"Perlino" redirects here. For the Polish village, see Perlino, Poland.
The action of the cream gene on a chestnut base coat produces palomino.Rosy pink skin and pale blue eyes are characteristics of cremellos, or "double-dilute" chestnuts.
The cream gene is responsible for a number of horse coat colors. Horses that have the cream gene in addition to a base coat color that is chestnut will become palomino if they are heterozygous, having one copy of the cream gene, or cremello, if they are homozygous. Similarly, horses with a bay base coat and the cream gene will be buckskin or perlino. A black base coat with the cream gene becomes the not-always-recognized smoky black or a smoky cream. Cream horses, even those with blue eyes, are not white horses. Dilution coloring is also not related to any of the white spotting patterns.
The cream gene (CCr) is an incomplete dominant allele with a distinct dosage effect. The DNA sequence responsible for the cream colors is the cream allele, which is at a specific locus on the solute carrier family 45 member 2 (SLC45A2) gene (previously known as MATP and OCA4, among others). Its general effect is to lighten the coat, skin and eye colors. When one copy of the allele is present, it dilutes "red" pigment to yellow or gold, with a stronger effect on the mane and tail, but does not dilute black color to any significant degree. When two copies of the allele are present, both red and black pigments are affected; red hairs still become cream, and black hairs become reddish. A single copy of the allele has minimal impact on eye color, but when two copies are present, a horse will be blue-eyed in addition to a light coat color.
The cream gene is one of several hypomelanism or dilution genes identified in horses. Therefore, it is not always possible to tell by color alone whether the CCrallele is present without a DNA test. Other dilution genes that may mimic some of the effects of the cream gene in either single or double copies include the pearl gene, silver dapple gene, and the champagne gene. Horses with the dun gene also may mimic a single copy of the cream gene. To complicate matters further, it is possible for a horse to carry more than one type of dilution gene, sometimes giving rise to coloring that researchers call a pseudo double dilute.
The discovery of the cream gene had a significant effect on breeding, allowing homozygous blue-eyed creams to be recognized by many breed registries that had previously registered palominos but banned cremellos, under the mistaken notion that homozygous cream was a form of albinism.
Colors produced
Cream coat colors are described by their relationship to the three "base" coat colors: chestnut, bay, and black. All horses obtain two copies of the SLC45A2 gene; one from the sire, and one from the dam. A horse may have the cream allele or the non-cream allele on each gene. Those with two non-cream alleles will not exhibit true cream traits. Horses with one cream allele and one non-cream allele, popularly called "single dilutes," exhibit specific traits: all red pigment in the coat is gold, while the black pigment is either unaffected or only subtly affected.[1][2] These horses are usually palomino, buckskin, or smoky black. These horses often have light brown eyes.[3] Horses with two copies of the cream allele also exhibit specific traits: cream-colored coats, pale blue eyes, and rosy-pink skin. These horses are usually called cremello, perlino, or smoky cream.
Horses that are heterozygous creams, that is, have only one copy of the cream gene, have a lightened hair coat. The precise cream dilute coat color produced depends on the underlying base coat color. Unless also affected by other, unrelated genes, they maintain dark skin and brown eyes, though some heterozygous dilutes may be born with pink skin that darkens with age. Some have slightly lighter, amber eyes. However, the heterozygous cream dilute (CR) must not be confused with a horse carrying champagne dilution. Champagne (CH) dilutes are born with pumpkin-pink skin and blue eyes, which darken within days to amber, green or light brown, and their skin acquires a darker mottled complexion around the eyes, muzzle, and genitalia as the animal matures.[4] It is also possible for a heterozygous cream horse to carry more than one of the other dilution alleles. (see "Cream mimics" below) In such cases, they may exhibit some characteristics more typical of a homozygous dilute.
