Overview of Canine Perineal Hernias
Perineal hernia is a condition in which a dog’s abdominal contents protrude into the perineal region adjacent to the anus. The exact cause is not known, but it is thought that hormones may be involved in weakening the muscles that form the caudal (toward the tail) extent of the abdominal cavity, also called the pelvic diaphragm.
Perineal hernias are much more common in dogs than cats. They can occur on one side or both sides at the same time. This problem occurs almost always in intact non-castrated male dogs, and most of the affected animals are over five years old.
Some dog breeds may be predisposed to having perineal hernias: Boston terriers, boxers, Welsh corgis, Pekingese and collies.
What to Watch For
Signs of a perineal hernia in dogs include:
Diagnosis of a Perineal Hernia in Dogs
Treatment of Perineal Hernias in Dogs
Home Care and Prevention
Bring your pet to the veterinarian if he is straining to defecate or urinate. Inability to urinate can quickly lead to deterioration and is considered a medical emergency.
If medical management is instituted, your dog must be monitored closely to make sure that symptoms do not return.
If surgical management is done, watch for potential complications after surgery, including:
Neutering of male dogs early in life may decrease their chance of having perineal hernias in the future. Neutering at the time of perineal hernia repair may minimize their chance for recurrence.
Information In-depth on Perineal Hernia in Dogs
A hernia is the abnormal protrusion of tissues or organs from one region into another through an opening in the wall of the cavity that normally contains it. A perineal hernia describes herniation of some of the abdominal contents through the pelvic diaphragm, which is composed of several muscles that run from the sacrum and tail vertebrae to the pelvis and surround the end portion of the rectum.
Although there is not a definite understanding of what causes this condition, it may be caused by hormonal influences, especially male hormones, involved in progressive weakening of the pelvic diaphragm musculature. Any animal that has another condition that leads to straining to defecate or urinate may get a perineal hernia secondarily. Common underlying conditions that cause straining include:
Perineal hernias are most common in middle age to older male dogs that have not been neutered. It is for this reason that hormones have been implicated as a possible contributing factor in causing this problem.
This condition is most commonly seen in Boston terriers, boxers, Welsh corgis, Pekingese and collies, although it can occur in any breed.
Straining to defecate or inability to defecate are frequent symptoms of perineal hernia. Usually there is a soft swelling alongside the anus that accompanies the straining. Early in the course of the problem, there may be no swelling or only a small one, but as the condition worsens the swelling tends to get bigger as more abdominal contents herniate out of the abdomen. In unusual cases, the intestines can get pushed into the hernia and become trapped leading to vomiting, pain or shock. In other cases, the bladder can move into the hernia and get stuck as it distends with urine. This rapidly becomes an emergency situation because the dog is unable to urinate.
A thorough physical examination is necessary for a dog that is straining to defecate. Your veterinarian will palpate the abdomen carefully to feel for abdominal masses or other abnormalities.
A digital rectal examination allows your veterinarian to feel for weakening of the muscles of the pelvic diaphragm and diagnose the condition. The hernia may occur on either side of the rectum or on both sides together. Palpation of the perineal swelling while performing digital rectal examination will help to rule out other problems with the anal sacs, tumors around the anus, or tumors in the rectum.
In some cases, if your veterinarian is unsure of the diagnosis, a contrast material like barium may be fed to the animal or given as an enema to delineate the rectum on X-rays and see the hernia.
In mild cases of perineal hernia or cases in which surgical correction is decided against, medical management may keep the animal comfortable for an extended period of time. The goal of medical management is to maintain a soft consistency of the stool so the dog has an easier time defecating. This is accomplished with stool softeners, such as lactulose, or high fiber diets. These treatments cause the stool to retain water and thus remain soft. Occasionally, some animals need periodic manual removal of the hardened stool by the veterinarian, or periodic enemas, often given at home by the owner.
When medical management is pursued, the animal must be closely monitored for worsening of the problem. It is especially important that the animal be watched for some of the serious symptoms such as vomiting or straining to urinate. It is very common for the problem to progress over time; for example, animals that initially require monthly enemas may later require weekly or daily enemas to keep the stool moving. When the condition reaches this point, surgery may be unavoidable.
For animals that have progressed despite medical management or those that are in a crisis because of intestinal or bladder entrapment within the hernia, surgery is usually recommended. The surgery entails making an incision over the swelling next to the anus, replacing the abdominal contents back into the abdomen, and repairing the hole through the pelvic diaphragm muscles. In some cases the defect in the muscles can simply be sewed back together. The most common repair involves the use of a muscle flap, created from another pelvic muscle, to cover the defect. This surgery, called an internal obturator muscle flap, is technically difficult but may be less likely to have postoperative recurrence.
Intact male dogs are also neutered at the time of the hernia repair to help reduce recurrence and treat some forms of prostatic disease that might be causing the animal to strain.
For animals that have bilateral perineal hernias, surgery can be performed on both sides at the same time; however, many surgeons prefer to wait several weeks prior to doing the second surgery to minimize postoperative discomfort and straining by the animal.
Follow-up Care for Dogs with Perineal Hernia
When medical management is the sole course of treatment, your veterinarian should be informed if the dog has any return of straining to defecate, starts vomiting, or begins straining to urinate. The treatments may need to be adjusted to keep the dog from needing to strain, or surgery may be indicated.
If surgical correction is done, some potential complications can occur. It is common for the dog to strain to defecate for several days after surgery, but this should not persist and definitely should not get worse or cause swelling again. Most animals are sent home with instructions to continue use of the stool softeners and/or special diet while the repair heals.
As with any incision, the incision can become infected or break open. The incision should be monitored daily for signs of swelling, redness, or discharge. Your veterinarian should be notified if these occur.
After repair of the hernia, the muscles that are used to close the defect in the pelvic diaphragm may be so weakened that they do not heal properly, leading to recurrence of the hernia. It is also possible that herniation occurs on the opposite side after repair is done on one side. If either of these occurs, the dog will show similar symptoms as before surgery and may need surgery again.
Another complication after surgical repair is fecal incontinence. The nerves that control the anal sphincter muscle can become injured during the surgery and may result in inability of the anus to close completely. This complication is usually only temporary.