Horse Coats: A Rainbow Of Colors

Horses come in a wide variety of colours and markings, with countless shades and combinations that make each horse unique. The most common colours and patterns are bay, chestnut, grey, black, pinto, and dun.

The colour of a horse's coat is determined by many factors, such as breed, genetics, age, and even season. While most horses retain their colour throughout their lives, some will develop a different coat colour from the one they were born with.

All horse colours originate from just three basic coat colours: bay, chestnut, and black. These are made up of only two types of pigment: red and black.

Horse Coat Characteristics

Chestnut horses: a red coat with no black, ranging from light to liver chestnut

Chestnut horses are characterised by their reddish-brown coats, with manes and tails that are the same colour or lighter. This is one of the most common horse colours and can be seen in almost every breed. The lightest chestnuts may be mistaken for palominos, while the darkest shades can appear black.

Chestnut is a base colour in the discussion of equine coat colour genetics. It is produced by a recessive gene and is considered "red" by geneticists. The two basic pigment colours of horse hairs are pheomelanin ("red") and eumelanin ("black"). These two hair pigment genes create two base colours: chestnut, which is fully red, and black, which is fully black. All other coat colours are created by additional genes that modify these two base colours.

The different types of chestnut horses range from light chestnut to liver chestnut. Light chestnut is a seldom-used term to describe a pale coat. Liver chestnut, on the other hand, is a very dark reddish-brown shade and is one of the rarer variations.

Sorrel is another term used to describe a specific shade of chestnut. Sorrel horses have coats on the lighter spectrum, ranging from light brassy copper to copper-red. This shade is common among western horses, and the term is particularly used by American stock-horse registries. In other parts of the English-speaking world, "sorrel" may refer to a light chestnut with a flaxen mane and tail.

Flaxen chestnut is a term used to describe a chestnut horse of any shade with a flaxen mane and tail. The flaxen allele creates a blonde, white, or silvery mane and tail on a red chestnut body. This variation is exclusive to certain breeds, such as the Haflinger and the Belgian Draft Horse.

Chestnut horses can also be further categorised by their roan patterns. Red roans, also known as strawberry roans, have a chestnut base coat with a roaning pattern. Liver chestnuts, when roaned over, are known as red roans.

Bay horses: a combination of red and black hairs, with red predominant on the body and black on the mane, tail and lower legs

Bay is the most common horse coat colour. It is a combination of red and black hairs, with red predominant on the body and black on the mane, tail, and lower legs. This black area of a bay horse's hair coat is called 'black points'. Without these black points, a horse is not a bay horse.

The coat colour of a bay horse can range from light copper red to a rich red blood bay, to a very dark red or brown called dark bay, mahogany bay, black-bay, or brown. The dark brown shades of bay are referred to in other languages by words that mean 'black-and-tan'. Dark bays can be so dark that their coats are almost black, with brownish-red hairs visible only under the eyes, around the muzzle, behind the elbow, and in front of the stifle.

Bay horses have black skin and dark eyes, except for the skin under any white markings, which is pink. The pigment in a bay horse's coat is rich and fully saturated, making them particularly lustrous in the sun if properly cared for. Some bay horses exhibit dappling, which is caused by textured, concentric rings within the coat. Dapples on a bay horse suggest good condition and care, though many well-cared-for horses never dapple. The tendency to dapple may also be, to some extent, genetic.

The red areas of a bay coat usually have a two-toned hair shaft, which, if shaved closely (such as when body-clipping for a horse show), may cause the horse to appear several shades lighter, a somewhat dull orange-gold, almost like a dun. However, as the hair grows out, it will darken again to the proper shade. This phenomenon is linked to the genetics that produce red coloration in horses, but usually not seen in body-clipped darker shades of bay because there is less red in the hair shaft.

The shades with the least amount of point coloration are called wild bays. Wild bays are true bays with fully pigmented reddish coat colour and black manes and tails, but the black points only extend up to the pastern or fetlock. Wild bay is sometimes found in conjunction with a trait called 'pangare' that produces pale colour on the underbelly and soft areas, such as near the stifle and around the muzzle.

Some breed registries use the term 'brown' to describe darker bays, though modern genetics have resulted in some terminology revisions, such as the use of 'bay or brown'. However, 'liver' chestnuts, horses with a red or brown mane and tail as well as a dark brownish body coat, are sometimes called 'brown' in some colloquial contexts. Therefore, 'brown' can be an ambiguous term for describing horse coat colour. It is clearer to refer to dark-coloured horses as dark bays or liver chestnuts.

To further complicate matters, there apparently exists more than one genetic mechanism that darkens coat colours. One is a theorized sooty gene that produces dark shading on any coat colour. The other is a specific allele of agouti linked to a certain type of dark bay, called seal brown. The seal brown horse has a dark brown body and lighter areas around the eyes, the muzzle, and flanks. A DNA test said to detect the seal brown (At) allele was developed, but the test was never subjected to peer review and, due to unreliable results, was subsequently pulled from the market.