Cream dilutions may have seasonal color variation between winter and summer coats, as seen in this palomino
Palomino is the best known cream-based coat color, and is produced by the action of one cream allele on a chestnut coat. It is characterized by a cream or white mane and tail and yellow or gold coat.[3] The classic golden shade akin to that of a newly minted gold coin is common, but there are other variations: the darkest shades are called sooty palominos, unusual but most often seen in Morgans, can include a mane and tail with darker hairs and heavy dappling in the coat.[5] The palest varieties can be nearly white, retaining darker skin and eyes, are sometimes mistakenly confused with cremello, and are called isabellas in some places.
Buckskin is also a well-known color, produced by the action of one cream gene on a bay coat. All red hairs in the base coat are diluted to gold. The black areas, such as the mane, tail and legs, are generally unaffected. The cream gene acting on a "blood bay" coat, the reddest shade, are pale gold with black points. They are sometimes called buttermilk buckskins. The cream gene acting on the darkest bays (sometimes mistaken for seal browns) may dilute to a sooty buckskin. True seal brown buckskins can be very difficult to identify owing to their almost all-black coats. It is only the reddish markings around the eyes, muzzle, elbow and groin, which are turned gold, that may give them away.[6]
Smoky black foal
Smoky black, a horse with a black base coat and one copy of the cream allele, is less well-known than the two golden shades. Since a single copy of the cream gene primarily affects red pigment, with only a subtle effect on black, smoky blacks can be quite difficult to identify. Smoky blacks may have reddish guard hairs inside their ears,[citation needed] and experienced horse persons may detect something "off" about the coat of a smoky black, though the slightly burnished look is often chalked up to sun bleaching, which can also be seen in true blacks. The palest can be mistaken for bays or liver chestnuts, especially if exposed to the elements. Smoky black coats tend to react strongly to sun and sweat, and many smoky blacks turn a chocolate color with particularly reddish manes and tails. Bleaching due to the elements means that the legs retain their color better, and can take on an appearance of having dark points like a bay horse. Smoky blacks, however, will lack rich red tones in the coat, instead favoring chocolate and orange tones. Because smoky blacks are often not recognized as such, breeders sometimes think that the cream gene "skipped" generations.
While there are "color breed" registries for palomino and buckskin horses, which generally record horses based on apparent phenotype and do not require a DNA color test, it is impossible for these colors to breed "true" due to the action of a single copy of the cream allele. Crossing two heterozygous dilutes will statistically result in offspring which are 25% the base color, 25% homozygous dilute, and 50% heterozygous dilute.
This smoky cream tobiano illustrates the difference between unpigmented (white) skin and hair, and skin and hair color due to the cream dilution.
When a horse is homozygous, meaning it has two copies of the cream allele, the strongest color dilution occurs.
Cremellos are homozygous cream chestnuts, and have a cream colored body with a cream or white mane and tail.
Perlinos are homozygous cream bays, which also have a cream-colored body but a mane and tail that may be somewhat more reddish in color than a cremello.
Smoky creams are homozygous cream blacks, and very difficult to visually distinguish from cremellos or perlinos.
All three shades can be difficult to distinguish from one another, and are often only firmly identified after a DNA test. While both red and black pigments are turned cream, the black pigment retains a little more color and tends to have a reddish or rusty tint.[7] Thus all-red coats are turned all-ivory, all-black coats are turned all-rusty cream, and bay coats have ivory bodies with slightly darker points.[3]
Perlinos may have a reddish-tinted mane
Horses with two copies of the cream allele can be collectively called double-dilutes, homozygous creams, or blue-eyed creams, and they share a number of characteristics. The eyes are pale blue, paler than the unpigmented blue eyes associated with white color or white markings, and the skin is rosy-pink. The true, unpigmented pink skin associated with white markings is clearly visible against the rosy-pink skin of a double-dilute, especially when their coat is wetted down. The palest shades of double-dilute coats are just off-white, while the darkest are distinctly rust-tinged. Their coats may be described as nearly white[1] or ivory[3] in addition to cream.
