Horse Colors, the Difference Between Gray and Roan
Many people are easily confused when it comes to identifying the horse colors known as gray, and roan. Sometimes this is made even more confusing because some people incorrectly refer to gray horses as roan – the Thoroughbred horse industry in particular will often call gray horses roan until they are very gray.
What is a Gray Horse
Gray, or grey, horses can be born any color, they develop white hairs over time, eventually turning the horse gray. Some horses go gray faster than others, they may pass through stages that could be considered rose gray, steel gray, dappled gray, or flea-bitten gray. The horse may appear “white” but since its skin is dark, and since it was not born white, the correct term is gray.
These two pictures show the same horse, Niska, photos are © Copyright owned by the author.
Some breeds where gray is a common color are Arabians, Lippizaners, Andalusians, and Thoroughbreds. Gray is more common than roan, and appears in more breeds.
What is a Roan Horse
Roan is a pattern that stays the same from birth to old age. The color may vary only slightly when the horse has a winter coat. Its head, lower legs and tail, will be a more solid color (unless they have white markings) while the body will have white and colored hairs throughout. Roan works in conjunction with the horse's natural colors so that a chestnut horse with the roan gene would be called a red roan, a black horse with the roan gene would be called a blue roan.
©B Nelson - Red Roan Miniature horse.
Some breeds where roan is a common color are the Quarter Horse, Mustang, Miniature Horses, and Belgian.
Horse Color Genetics of Gray
Gray is a dominant gene, represented by G. A horse that is Gg, or GG, will be gray. A horse that is gg will be non-gray. Gray is dominant over all other colors excluding white, so if the horse has the gene for gray it will turn gray regardless of what color it was born. In order for a horse to be gray it must have at least one gray parent. A horse that is GG will always produce gray foals, if a gray horse ever produces a non-gray foal you know its genes are Gg.
Horse Color Genetics of Roan
Roan is dominant, but in the homozygous state it is fatal. Roan is represented by R. A horse that is Rr will be roan. A horse that is rr will not be roan. The homozygous combination of RR has been suspected as being lethal at the embryo level, however recent DNA tests have found this to not always be the case, none the less many horse breeders will not breed two roans together just in case, as it might affect 1 in 4 breedings (with 1 in 4 being non-roan, and 2 in 4 being roan). In order to be roan a horse must have at least one roan parent.
It is possible for a horse to have both the genes for roan, and the genes for gray. Roan is sometimes indicated by Rn rather than R.