Erika,

In order for your horse to be a Amber Champagne he/she would have to have at least 1 copy of a champagne gene (N/Ch) as well as have their “base coat” color be bay. It may be more likely that your horse has a silver gene, but again that is something that would have to be tested. Possibly your first guess is the one that is correct. Which would mean your horse is a Red Dun (Chestnut/Sorrel (e/e + Dun D/d). There are obviously a couple of different modifier that could cause your horse resemble an Amber Champagne phenotypically. One is Your horse may have a silver gene. Unfortunately, it’s hard to tell whether or not a horse has the silver gene when looking to the parents. The reason for this is that Silver has no effect on red pigment. So while chestnuts and sorrels can have a dominant silver gene there is no way to tell by phenotype and sometimes Bays with silver genes are mistakenly called/registered as Chestnuts/Sorrels due to the Silver diluting the Black pigment on their “points” being lightened considerably by the Silver dilution. It will also dilute the mane and tail causing them to look as if they have the flaxen mane in tail commonly seen on Chestnuts/sorrels.

Another possibility, though an unlikely one, would be that your horse possibly has a pearl gene, also known as the “Barlink factor” in Quarter Horses, Paints, and Similar related breeds. Pearl behaves as a recessive gene with respect to the hair color. One dose of the mutation does not change the coat color of black, bay or chestnut horses. Two doses on a chestnut background produce a pale, uniform apricot color of body hair, mane and tail. Skin coloration is also pale. Pearl is known to interact with Cream dilution to produce pseudo-double Cream dilute phenotypes including pale skin and blue/green eyes.

As for Champagne, the best way to tell if your horse is in fact Champagne, phenotypically, is by looking at the horse’s skin color. The actual skin of Champagne-diluted horses is pinkish/lavender toned and becomes speckled with age; the speckling (also known as mottling) is particularly noticeable around the eye, muzzle, under the tail, udder and sheath (similar to that of Appaloosas) with purple and pink speckles in what is called “pumpkin skin.” The eye color of a Champagne is blue-green at birth and darkens to amber as the horse ages.

The dun gene is a dominant one, only one copy is needed for the color to be displayed, a dun carrier will always show the dun traits: dorsal stripe,leg bars, ear barring, etc.