Equine coat color

Cream dilution is an incomplete dominant gene that produces a lightened or "partial dilute" coat color when one copy of the allele is present and a fully dilute (or "double dilute") with two copies. The double cream dilute phenotypes overlap regardless of base coat color and often cannot be distinguished visually. Sometimes the creme allele is combined with an unrelated dilution gene from another family, which creates a cremello-like coat. Such coloration is called a "pseudo-double dilute." These distinctions usually require DNA testing to verify which alleles are present.

• Cremello: A horse with a chestnut base coat and two cream genes that wash out almost all color until the horse is a pale cream or light tan color. Often called "white", they are not truly white horses, and they do not carry the white (W) gene. A cremello usually has blue eyes.

A palomino

• Buckskin: A bay horse with one copy of the cream gene, a dilution gene that "dilutes" or fades the coat color to a yellow, cream, or gold while keeping the black points (mane, tail, legs).
• Palomino: chestnut horse that has one cream dilution gene that turns the horse to a golden, yellow, or tan shade with a flaxen or white mane and tail. Often cited as being a color "of twenty-two carat gold",[4] palominos range in shades from extremely light, almost cremello, to deep chocolate, but always with a white or flaxen mane and tail.
• Perlino: similar to a cremello, but is genetically a bay base coat with two dilute genes. Eyes are usually blue. Mane, tail and points are not black, but can sometimes be darker than the body coat, generally a reddish or rust color, though not to be confused with a red dun.
• Smoky black: A horse which visually appears to be only black, but actually has a black base coat and one copy of the cream gene.
• Smoky Cream: Virtually indistinguishable from a cremello or perlino without DNA testing, a horse with a black base coat and two copies of the cream gene.

• Dun is Yellowish or tan coat with primitive markings, sometimes called "dun factors": a darker-colored mane and tail, a dorsal stripe along the back and occasionally faint horizontal zebralike stripings on the upper legs and a possible transverse stripe across the withers. There are several variations:
  • Grulla, or Blue Dun: A horse with a black base color and the dun gene. Coat is a solid "mouse-colored" gray or silver (can also be almost brownish-gray) with black or dark gray primitive markings.
  • Red Dun: A chestnut base coat with dun factors. Coat is usually pale yellow or tan with chestnut (red) primitive markings.
  • "Bay Dun" or "Zebra dun" are terms sometimes used to describe the classic dun color of yellow or tan with black primitive markings, used when necessary to distinguish it from red duns or grullos.
  • "Buckskin dun" or "Dunskin" describes a bay dun that also carries the cream gene dilution and has a coat of pale gold with a black mane, tail, legs and primitive markings.

Mixtures of dliution genes produce colors such as "dunalino" — a red dun that also carries a single cream gene and thus has a pale gold coat, white mane and tail, and very faint primitive markings.

• Champagne: Produced by a different dilution gene than the cream gene. It lightens both skin and hair, but creates a metallic gold coat color with mottled skin and light-colored eyes. Champagne horses are often confused with palomino, cremello, dun, or buckskins.
• Mushroom dilutes red-based horses to a pale tan colour, so far found only in Shetland ponies or ponies with Shetland influence.
• Pearl: Also called the "barlink factor", A dilution gene that when homozygous, lightens red coats to a uniform apricot color, often also resulting in horses with blue eyes. When combined with cream dilution, it may produce horses that appear to be cremello or perlino.

Silver dapple horses

• Silver or silver dapple: Caused by a dilution gene that only acts upon black hair pigment, it lightens black body hair to a chocolate brown and the mane and tail to silver in most cases. The gene may be carried but will not be visible on horses with a red base coat. Silver horses have informally been called Chocolate, Flaxen, or Taffy.

There are a group of coat patterns caused by the leopard gene complex. Not every horse with leopard genetics will exhibit hair coat spotting. However, even solid individuals will exhibit secondary characteristics such as vertically striped hooves and mottled skin around the eyes, lips, and genitalia, plus a white sclera of the eye.[5] Several breeds of horse can boast leopard-spotted (a term used collectively for all patterns) individuals including the Knabstrupper, Noriker, and the Appaloosa. There are several distinct leopard patterns:

• blanket: white over the hip that may extend from the tail to the base of the neck. The spots inside the blanket (if present) are the same color as the horse's base coat.
• varnish roan: a mix of body and white hairs that extends over the entire body—no relation to genetic roan.
• snowflake: white spots on a dark body. Typically the white spots increase in number and size as the horse ages.
• leopard: dark spots of varying sizes over a white body.
• few spot leopard: a nearly white horse from birth that retains color just above the hooves, the knees, "armpits", mane and tail, wind pipe, and face.
• frost: similar to varnish but the white hairs are limited to the back, loins, and neck.

A pinto has large patches of white over any other underlying coat color. Sometimes called "Paint" in the western United States, a word that which technically refers to the American Paint Horse, a specific breed of mostly pinto horses with known Quarter Horse and/or Thoroughbred bloodlines. Other regional terms for certain pinto spotting patterns include "blagdon" in the UK. Pinto spotting is produced by a large number of genetic mechanisms, with dozens now mapped and identifiable through DNA testing.

