Rare Horse Colours: Exploring Unusual Coats and Markings

Most horses come in a handful of familiar shades, which is exactly why rare horse colours turn heads at a show or out hacking. A pure white Thoroughbred, a champagne with hazel eyes, a Shetland pony the colour of a mushroom: each one is the product of a specific gene, and for most of them scientists now know which one. This guide explains what actually makes a coat colour rare, works through the rarest horse colours and markings one by one, shows you how to tell the look-alikes apart and flags the health points that come with a few of them. Where a claim rests on a study, the study is named so you can check it yourself.

How Horse Colours Work: Two Pigments, Three Base Coats

Every horse colour starts from just two pigments: black (eumelanin) and red (phaeomelanin). Two genes decide how those pigments are used, and between them they produce the three base coats that everything else is built on.

• Chestnut: the Extension gene (MC1R) is set to red only, so the horse makes no black pigment in its coat and has no black points. The British “chestnut” covers what American breeders split into chestnut and sorrel.
• Bay: the horse can make black pigment, and a working Agouti gene (ASIP) confines it to the points: mane, tail, lower legs and ear rims. Our guide to bay horses and their shades covers everything from blood bay to seal brown.
• Black: the horse can make black pigment and carries two copies of a non-working Agouti gene, so the black is not confined to the points and covers the whole coat.

That last point matters, because plenty of colour articles still describe black horses as carrying a “dominant black gene”. They do not. Rieder and colleagues (Mammalian Genome, 2001, PMID 11353392) found no dominant black mutation in horses at all. They identified black as a recessive trait, caused by an 11-base deletion in the Agouti gene that was present in two copies in all 24 black horses they tested, from 9 different breeds. It is why two bay parents that each carry one copy can produce a black foal.

On top of the base coat sit the modifiers. Dilution genes such as cream, pearl, champagne, silver, dun and mushroom lighten one or both pigments. White-pattern genes such as grey, roan, dominant white, tobiano, frame overo and the leopard complex remove pigment from some or all of the coat. Across the hundreds of horse breeds recorded worldwide, almost every unusual colour you will ever see is one of those modifiers working on a chestnut, bay or black horse underneath.

What Makes a Horse Colour Rare?

Nobody keeps a worldwide census of horse colours, so any “top 10 rarest” ranking you read is an opinion rather than a count. What can be said with confidence is why some colours stay scarce. It almost always comes down to one of five reasons:

• It needs two copies of a gene. Cremello, perlino and mushroom only show when a foal inherits the gene from both parents, and pearl only shows in a double dose or alongside cream, so both parents have to carry something.
• It began as a new mutation. Dominant white keeps arising as fresh mutations, often traced to a single founding horse, and the only heritable brindle described so far traces back to one Quarter Horse mare.
• It is confined to a few breeds. Champagne is found almost entirely in American breeds, and mushroom has so far been confirmed only in Shetland ponies and the closely related Miniature Horse.
• A breed standard shuts it out. The Friesian studbook registers black horses only, the Cleveland Bay must be bay, and the Suffolk is always “chesnut”, the breed's own old spelling.
• It hides. Silver can sit invisibly on a chestnut and a smoky black can pass for an ordinary black, so these colours are under-recorded as well as uncommon.

That means the rarest colour depends on where you are standing. Cream dilutions are found in Connemara ponies and Welsh ponies but are absent altogether from the Arabian. True white is extraordinary in a Thoroughbred yet it is the defining colour of the Camarillo White Horse, a breed built around it.

It is also worth separating rare colours from rare breeds, which in Britain usually means the Rare Breeds Survival Trust watchlist. A Cleveland Bay is one of the rarest horses in the country and comes in one of the commonest colours there is.

Rare Horse Colours Explained, Gene by Gene

The colours below are the ones most often described as rare. They are grouped by the gene responsible, because that is what decides how rare they really are and how they are inherited.

True White (Dominant White)

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A true white horse is born white, or nearly so, and stays that way. Its white coat grows from pink, unpigmented skin, which is the quickest way to separate it from a grey. The genetics are unusual. White in horses is caused by mutations in the KIT gene, and they are not all the same mutation. Haase and colleagues (PLoS Genetics, 2007, PMID 17997609) found four separate KIT mutations behind dominant white in Franches-Montagnes horses, Arabians, Camarillo White Horses and Thoroughbreds. A follow-up in 2009 (Animal Genetics, PMID 19456317) added seven more, in Thoroughbred, Icelandic, German Holstein, Quarter Horse and South German Draft families, and the authors note that more variants have been characterised at the horse KIT gene than at any other known gene in livestock.

