What is a Perineal Hernia in Dogs
A perineal hernia is a gradual weakening of the muscles around the rectum (pelvic diaphragm). The perineal hernia allows fat or organs (bladder, intestines, prostate) from the abdominal cavity to bulge into the area surrounding the rectum, resulting in a bulging sac beneath the skin. Perineal hernias are usually seen in middle-aged to older entire male dogs. Hormonal influences and chronic straining are thought to contribute to the weakening of these muscles over time. Any condition that results in straining, such as constipation, can increase pressure on the pelvic muscles and contribute to hernia formation.
Further reading: Types of Hernias
Written by Gill Burkhill, Veterinary Surgeon, Animal Trust Vets CIC | Published April 2026 | Review date April 2029 | This advice is for UK pets only and is not a replacement for seeing a vet
Perineal hernia symptoms in dogs
A perineal hernia may appear as swelling on either or both sides of your dog’s anus. Depending on how much tissue is herniated, it may even push the rectum to one side. The swelling is usually soft and may change in size.
Dogs with perineal hernias often repeatedly strain as if to defecate. They may have difficulty passing faeces or become constipated.
If the bladder has become herniated, they may also strain to pass urine, have urinary incontinence, or be unable to urinate. In severe cases, such as when the intestine has herniated or if bladder herniation prevents urination, dogs may become lethargic and stop eating. Loss of blood supply to the bladder or intestine can be life-threatening and requires urgent veterinary attention.
When to contact your vet
Contact your vet if your dog shows any of the signs listed above. Seek urgent veterinary attention if your dog is unable to pass urine, becomes lethargic, or stops eating.
Diagnosis of a dog perineal hernia
A rectal examination can confirm the defect in the muscular wall. Abdominal radiographs and ultrasound may be used to evaluate the contents of the hernia. Ultrasound can also help assess the health of the prostate gland.
Blood and urine tests are usually required to evaluate your dog’s overall health.
Perineal hernia treatment in dogs
If clinical signs are mild, medical management may be attempted, but it is rarely successful in the long-term. Non-surgical management may include a high fibre or moist diet, stool softeners, and manual removal of impacted faeces.
Surgery is the treatment of choice. As hormonal influences in intact male dogs are associated with the development of perineal hernia, castration is recommended at the time of surgery to reduce the risk of recurrence.
During surgery, the weakened muscles of the pelvic diaphragm are reconstructed to close the defect. This often involves repositioning nearby muscles to strengthen the repair and provide long-term support.
Prevention of dog perineal hernia
It is not always possible to prevent a perineal hernia. However, the risk may be reduced by neutering male dogs and by managing conditions that cause chronic straining, such as constipation or prostate disease.
Early veterinary attention for dogs showing signs of straining may also help reduce the risk of hernia development.
Outlook
With appropriate surgical treatment, the prognosis is very good. Recurrence rates are generally low, particularly when castration is performed, and underlying causes of straining are managed.
A range of complications is possible, but these occur in a minority of cases. Most complications are treatable and often resolve within 4–6 weeks.
Recurrence can occur and is usually associated with surgical technique or failure to identify and manage underlying conditions that contributed to the hernia.