While most of us are familiar with common colors like bay, chestnut, and gray, the equine world boasts a spectrum of rare and stunning coat colors that few ever witness. Influenced by nature and selective breeding, these rare colors add an extra layer of intrigue to these majestic animals.
To showcase the extraordinary diversity of equine coloration, I’ve compiled this guide to the rarest horse colors. I delve into the genetic underpinnings of these unique hues and explore the breeds where they are most commonly found.
Sunshine
Sunshine is a newly discovered variant of the MATP or SLC45A2 gene. Identified in 2019, this variant was first found in Captain Sunshine, a stallion that’s a cross between a Standardbred and a Tennessee Walking Horse in America. So far, Captain Sunshine and his offspring are the only known horses with this unique color dilution.
The MATP gene produces the various cream dilutes:
- Palomino
- Buckskin
- Smoky black
- Cremello
- Perlino
- Smoky cream
- Pearl
When a horse has a single copy of the Sunshine gene, its effect isn’t visible. However, when combined with a single copy of the cream gene, it produces a horse that looks like it has two copies of the cream gene – a “double cream” look-alike. Currently, no horses are known to have two copies of the Sunshine gene, but if they did, they would likely resemble double cream horses as well.
Note: “Double cream” refers to horses like cremello, perlino, and smoky cream, which carry two copies of the cream gene and have very light coats, pink skin, and blue eyes.
Genetically, Captain Sunshine is a bay horse with one copy of cream, and one copy of sunshine (verified by DNA testing). Without the sunshine, he would be buckskin. Without the cream, he would just look like a bay horse.
But – with both dilutions, he looks like a perlino. He has pink skin, blue eyes, and a buff-colored coat with slightly darker points, mane, and tail.
Snowdrop
We mentioned this rare horse color above – it was discovered in Gypsy Cobs in 2019 and is named after the horse in which it was first identified. It too is a newly discovered variant of the MATP / SLC45A2 gene.
Like pearl and sunshine, snowdrop doesn’t show up in horses with just a single copy. When there are 2 copies present, or it’s combined with a copy of cream, it produces a double cream look-alike.
Unlike sunshine, which is a brand new variant of this gene, ‘Snowdrop’s’ parents both carry a single copy. However, it’s not visible so it went undetected until they produced a foal together that had 2 copies. But – the fact that the parents carry it means the variant was already in the breed before ‘Snowdrop’, and may even be in other breeds depending on how old it is.
It’s also quite likely other ‘double cream’ Gypsy Cobs are in fact snowdrop, or snowdrop/cream. Without testing though we’ll never know!
Horses with 2 copies of snowdrop, or a copy of cream and snowdrop, have pink skin, blue eyes, and a pale buff colored coat.
Pearl
Pearl is the 3rd recently discovered variant of the MATP / SLC45A2 gene. It is predominantly found in Iberian PRE breeds (Andalusians, Lusitanos) but is also in American Paints and Gypsy Cobs, likely courtesy of Spanish founding stock in some of these pedigrees.
In double copy, very common in the Spanish breeds, it produces a dark double cream phenotype. So a bay pearl often looks like a very dark perlino or even a smoky cream. A chestnut pearl may look apricot and black pearls can look like amber champagnes.
Pearls were traditionally thought to be champagnes. However, genetic champagne does not exist in these breeds (champagne is a New World dilution i.e. it first appeared in American breeds after colonization).
When a Paint-bred mare of unusual apricot coloring turned up in America she too was initially considered champagne. But when extensive research failed to turn up any known champagne horses in her pedigree, researchers went to work and eventually tracked the culprit variant to the MATP gene. They called it ‘Barlink’ after the line of Paints in which it was found.
At the same time, the ‘champagne’ Spanish horses were also being investigated, and when ‘Barlink’ was discovered, the horses were tested for it. Sure enough, they too carried the same variant of the MATP gene. After much discussion, it was decided to use Perla, the name Spanish breeders were using, because it predated ‘Barlink’.
Like sunshine and snowdrop, pearl is not visible in single copy. When carried with a copy of cream, it produces a double cream look-alike with diluted skin, coat, and eyes. But, the true beauty of pearl lies in the homozygotes – the ones that carry 2 copies of the variant!
In Spanish horses, it tends to produce a highly iridescent horse. Interestingly, though, this iridescence is not always present in pearls from other breeds, suggesting it’s not linked to pearl.
Outside of the above breeds, it’s also found in Peruvian Pasos, Gypsy Cobs, and one or two other breeds that have Spanish ancestry. However, it almost certainly originated in one of the PRE breeds.
Mushroom
Mushroom is only found in UK Shetland Pony lines and a few other small equine breeds that have used these lines as foundation breeding stock, notably miniature ponies. Although formally identified in 2019, it is thought to have originated with a mare in the late 1800’s. She has a line of descendants described variously as ‘taffy’, ‘flaxen chestnut’ and similar.
A UK breeder first brought the color to the public’s attention when she noticed some of her chestnut ponies had an unusual sepia tone with light manes and tails, similar to silver. Silver however does not dilute red pigment, and testing for silver returned negative results. The ponies were also verified as definitely chestnut.
Subsequent research uncovered the causal variant in a gene called MFSD12, which is known to influence pigment production. Specifically, it helps control how much of each pigment (black and red) is produced.
Mushroom only affects red pigment and only when 2 copies of the variant are present. It’s not visible in single copy.
Chestnut ponies with 2 copies are various shades of sepia with flaxen manes and tails. The red coat pigment in bay ponies is also affected; these ponies look a bit like sooty buckskins as they retain their black points and any black pigmented hair on their bodies.
