. The condition also occasionally occurs in males. When it does the surgery is the same. Post surgical scaring reinforces and blocks future hernias at the site – if the surgery is done meticulously, it will not reoccur. These hernias must be repaired very delicately so as not to restrict blood flow to the leg. The surgery is especially challenging in toy dogs and cats. ( read as it occurs in human here )

Perineal Hernias:

Perineal hernias occur just lateral to your pet’s anus. Many more are seen in elderly dogs than in cats. They are most common in male dogs that have not been castrated. In these pets they may occur secondarily to an enlarged prostate – but vets see them in female dogs as well. Some feel that poorly developed muscle mass in the rump area and male hormones predispose to this condition. These hernias can be confused with enlarged or ruptured anal sacs (glands). Inherited weakness in the structures that form the ligamentous ring around the anus are also thought to contribute to this condition. Sometimes only one side is affected but, more commonly, both sides prolapse (bulge) to some degree. One sees this condition most frequently in toy and small breeds. The problem occurs when pets strain to pass hard stools or when a chronically inflamed anal sac causes straining. Sometimes straining (tenesmus) is due to a general inflammation of the anal region. Those pets often scoot. When an enlarged prostate is not the underlying cause, the cause is usually feeding an improper diet. It is usually just fat that works its way into the hernia sac but there are cases in which the bladder or portions of it is also within the hernia sac. When that occurs, the problem becomes a medical emergency because the pet cannot 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 that for femoral hernias. But in these cases, the difficult part is finding enough tissue surrounding the anus to unite with the pelvic structures. It is a difficult tunneling operation because the pelvic bones prevent good exposure of the surgical site. Many veterinarians 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 this surgery. The maintenance of sterility during the operation is hard since this is a very contaminated area. Pre and post surgical antibiotics prevent infection. Sometimes two or more operations are required before the defect is completely closed. When one surgically correct this condition it is common to remove the anal sacs as well since they were often the original cause of straining. Again, improper diet is the root of many of these cases. So be sure your pet get plenty of vegetable fiber in its diet and stays well hydrated.

Diaphragmatic Hernias:

Although diaphragmatic hernias can be congenital (a birth defect), all the ones I have repaired occurred subsequent to car accidents. This problem occurs when, due to collision, 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 repair. Pets with this condition often come into the hospital gasping for breath. They are reluctant to lie down because on their side, they have even more difficulty obtaining enough oxygen. Often, they become very agitated if their rear legs are elevated. In fact, that is a simple test veterinarians often utilize when they are suspicious a diaphragmatic tear has occurred. X-rays confirm the diagnosis and usually show indistinct areas of the diaphragm at the point of the tear.

In the drawing I made of the cat at the top of this page, everything between the red and the yellow dotted lines belongs behind the red dotted line ( the diaphragm ). In that cat a tear in the diaphragm has allowed organs from the abdomen to press against the heart and squeeze the cat’ lungs so that they cannot fully inflate. If the x-rays are not as obvious as this one, veterinarians often repeat them after giving the pet an oral dose of barium sulfate. On subsequent x-rays the barium will outline the intestinal tract and show your veterinarian if segments of the intestine have passed through the tear and into your pet’s chest cavity. These tears can be any size. They most commonly occur where the diaphragm attaches to the rib cage. When corrective surgery is performed, one must have another person “bag” the pet (breath for the animal). The surgical approach can be quite difficult because the liver and stomach tend to block access to the region of the tear. But once a tear has been repaired your pet can resume a normal life.

Scrotal Hernias:

Scrotal hernias are much more common in horses and humans than dogs and cats. I have never encountered one in a dog or a cat but I am told that they do occasionally occur. Repair of a scrotal hernia would be similar to repair of an inguinal or femoral hernia. Again, such a hernia would only become life threatening if a loop of intestine or the bladder passed down into the scrotum and became constricted. If a dog or cat with a scrotal hernia was presented to me, I would just suggest that the dog or cat be neutered through the same incision. 

Pericardial-peritoneal Hernias:

Most pericardia-peritoneal hernias occur as a congenital defect (a problem your pet is born with). In this particular condition, an inherited pathway or tunnel runs from the pet’s abdomen to the sac that surrounds the heart ( the pericardial sac ). Symptoms of the disease are similar to the symptoms as one might see in heart or lung failure because the intestines/and/or liver lobes that have pass into the pet’s chest surround and press on its heart and lungs. Repair of such a defect would best be attempted at a large central veterinary specialty practice or university veterinary school.

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