Variations of pinto based on the observable color include:

• Piebald: a black-and-white (term more commonly used in the UK than the US). This is pinto spotting on top of black.
• Skewbald: a spotting pattern of white over chestnut or any other color other than black (term more commonly used in the UK than the US).
• Tricoloured: A variation of Skewbald, specifically referring to pinto spotting over a bay base coat or other coat color that features black points.

Terminology variations based on the observable shape of the white patterns include:

• Overo: Describes a group of spotting patterns genetically distinct from one another, characterized by sharp, irregular markings with a horizontal orientation, usually more dark than white. In some cases, the face is usually white, often with blue eyes. The white rarely crosses the back, and the lower legs are normally dark. Variations include "frame overo" and "splashed white".
• Sabino: Describes a range of spotting patterns characterized by high white on legs, belly spots, white markings on the face extending past the eyes and/or patches of roaning patterns standing alone, or on the edges of white markings. Usually produced by certain dominant white or "white spotting" alleles, though not all sabino patterns have been genetically mapped. Sometimes grouped with the overo color pattern group by breed registries that record spotting patterns even thoug created by different genetics from frame or splash.
• Tobiano: Spotting pattern characterized by rounded markings with white legs and white across the back between the withers and the dock of the tail, usually arranged in a roughly vertical pattern and more white than dark, with the head usually dark and with markings like that of a normal horse. i.e. star, snip, strip, or blaze. Produced by the Tobiano (TO) gene.
• Tovero: spotting pattern that is a mix of tobiano and overo coloration, such as blue eyes on a dark head, usually results from the presence of more than one spotting pattern gene.

Roaning adds white hairs to any of the other colors and, unlike gray, the color does not steadily lighten over the horse's lifetime, though there may be some minor color variation from year to year or especially between summer and winter coats.

A black rabicano stallion showing classic ticking on flanks and a white "skunk tail"

• Classic Roan: a color pattern that causes white hairs to be evenly intermixed within the horse's body color. Roans are distinguishable from greys because roans typically do not change color in their lifetimes, unlike gray that gradually gets lighter as a horse ages. Roans also have heads that are either solid-colored or much darker than their body hair, and do not lighten. Variations of roan include:
  • Red Roan: A chestnut base coat with a roaning pattern with the mane and tail being the same red as the body. Red roan is sometimes called Strawberry Roan, and the term Red Roan is occasionally used to describe a Bay Roan.[6]
  • Bay Roan: A Bay base coat with a roaning pattern (the mane and tail of the Bay Roan will be Black). Bay roans are sometimes also called Red Roans.[6]
  • Blue Roan: A black with a roaning pattern, not to be confused with a gray or a blue dun/grullo. A roan tends to have a darker head, while grays not only lighten with age, but their heads tend to lighten before the rest of their bodies. A blue roan has mixed-color hairs, a blue dun will usually be a solid color and have dun striping.

Rabicano: A roan-style effect that is caused by a yet-to-be-mapped genetic modifier that creates a mealy, splotchy, or roaning pattern on only part of the body, usually limited to the underside, flanks, legs, tail and head areas. Unlike a true roan, much of the body will not have white hairs intermingled with solid ones, nor are the legs or head significantly darker than the rest of the horse.

One of the rarest colors, a true genetic white horse has white hair and fully or largely unpigmented (pink) skin. These horses are born white or mostly white and remain white for life. The vast majority of so-called "white" horses are actually grays with a fully white hair coat. A truly white horse occurs one of two ways: either by inheriting one copy of a dominant white ("W") allele that produces white when heterozygous but may be a genetic lethal if homozygous, or by inheriting two copies of a non-lethal dominant white ("W") allele that produces a white coat when homozygous. There are also some genetic lethal genes unrelated to the W allelic series: a foal homozygous for the frame overo gene will have a condition known as lethal white syndrome dies shortly after birth.[7]

There are no "albinos" in the horse world. Albino, defined as animals with a white coat with pink skin and reddish eyes, is created by genetic mechanisms that do not exist in horses.[8] In some cases, homozygous dominant white (W) is thought to be an embryonic lethal, though this does not occur with all W alleles.

A white marking, such as the large snip on this horse's muzzle, usually has pink skin underneath it, except on the edges.

White markings are present at birth and unique to each horse, making them useful in identifying individual animals. Markings usually have pink skin underneath them, though some faint markings may not, and white hairs may extend past the area of underlying pink skin. Though markings that overlie dark skin may appear to change, the underlying skin color and hair growing from pink skin will not. The distinction when white markings confined to the face and legs or a few small body spots become extensive enough to constitute a white spotting pattern is usually determined by breed standards set by registries. White markings generally are now hypothesized to be a minimal expression of certain genes in the dominant white (W) allelic series.