Has your dog suddenly developed a soft swelling to the side of the rectum? Has your dog been straining to defecate? Is your dog a male that hasn’t been neutered? Then that swelling may not be your dog’s anal glands, but rather a perineal hernia.
The perineum is the area of real estate on the body between the rectum and reproductive organs. A hernia develops due to a defect or weakness in the muscles of the perineal area and the pelvic diaphragm. The pelvic diaphragm is the connective tissue that holds the muscles, the pelvis, the rectum, and the urogenital canals together.
These hernias are most commonly seen in Boston terriers, collies, boxers, Pekingese, and mixed breeds thereof. Approximately 97% of these hernias occur in male dogs, of which 95% have not been neutered. The highest incidence of hernias occurs in males from 6 to 14 years of age with a peak in occurrence from 7 to 9 years of age. Approximately 2/3 of all cases are unilateral (only happens to one side), while 1/3 of the pets will herniate on both sides. The propensity for development of perineal hernias in intact males is believed to be due to the effects of testosterone and prostatic disease. Neutering the dog at the time of surgery will help prevent the appearance of an additional hernia on the opposite side. Male dogs are predisposed to herniation on the right side, but why the right side is more commonly affected has not yet been determined.
It is not uncommon for the hernial sac to contain loops of intestines, the prostate, or even the bladder. If the pet is straining to urinate, emergency surgery may be indicated.
The most common clinical signs associated with a perineal hernia are constipation and tenesmus, or straining. The majority of these dogs will also have an obvious swelling below and to the side of the anus. Most of these pets will require surgical correction to repair the hernia. If the pet has a surgical risk, stool softeners and enemas may be tried, but the response to conservative therapy is typically unrewarding and the condition will often deteriorate.
Complications following surgery can include fecal incontinence, nerve paralysis, rectal prolapse, and excessive straining. A surgical failure rate of 10% to 46% is not uncommon -- especially when straining is not controlled following surgery.
Bojrab, Joseph. Current Techniques in Small Animal Surgery. 3rd Edition. Lea & Febiger, 1990. Pp. 442-449.