What Is A Grey Horse? Breeds, Colors Changing and Genetics


There is something undeniably eye-catching and enchanting about a Grey horse. Horses with a grey coat are not as common as brown, bay, and chestnut-colored types, which has historically made them very popular. Unfortunately, this beautiful coloring has also been linked to a high risk of developing skin cancer – a fact owners must be aware of and a reason why inexperienced breeders are strongly discouraged from breeding purely for color and appearance.

Grey horses are not strictly grey in color, but rather viewed as grey due to a pattern produced by white hairs of a certain pigment strength – which is why you get horses with a ‘dapple’ or ‘flea-bitten’ grey appearance. Grey horses were normally born a different color, only to grey-out as they age and the strength of greying can differ between each individual horse and breed.

The unique greying process of these horses can produce a range of beautiful and interesting color variations throughout their lives that begin in foals all the way through to old age. If you currently own or care for a grey horse or are planning to buy one and wish to know a little more about them, please read on. This brief guide will look into their coloring and genetics, plus their predisposition to skin cancer and how this can be prevented.

What Color are Grey Horses Born?

Grey horses can be born any color from bay, palomino, and chestnut, through to brown and black but as they age, the hairs of their coat turn white, causing them to gradually lose their birth color and appear grey every time they shed their coat.

Unlike true white horses, grey horses do not start out with a light base color – quite the opposite. Many grey horses are born with a dark base coat color, but because the grey gene is a modifier, their coats slowly transform to a grey shade.

What Breed is a Grey Horse?

The grey horse coloring is found in many breeds, most notably in the Andalusian and Lipizzaner breeds which were showcased as performance stallions in circuses though they are now known best as modern riding and show horses.

Additionally, all of the grey Thoroughbred breeds today are thought to descend from an Arabian gray born in the early 18th century.

The grey coat coloring is recognized by most breed registries today and can also be found in the following horse breeds:

  • Welsh Ponies
  • American Quarter Horses
  • Lusitano
  • Spanish Norman
  • Araboulonnais
  • Camargue Horse
  • Carthusian Horse
  • Dilbaz
  • Kladruby
  • Unmol
  • Chumbivilcas

Are Grey Horses Rare?

While they may not be as common as their fellow brown, bay, and chestnut breeds, grey horses still make up a large proportion of modern horse breeds. In the context of the horse racing world, however, greys have rarely made an appearance, with the grey coat color making up only 3 percent of all Thoroughbreds.

Changes in the Color of Grey Horses

The gradual greying process gives grey horses a unique pattern at each stage of their life. Let’s look at the following ways their coat color changes:

Foals

Up until they are one year old (the foal stage), grey horses will still appear to be their birth color, e.g. they will retain their base coat color of black, bay, or brown etc. A subtle indication that a foal or even a weanling (around 6 months old) has begun the process of greying out can be found around their eyes and mouth. A grey ring around a foal’s eyes is a sure sign they will be grey in later life.

Young Grey Horses

Between their first year (yearlings) and up to six years old, a young grey horse will start to show more obvious signs of greying. After their first birthday, their coat will begin to display a grey shade likened to dark steel. And by the time they are two years old, white hairs begin to come through to mark the start of the ‘dappling’ phase.

Dapple Grey

Dapples on a grey horse’s coat refer to the rings of dark hair that highlight the new white hairs springing through on their coat, creating a dappled effect that stippling from a paintbrush.

People often assume that dapple grey is a fixed and constant appearance of some horses, but in most cases, this dappling is simply a transition from a dark base coat color to a uniform grey or white.

Late Stage Greying

As grey horses age, the dappling effect fades and the encircled grey markings gradually become washed out and replaced by a coat of white hair. Dapples will begin to fade at age 4, but some grey horses will retain their dappled appearance for life.

Complete Depigmentation

By the age of 6 years old, most grey horses will see their dapples disappear completely to make way for an almost pure white coat, and this is known as full depigmentation. It can take some grey horses longer for their coat to lose its former dapples of darker pigment, resulting in subtle speckles and markings as characterized below.

Flea-bitten Grey

If a grey horse is ‘Flea-bitten’ it is not as unpleasant as it sounds! Flea-bitten merely refers to the appearance of a grey horse’s coat that has not fully undergone depigmentation towards the end of its cycle. This usually occurs in grey horses older than 10 years of age and appears in the form of speckles and blotches of leftover pigment that haven’t faded, resembling little flea bites all over the coat.

Blood Marks

In a rare side effect of the greying process, some grey horses can develop a series of large red patches as they age known as blood marks which gives their coat an overall reddish pink appearance. These patches can become larger before disappearing just as dapple marks do.

A blood-marked grey horse is not to be confused with a Rose Grey horse, which is the result of a bay or chestnut offspring developing subtle shades of pink and grey.

Genetics of Grey horses

The grey gene in horses is caused by a malfunction in the pigment cells, leading to the production of pigment that is destined to fade and burn out as the horse ages. The speed at which a grey horse will lose its original base color pigment over time is not only determined by breed, but also by the number of grey mutation copies they inherit.

Grey horses with two copies of the grey genotype will turn grey and eventually white much faster and earlier in life than those with only a single copy of the grey gene. Sadly, grey horses with two copies of the grey gene variant can also develop melanomas earlier in life. (We’ll delve more into cancer prevention in grey horses later on.)

Because the grey gene is dominant, the pairing of a grey parent and a chestnut parent horse, for example, is 50 percent likely to produce a grey foal. And depending on the unique genetic contribution from each parent, the foal can inherit either one or two copies of the grey variant.

What Colors Look Good on a Grey horse?

Grey horses tend to look best with dark contrasting colors. Opt for matte dark colors such as navy blue, dark grey, deep purple, maroon red with your saddle and coordinating accessories.

How Much Does a Grey Horse Cost?

Depending on factors like breed, health history, and training, grey horses can cost between $500 and up to as much as $150,000. Less common coat colors, such as grey, will affect the price of a horse and this can go either way for grey horses. Some greys are priced high due to their striking appearance, whilst others may be priced lower due to the high risk greys carry for melanomas.

Are Grey Horses More Prone to Cancer?

Greys are sadly predisposed to melanomas (tumors of the skin cell that produces pigment). The exact cause of the development of these tumors is still largely unknown, but melanomas are particularly prevalent in horses with two copies of the gene variant due to the increased rate of cell proliferation and potential cell mutation.

Grey horses have thicker, tougher skin, which is unfortunately why many are put to work in hot climates and go on to develop melanomas. The reason their skin develops this tough layer over time is due to the unique function of their greying gene – it prevents pigment granules from entering their hairs and instead pushes these granules into the surrounding skin.

In most cases, this type of melanoma is benign, but it has been identified by a research team from the Uppsala University in Sweden that around 75 percent of grey horses older than 15 years may develop a form of melanoma that can become malignant. Recognizing the signs and types of melanoma in your grey horse can be crucial in treating the tumor and preventing a localized tumor on the lips, eyelids, or under the tail from spreading to internal organs.

Early Detection and Treatment

The earliest signs of a melanoma tumor will be an external lump or growth on the skin and the sooner this can be spotted and examined thoroughly by a vet, the better their chances. It will be up to your vet to determine one of two treatment options – whether the tumor is benign enough to leave and monitor or remove immediately depending on the size and how it affects your horse’s daily life.

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