The off-white coat, pale blue eyes, and rosy pink skin distinguish the coats of double-dilutes from those of true white horses. True white horses have unpigmented skin and hair due to the incomplete migration of melanocytes from the neural crest during development.[8]
No health defects are associated with the cream gene. This is also true of the normal variations in skin, hair and eye color encoded on the human SLC45A2 gene.[9] True white coat coloring can be produced by at least half a dozen known genes, and some are associated with health defects. Some genes which encode a white or near-white coat when heterozygous, popularly called "dominant white," may be lethal in homozygote embryos.[10] Another specific mutation on the endothelin receptor type B (EDNRB) gene is associated with the frame overo pattern produces Lethal white syndrome if homozygous, but carriers can be identified with a DNA test.
A light palomino foal. Its light cream coat color gives it a superficial resemblance to a cremello, but it has dark skin and eyes, so it can only have one copy of the cream dilution gene, and cannot be a double-dilute cremello or a pseudo-double dilute.Comparison between the lightly pigmented blue eye of a perlino (top) versus a pure blue "unpigmented" eye, created by an unpigmented layer of cells at the front of the eye.
Other coat colors may mimic the appearance of a cream coat color. The presence or absence of the cream gene can always be verified by the use of a DNA test. Also, as explained in "Mixed dilutes" below, horses may simultaneously carry more than one dilution gene. Dilution genes which, by themselves, may be confused with cream dilutions include the following:
Bay dun vs. buckskin: the action of the dun gene on bay produces a buckskin-like coat. Additional confusion occurs because in some countries, it is still customary to refer to buckskins as "dun", particularly in the British pony breeds. Bay duns tend to have a flatter coat color, more tan or peanut butter-colored than bronze, and also exhibit primitive markings.
Amber champagne vs. buckskin: the action of the Champagne gene on bay can also produce a buckskin-like coat. Champagnes can be identified by their freckled skin, hazel eyes, and chocolate (rather than black) points.
Flaxen chestnut vs. palomino: Horses having light chestnut coats with flaxen manes and tails, such as those found in the Haflinger breed, can be confused with palominos. However, unlike chestnuts, palomino is inherently a heterozygous condition and thus cannot be true-breeding. Furthermore, even the lightest chestnut will retain "red" character in the hair, rather than gold.
Gold champagne vs. palomino: the action of the Champagne gene on chestnut was for many years called pumpkin-skinned palomino. However, lighter, freckled skin and hazel eyes identify a gold champagne, which can otherwise look much like a palomino.
Pearl vs. palomino: the action of the pearl gene only occurs when the pearl allele is homozygous. In such cases, the red hairs are lightened to an apricot color.[23]
Pseudo-double-dilute vs. cremello: A horse that has one cream allele and one pearl allele may resemble a homozygous cream, including pinkish skin and blue eyes. A combination of one cream and one Champagne allele may also produce a similar phenotype, though may be distinguishable by lighter yellowish or blue eyes and pale, faintly freckled skin.
White vs. double dilute: White horses with blue or dark eyes and pink skin are born white and remain so throughout life. Cremello and isabelline horses that bleach out in the sun may approach a near-white shade, but have some skin pigment, exhibited by a slightly more peach skin tone and blue-eyed creams have a less vivid shade of blue when compared to that of an unpigmented blue-eye.
Gray vs. double dilute: Gray horses are born a normal color and grow progressively lighter in their coat, while double-dilute creams do not. Grays that are not affected by a dilution gene do not have blue eyes or pink skin unless they are due to white markings. There are, however, records of palominos, buckskins, smoky blacks, and double-dilute creams that also carry the gray gene.[1]
Mixed dilutes
If a horse carries more than one type of dilution gene, additional cream mimics and other unique colors may occur. The combined effects of champagne and a single cream gene can be hard to distinguish from a double-dilute cream. Freckled skin and greenish eyes, or pedigree knowledge can yield clues, though the mystery can also be solved with a DNA test.
The pearl gene or "barlink factor" is a recessive gene that affects only red pigment.[2] When a single copy each of pearl and cream are present, the effect is quite similar to cremello. Dilutes combining the pearl gene with one copy of the cream gene are known as "pseudo-double dilutes" and produce a cream dilute phenotype that includes pale skin and blue/green eyes.[2] DNA tests and patience are effective in determining which is the case.
