Join Date: Jan 2010
Location: Gloomy Indianapolis
Agree with Cat, it's a modifier gene like Dun or Bay. My bay gets a light muzzle in the winter too, as well as his belly by his daddy parts gets almost white. In the summer though, he goes back to his normal mahogany bay color. From what I've read, being a "mahogany" bay, is actually an indicator of the sooty modifier at work. Sooty causes dark hairs to be interspersed through the coat, most heavily along the neck and withers and sometimes the head. When Jack was a baby he was a BRIGHT copper bay, but every year he's gotten darker and now is almost purple looking at times.
The first is a pic of Jack at 2, nice and bright copper, but you can already see him getting darker along the neck and withers. And the second was only a month ago. (Excuse the mud, this was pre grooming, lol) You can kindof see the white fuzzies peeking out by his rear legs.