The addition of dilution genes or various spotting pattern genes creates many additional coat colours, although the underlying bay coat colour genetics usually manifest by a warm-toned red, tan, or brownish body colour and the appearance of black points.

Black horses: a pure black coat, with no brown hairs

Black horses are characterised by a pure black coat, with no brown hairs. This coat colour is created by the eumelanin pigment gene, which produces black.

Black horses are relatively uncommon, though they are not considered "rare". Most black foals are born a mousy grey colour, and their black colour will show through as their foal coat begins to shed. To be considered a black horse, the animal must be completely black, except for any white markings. Black horses may be categorised as either "fading black" or "non-fading black". Fading black horses will reveal lighter hairs when exposed to sunlight for extended periods, whereas non-fading black horses will retain their colour. Non-fading black coats may also have a bluish tinge to them.

It can be difficult to distinguish between black horses and dark bay horses, especially during the winter when the coats of dark bay horses turn a darker shade. However, there is a visible difference between the two coat colours in the fine hairs around the eyes and muzzle. On a black horse, these hairs are black, even if the horse has been sun-bleached. On other colours, these hairs will be lighter. The hairs around the coronet band of the hoof will also be black on a black horse, but on a chestnut horse (no matter the shade), they will always be red.

Some horse breeds are always black, including the Friesian and Mérens horse. The allure of a pure black coat has led horse breeders to create all-black breeds, such as the Friesian horse. However, breeding pure black horses is challenging due to the fact that some black coats fade with exposure to light and sweat, and that breeding two "black" horses together does not always produce black offspring.

Dun horses: a yellow or tan coat with primitive markings, such as a darker-coloured mane and tail

Dun horses are characterised by their yellowish or tan coats, with darker-coloured primitive markings on their mane and tail. The colour is considered to be the most ancient of all horse colours and is usually found in breeds with primitive origins, such as the Fjord or Przewalski's horse.

Dun horses exhibit a variety of shades but all showcase some of the characteristic "primitive" dun factors. These include a dorsal stripe, horizontal striping on the legs, dark-tipped ears, a darker area around the forehead and nasal bone, and cobweb-like patterns throughout the coat.

The colour of the points (mane, tail, and lower legs) of a dun horse depends on the underlying coat colour genetics. Duns with a chestnut base may appear light tan, while those with a black base are a smoky grey. The primitive markings, mane, tail, and other dark areas are usually the shade of the undiluted base coat colour.

The dun gene is a dilution gene that affects both red and black pigments in the coat colour of a horse. It lightens most of the body while leaving the mane, tail, legs, and primitive markings the shade of the undiluted base coat colour. The dun gene may interact with all other coat colour alleles.

The Fjord horse breed, which is predominantly dun, uses unique Norwegian-based terminology to distinguish between the different shades of dun horses. "Brown dun", or "brunnblakk", is a zebra dun, "rødblakk" is a red dun, "grå" (literally "grey") is a grullo, buckskin duns are called "ulsblakk" or "white dun", and a dunalino (dun + palomino) is called a "yellow dun" or "gulblakk".

Roan horses: a colour pattern that results in white hairs being mixed with the horse's original colour

Roan horses are characterised by a mixture of coloured and white hairs on the body, while the head and "points" (lower legs, mane, and tail) are mostly solid-coloured. The white hairs are interspersed throughout the coat, with fewer scattered white hairs or none at all on the head, legs, mane, and tail. The roan pattern is dominantly inherited and is found in many horse breeds. Roan is always present at birth, though it may be hard to see until after the foal coat sheds out. The coat may lighten or darken from winter to summer, but unlike the grey coat colour, roans do not become progressively lighter in colour as they age.

The roan pattern is visually appealing, making roan horses highly sought after and desired by equestrians around the world. Roan is not a breed of its own, but a unique genetic composition that exists in various breeds and presents itself on different base horse colours. The classic roan pattern, also known as true roan, is genetically and visually different from other roan-like patterns. In the classic roan pattern, the white, unpigmented hairs are mixed evenly throughout the roan-patterned area.

The classic roan coat colour is an inherited trait through an autosomal dominant gene. This means that the roan trait is passed down from the parents, and only one copy of the gene is needed for the offspring to display the trait. If a horse inherits the roan gene from at least one of its parents, it will display the roan pattern on its coat.

There are three specific classic roan variations that are most commonly recognised by horse registries: red roan, bay roan, and blue roan. Red roan is used to describe roan horses with a deep chestnut-based coat, while strawberry roan is the term for lighter chestnut-coloured horses. Bay roan refers to a horse that exhibits the roan pattern but has a bay-coloured base coat. Blue roan horses have a black-coloured base coat, with the roan colouring giving them a bluish tint. While blue roans can sometimes appear solid when first born, their coats can evolve into the roan pattern if they carry the roan pattern gene.

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