horse coat color Horses exhibit a diverse array of coat colors and distinctive markings. A specialized vocabulary has evolved to describe them. While most horses remain the same color throughout life, a few, over the course of several years, will develop a diff ...

that has the sooty trait is characterized by black or darker hairs mixed into a horse's coat, typically concentrated along the topline of the horse and less prevalent on the underparts. Sootiness is presumed to be an inherited trait, though the precise genetic mechanism, or series of mechanisms, is not well understood. In most cases, sooty coats exhibit pronounced

countershading Countershading, or Thayer's law, is a method of camouflage in which an animal's coloration is darker on the top or upper side and lighter on the underside of the body. This pattern is found in many species of mammals, reptiles, birds, fish, and ...

; the dorsal region is darker than the ventral region. However, some forms seem to produce darker lower parts. The "false dorsal" or "countershading dorsal" can mimic the dorsal stripe associated with

dun A dun is an ancient or medieval fort. In Ireland and Britain it is mainly a kind of hillfort and also a kind of Atlantic roundhouse. Etymology The term comes from Irish language, Irish ''dún'' or Scottish Gaelic ''dùn'' (meaning "fort"), ...

horses and is associated with the sooty trait. The most extensive expression of sooty produces a dark, often-dappled cast oriented down from the topline. Many horses with the sooty trait have a darker mask on the bony parts of the face. It was once thought that the sooty trait was responsible for turning

chestnut The chestnuts are the deciduous trees and shrubs in the genus ''Castanea'', in the beech family Fagaceae. They are native to temperate regions of the Northern Hemisphere. The name also refers to the edible nuts they produce. The unrelat ...

into liver chestnut, however it is not known to evenly darken the coat. The sooty trait is responsible for many dark

bays A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a gulf, sea, sound, or bight. A cove is a small, circular bay with a narr ...

and has a particularly pronounced effect on

buckskins Buckskins are clothing, usually consisting of a jacket and leggings, made from buckskin, a soft sueded leather from the hide of deer. Buckskins are often trimmed with a fringe – originally a functional detail, to allow the garment to shed ...

and

palomino 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. Genetically, the palomino color is created by a single allele of a dilution gene called t ...

s. Although this trait has been called the "sooty gene", similar coat-darkening conditions studied in mice suggest that coat darkening is a

polygenic A polygene is a member of a group of non-epistatic genes that interact additively to influence a phenotypic trait, thus contributing to multiple-gene inheritance (polygenic inheritance, multigenic inheritance, quantitative inheritance), a type of ...

trait. Just as in horses, the degree of sootiness in mice varies widely; some individuals have darker hairs that form a

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

line, while others have extensive sootiness throughout.Silvers 1979. " llow mice are often characterized...by variable degrees of sootiness. In some animals the sootiness is confined to a mid-dorsal streak, in others this streak is wider, covering the entire back and sometimes the flanks, so that only the belly is phenotypically "yellow." This situation is due to the admixture of hairs possessing significant amounts of eumelanin to the yellow fur." A statistical analysis of 1369 offspring of five Franches-Montagnes stallions indicated that darker shades of chestnut and bay might follow a recessive mode of inheritance. Horses without any sooty effect are termed "clear-coated."

References

{{Equine coat colors Horse coat colors

See also

References