Gray horse

A gray horse (or grey horse) has a special kind of coat that changes over time. Unlike other colors that stay the same, a gray horse starts with colored hair and gradually develops white hairs. These white hairs mix in with the original color as the horse gets older. Some gray horses turn white very quickly, while others change color very slowly. In the end, most gray horses become completely white, but they still have dark skin and eyes.

Gray horses can be born with any base color, depending on other genes they have. As they age, their coats may look dappled, roan-like, or even develop small dark spots called “fleabitten gray.” Many different horse breeds have gray horses, but this color is especially common in breeds descended from the Arabian, such as the Thoroughbred, American Quarter Horse, and Welsh pony. Breeds like the Percheron, Andalusian, and Lipizzaner also often have gray horses.

It’s important to know that a gray horse that looks completely white still has black skin and dark eyes. This helps tell it apart from a true white horse, which usually has pink skin and sometimes blue eyes. The gray color comes from a special gene, and a horse only needs one copy of this gene to have a gray coat. This makes gray a very common coat color in many horse breeds.

Prevalence

Gray coats are common in many horse breeds. About one in ten horses carries the change that causes graying as they grow older. Most Lipizzaners and many Andalusian horses are gray. Breeds like the Percheron and Boulonnais from France are often gray too. You can also find gray coats in Welsh Ponies, Thoroughbreds, and American Quarter Horses. All these breeds share roots with the Arabian horse. In fact, all gray Thoroughbreds come from a horse named Alcock's Arabian, born in 1700. Gray coats make up about 3% of Thoroughbreds.

Gray coats can also affect horses with spotted patterns like pintos and leopard complex horses, such as Appaloosas. This can make the spots appear lighter or less clear.

Changes in the color of gray horses

A gray foal can be born any color, but bay, chestnut, or black colors are most common. As the horse grows older, white hairs start to replace its original coat color. These white hairs usually appear first around the muzzle, eyes, and flanks, often by the age of one year. Over time, the white hairs spread until the horse's coat may become completely white. Some gray horses develop small reddish-brown spots on their white coat, and these horses are sometimes called "fleabitten gray."

Different horse breeds and individual horses gray at different speeds, so it’s hard to guess a horse’s age just by its color. A very young horse will never have a white coat, unless it is a true white horse. By their teens, most gray horses are fully gray. Sometimes, older horses in their late teens or twenties may have a few gray hairs, but this is not the same as the gray gene and does not lead to a fully gray coat. Because a gray horse’s color changes over time, the color listed on breed registry papers might need to be updated. This color change can sometimes cause confusion for people who are not familiar with horses, like police officers or border guards, when a horse that is listed as gray appears completely white.

Other factors, such as white markings, certain white spotting patterns, or dilution genes, can also affect the skin and eye color of a horse.

The genetics of gray

See also: Equine coat color genetics

A gray horse has a special gene that makes its hair turn lighter over time. If a horse has just one copy of this gene, it will become gray. All gray horses need to have at least one gray parent. Scientists found that this graying comes from a change in a gene that happened thousands of years ago in one horse.

This gray gene does not change the horse’s skin or eye color, so gray horses usually have dark skin and eyes. Some gray horses might develop a type of skin growth called melanoma as they get older, but many of these grow very slowly.

Horse coat colors sometimes confused with gray

White horses

Main articles: White (horse) and Dominant white

Many people think a gray horse is "white", but most white horses have pink skin and sometimes blue eyes. A gray horse usually has dark skin and dark eyes, even if its hair looks white. Sometimes a gray horse can be born with pink skin, blue eyes, and very light hair, but special tests can help figure out its true color.

Roan

Some gray horses that are changing color might look like a roan or a rabicano. But roans and rabicanos look different. Roans have white patches mixed with dark hair, and the head and legs stay darker. Rabicanos also have white patches mostly on the body with a dark head. With gray horses, the head often lightens first, especially around the eyes and muzzle. Roans do not change color with age, but gray horses get lighter as they grow older.

The varnish roan is a special color seen in Appaloosa horses. It can change a little with age, but unlike gray horses, it does not become fully white.

Diluted colors

Some other horse colors can look like gray. For example, a "blue dun" or grullo might seem solid gray, but it is caused by a different gene and does not get lighter with age. Light cream-colored horses, like cremello or perlino, are also not gray unless they inherit the gray gene from a parent. The pearl gene and the champagne gene can also make a horse’s coat look lighter, which might be mistaken for gray.

Even though it is called "silver dapple", this gene does not make a horse gray. It changes black hair to a dark brown and the mane to a pale color, but the horse stays this color forever unless it also has the gray gene.

Mythology

Gray horses, like white horses, have appeared in stories and myths throughout history. In these tales, gray horses often have special features, such as seven heads or eight feet. Some stories also tell of gray horses that could predict the future or warn of danger.

Main article: White horse (mythology)