What is a Perineal Hernia?
A perineal hernia is a bulging of pelvic and/or abdominal contents through a separation in perineal muscles and surrounding tissue (pelvic diaphragm) causing a swelling of the skin near the anus. Contents of the hernia can include fat, fluid, a portion of the rectum, the prostate gland, the urinary bladder, or part of the small intestine. In many cases there are two hernias, one on either side of the anus.
Intact male dogs over the age of eight are most likely to develop a perineal hernia. Female dogs, neutered dogs, and cats can also develop perineal hernias. Perineal hernias occur because of weakness in the muscles and connective tissue in the perineal region. The exact reasons are not fully understood, but hormone related muscle degeneration is one theory. A second theory involves conditions that can cause chronic straining including urinary tract infections, prostate enlargement, rectal dilation, diarrhea, and constipation. Over time, the straining causes weakening and eventual failure of the pelvic muscles leading to herniation of abdominal contents.
Diagnosis
A non-painful, soft swelling located to the side of the anus is usually the first sign noticed. Soon thereafter, pets often strain to defecate because fecal material begins to collect in a rectal pouch within the hernia. Some pets become depressed and stop eating due to urinary bladder or small intestine entrapment within the hernia. Organ entrapment can quickly become life threatening, therefore immediate veterinary attention is recommended.
Treatment
There are several surgical techniques used to close and reinforce the hernia. However, only the internal obturator muscle transposition provides consistent results. It is recommended that intact male dogs be neutered at the same time repair is preformed to reduce the chance of repair failure. If entrapment of the urinary bladder and/or small intestine is suspected, an emergency surgery is performed to evaluate and replace the bladder and/or intestine back into the abdomen prior to repairing the hernia. If the hernia is not considered an emergency, the underlying cause of the hernia should be treated and surgical repair preformed before organ entrapment has a chance to occur. Medical management typically yields poor results with patients constantly straining to defecate and/or urinate and often leads to enlargement of the hernia with an increased probability of bladder or intestinal entrapment. The prognosis with surgical repair is good to excellent; however, there is a risk of hernia recurrence especially if there is ongoing straining. Patients that have bladder or small intestine entrapment may have higher complication rates.