The horse is one of the most recognizable animals on earth. The equine color pigments responsible for the horse’s unique coloration are produced in the hair follicles by cells called melanocytes. Pigment is transferred to individual hairs as the follicles grow. Several nutrients support the growth and health of these cells, and multiple genes influence their activity.
There are two basic equine colors: black and red. Black points, which include the mane, tail and ear rims, plus the lower legs, are the definition of the term “bay.” The body color of a bay can be a light reddish-brown, known as a liver or mahogany bay; or it can be a dark brown, referred to as a seal brown.
A chestnut horse has a body coat that’s reddish brown, with a mane and tail the same shade or lighter. Some breed registries use the word sorrel to describe a reddish-brown with no black markings, but most refer to this shade as chestnut.
Champagne, also known as palomino, is a recent genetic variation that results in the discoloration of skin and hair to a golden-colored tone, with no trace of black or red. A horse with the champagne gene has the appearance of a palomino, but with darker, more pronounced markings and a slightly different face and head shape than the traditional palomino.
The gene for champagne is recessive to all other dilution genes (such as the cream and cremello) and dominant over all other color-modifying genes. Horses with the gene have an excellent chance of producing offspring with the same color and markings as themselves.
Roan is another newer dilution gene. It creates a mealy, splotchy effect on only some of the horse’s body, typically around the face and legs. It is often used in conjunction with other dilution genes, such as the sorrel and chestnut genes.
Buckskin is a color that appears in many breeds of horses, including the American Quarter Horse, Andalusian, Morgan and Tennessee Walking Horse. Some breed registries, however, do not accept buckskin, including the Arabian and Shire horse registries.
Bay dun is a variant of the classic bay color, with black pigment diluted to slate and red pigment diluted to a dustier shade. The coats of most bay duns also have primitive markings, such as a dorsal stripe and a dot on the forehead. The term “buckskin” is sometimes applied to other color variations as well, such as a roan with a flaxen or wine-colored mane and tail.