Some of the terms used to describe these combinations include:
Dunalino, yellow dun or palomino dun: a chestnut-based coat with one cream allele and at least one dun allele. The points are reddish, but the body coat is a paler, flatter shade of gold and primitive markings are visible.
Dunskin, buckskin dun, or buttermilk dun: a bay-based coat with one cream allele and at least one dun allele. These are quite difficult to tell apart from ordinary duns. They are a slightly paler shade, and retain their dark points and primitive markings.
Cream dun, cremello dun or linebacked cremello: a blue-eyed cream horse also carrying the dun gene. The primitive markings associated with the dun color are usually quite visible, especially on horses with a bay or black base coat.
Smoky grulla, silver grulla or smoky black dun: a black-based coat with one cream allele and at least one dun allele. The effect is of an extra-pale grulla.
Double-cream champagne: any blue-eyed cream horse that also carries the champagne gene. The champagne traits are, in the few known individuals, not visible. The skin is quite pink.
Amber cream or buckskin champagne: a bay-based coat with one cream allele and at least one champagne allele. The skin and eyes have champagne traits such as skin mottling, while the coat is a pale buff color. The points are a soft, pale grayish-chocolate.
Classic cream or smoky black champagne: a black-based coat with one cream allele and at least one champagne allele. is also an acceptable term. Like an amber cream, they retain champagne traits in the skin and eyes, and range from pale buff to pale chocolatey-gray. Even though the coat is black-based, the mane and tail tend to be darker.
Gold cream: chestnut-based coat with one cream allele and at least one champagne allele. Formerly referred to as "ivory champagne." The champagne traits remain in the skin and eyes, and the coat is an all-over ivory color.
Sable cream or brown buckskin champagne: brown-based coat with one cream allele and at least one champagne allele. The coat color falls between amber and classic cream.
Silver buckskin: bay-based coat with one cream allele and at least one silver dapple allele. The effect varies, as silver dapple does not act on red coats, but the buckskin's golden tone is somewhat lost.
Silver smoky black: black-based coat with one cream allele and at least one silver allele. The effect varies from chestnut-like to silver black-like. Lighter eyes can help with identification.
Genes in horses such as Frame and Sabino1 produce white spotting by interrupting or limiting the migration of melanocytes from the neural crest, while the cream mutation affects the nature of the pigments produced by melanocytes. Therefore the skin, eyes, and hair of horses with the cream mutation do not lack melanocytes, melanosomes, or melanins, but rather exhibit hypomelanism.[1]
Prior to the mapping of the cream gene, this locus was titled C for "color".[3] There are two alleles in the series: the recessive, wildtype allele C and the incomplete dominantCCr.[2] The CCr allele represents the N153D SLC45A2 mutation.
C/C recessive homozygotes are not affected by cream and have no true cream traits.
C/CCr heterozygotes have one cream allele, and one wildtype non-cream allele. Only red pigment in the hair is diluted, as seen in buckskins and palominos.
CCr/CCr homozygotes (homozygous creams) have no wildtype non-cream alleles. The red and black pigment in the hair are diluted to cream, the eyes are light blue and the skin is rosy pink.
Cream was first formally studied by Adalsteinsson in 1974, who reported that the inheritance of palomino and buckskin coat colors in Icelandic horses followed a "semi-dominant" or incomplete dominant model. Adalsteinsson also noted that in heterozygotes, only the red pigment (pheomelanin) was diluted.[17]
The discovery that the palomino coat color was inextricably linked to the cream coat color was very significant. At one time, double dilutes, particularly cremellos, were barred from registration by many breed organizations.[25] Cremello was thought by some to be a lethal white or albino coloring and a potential genetic defect.[26] There also were known health implications of albinism in humans,[27] and cultural prejudices; while a heroic figure such as Roy Rogers rode a golden palomino, the "Albino" in Mary O'Hara's Thunderhead portrayed a horse with a freakish defect. These coat colors carried vastly different cultural significance. Because the experience of breeders of palomino and buckskin horses indicated that blue-eyed cream offspring of these animals were not genetically defective, some of the research that took place nearly thirty years after Adalsteinsson's studies that identified the nature of cream dilution was directly supported by breed registries that had historically barred blue eyed creams.
