Equine coat color

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This article is about basic information on equine coat colors. For details on color genetics, see Equine coat color genetics.
Mustangs on the range, showing a wide range of coat colors

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 different coat color from that with which they were born. Most white markings are present at birth, and the underlying skin color of a horse does not change, absent disease.

The basic outline of equine coat color genetics has largely been resolved, and DNA tests to determine the likelihood that a horse will have offspring of a given color have been developed for some colors. Discussion, research, and even controversy continues about some of the details, particularly those surrounding spotting patterns, color sub-shades such as "sooty" or "flaxen", and markings.

Basic coat colors[edit]

Bay (left) and chestnut (right) mustangs.

Genetically, all horses start out as either chestnut, called "red" by geneticists, represented by the absence of the extension gene ("e"); or black based on the presence of the extension gene ("E"). Therefore, red ("ee") and black ("EE" or "Ee") are the two base colors.[1][2] The Bay color is expressed when the common genetic modifier, the Agouti gene works on the Black. The vast range of all other coat colors are created by additional genes' action upon one of these three coat colors.

Statistically, the most commonly seen horse color phenotypes are identified by the following terms:

A dapple gray

Other coat colors[edit]

A black horse
A buckskin
This photograph shows the difference between a Pinto horse and an Appaloosa. The Pinto is on the left, the Appaloosa on the right.
A palomino
Variations of pinto color patterning include:
  • Piebald: a black and white spotting pattern (term more commonly used in the UK than the USA)
  • Skewbald: a spotting pattern of white and any other color other than black, or a spotting pattern of white and two other colors, which may include black. (term more commonly used in the UK than the USA).
  • 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". Sometimes Sabino (below) is also classified in the overo family.
  • Sabino: Often confused with roan or rabicano, a slight spotting pattern 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
  • 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.
  • Tovero: spotting pattern that is a mix of tobiano and overo coloration, such as blue eyes on a dark head. May also refer to horses with Tobiano coloring that carry a recessive overo gene.
Left to right: A young gray (with few white hairs), a chestnut, and a bay roan
Silver dapple horses

Other color modifiers[edit]

Markings and other unique identifiers[edit]

Main article: Horse markings
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. Horses may also be uniquely identified by an unusual eye color, whorls, brands and chestnuts.

Color breeds[edit]

Main article: Color breed

Registries have opened that accept horses (and sometimes ponies and mules) of almost any breed or type, with color either the only requirement for registration or the primary criterion. These are called "color breeds". Unlike "true" horse breeds, there are few if any unique physical characteristics required, nor is the stud book limited to only certain breeds or offspring of previously registered horses. As a general rule, the color also does not always breed on (in some cases, due to genetic improbability), and offspring without the stated color are usually not eligible for recording with the color breed registry. The best-known color breed registries are for buckskins, palominos, and pintos.

Some "true" breeds also have color that usually breeds on as well as distinctive physical characteristics and a limited stud book. These horses are true breeds that are said to have a "color preference". They are not color breeds, and include the Friesian horse (must be uniformly black for mainstream registration), the Appaloosa (Leopard or other Leopard complex patterns) and the American Paint Horse. In some breeds, though not all, offspring of animals registered in these stud books can also be registered, sometimes with restrictions, even if they do not have the desired color.

See also[edit]

Notes[edit]

  1. ^ http://www.thehorse.com/articles/31651/equine-coat-color-genetics-101
  2. ^ Marklund, L.; M. Johansson Moller; K. Sandberg; L. Andersson (1996). "A missense mutation in the gene for melanocyte-stimulating hormone receptor (MC1R) is associated with the chestnut coat color in horses". Mammalian Genome 7 (12): 895–899. doi:10.1007/s003359900264. PMID 8995760. 
  3. ^ a b "General Glossary". American Quarter Horse Association. Archived from the original on August 24, 2010. Retrieved August 25, 2012. 
  4. ^ Metallinos, DL; Bowling AT; Rine J (June 1998). "A missense mutation in the endothelin-B receptor gene is associated with Lethal White Foal Syndrome: an equine version of Hirschsprung Disease". Mammalian Genome (New York: Springer New York) 9 (6): 426–31. doi:10.1007/s003359900790. PMID 9585428. Retrieved 2008-09-04. 
  5. ^ Castle, William E. (1948). "The Abc of Color Inheritance in Horses". Genetics 33 (1): 22–35. PMC 1209395. PMID 17247268. "No true albino mutation of the color gene is known among horses, though several varieties of white horse are popularly known as albinos." 

References[edit]

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