Point coloration is animal coat coloration with a pale body and relatively darker extremities, i.e. the face, ears, feet, tail, and (in males) 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.
Point coloration in cats originated in the Siamese and closely related Asian breeds, and is found in many Western-developed modern breeds. It is a form of partial albinism resulting from a mutation that affects tyrosinase, an enzyme involved with melanin production. The mutated enzyme is thermolabile; it fails to work at normal body temperatures, but becomes active in cooler areas of the skin. [1] As a result, dark pigment is limited to the coldest areas of the body, that is, the extremities. Pointed kittens are born white, since the womb is uniformly warm. As the kitten ages, the cooler areas darken while warmer areas remain cream to white in color. Points are not limited to solid colors or dark colors. It is possible to have a red (orange color) or fawn (pale warm gray) point. It is also possible to have a tortoiseshell or tabby point. A cat (of any breed) with this coloration is often called a colorpoint cat to distinguish it from others.
As the expression of the gene responsible for the pointed pattern is regulated by temperature, pointed cats who live in cooler environments often show increased darkening of their fur relative to cats who live in warmer climates, sometimes even developing large dark areas along their sides.
Because of the pigment restriction caused by the temperature sensitive tyrosinase, pointed cats' eyes are always shades of blue because the blue layer in the eye common to all cats is not covered by another color. The back of the eye also lacks pigment, giving colorpoint cats' pupils an eerie red and silver reflection in the dark, unlike a normally pigmented cat's shining silver-green or -blue.
The point gene allele is at the C locus, where pure albinism is also carried, and is written as cs. Point is recessive, so two copies of cs, one from each parent, are needed for points to be expressed. Also carried on the C locus is the gene for the sepia pattern, which allele is represented by cb. This is the darkest of all of the pigment restricting patterns—pigment is only paled at the warmest point in the body: the abdomen. Sepia cats have amber-yellow to green eyes. When a cat carries the genes cs and cb, the intermediate mink pattern is formed, in which the pigment distribution is between sepia and point. The eye color of mink cats is on the blue-green spectrum (aquamarine).
The lynx point pattern is formed by mating a colorpoint cat with a tabby cat (or breeding cats that already possess the lynx point pattern). It is characterized by a mixture of the darkening (reduced) of point coloration with distinct tabby striping on the head, tail, and legs, and an otherwise uniform and comparatively pale body. It is an accepted pattern in some cat registries, but not others, for particular breeds (mostly Siamese-related).
Point coloration is inherent to the Siamese breed and some other closely related breeds but with most other breeds the colorpoints (including lynx) were brought into some breed lines long after their establishment, but there are exceptions. For example, lynx point was a feature of some of the foundation stock of the Siberian, now called the Neva Masquerade. [2]
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Tan points on dogs includes point coloration on a black or dark base coat with tan cheek spots, eyebrows, feet, forelegs and tail vent. [3] Typical tan point breeds include Dobermann and Rottweiler. [4]
Rarely, dogs may also have a point coloration similar to that of Siamese cats. [5]
In horses, point coloration is most often produced by the action of the agouti gene. It acts on the extension gene, when present, to suppress black color to all but the extremities of the horse; the legs, mane, tail and tips of the ears. If the extension gene is not present, the effect of agouti is not visible, as there is no black color present to suppress. Points are most typically seen on a bay-colored horse, which has a black mane, tail, legs, and ear tips while the body and head will show the underlying chestnut or "red" base color.
Other genes white markings may affect a horse's coat color in addition to agouti, and if present, can further alter or suppress black hair color and may mask any point coloration. In particular, Gray horses are born dark and lighten with age; if born bay, they will eventually lose point coloration as the body hair silvers with age, though often the points are the slowest areas of the body to go gray.
Point coloration may also be visible on horses with other dilution genes that act upon a bay base coat. These include:
A dilution gene that produces what looks like point coloration, but from a completely different genetic mechanism is the dominant Dun gene, which dilutes the color of the body coat but not the points, including primitive markings—a dorsal stripe down the back and, less often, horizontal striping on the upper legs. On a bay base coat the dun gene leaves black points, producing a Bay Dun or "Zebra" Dun. But the gene also leaves the points dark when it appears with other base colors. These include the “blue dun” or grullo, which has a black base coat, and the red dun, which has a chestnut base coat.
Similarly, darker coloration at the points is also preserved in horses with the roan gene, a patterning gene, producing a body coat of mingled white and dark hairs, but leaving the points the darker base color in all horses, not just those carrying agouti.
Most other genes that produce spotting patterns or white markings allow point coloration produced by agouti to show except where masked by white depigmentation. There are not always separate names for a pattern over a bay base coat, but one exception is the Bay pinto, sometimes called ”tricoloured”.
All pointed white rabbits of true breeding have red eyes. [6] The pointed white rabbit is created with the ch gene. [7] Its presentation is typified in the Himalayan rabbit breed (the first rabbit breed with a pointed white coat) and in the Californian breed.
Some rabbits that appear to be pointed white lack the red eyes, which indicates they are of different breeding. The following such coat colors are examples of those created, not with the ch gene, but with the cchl, cchd, or cchm gene in conjunction with the e gene:[ citation needed ]
No pointed white rabbit can produce orange pigment; therefore, the points are always either black, blue, chocolate, or lilac.[ citation needed ] The resulting point coloration is sometimes in conjunction with a coat pattern, such as: white agouti, marten, broken, Vienna, or harlequin. (Such coats may not be recognized for showing.)
Breeds of rabbit that include varieties with point coloration include: [8] [9]
The C - Albino locus gene causes dilution of yellow and black coloration, causing Himalayan or Siamese markings depending on the allele is affected.
