Atresia ani

From Dog

Atresia ani is a genetic disease of dogs characterized by malformation or non-formation of the anus[2].

It is the most common anorectal anomaly in dogs and an increased incidence is found in females and in several breeds, including Miniature Poodles, Toy Poodles and Boston Terriers[3].

A number of forms have been characterized including:

  • Type I - congenital anal stenosis
  • Type II - imperforate anus alone
  • Type III - imperforate anus combined with more cranial termination of the rectum as a blind pouch
  • Type IV - discontinuity of the proximal rectum with normal anal and terminal rectal development

Rectovaginal fistula formation are sometimes observed in these affected patients.

Surgical repair is the treatment of choice, but postoperative complications can occur, including fecal incontinence, persistent megacolon, anal stricture, recurrent cystitis and colonic atony secondary to prolonged preoperative distension.

Surgical repair of type I or II atresia ani using balloon dilation usually results in long-term survival and fecal continence in most cases[4].

Canine patients with type III AA have a poorer outcome and require more extensive surgical repair[5].


  1. Uni of Tennessee College of Medicine
  2. Prassinos NN et al (2003) Congenital anorectal abnormalities in six dogs. Vet Rec 153(3):81-85
  3. Vianna ML & Tobias KM (2005) Atresia ani in the dog: a retrospective study. J Am Anim Hosp Assoc 41(5):317-322
  4. Tomsa K et al (2011) Treatment of atresia ani type I by balloon dilatation in 5 kittens and one puppy. Schweiz Arch Tierheilkd 153(6):277-280
  5. Ellison GW & Papazoglou LG (2012) Long-term results of surgery for atresia ani with or without anogenital malformations in puppies and a kitten: 12 cases (1983-2010). J Am Vet Med Assoc 240(2):186-192