Grey (horse)

Gray
A gray Lipizzan horse. Grays are typically born a darker color, and their hair coat will be pure white before they are 10 years old.
Other names	Grey
Variants	dapple gray flea-bitten gray iron gray rose gray
Genotype
Base color	Any
Modifying genes	Graying gene (G) dominant when single allele present
Phenotype
Body	Born any color, progressively lightens with age until completely white, flea-bitten form may develop red hairs in a freckling pattern throughout coat, sometimes increasing with age
Head and Legs	May not gray at same rate as body, head may be first part of body to lighten, legs may be among last parts of body to lighten
Mane and tail	May not gray at same rate as body, lighter or darker
Skin	Usually black, except under white markings present at birth
Eyes	Usually dark brown, unless base color affected by other genes which lighten eye color
Other notes	Dominant over all other coat colors, when gray gene is present, horse will always become gray, may be masked if horse's base color is white

Gray or grey is a coat color of horses characterized by progressive silvering of the colored hairs of the coat. Most gray horses have black skin and dark eyes; unlike many depigmentation genes, gray does not affect skin or eye color. Their adult hair coat is white, dappled, or white intermingled with hairs of other colors. Gray horses may be born any base color, depending on other color genes present. White hairs begin to appear at or shortly after birth and become progressively lighter as the horse ages. Graying can occur at different rates—very quickly on one horse and very slowly on another.

Gray horses appear in many breeds, though the color is most commonly seen in breeds descended from Arabian ancestors. Some breeds that have large numbers of gray-colored horses include the Thoroughbred, the Arabian, the American Quarter Horse, the Percheron, the Andalusian, the Welsh pony, and the most famous of all gray horse breeds, the Lipizzaner.

People who are unfamiliar with horses may refer to gray horses as "white." However, a gray horse whose hair coat is completely "white" will still have black skin (except under markings that were white at birth) and dark eyes. This is how to discern a gray horse from a white horse. White horses usually have pink skin and sometimes even have blue eyes. Young horses with hair coats consisting of a mixture of colored and gray or white hairs are sometimes confused with roan. Some horses that carry dilution genes may also be confused with white or gray.

While gray is commonly called a coat color by breed registries, genetically it may be more correct to call it a depigmentation pattern. It is a dominant allele, and thus a horse needs only one copy of the gray allele, that is, heterozygous, to be gray in color. A homozygous gray horse, one carrying two gray alleles, will always produce gray foals.