Point colors in rats include:
There is only one type of guinea pig with a pointed coat. It is called the Himalayan, has either Black (a very dark brown) or Chocolate, tipped on the Ears, Nose, and Feet.
Some breeds of sheep exhibit point coloration.
The Siamese cat is one of the first distinctly recognised breeds of Asian cat. Derived from the Wichianmat landrace, one of several varieties of cats native to Thailand, the original Siamese became one of the most popular breeds in Europe and North America in the 19th century. The carefully refined, more extreme-featured, modern-style Siamese is characterised by blue almond-shaped eyes; a triangular head shape; large ears; an elongated, slender, and muscular body; and various forms of point colouration. Other than colouration, the modern-style Siamese bears little resemblance to the original stock, and the more moderate, traditional, or "old-style" Siamese, with a much rounder head and body, has been re-established by multiple registries as the Thai cat.
A bicolor cat is a cat with white fur combined with fur of some other color, for example solid black, tabby, or colorpointed. There are various patterns of bicolor cat. These range from the Van-patterned through to solid color with a throat locket or medallion. Bicolor coats are found in many cat breeds, as well as being common in domestic longhair and domestic shorthair cats.
Roan is a coat color found in many animals, including horses, cattle, antelope, cat and dogs. It is defined generally as an even mixture of white and pigmented hairs that do not "gray out" or fade as the animal ages. There are a variety of genetic conditions which produce the colors described as "roan" in various species.
Tonkinese is a domestic cat breed produced by crossbreeding between the Siamese and Burmese. Members of the breed are distinguished by a pointed coat pattern in a variety of colors. In addition to the modified coat colors of the "mink" pattern, which is a dilution of the point color, the breed is now being shown in the foundation-like Siamese and Burmese colors: pointed with white and solid overall (sepia).
Cat coat genetics determine the coloration, pattern, length, and texture of feline fur. The variations among cat coats are physical properties and should not be confused with cat breeds. A cat may display the coat of a certain breed without actually being that breed. For example, a Neva Masquerade could wear point coloration, the stereotypical coat of a Siamese.
The Javanese, also known as the ColorpointLonghair in some registries, is a variety of purebred domestic cat.
The Oriental Shorthair is a breed of domestic cat that is developed from and closely related to the Siamese cat. It maintains the modern Siamese head and body type but appears in a wide range of coat colors and patterns. Like the Siamese, Orientals have almond-shaped eyes, a triangular head shape, large ears, and an elongated, slender, and muscular body. Their personalities are also very similar. Orientals are social, intelligent, and many are rather vocal. They often remain playful into adulthood, with many enjoying playing fetch. Despite their slender appearance, they are athletic and can leap into high places. They prefer to live in pairs or groups and also seek human interaction. Unlike the breed's blue-eyed forebear, Orientals are usually green-eyed. The Oriental Longhair differs only with respect to coat length.
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.
Brindle is a coat coloring pattern in animals, particularly dogs, cattle, guinea pigs, cats, and, rarely, horses. It is sometimes described as "tiger-striped", although the brindle pattern is more subtle than that of a tiger's coat.
Ojos Azules was a breed of shorthaired domestic cat with unusual blue or odd eyes caused by a dominant blue eye (DBE) genetic mutation. The breed came in all coat colors, however, only particolors, colorpoints, and intermediate colors with a characteristic white tail tip were permitted. The breed also had a semi-longhaired coat variety, the Ojos Azules Longhair. Due to the lethal side effects of the Ojos Azules gene, breeders stopped working with this blue eye mutation.
The Colorpoint Shorthair is a variety of Siamese cat. The only major registries to recognise them are the Cat Fanciers' Association (CFA) and the World Cat Federation (WCF). This breed was established from breeding American Shorthairs with the Siamese to produce different point colors, beyond the four standard Siamese colors.
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 tabby cat, or simply tabby, is any domestic cat with a distinctive M-shaped marking on their forehead, stripes by their eyes and across their cheeks, along their back, around their legs and tail, and characteristic striped, dotted, lined, flecked, banded, or swirled patterns on the body: neck, shoulders, sides, flanks, chest, and abdomen. The four known distinct patterns, each having a sound genetic explanation, are the mackerel, classic or blotched, ticked, and spotted tabby patterns.
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.
Plush Lop is a breed of domestic rabbit with two varieties: Miniature and Standard. There is also a Canadian Plush Lop breed in development. Similar in appearance, the Velveteen Lop breed is also in development. Miniature Plush Lops were the first to be developed. Devie D'anniballe began creating this breed in 1995 in the United States. She succeeded in developing them by combining the previously existing breeds of Holland Lop, Mini Rex, and Mini Lop. Her aim was to create the perfect pet by retaining the good qualities of these breeds, while "breeding out" all the problems existing in these breeds.
The Balinese is a long-haired breed of domestic cat with Siamese-style point coloration and sapphire-blue eyes. The Balinese is also known as the purebred long-haired Siamese since it originated as a natural mutation of that breed and hence is essentially the same cat but with a medium-length silky coat and a distinctively plumed tail.
The agouti gene, the Agouti-signaling protein (ASIP) is responsible for variations in color in many species. Agouti works with extension to regulate the color of melanin which is produced in hairs. The agouti protein causes red to yellow pheomelanin to be produced, while the competing molecule α-MSH signals production of brown to black eumelanin. In wildtype mice, alternating cycles of agouti and α-MSH production cause agouti coloration. Each hair has bands of yellow which grew during agouti production, and black which grew during α-MSH production. Wildtype mice also have light-colored bellies. The hairs there are a creamy color the whole length because the agouti protein was produced the whole time the hairs were growing.
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