Perineal Hernia

Signalment

• More common in dogs, rare in cats
• 93% in intact dogs
• Most occur animals older than 5 years old,median age in cats and dogs is 10 years.
• Predisposed in breeds with short tails
• Breed predisposition:
  • Boston terriers
  • Boxers
  • Perkinese

Description

Perineal hernia is the protrusion of the pelvic or abdominal viscera through the structures of the pelvic diaphragms, causing the displacement of the perineal skin. It occurs when the pelvic diaphragm weakens. Possible implicated aetiologies are:

• hormonal imbalance in sexually intact animals.
• tenesmus
• structural weakness of the pelvic diaphragm; female dogs have stronger pelvic diaphragm muscles compared to male dogs
• congenital predisposition
• prostatic disease

Perineal hearnia can be unilateral or bilateral. Depending of the location of the hernia, it can be further classified as a dorsal, ventral, sciatic or caudal hernia. The hearniated content, contained by the perineal fascia, is known as the hernial sac. The hernial sac can contain pelvic or retroperitoneal fat, serous fluid, a deviated or dilated rectum, a rectal diverticulum, prostate, urinary bladder or small intestine. In cats, the hernial sac frequently only contain the rectum. The contents may become strangulated or obstructed.

Diagnosis

Clinical Signs

• perineal swelling
• constipation, obstipation
• dyschezia, tenesmus
• rectal prolapse
• stranguria, anuria
• vomiting
• flatulence
• faecal incontinence

On physical examination, a weakened pelvic diaphragm can be digitally palpated, with or without perineal swelling.

References

• Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company.
• Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition) BSAVA
• Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.