Cryptic creams
Smoky black Icelandic horse
The cream gene's preferential effect on red pigment has not yet been explained. The champagne dilution affects both black and red pigments equally, the silver dapple gene affects only black pigment, and pearl exhibits a recessive mode of inheritance and only affects red pigment.[2] Unlike the cream gene, pearl does not seem to affect the mane and tail to a greater extent than the body coat, a feature of cream that is most vividly illustrated in the palomino coat color. This characteristic of the cream gene is also unexplained. The disparity in effects on red and black pigments is easy to identify in buckskins, with their black points, but it is also visible in CCr/CCr homozygotes: perlinos (homozygous cream on a bay coat) often retain points that are a darker shade of cream.[3]
Sooty palomino, with streaks in its mane
This unusual feature enables what are called cryptic creams.[1] A certain percentage of dark bay, seal brown, and black horses exhibit such subtle dilution of their coats as to be misregistered. In the study that mapped the cream gene, three horses registered as seal brown, dark bay or bay were actually smoky black and buckskin.[1] This is one way by which the cream gene is transmitted through generations without being identified. Horses born palomino, buckskin, and smoky black, but also carry the gray gene, have a hair coat that turns white as they age and are usually registered as "gray" rather than as their birth color. This is particularly a common occurrence in the Connemara breed. Horses sold after turning fully gray may surprise breeders by producing golden or cream offspring.[1]
This effect - stronger expression on red pigment - is also seen in coat pattern genes in horses. In general, white markings are more pervasive in chestnuts than in non-chestnuts, to the extent that homozygous non-chestnuts (which carry the "Extension" (E) gene and may also carry the Agouti gene) were more modestly marked than non-chestnuts heterozygous for the E allele.[28][29][30] This effect has also been identified and studied in the Leopard complex patterns.[31]
Analogous conditions in other animals
The SLC45A2 gene is best known in humans as being the location of a mutation that results in human type IV oculocutaneous albinism (OCA4). Type IV oculocutaneous albinism, like other types of human albinism, results in hypopigmentation of the skin and eyes, with increased rates of skin cancer and reduced visual acuity.[32] None of these effects are associated with the equine cream gene. Other human SLC45A2 polymorphisms result in normal pigment variations, specifically fair skin, light eyes, and light hair in Caucasian populations.[9]
A presumed knockout mutation in the same gene causes the phenotype of white tigers, which retain black striping though they lack the typical orange background pigmentation.[33] A polymorphism on the mouse SLC45A2 gene is known to be the cause of the underwhite coat color phenotype. The phenotype was first identified in the 1960s, and since then has been mapped successfully. Affected individuals have a reduction in eye and coat pigmentation, and irregularly shaped melanosomes.[24]
Palomino is a genetic color in horses, consisting of a gold coat and white mane and tail; the degree of whiteness can vary from bright white to yellow. The palomino color derived from the inter-breeding of Spanish horses with those from the United States. Genetically, the palomino color is created by a single allele of a dilution gene called the cream gene working on a "red" (chestnut) base coat. Palomino is created by a genetic mechanism of incomplete dominance, hence it is not considered true-breeding. However, most color breed registries that record palomino horses were founded before equine coat color genetics were understood as well as they are today, therefore the standard definition of a palomino is based on the visible coat color, not heritability nor the underlying presence of the dilution gene.
A dilution gene is any one of a number of genes that act to create a lighter coat color in living creatures. There are many examples of such genes:
Bay is a hair coat color of horses, characterized by a reddish-brown or brown body color with a black point coloration on the mane, tail, ear edges, and lower legs. Bay is one of the most common coat colors in many horse breeds.
