Perineal Hernia


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Key Points

A perineal hernia is a condition that occurs in both dogs and cats in which there is an abnormal displacement of pelvic and/or abdominal organs (small intestine, rectum, prostate, bladder, or fat) into the region around the anus called the perineum

A perineal hernia is most successfully treated using the internal obturator muscle flap technique

Castration is always performed at the same time as the perineal hernia surgery so that the prostate will shrink, thus minimize straining during bowel movements

Success is highly dependant on the training and experience of the surgeon

 

Anatomy

  • The pelvic diaphragm is a set of muscles that are attached to each other and surround a hole called the anus
  • The pelvic diaphragm consists of the levator ani, coccygeus and external anal sphincter muscles
  • This diaphragm is a dam that keeps the internal organs such as bowel, prostate and bladder in place.

Perineal hernia – definition and clinical signs

  • A perineal hernia is a condition that occurs in both dogs and cats in which there is an abnormal displacement of pelvic and/or abdominal organs (small intestine, rectum, prostate, bladder, or fat) into the region around the anus called the perineum.
  • This condition occurs secondary to a weakening of the muscles, which form the pelvic diaphragm.
  • Signs of this problem include straining to urinate or have bowel movements, constipation, and swelling around the anal region.

 

Causes of Perineal Hernias

  • The reasons for development of this disease are not completely understood.
  • The vast majority of cases occur in intact male dogs that are middle-aged or geriatric. The most probable cause is prostate enlargement due to the animal not being neutered.  Straining due to an enlarged prostate weakens the pelvic diaphragm.
  • Other theorized causes of perineal hernias include anatomic factors, hormonal imbalances, damage to the nerves of the pelvic diaphragm, and straining due rectal disease.

 

Diagnosis

  • The condition is easily diagnosed by digital rectal palpation during a physical examination.
  • X-rays or ultrasound may be required to further define the hernia.

 

Surgery

  • A perineal hernia does not require emergency surgery, however, if the bladder is located in the hernia, emergency treatment may be needed, as the pet may not be able to urinate.
  • Prior to surgery an epidural is done to relieve pain and minimize straining after surgery.
  • A perineal hernia is most successfully treated using the internal obturator muscle flap technique. This surgical procedure creates a new pelvic diaphragm with the transposed muscle flap. The internal oburator muscle is an external rotator muscle of the hip and can be safely sacrificed with no ill effect to use of the limb.
  • Other procedures that may be performed include the following:
    • Colopexy, a procedure in which the colon is tacked to the left body wall and helps to prevent pressure on the repaired hernia
    • Cystopexy, a procedure in which the bladder it tacked to the right body wall.
    • Ductus deferensopexy, a procedure in which the ductus deferens (a cord that goes to the testicle) is attached to the body wall to help prevent the prostate from herniating
    • These procedures are never used as a primary treatment, rather are always used in conjunction with the obturator flap procedure.
  • Castration is always performed at the same time as the perineal hernia surgery so that the prostate will shrink, thus minimize straining during bowel movements.
  • Below is the hind end of a dog that has a severe perineal hernia (Fig 1).  When the hernia is opened, small intestine, bladder and prostate were found to be in the hernial sac (Fig 2).  These organs were placed back into the abdomen and the hernia was repaired.

Fig 1

Fig 2

 

Convalescence period

  • By 10 to 14 days after the surgery most of the swelling at the level of the surgery will have resolved.
  • Some straining during bowel movements is expected and usually will abate in 7 days.
  • By 6 to 8 weeks after surgery, complete healing has taken place.

 

Success

  • Surgery is successful 80% of the time.
  • Success is highly dependant on the training and experience of the surgeon.  In my opinion this type of case usually should be referred to a specialist for surgery.
  • Failure of the surgical procedure results in recurrence of the hernia. A second procedure would be needed to repair the hernia again.

 

Potential complications

  • Infection
  • Straining to have a bowel movement, can be due to irritation and inflammation of the rectum, which is adjacent to the surgical site. Adding Metamucil to your pet’s food after the surgery will soften the stools so that bowel movements will occur more easily.
  • Fecal incontinence is more common if your pet has hernias on the left and right sides. The cause of the incontinence is due to weakening of the valve of the anus. With this type of problem, stool may accidentally fall out of the anus when the pet is exited, or while barking. In most cases, this is a temporary problem.
  • Urinary incontinence is usually not seen unless the bladder has been chronically located in the hernia.  This is due to stretching of the nerves of the bladder and usually resolves with time.
  • Anesthetic death is an uncommon complication.

 

Postop care

  • Stool softeners help to minimize the straining and constipation.
  • If your pet has a significant amount of straining a medication called Proctofoam will be prescribed; it has a local anesthetic and a steroid in it.  It should only be needed for a couple of days.
  • Pain medication will be prescribed to minimize discomfort.
  • Licking the incision can be prevented by using an Elizabethan collar.
  • Sutures do not need to be removed as these usually are internal and will dissolve with time.
  • During the first 3 weeks after surgery, activity is restricted to short leash walks outside. Running, jumping, or rough play is forbidden. Gradually increasing the activity, following the third week after surgery, allows for a safe recovery.

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