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Equine Health Resource

Atresia Ani & Atresia Coli

These are birth defects that prevent a horse from passing feces. “Atresia” refers to a body orifice that is abnormally small or completely closed. Atresia ani is either an abnormally small or nonexistent opening at the anus. Atresia coli is where a section of the colon is missing.

The genetic basis for this birth defect is not clear and it is poorly understood. It can occur in any breed. It is not the same as Lethal White Syndrome, which is seen primarily in the American Paint breed.


The genetics of this condition are not clear at this time and therefore methods for prevention are uncertain.
Author: Doug Thal DVM Dipl. ABVP


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