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What is a Diplomate?
The term "ACVS Diplomate" refers to a veterinarian who has been board certified in veterinary surgery.

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Perineal Hernias

Associated Terms:

Caudal Hernia, Colopexy, Ventral Hernia, Dorsal Hernia, Sciatic Hernia

The term "ACVS Diplomate" refers to a veterinarian who has been board certified in veterinary surgery. Only veterinarians who have successfully completed the certification requirements of the ACVS are Diplomates of the American College of Veterinary Surgeons and have earned the right to be called specialists in veterinary surgery.

Your ACVS board-certified veterinary surgeon completed a three-year residency program, met specific training and caseload requirements, performed research and had research published. This process was supervised by ACVS Diplomates, ensuring consistency in training and adherence to high standards. After completing the residency program, the individual passed a rigorous examination. Only then did your veterinary surgeon earn the title of ACVS Diplomate.


Perineal hernias result from weakening or complete failure of the muscular diaphragm of the pelvis. Normally, the pelvic diaphragm allows for rectal support and keeps the abdominal contents from encroaching on the rectum. Pets with perineal hernias will demonstrate a swelling adjacent to the rectum on one or both sides coupled with signs of constipation, difficulty defacating, lethargy, difficulty urinating, and altered tail carriage.

The underlying cause for weakening or failure of the pelvic diaphragm is unclear at this time. However, many theories are proposed, all of which may be working separately or in unison to allow for pelvic diaphragm weakening or failure. The disease primarily affects older pets, usually between the ages of 7 to 9 years. Non-castrated male dogs and cats are also over-represented.

Signs and Symptoms: 

Pets with perineal hernias typically demonstrate a swelling adjacent to the anus on one or both sides (Figure 1). The swelling may contain herniated abdominal and pelvic canal contents, such as a dilated rectum, prostate, urinary bladder, fat, omentum, and small intestine. Clinical signs seen in pets with perineal hernias are related to the organs entrapped in the hernia. Typically, these signs include:

  • constipation
  • straining to defecate
  • straining to urinate
  • inability to urinate
  • urinary incontinence
  • abdominal pain
  • lethargy
  • depression
  • anorexia
  • altered tail carriage



To diagnose perineal hernia your veterinarian will perform a thorough rectal examination. This will help to determine the presence or absence of a mass-like lesion, prostate disease, contents of the hernia, and to determine unilateral or bilateral disease. Some patients may require analgesic or sedative administration for completion of a rectal exam. Once the diagnosis of perineal hernia has been made, a thorough metabolic and abdominal work-up should be instituted. Your primary care veterinarian will likely recommend a complete blood count, biochemical profile, and urinalysis to determine any concurrent systemic illness. Advanced diagnostic imaging (ultrasound and abdominal radiographs) may be recommended to help determine hernia contents, bladder position and size, colon position and size, prostate disease, or the presence of cancer (Figure 2).

Patients demonstrating any swelling adjacent to the rectum along with the clinical signs mentioned above should seek veterinary advice as soon as possible. Organ entrapment into the perineal hernia may be life threatening and necessitate emergency stabilization prior to definitive surgical intervention. Your veterinarian may wish to refer you and your pet to an ACVS board certified veterinary surgeon for surgical repair of a perineal hernia.

Perineal hernias, by themselves, may cause constipation, which in turn, may damage the motility function of the colon. Perineal hernias may also disrupt your pet’s ability to urinate. Occasionally excessive straining may cause the urinary bladder to retroflex (flip over backwards into the pelvic canal) leading to urinary obstruction and potentially loss of blood supply to the bladder. Entrapment of a loop of intestine into the hernia may cause significant pain and loss of the blood supply. Emergency surgery is indicated for pets with signs of abdominal pain, inability to urinate, and a strangulated loop of small intestine.


Treatment of non-emergency perineal hernia may consist of either medical or elective surgical therapy. Medical therapy is indicated for preparing a patient for surgery, but is generally unsuccessful at permanently controlling the disease process. Medical management will consist of a combination of enemas, stool softeners, IV fluid therapy, dietary management, and analgesics. Surgery is aimed at repairing the pelvic diaphragm and potentially suturing or tacking the colon and the bladder to the abdominal wall to help prevent reoccurrence and colon or bladder entrapment. The surgery typically involves placing sutures to restore the pelvic diaphragm and the incorporation of an internal obturator muscle flap to bolster the repair. The internal obturator is a muscle that is elevated from the floor of the pelvis plastic-Surgical mesh may be implanted in more severe case. It may also be necessary to transfer a flap of muscle from one of the rear legs to aid in closure of the hernia defect in severe cases or cases that have failed initial repair. It is recommended that all patients be castrated during the surgical procedure to help decrease the risk of reoccurrence.

During initial hospitalization, all patients are monitored for complications. Should complications arise, medical or surgical intervention may be recommended.

Aftercare and Outcome: 

After surgery, your pet may be placed on a broad-spectrum antibiotic. All patients will receive pain medications to reduce their post-operative discomfort. Dietary modification with a high fiber diet coupled with stool softeners are sometimes used to help with reducing the pain and straining associated with defecation. In addition, it helps to reduce the potential for breakdown of the repaired tissue. Your pet should be kept calm and quiet for the first two weeks after surgery to allow for tissue healing. Elizabethan collars are warranted to prevent patient damage to the surgical repair. Cold compresses applied to the surgical site may be recommended to help diminish swelling and perineal irritation.

The prognosis is good for the majority of cases; however, in 10-15% of the cases, recurrence of the hernia may occur within a year. Prevention of over activity and self-trauma may help lower this recurrence rate.

There is no proven means to prevent perineal hernias from forming. The problem is rarely seen in castrated male dogs so early castration in dogs not intended for breeding purposes is recommended.

Content Theme: 
Also known as: 
Perineal Hernias
Caudal Hernia
Ventral Hernia
Dorsal Hernia
Sciatic Hernia

This Animal Health Topic was written by and reviewed by Diplomates of the American College of Veterinary Surgeons.  Any opinions stated in this article are not necessarily the official position of the American College of Veterinary Surgeons.

The American College of Veterinary Surgeons recommends contacting an ACVS board-certified veterinary surgeon or your general veterinarian for more information about this topic.

To find an ACVS Diplomate, visit www.acvs.org/find-a-surgeon.