In four of those seven new families only one white horse was available to test, presumed to be the founder of its mutation. That is part of what keeps white so rare: a new white line can start with a single white foal born to coloured parents. The best-known case in racing is the Japanese mare Shirayukihime, a white Thoroughbred foaled in 1996 to non-white parents. Her granddaughter Sodashi, a pure white Thoroughbred racehorse, won the Hanshin Juvenile Fillies in 2020 and the Oka Sho, the Japanese 1000 Guineas, in 2021. The amount of white also varies: Haase's team describe dominant white as ranging from roughly half the coat depigmented to completely white.

Cremello and Perlino

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Cremello and perlino are double doses of the cream gene. Cream is incompletely dominant: one copy lightens red pigment only, turning a chestnut into a palomino and a bay into a buckskin, while two copies dilute both pigments to a pale cream. Mariat, Taourit and Guérin (Genetics Selection Evolution, 2003, PMID 12605854) identified the cream mutation in the MATP gene, now known as SLC45A2, and describe the double dilute as “a nearly white colour with pink skin and blue eyes”.

• Cremello: a chestnut underneath, with two cream genes. Cream all over, mane and tail included.
• Perlino: a bay underneath, with two cream genes. Very similar, but the mane, tail and lower legs are often a shade darker or warmer than the body.
• Smoky cream: a black underneath, with two cream genes. Practically impossible to tell from the other two by eye.

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For years some breed registries that happily registered palominos refused cremellos, on the mistaken belief that the double dilute was a form of albinism. It is not: the cream gene dilutes pigment rather than removing it. Many societies have since changed their rules, and the Morgan horse registry is one that now accepts cremellos and perlinos alongside its traditional bays, blacks and chestnuts.

Smoky Black

One cream gene on a black horse does very little you can see. A smoky black may look like an ordinary black, or like a black that has faded in the sun, and it is one of the most under-recognised colours for exactly that reason. The first clue is often a palomino or buckskin foal turning up from a “black” parent, which breeders sometimes put down to the colour skipping a generation. It has not skipped anything. The cream gene was there all along, and a DNA test would have shown it.

Pearl

Pearl is a second, much rarer variant of the same SLC45A2 gene as cream, and it behaves differently. Holl and colleagues (Animal Genetics, 2019, PMID 31006892) describe it as recessive: one copy does nothing visible, while two copies dilute both red and black pigment. The twist comes when pearl meets cream. A horse with one pearl allele and one cream allele looks very like a cremello or perlino, and the paper describes exactly that: horses that appeared to be double cream dilutes but tested as carrying only one cream gene. The same study identified a third variant of the gene, which the authors called sunshine after the horse it was found in.

Champagne

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Champagne is a dominant dilution, so a champagne foal always has at least one champagne parent. Cook and colleagues (PLoS Genetics, 2008, PMID 18802473) traced champagne to the SLC36A1 gene and found the variant in all 85 champagne horses they tested and in none of the 97 non-champagne horses. It turns red pigment gold and black pigment a chocolate brown, which gives four named shades:

• Gold champagne: chestnut base.
• Amber champagne: bay base.
• Classic champagne: black base.
• Sable champagne: seal brown base.

The giveaway is in the skin and eyes rather than the coat. Champagne foals are born with bright pink skin and blue eyes; as they mature the eyes darken to hazel or amber and the skin turns pinkish with darker freckles, easiest to see around the eyes and muzzle. Cook's team point out that champagne can be difficult to tell from cream, and the skin is the best field test. Champagne is found almost exclusively in American breeds, notably the American Cream Draft, nearly all of which are gold champagne, the Tennessee Walking Horse, the American Saddlebred and the Missouri Fox Trotter. That goes a long way to explaining why it is so seldom seen in British and South African yards.