Black ponies are not affected at all, which is consistent with the variant not affecting black pigment.
Champagne
Champagne is a variant of the SLC36A1 gene. It’s thought the gene may help regulate cellular pH levels in pigment cells, and the champagne variant alters this, leading to changes in both black and red pigment.
As a New World variant, it first occurred in a horse somewhere in the Americas after colonization. Today it’s found in a number of American breeds, notably the Saddlebred, Quarter Horse, Tennessee Walker, Missouri Fox Trotter, American Cream Draft, Miniature Horses and crosses of these breeds.
The variant dilutes both skin and hair pigment, producing a diluted-appearing horse often with a highly iridescent metallic appearance coat. Some shades are similar in appearance to cream dilutes – a gold (chestnut) champagne can be mistaken for a palomino, whilst an amber (bay) champagne often looks like a buckskin. Black (classic) champagnes usually have a lilac tone to their coats.
The distinguishing features though are their amber-colored eyes and lighter freckled skin. Champagne foals are also usually born quite dark, with green eyes, and lighten with age. Cream dilutes are born light with either grey or brown/black eyes, and darken with age.
Chimera
Chimera horses are extremely rare and result from a unique occurrence where two embryos fuse in the womb, creating a horse with two sets of DNA. This means the horse can display two different coat colors or patterns that wouldn’t be possible from a single set of genetics.
For example, a chimera might have patches of both bay and chestnut coloring or stripes resembling a brindle pattern. The stallion pictured above was initially thought to be a brindle due to his striped appearance, but DNA tests confirmed he is a chimera.
Brindle / Blashko
Brindle is a rare and striking coat pattern in horses, characterized by alternating dark and light bands of color. This unique coloration results from specific genetic mutations that affect hair and skin development.
Interestingly, brindle horses are almost exclusively female, suggesting a sex-linked inheritance pattern that indicates the responsible genes are located on the X chromosome.
Two genes have been linked to the brindle pattern: MBTPS2 and IKBKG. Mutations in the MBTPS2 gene disrupt hair structure, leading to the distinctive striped appearance. This gene variant results in a coat pattern composed of vertical stripes of differently textured hairs, producing the brindle effect.
All horses with this variant are members of the same family, tracing back to a single Quarter Horse mare with a brindle coat pattern. Today, her brindle descendants are predominantly Quarter Horses and American Paints in the United States.
The IKBKG gene variant is similar to a condition in humans called Incontinentia Pigmenti (IP). Mutations in this gene affect skin and hair follicle development, resulting in abnormalities like vertical streaks of lighter and darker hair. As the horse matures, the affected areas may grow stubbly, coarse hair or remain permanently bare. Affected horses with this variant are also all female, heterozygous for the variant, and descend from one founding female.
Roan in Thoroughbreds
In 1982 a bay thoroughbred colt was born on a stud farm in New Zealand. He went through the 1983 Magic Millions yearling sales and ended up in Western Australia. The colt was subsequently named Catch A Bird for obvious reasons, and his legacy to his breed was his unusual color.
Catch A Bird had vertical white stripes running down his sides, a striking contrast to his rich bay coat. He created quite a sensation at the time but at stud, although he didn’t reproduce his own stripy self, he did produce some roans.
Roan thoroughbreds didn’t exist until then so these ones were an unexplained mystery at the time. However, with our modern understanding of the KIT gene, it’s now clear he carried a spontaneous variant in a similar location on KIT to that which produces true roan. In him, it produced white stripes but in his offspring, it produced a classic roan phenotype.
Note: This is not the same roan variant found in other breeds like Quarter Horses, which is to be expected with a new variant.
White / White Spotting ex Dominant White
White spotting refers to various patterns where white markings appear on horses that are otherwise solid in color. Previously called “dominant white,” this term was changed because it can be misleading; not all horses with these patterns are entirely white. The range can vary from minimal white markings to horses that are almost completely white.
Instead of being a single genetic trait, white spotting consists of multiple variations. Each new variation discovered is assigned a unique identifier like “W5” or “W20.” So far, there are 34 recognized variants in this series.
An interesting note is that Sabino 1, a gene causing white spotting patterns, was initially classified under this group. Researchers later expanded the category to include other variations, leading to the current naming system.
These “W” variants are found in a variety of breeds, including purebred Arabians, Quarter Horses, draft breeds, Icelandic Ponies, Standardbreds, and Warmbloods. Thoroughbreds are particularly notable for producing many of these variants, likely due to their large numbers and extensive breeding. Well-known variants like W5, W20, and the Japanese W22 all originated from Thoroughbreds.
Manchado
Manchado is a rare coat pattern found only in Argentinean horses across various breeds. It features large, irregular white patches on the neck, body, and flanks, while the head and legs usually remain the horse’s original darker color.
Manchado horses seem to appear randomly, even in breeds that seem unrelated, which can be puzzling. Experts believe the gene responsible for Manchado has been present as a rare recessive trait in some local horse populations in Argentina for centuries, particularly passed down through mare lines.
Many of these horses descend from lines existing before formal studbooks and pedigree records. Even though Manchado horses and the breeds in which it occurs might seem unrelated today, they likely share a common ancestor carrying the Manchado gene – this connection just hasn’t been documented.
Because the trait is rare and recessive, there are probably not many carriers of the Manchado gene. This reduces the chances that two carriers will breed together. Even when they do, there’s only a 25% chance their offspring will display the Manchado pattern, contributing to its rarity.
