HGG Community Forums

At, A, and A+ are all types of agouti and thus restrict black pigment on a horse. They are different because they restrict varying levels of black pigment. If you have two different agouti genes, the one that restricts more pigment will be dominant because it hides the expression of the other gene.

Going by levels of pigment restricted from least to most:

At (brown) - only restricts a little bit of pigment on the body and facial area. When homozygous, it restricts a little more pigment. I'm not sure why.

This horse is aAt:


Kc Brown H285

This horse is AtAt:


CAD Serial Song 1


A (classic bay, but just "bay" in a horse's color name) restricts most black body and facial pigment. It will mask At if the horse is a carrier.

This horse is AA:

Peppy Two Bars

This horse is AAt, but is still a classic bay:


LF3 Grendel Tahlia

A+ (Wild bay, but just "bay" in a horse's color name) - restricts almost all black pigment except the mane tail, knees, hocks, and pasterns. It will mask both At and A if they are present.

This horse is A+A+


M1 hom ax wb


This horse is AA+. The A+ hides the A.


Lukey

Thanks much! that was a great explanation. Sorry about the double posts - I haven't mastered posting from my phone.