Silver (Silver Dapple)

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Silver dilutes black pigment only and leaves red untouched. Brunberg and colleagues (BMC Genetics, 2006, PMID 17029645) mapped silver to the PMEL17 gene, now called PMEL, and describe the effect as most visible in the mane and tail, which are diluted to a mix of white and grey hairs. On a black horse the body is lightened too, often to a chocolate or silvery shade, and sometimes dappled. On a bay the red body stays red and only the black points lighten, giving a bay with a pale, silvery mane and tail. Despite the name, not every silver is dappled.

Because it cannot act on red pigment, silver is invisible on a chestnut. Brunberg's team found exactly that: a chestnut that carried the mutation and produced several silver foals by non-silver stallions. It is why silver can surface out of nowhere, and why it is so often confused with a flaxen chestnut. A dark liver chestnut with a pale mane, the classic look of the Black Forest Horse, is regularly taken for a silver, but it has no black pigment for silver to act on. Silver is well documented in the Rocky Mountain Horse and the Icelandic horse, and it turns up in American Miniature Horses, whose registries place no restriction on colour.

Mushroom

Mushroom is the newest colour on this list and, for now, one of the most breed-specific. It dilutes a chestnut coat to a pale sepia or beige, and Shetland breeders had a name for it long before anyone knew the cause. Tanaka and colleagues (Genes, 2019, PMID 31635058), a team that included a Gloucestershire equine vet, traced mushroom to a variant in the MFSD12 gene. The variant matched the colour perfectly in 96 Shetland ponies, turned up in the closely related Miniature Horse and was absent from 252 horses of seven breeds not known for the colour. The researchers propose that it is recessive, which would mean a mushroom foal needs a copy from each parent.

Chocolate Palomino

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A palomino is one cream gene on a chestnut: a golden coat with a flaxen or white mane and tail. A chocolate palomino is the same recipe on a very dark, liver chestnut base, so the body comes out anywhere from deep gold to dark chocolate, and the light mane and tail provide the contrast. Because only one cream gene is involved, palomino can never breed true. Put two palominos together and a foal can be chestnut, palomino or cremello.

Do not confuse any of these with a flaxen chestnut. The Haflinger is always chestnut with a flaxen mane and tail, and however golden it looks it carries no cream gene. Flaxen is a chestnut trait; palomino is a dilution.

Brindle

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Brindle is the colour most often named as the rarest of all, and with good reason. The only heritable form described so far is brindle 1, or BR1. Murgiano and colleagues (G3, 2016, PMID 27449517) studied 39 closely related brindle-family horses, mostly registered American Quarter Horses and Paints, all descended from a single Quarter Horse mare born in 1985. BR1 horses show irregular vertical stripes along the neck, back, hindquarters and upper legs. The stripes are mainly in the texture of the coat, and in some horses they are also a different colour.

The inheritance is unusual too. BR1 is carried on the X chromosome. In the study family every daughter of one stallion showed the stripes, while his sons out of normal mares did not, and the stallion himself had no stripes at all, only a sparse mane and tail. The researchers traced BR1 to a variant in the MBTPS2 gene that was absent from 457 control horses of diverse breeds.

Chimera

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Not every striped or patchwork horse carries BR1. The same paper notes that “brindle” has been used for similar-looking horses in several breeds, and that some of them may be rare spontaneous chimeras. A chimera is a single animal made up of two genetically different cell lines; one way this happens is when two very early embryos fuse into one. If the two lines code for different colours, the coat can show both, as stripes, splashes or irregular patches.

Confirming a chimera takes DNA testing of more than one tissue. Because the pattern comes from how that individual foal formed rather than from a gene it inherited, it is not passed on as a pattern, which is why every chimera coat is a genuine one-off.

Colours That Look Rare but Are Not: Grey, Black and Dun

Three colours regularly appear on “rarest horse colours” lists without deserving the title. They are worth understanding because they are the ones most often confused with the genuinely rare colours above.

Grey

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Grey is the colour most often mistaken for white, and it is not rare at all. A grey foal is born coloured, often bay, chestnut or black, and loses pigment from its hair year by year until many are white in old age, sometimes passing through a dappled stage on the way. The skin stays dark throughout. The famous Lipizzaners of the Spanish Riding School are born dark and whiten with age, grey is by far the commonest colour in the Andalusian, and it is the colour of Britain's Windsor Greys.