At right is displayed the color traditionally called liver.
Point coloration is animal coat coloration with a pale body and relatively darker extremities, i.e. the face, ears, feet, tail, and scrotum. It is most recognized as the coloration of Siamese and related breeds of cat, but can be found in dogs, rabbits, rats, sheep, guinea pigs and horses as well.
A gray horse has a coat color characterized by progressive depigmentation of the colored hairs of the coat. Most gray horses have black skin and dark eyes; unlike some equine dilution genes and some other genes that lead to depigmentation, gray does not affect skin or eye color. Gray horses may be born any base color, depending on other color genes present. White hairs begin to appear at or shortly after birth and become progressively more prevalent as the horse ages as white hairs become intermingled with hairs of other colors. Graying can occur at different rates—very quickly on one horse and very slowly on another. As adults, most gray horses eventually become completely white, though some retain intermixed light and dark hairs.
The champagne gene is a simple dominant allele responsible for a number of rare horse coat colors. The most distinctive traits of horses with the champagne gene are the hazel eyes and pinkish, freckled skin, which are bright blue and bright pink at birth, respectively. The coat color is also affected: any hairs that would have been red are gold, and any hairs that would have been black are chocolate brown. If a horse inherits the champagne gene from either or both parents, a coat that would otherwise be chestnut is instead gold champagne, with bay corresponding to amber champagne, seal brown to sable champagne, and black to classic champagne. A horse must have at least one champagne parent to inherit the champagne gene, for which there is now a DNA test.
The silver or silver dapple (Z) gene is a dilution gene that affects the black base coat color and is associated with Multiple Congenital Ocular Abnormalities. It will typically dilute a black mane and tail to a silvery gray or flaxen color, and a black body to a chocolaty brown, sometimes with dapples. It is responsible for a group of coat colors in horses called "silver dapple" in the west, or "taffy" in Australia. The most common colors in this category are black silver and bay silver, referring to the respective underlying coat color.
Equine coat color genetics determine a horse's coat color. Many colors are possible, but all variations are produced by changes in only a few genes. Bay is the most common color of horse, followed by black and chestnut. A change at the agouti locus is capable of turning bay to black, while a mutation at the extension locus can turn bay or black to chestnut.
The dun gene is a dilution gene that affects both red and black pigments in the coat color of a horse. The dun gene lightens most of the body while leaving the mane, tail, legs, and primitive markings the shade of the undiluted base coat color. A dun horse always has a dark dorsal stripe down the middle of its back, usually has a darker face and legs, and may have transverse striping across the shoulders or horizontal striping on the back of the forelegs. Body color depends on the underlying coat color genetics. A classic "bay dun" is a gray-gold or tan, characterized by a body color ranging from sandy yellow to reddish brown. Duns with a chestnut base may appear a light tan shade, and those with black base coloration are a smoky gray. Manes, tails, primitive markings, and other dark areas are usually the shade of the undiluted base coat color. The dun gene may interact with all other coat color alleles.
The Fjord or Norwegian Fjord Horse is a relatively small but very strong horse breed from the mountainous regions of western Norway. It is an agile breed of light draught horse build. It is always dun in colour, with five variations in shade recognised in the breed standard. One of the world's oldest breeds, it has been used for hundreds of years as a farm horse in Norway, and in modern times is popular for its generally good temperament. It is used both as a harness horse and under saddle.
Chestnut is a hair coat color of horses consisting of a reddish-to-brown coat with a mane and tail the same or lighter in color than the coat. Chestnut is characterized by the absolute absence of true black hairs. It is one of the most common horse coat colors, seen in almost every breed of horse.
Horses exhibit a diverse array of coat colors and distinctive markings. A specialized vocabulary has evolved to describe them.
A white horse is born predominantly white and stays white throughout its life. A white horse has mostly pink skin under its hair coat, and may have brown, blue, or hazel eyes. "True white" horses, especially those that carry one of the dominant white (W) genes, are rare. Most horses that are commonly referred to as "white" are actually "gray" horses whose hair coats are completely white. Gray horses may be born of any color and their hairs gradually turn white as time goes by and take on a white appearance. Nearly all gray horses have dark skin, except under any white markings present at birth. Skin color is the most common method for an observer to distinguish between mature white and gray horses.
