The genetics of anhidrosis

Q:Can a horse inherit a susceptibility to anhidrosis? I’m considering breeding my 9-year-old Quarter Horse mare, who is lovely in every respect but has a very limited capacity to sweat. She was actually relocated up here from down south because living in a hot climate was intolerable and unsafe for her.

My mare sweats a bit now, but not nearly close to normal. Even though our summers here are fairly temperate, I have to keep a close eye on her. I don’t ride her when the temperature is above 80 degrees or it’s humid. She is otherwise healthy, has great gaits and is highly trainable so I would love to have a foal from her. But I don’t want to breed another horse that can’t sweat normally.

If anhidrosis can be inherited, would selecting a stallion who doesn’t have the problem “cancel out” my mare’s DNA contribution?

Megan Simmons

Menomonie, Wisconsin

A:I am so pleased you asked this question, as it’s clear you are thinking hard about whether all your mare’s traits are worth passing on to the next generation instead of just focusing on the “good ones.” Anhidrosis has a substantial impact on affected horses, so it really is a welfare concern that is to be avoided as much as possible.

Anhidrosis, the complete or partial inability to sweat, occurs more frequently in some breeds and among horses with a family history of the condition, which suggests a heritable component. A research team led by Samantha Brooks, PhD, and Laura Patterson Rosa, DVM,

PhD, of the University of Florida, has been investigating the genetics of anhidrosis and attempting to identify

Anhidrosis, the complete or partial inability to sweat, has such a substantial impact on affected horses that it is a welfare concern.