Roan (horse)

Horses with the roan pattern have an even mixture of white and colored hairs in the coat. The unaffected color on the legs often forms a sharp, inverted "V" above the knee and hock, not seen in other roan-like coat patterns. The nonwhite background coat may be any color, as determined by unrelated genetic factors. Often, the background coat color is used in combination with the word roan to describe the shade of a roan horse's coat, such as bay roan or gold champagne roan, but colloquial terms also are used for some colors. The most common terms for various roan colors are: • Blue roan is loosely applied to any roan with a dark underlying coat that gives it a bluish cast. In the strictest sense, though, "blue roan" is a common synonym for a roan with a black background coat. • Red roan used to include both chestnut and bay roans. In 1999, the American Paint Horse Association changed its coat color descriptions; roans with a chestnut background coat are registered "red roan", while "bay roan" is its own category. The American Quarter Horse Association followed suit in 2003. Previously, the term strawberry roan described the pinkish color of a light chestnut or sorrel roan. While less common, the term lilac roan may be applied to a dark chestnut roan, and honey roan to palominos or the lightest sorrels. • Bay roan replaced red roan as the term for a roan with a bay background coat. Some roan horses have more white hair than others, and even individual horses may look lighter or darker based on the season, and their coats may vary from year to year. While roan is always present at birth, the soft first coat of newborn foals may not show the white hairs well. Some roan horses get darker with age. Generally, roans appear to have more white hair when they have their short summer coats and darker when they have their winter coats. These peculiar tendencies of roans led to the Icelandic word for roan, which translates as "always changing color." Roans have other unusual characteristics. If the skin is damaged by even a very minor scrape, cut, or brand, the coat grows back in solid-colored without any white hairs. These regions of solid-colored coat are called "corn spots" or "corn marks", and can appear even without the horse having had a visible injury. Another trait is reverse dappling; many horses develop rings of hair that appear slightly different-colored, called dapples, which often indicate good health. Usually dapples are darker than the surrounding coat, but on a roan, the dapples are lighter. File:Cornmarks.jpg|Corn marks or corn spots occur where a roan's skin has been damaged. The hair grows back in without any white. File:Bayroanlegs.JPG|The forelegs of this bay roan show the characteristic inverted "V" of dark hair not affected by roan. File:Kabayos03.jpg|This strawberry roan mare, though very light-colored, is still identifiable as a roan by the dark color of her extremities and the brand on her hindquarters, which has grown back in without white hairs. File:Reverse-dapples.jpg|Reverse dapples on a bay roan File:900-231 Herzog Carl Alexander.jpg|This dark bay roan, painted in the 18th century carrying the Duke of Württemberg, has dark extremities and corn spots. ==Terminology==

In the most general sense, the word "roan" refers to any animal with a mixture of white and colored hairs in the coat. Recent research into equine coat color genetics indicates that "true roan" or "classic roan" is distinct from several similar patterns that are collectively called "roaning". Therefore, the existence of other types of roaning conditions not covered by those mentioned here is possible and likely. The patterns identified as "roaning" have particular qualities that can be used to tell them apart from true roan. ==Roan mimics==

Gray vs. roan Roans are sometimes mistaken for grays. However, grays lighten with age, while roans do not. Gray is one of the most common coat colors found in horses, and is found in almost all breeds. The defining characteristic of the gray coat is that it becomes progressively lighter over time. Gray foals may be born any color, and there may be no indication of the future gray coat at birth. Mature grays may retain none of their original coat color, and have a "white" coat, while the color of the skin and eyes is unchanged. The first white hairs are usually seen around the muzzle and eyes. Thoroughbred and Arabian Horses registered as "roan" are often gray, especially chestnuts turning gray. Unlike blue roans, grullos are solid color and appear bluish due to low amounts of pigment in each hair, not interspersed white hairs. Like other dun coat colors, grullos have dark or black primitive markings, always including a stripe down the back. While true roans have an even intermixture of white hairs throughout the body, except the extremities, the white hairs of a rabicano are densest around the base of the tail and the flank. The borders of these white patches can be heavily roaned, and some sabinos can be mistaken for roans. Patches of skin that lie close to the bone, such as on the face and legs, and the point of shoulder and point of hip, do not grow as much white hair. These darker patches are called "varnish marks" and are not found in true roans. Varnish roans can also be distinguished from true roans by the presence of leopard complex characteristics, such as the white sclera, finely striped hooves, and mottled skin around the eyes, muzzle, and genitals. ==Prevalence==

True or classic roan is common in European draft breeds such as the Brabant, Ardennes, Trait Du Nord, Italian Heavy Draft, and Rhenish-German Cold-Blood. British ponies such as Dales, Welsh, Gypsy Cob, Shetland, Connemara, and New Forest ponies may be roan. Icelandic Horses and Miniature Horses may also be roan. The Hokkaido Pony of Japan may also be roan. To date, only one Thoroughbred family has been genetically verified as true roan, and there are no Arabians that are true roan. A small number of Thoroughbred offspring of the brindle-patterned stallion Catch A Bird phenotypically appear to be true roan, and though few of those reproduced, some offspring of his daughter Slip Catch, though registered as bay, have apparently been verified as carrying the roan gene. Nonetheless, most Thoroughbreds and Arabians with roan-like coats are most likely related to graying or rabicano characteristics. Thoroughbred "roans" are described by the Jockey Club as a mixture of white with red or brown hairs, but which researchers identify as chestnuts turning gray. The Arabian Horse Association defines "roan" as an even mixture of white and colored, usually chestnut, hairs, but researchers suggest most animals so classified are probably either rabicano, or have a partially-spotted pattern that results from a dominant white allele. ==Genetics==

Roan is a simple dominant trait symbolized by the Rn allele. Other studies at the time were using progeny ratios to identify potential lethality related to other coat colors, such as "dominant white" and "lethal white", so roan was believed to follow a similar pattern. The belief in "lethal roan" persisted until recently, when homozygous roan stallions with large numbers of offspring - all roan - were satisfactorily identified. In some breeds, homozygous roans can be identified by an indirect DNA marker test. The same blood type marker, albumin, was linked to another blood protein called vitamin D-binding protein. In 1982, a linkage grouping was proposed, including three genes for serum proteins, and three for coat color: tobiano spotting, chestnut, and roan. Research since equine linkage group II was defined has identified the exact location of the tobiano allele and the chestnut allele. The region of the chromosome that harbors the roan gene is homologous to parts of chromosomes in other species that also control coat color, even some similar to roan. The effect of linkage between roan and chestnut is readily observed. If a horse possesses one chromosome with the wildtype nonchestnut allele and the dominant roan allele (E and Rn), while the other chromosome contains the recessive chestnut allele and the recessive nonroan allele (e and rn), it will outwardly appear blue roan, barring the influence of other genes. Normally, the chestnut and roan alleles would be separated during chromosomal crossover, but these two linked genes usually remain together. Such a horse will produce sex cells that are either E/Rn or e/rn. Mated to chestnut nonroan partners (e/rn), the horse would produce primarily blue roans, or chestnut nonroans, but few chestnut roans and few black nonroans. If the recessive e and dominant Rn were on the same chromosome, though, the horse would be expected to produce primarily chestnut roans and nonchestnut nonroans with chestnut, nonroan partners. Cultural/Historical References The Blue Roan was a popular horse kept and ridden by the 10th Sikh Guru, Guru Gobind Singh during the late 17th-early 18th century. He was known as the "Blue Horse Rider" or "One Who Rides the Blue Horse" during his time. == See also ==