Jump to navigation Jump to search This article is about visually white horses. For the dominant white gene, see Dominant white. White clydesdale (Cheval) PDF are born white and stay white throughout their lives.
White horses may have brown, blue, or hazel eyes. True white horses have pink skin and white coats, and many have dark eyes, as here. White horses have unpigmented skin and a white hair coat. Many white horses have dark eyes, though some have blue eyes. In contrast to gray horses which are born with pigmented skin they keep for life and pigmented hair that lightens to white with age, truly white horses are born with white hair and mostly pink, unpigmented skin. The genetics behind this white Thoroughbred, and her white family members, are not yet understood.
Dominant white is best known for producing pink-skinned all-white horses with brown eyes, though some dominant white horses have residual pigment along the topline. Dominant white is, as the name implies, a genetically dominant color. Sabino-white horses are pink-skinned with all-white or nearly-white coats and dark eyes. They are homozygous for the dominant SB1 allele at the Sabino 1 locus, which has been mapped to KIT. This « white-born » or « fewspot » Appaloosa foal has a mostly pink-skinned white coat. Appaloosa and Knabstrupper breeds with their spotted coats. Leopard is genetically quite distinct from all other white and white-spotting patterns.
The fewspot leopard pattern, however, can resemble white. Affected foals are carried to term and at birth appear normal, though they have pink-skinned all-white or nearly-white coats and blue eyes. This horse is gray, not white. Its hair coat is completely white, but its underlying skin, seen around the eye and muzzle, is black. True white horses have unpigmented pink skin and unpigmented white hair, though eye color varies. The lack of pigment in the skin and hair is caused by the absence of pigment-producing cells called melanocytes. Some coat colors are characterized by light or white-like coats and even pinkish skin, however these white-like coats are not lacking melanocytes.
Gray horses have the most common « white-like » coat color. However, the most noticeable difference between a gray horse whose hair coat is completely white and a white horse is skin color: most gray horses have black skin and dark eyes, white horses have light, unpigmented skin. The gray gene does not affect skin or eye color, so grays typically have dark skin and eyes, as opposed to the unpigmented pink skin of true white horses. This « Ivory Champagne » foal has both cream dilution and champagne dilution genes, shown by DNA testing as well as visibly semi-pigmented, rosy skin and a cream-colored coat that can be mistaken for white. True white hair is rooted in unpigmented skin that lacks melanocytes. In contrast, diluted coat colors have melanocytes, but vary due to the concentration or chemical structure of the pigments made by these pigment-producing cells, not the absence of the cells themselves. There are at least five known types of pigment dilution in horses, three which, as described below, can act to produce off-white phenotypes.