Born With No Anus or Rectum in Foals

Atresia Ani

Atresia ani is a rare congenital condition in which a foal is born without an anus. It also may cause part or all of the rectum to be missing. This condition can vary in severity. Surgery is the only option for foals born with this condition and the outcome depends on how badly the foal’s gastrointestinal tract is affected.

Symptoms and Types

Foals with this condition display signs such as:

  • Colic-like symptoms (e.g., abdominal pain)
  • Straining to pass a bowel movement
  • Swelling of space where anus should be (if rectum intact)


Although this condition is congenital, meaning present at birth, it has not yet been linked to hereditary genetics.  Mutagens in the environment during prenatal development could also be a cause.


A veterinarian can easily diagnose atresia ani. If the rectum or anus is missing, in whole or part, that is a surefire indicator of the diagnosis. Your veterinarian will make a thorough inspection of your horse’s body, and will prescribe immediate treatment for this problem.

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