The cause was identified by Rosengren Pielberg and colleagues (Nature Genetics, 2008, PMID 18641652) as a duplicated stretch of DNA in the STX17 gene. It is dominant, so every grey has at least one grey parent. A 2024 follow-up by Rubin and colleagues (Nature Communications, PMID 39209879) found two versions of the grey allele: G3, carrying three copies of the duplicated sequence, which is by far the commonest and is linked to fast greying and a high incidence of melanoma, and G2, carrying two copies, which is linked to slow greying and a low incidence of melanoma.

That melanoma link is the one health issue every grey owner should know about. In a study of 296 grey Lipizzaners, Seltenhammer and colleagues (Equine Veterinary Journal, 2003, PMID 12638791) found dermal melanomas in half the horses, and in 51 of the 68 horses aged over 15. Most (75.6 per cent) were under the tail, and none of the affected horses in that study suffered a severe clinical effect or was held back in its work. The figure varies by breed: a study of 335 grey Quarter Horses by Teixeira and colleagues (Journal of Veterinary Internal Medicine, 2013, PMID 23875712) found melanomas in 16 per cent. Our guides to melanoma in horses and equine melanoma in grey horses cover the condition in detail.

True Black

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Black horses are far from rare, and the Friesian is proof of that. What catches people out is the genetics. As covered above, black is recessive, not dominant, so a black foal needs a copy of the black allele from each parent. Many blacks also fade to a rusty brown in strong summer sun, which is why breeders prize a black that holds its colour. A black that fades markedly is worth a colour test, because it may be a smoky black.

It is also easy to confuse a black with a very dark bay or brown. Look at the muzzle. As Horse & Hound's guide to horse coat colours puts it, a black horse has a fully black muzzle, while a brown or dark bay shows lighter hair there.

Dun and Roan

Dun is often listed among the unusual colours, but it is the wild-type colour of the horse. Imsland and colleagues (Nature Genetics, 2016, PMID 26691985) showed that dun is present in ancient horse DNA from before domestication, and that most domestic horses are non-dun because of regulatory mutations that switch the dilution off. Dun horses carry a dorsal stripe and other primitive markings, and our guide to dun horses explains how the dilution works hair by hair.

Roan is another pattern that is often misread, either as rare or as grey. A roan is born with white hairs mixed through its body colour, keeps a darker head and legs, and does not whiten with age the way a grey does.

How to Tell Look-Alike Horse Colours Apart

Most yard arguments about rare colours come down to a handful of look-alikes. The coat alone rarely settles them. The skin, the eyes and the horse's history usually do.

Colour	Skin	The tell-tale sign
Grey	Dark	Born coloured, gets whiter every year
Dominant white	Pink under the white hair	Born white or largely white
Cremello, perlino, smoky cream	Pink	Blue eyes and a cream rather than white coat
Pearl with one cream gene	Not a reliable guide	Looks double-cream but tests as carrying one cream gene
Champagne	Pinkish with darker freckles	Hazel or amber eyes in an adult
Silver on a black or bay	Dark	Pale, silvery mane and tail on a darker body
Flaxen chestnut	Dark	Red body with no black pigment anywhere
Palomino	Dark	Golden body from a single cream gene
Leopard complex	Mottled pink and dark around eyes and muzzle	White sclera round the eye and striped hooves

If in doubt, test. DNA colour tests are usually run on a pulled hair sample, and a test is the only reliable way to separate a pearl-cream from a cremello, or a smoky black from a plain black.

Rare Horse Markings and Patterns

Colour is only half of a horse's description. UK horse passports describe the animal, including its colour, and the white markings and hair whorls are what tell two bays of the same shade apart. Most face and leg markings, such as a star, snip, blaze, sock or a full white stocking, are common. What makes a marking unusual is its type, its shape or where it sits.

Uncommon Markings Worth Knowing

• Bend-Or spots: small dark red to black spots, most often on chestnuts and palominos, that can appear as a horse ages. They are named after the chestnut Thoroughbred stallion Bend Or, who carried them, and Sponenberg and Bellone's Equine Color Genetics notes that most chestnuts have at least one.
• Birdcatcher spots: small white spots that often appear later in life and can disappear again, named after the Thoroughbred Birdcatcher. They look like scars but are not caused by skin damage.
• Rabicano: white ticking on the flanks and white hairs at the base of the tail, sometimes called a skunk tail. Unlike a true roan, it is confined to part of the body.
• Corn marks: patches of solid dark hair on a roan, which grow in where the skin has been scratched or damaged.
• Unusual whorls: hair whorls are present from birth and never change, which is why they are used for identification. An unusual one, such as a double whorl on the forehead, is always worth recording.
• Blue or “wall” eyes: less common than brown eyes, and recorded as a distinguishing feature.

