Horses exhibit a diverse array of coat colours and distinctive markings, described with a specialized vocabulary. Often, a horse is classified first by its coat colour, before breed or sex. Horses of the same colour may be distinguished from one another by white markings, which, along with various spotting patterns, are inherited separately from coat colour.
Many genes that create horse coat colours have been identified, although research continues to further identify factors that result in specific traits. One of the first genetic relationships to be understood was that between recessive “red” (chestnut) and dominant “black”, which is controlled by the “red factor” or extension gene. Additional alleles control spotting, graying, suppression or dilution of colour, and other effects that create the dozens of possible coat colours found in horses.
- Bay (left) and chestnut (right)
Chestnut, bay, and black are the basic equine coat colours. These colours are modified by at least ten other genes to create all other colours, including dilutions such as palomino and spotting patterns such as pinto. Horses which are white in coat colour are often mislabeled as “white” horses. However, a horse that looks white is usually a middle-aged or older gray. Grays are born a darker shade, get lighter as they age, and usually have black skin underneath their white hair coat (with the exception of pink skin under white markings). The only horses properly called white are born with a white hair coat and have predominantly pink skin, a fairly rare occurrence. There are no truly “albino” horses having both pink skin and red eyes.
(Adapted from Wikipedia)