Summary
A perineal hernia is a common condition most typical of intact (non-neutered), middle aged to older male dogs. It happens when a weakness in the muscles that make up the pelvic floor allow some of the pelvic contents to poke through and protrude into the perineal area (between the anus and scrotum).
Here's some background: A hernia is best defined as a defect in a structure that defines the borders of a body cavity. This defect in a "wall" of the body may or may not lead to the partial or complete spilling out of the contents of one area into the other.
Hernias may be caused by trauma, infections, tumors, and even hormonal issues, but most commonly occur congenitally. In other words, the animals were born with the defect. This is the case with umbilical and inguinal hernias, for example. In the case of perineal hernias, however, the defect is acquired later in life as a result of perineal wall weakness.
While the cause of perineal hernias remains unclear, it's been postulated that the influence of male hormones is responsible for the debilitation of the muscles of the pelvic floor. This theory is well-accepted in part because affected dogs often suffer testicular tumors and prostatic enlargement as well. But since females and even castrated males can be affected (though very uncommonly), hormonal influence is unlikely to be the only causative factor.
Symptoms and Identification
Perineal hernias are usually very easy to identify. Dogs with perineal hernias will have a telltale swelling adjacent to the rectum (on one or both sides). Constipation, lethargy, difficulty urinating, and a change in how they carry their tail are also typical of this condition.
To differentiate this swelling as a hernia and not a tumor, the contents of the swelling can be palpated. If they can be pushed back into the pelvic cavity, confirmation of a hernia is successfully achieved. Simultaneous rectal examination is also very helpful in discerning the degree and extent of herniation.
If the pelvic contents herniate into this area, life-threatening damage may occur. The bladder, in particular, is one organ that may stray into this area. If it does, the swelling may be severely enlarged and the skin overlying it may be stretched and tense, bluish-reddish and weepy. This is considered a life-threatening emergency!
Affected Breeds
All breeds of dogs may suffer perineal hernias but it's been suggested -- though not well studied -- that dogs with rudimentary tails (such as French Bulldogs and Boston Terriers) might have a structural predisposition to this condition.
Treatment
Surgical repair along with concurrent castration is the standard approach to treating these patients.
Note: Perineal hernia repair in considered a highly specialized procedure typically only undertaken by residency-trained, board-certified veterinary surgeons.
Veterinary Cost
The veterinary cost of perineal hernia depends largely upon the level of care elected and the geographic locale. Treatment of perineal hernias at a regional specialty center or veterinary school can be very expensive -- upwards of $5,000 (or more, should complications arise). Local specialists may charge less, but this will depend on the geographic location.
The possibility of future expenses should be factored into the total cost of a perineal hernia. Since up to 15% of perineal hernias will recur after surgical treatment, the cost of future surgeries should not be overlooked.
Prevention
There is no known means of proven prevention for perineal hernias in intact male dogs. However, because the problem is only rarely seen in neutered males, early castration of males is recommended.
References
Bellenger, C. R. and Canfield, R. B. 2003. TextBook of Small Animal Surgery. 3rd ed. WB Saunders, Philadelphia. pp. 487-498.
Burrows, C. F. and Harvey, C. E. 1973. Perineal hernia in the dog. J. Small Anim. Pract. 14: 315 - 332.
Szabo, S., Wilkens, B. and Radasch, R. M.2007. Use of polypropylene mesh in addition to obturator transposition: A review of 59 cases (2000 - 2004). J. Am. Anim. Hosp. Assoc., 43: 136 - 142.