Coloured, Spotted and Overo Patterns

In Britain a horse with large patches of white is simply “coloured”: piebald if black and white, skewbald if any other colour and white. American breeders say pinto, and “paint” refers to a specific breed, the American Paint Horse. Two white patterns in particular deserve a closer look.

The leopard complex (LP) produces the spots of the Appaloosa, the Knabstrupper and the Noriker, and in Britain of the British Spotted Pony. It also brings mottled skin, a white sclera round the eye and striped hooves, even on horses with few spots. Bellone and colleagues (PLoS One, 2013, PMID 24167615) traced LP to an insertion in the TRPM1 gene, and showed that horses carrying two copies are also affected by congenital stationary night blindness.

Frame overo is the pattern with a serious catch. Metallinos and colleagues (Mammalian Genome, 1998, PMID 9585428) found that all 40 frame overo horses they tested carried one copy of a mutation in the endothelin-B receptor gene, and that foals with two copies are born all or nearly all white and die shortly after birth from a blocked intestine. This is lethal white foal syndrome. Santschi and colleagues (American Journal of Veterinary Research, 2001, PMID 11197568) tested 945 horses from white-patterned bloodlines and never found an adult with two copies. Carriers can show little or no visible frame pattern, and the authors conclude that a DNA test is the only way to know for certain whether a pairing can produce an affected foal. A white foal from two coloured parents is not a rare colour to celebrate, so have both parents tested before breeding.

Health Considerations for Rare Coat Colours

Most rare colours are purely cosmetic. A few are linked to specific health problems, and they are worth knowing before you buy or breed:

• Grey and melanoma. Covered above. Check under the tail and around the sheath or udder when grooming, and ask your vet about any lump that appears or changes.
• Pink skin and sun damage. True whites, cremellos, perlinos and champagnes, along with any horse with white face markings, have pink skin that burns far more easily than dark skin. Dugan and colleagues (Journal of the American Veterinary Medical Association, 1991, PMID 2004985) found that squamous cell carcinoma of the eye and eyelids became more common as solar radiation rose, and was more prevalent in every other hair colour than in bays, browns and blacks. Shade, a fly mask that blocks UV and sun cream on pink muzzles are sensible habits, particularly under a South African summer sun.
• Silver and the eyes. The same PMEL mutation that makes a silver causes multiple congenital ocular anomalies (MCOA). Andersson and colleagues (PLoS One, 2013, PMID 24086599) found that horses with two copies show a wide range of eye defects, including cataracts, while horses with one copy mostly have cysts inside the eye. An earlier study by the same group found MCOA most common in silver Rocky Mountain Horses. Ask for a thorough eye examination at the pre-purchase vetting of any silver, and think carefully before breeding two silvers together.
• Leopard complex and night vision. Horses with two copies of LP have congenital stationary night blindness, as above. Our Appaloosa breed guide covers the other eye problems associated with the breed.
• Frame overo and lethal white. Covered above. The risk is avoidable with a DNA test on both parents before breeding.

Testing and Breeding for Rare Colours

DNA tests are available for most of the colour genes in this guide, and they are usually run on a pulled hair sample. Several of the studies cited here involved researchers from the University of California, Davis Veterinary Genetics Laboratory, one of the laboratories that offers them. If you are breeding for a rare colour, the genetics above boil down to a few practical points:

• Two-copy colours need a carrier on both sides. Cremello, perlino, smoky cream, pearl and mushroom all need a dilution gene from both parents. Test both horses rather than assuming.
• Dominant colours cannot skip a generation. A foal showing grey, champagne or silver has a parent carrying the same gene, even if that parent's own colour hides it, as silver does on a chestnut or cream does on a smoky black.
• Some pairings should never be made blind. Two frame overo carriers risk a lethal white foal, and two silvers risk a foal with the more severe form of MCOA.
• Colour is never the first priority. A rare colour on a poorly made or unsound horse is still a poorly made or unsound horse. Breed for conformation, temperament and health first and treat an unusual coat as a bonus.

Frequently Asked Questions