Perineal hernia is a failure of the levator ani and coccygeus muscles, resulting in herniation of pelvic and/or abdominal viscera into the perineum. Perineal hernias occur most often in middle-aged to older intact male dogs. They often occur in mixed-breed dogs, but breed predispositions have been reported in Welsh Corgis, Boston Terriers, Boxers, Collies, Kelpies, Dachshunds, Miniature Poodles, Old English Sheepdogs, and Pekingese.
Etiology and Pathogenesis of Perineal Hernia in Dogs
Many factors are involved in perineal hernias, including breed predisposition, hormonal imbalance, prostatic disease, chronic constipation, and weakness of the pelvic diaphragm due to chronic straining. The higher incidence among sexually intact males is evidence that hormonal influences probably play a primary role. Prostatic hypertrophy attributed to sex-hormone imbalance has been strongly implicated. Both estrogens and androgens have been cited as causative agents.
Clinical Findings of Perineal Hernia in Dogs
The primary clinical findings of perineal hernia in dogs include the following:
perineal swelling, which is usually not painful
constipation or obstipation
tenesmus
dyschezia
stranguria/dysuria
Diagnosis of Perineal Hernia in Dogs
Patient history
Physical examination
Diagnosis of perineal hernia in dogs is based on history and physical examination; fluctuant and reducible perineal swelling is a key finding. Rectal examination will reveal unilateral or bilateral weakness of the pelvic diaphragm with deviation of the rectal wall toward the side of herniation (unilateral) or dilation of the rectum (bilateral). A firm mass associated with bladder herniation may also be palpable.
Abdominal radiographs may reveal fecal distension of the rectum, increased soft tissue in the perineum because of bladder herniation, or herniated, gas-filled bowel loops. Perineal ultrasonography can be used to determine whether the prostate, urinary bladder, or bowel loops are present within the hernia.
Treatment of Perineal Hernia in Dogs
Surgical correction
Perineal hernia is uncommonly an emergency, except when the bladder has herniated, resulting in urinary obstruction, or when a loop of intestine is strangulated, resulting in ischemia. If catheterization in not possible, urine should be removed by cystocentesis and an attempt made to reduce the hernia. An indwelling urinary catheter may be necessary to ensure urethral patency and prevent recurrence of obstruction.
Surgical correction is always indicated, and concurrent castration to decrease recurrence is recommended. The prognosis is guarded because of the high incidence of recurrence (10–46%) and because of postoperative complications such as infection, rectocutaneous fistula, anal sac fistula, sciatic and pudendal nerve entrapment, and rectal prolapse (1).
Key Points
Perineal hernia is an uncommon disease that most often effects middle-aged to older intact male dogs.
Diagnosis is based on consistent clinical signs and rectal palpation. Dogs may present emergently due to urinary obstruction secondary to bladder herniation.
Surgical correction is the primary treatment, but herniation can recur in 10–46% of dogs.
For More Information
Also see pet owner content regarding perineal hernia in dogs.
References
Tobias KM, Crombie K. Perineal hernia repair in dorsal recumbency in 23 dogs: description of technique, complications, and outcome. Vet Surg. 2022;51(5):772-780. doi:10.1111/vsu.13812