Black is a hair coat color of horses in which the entire hair coat is black. Black is a relatively uncommon coat color, and it is not uncommon to mistake dark chestnuts or bays for black.
The American Cream Draft is an American breed of draft horse, characterized by the cream or "gold champagne" color of its coat. It was developed in Iowa during the early twentieth century from a cream-colored mare named Old Granny. A breed registry was formed in 1944 but became inactive for several decades when breed numbers dropped due to the mechanization of farming. It was reactivated in 1982 and population numbers have slowly grown since then. It is a rare breed: its conservation status is considered critical by The Livestock Conservancy and the Equus Survival Trust.
Smoky black or black carrying cream is a coat color of horses which has the same phenotype as black. Smoky black is produced by the action of a heterozygous cream gene on an underlying black coat color. Therefore, smoky black is a member of the cream family of coat color dilutions, and found in horse populations that have other cream-based colors such as palomino, buckskin, perlino, cremello and smoky cream. All smoky blacks must have at least one parent with the cream gene, and a smoky black can only be verified through DNA testing or parentage. Smoky black has been mistaken for faded black, dark bay or brown, grullo or even liver chestnut.
The Pearl gene, also known as the "Barlink factor", is a dilution gene at the same locus as the cream gene, which somewhat resembles the cream gene and the champagne gene but is unrelated to champagne. It is a somewhat rare dilution gene found in the American Quarter Horse, American Paint Horse, and Peruvian Paso. The same mutation appears in Iberian horse breeds such as the Lusitano and Andalusian. The existence of the pearl gene in Quarter Horses and Paints is probably because these breeds have some Iberian ancestors.
The leopard complex is a group of genetically related coat patterns in horses. These patterns range from progressive increases in interspersed white hair similar to graying or roan to distinctive, Dalmatian-like leopard spots on a white coat. Secondary characteristics associated with the leopard complex include a white sclera around the eye, striped hooves and mottled skin. The leopard complex gene is also linked to abnormalities in the eyes and vision. These patterns are most closely identified with the Appaloosa and Knabstrupper breeds, though its presence in breeds from Asia to western Europe has indicated that it is due to a very ancient mutation.
Seal brown is a hair coat color of horses characterized by a near-black body color; with black points, the mane, tail and legs; but also reddish or tan areas around the eyes, muzzle, behind the elbow and in front of the stifle. The term is not to be confused with "brown", which is used by some breed registries to refer to either a seal brown horse or to a dark bay without the additional characteristics of seal brown.
1 2 3 4 5 6 Locke, MM; LS Ruth; LV Millon; MCT Penedo; JC Murray; AT Bowling (2001). "The cream dilution gene, responsible for the palomino and buckskin coat colors, maps to horse chromosome 21". Animal Genetics. 32 (6): 340–343. doi:10.1046/j.1365-2052.2001.00806.x. PMID11736803. The eyes and skin of palominos and buckskins are often slightly lighter than their non-dilute equivalents.
↑ "Coat Colors of TWHs". Colors and Markings. Tennessee Walking Horse Breeders' and Exhibitors' Association. Archived from the original on August 5, 2007. Retrieved December 30, 2008.
↑ MFTHBA Color Panel. "What Color Is Your Horse?". Missouri Fox Trotting Horse Breed Association. Retrieved December 30, 2008.
↑ American Miniature Horse Association. "Coat Color Chart". Registration. Archived from the original on November 9, 2009. Retrieved December 30, 2008.
↑ The Jockey Club. "Coat Colors Of Thoroughbreds". Interactive RegistrationTM Help Desk: How to Identify a Thoroughbred. The Jockey Club. Retrieved February 17, 2008.
↑ " Introduction to Coat Color Genetics"from Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis. Web Site accessed March 27, 2008
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