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Roan is a coat color found in many animals, including
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million y ...
s,
cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...
,
antelope The term antelope is used to refer to many species of even-toed ruminant that are indigenous to various regions in Africa and Eurasia. Antelope comprise a wastebasket taxon defined as any of numerous Old World grazing and browsing hoofed mammals ...
,
cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...
and
dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...
s. It is defined generally as an even mixture of white and pigmented hairs that do not "gray out" or fade as the animal ages."''roan'', ''a''. and ''n.1''"
Oxford English Dictionary The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a com ...
. 2nd edition 1989. OED Online.
Oxford University Press Oxford University Press (OUP) is the university press of the University of Oxford. It is the largest university press in the world, and its printing history dates back to the 1480s. Having been officially granted the legal right to print books ...
. 3 June 2008. .
There are a variety of genetic conditions which produce the colors described as "roan" in various species.


Roan horses

A horse with intermixed white and colored hairs of any color is usually called a roan. However, such mixtures, which can appear superficially similar, are caused by a number of separate genetic factors. Identifiable types of roans include true or classic roan,
varnish roan Varnish roan describes a horse with coloration similar to roan, but with some changes in color over the years, though not to the extreme of a gray. This type of roaning only occurs in conjunction with the Leopard complex. Varnish roans are born w ...
, and
rabicano Rabicano, sometimes called white ticking, is a horse coat color characterized by limited roaning in a specific pattern: its most minimal form is expressed by white hairs at the top of a horse's tail, often is expressed by additional intersperse ...
, though other currently unknown factors may be responsible for ambiguous "roaning."
Gray Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed o ...
horses, which become lighter as they age until their hair coat is nearly completely white, may be confused with roans when they are young.
Duns Duns may refer to: * Duns, Scottish Borders, a town in Berwickshire, Scotland ** Duns railway station ** Duns F.C., a football club ** Duns RFC, a rugby football club ** Battle of Duns, an engagement fought in 1372 * Duns Scotus ( 1265/66–1308 ...
, which are solid-colored horses affected by the dun dilution factor on their bodies but with darker points, are also sometimes confused with roans, but they do not have the intermixed white and colored hairs of a roan. Horses with the classic or true roan pattern may be any base color which is intermingled with unpigmented white hairs on the body. Except for white markings under the control of other genes, the head, mane, tail, and lower legs are dark. Roan is a simple dominant trait symbolized by the ''Rn''
allele An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...
. The University of California, Davis School of Veterinary Medicine's genetics services have developed a
DNA test Genetic testing, also known as DNA testing, is used to identify changes in DNA sequence or chromosome structure. Genetic testing can also include measuring the results of genetic changes, such as RNA analysis as an output of gene expression, or ...
that uses
genetic marker A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species. It can be described as a variation (which may arise due to mutation or alteration in the genomic loci) that can be ...
s to indirectly determine the number of ''Rn'' or ''rn'' alleles a horse has. The
mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mi ...
responsible for true roan has not yet been identified exactly, but been assigned to equine
chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
21 (ECA21) in the KIT sequence. The overall effect is that of a silver or lightened appearance to the affected part of the coat. Descriptions of roan coat colors are as follows: * Red Roan or strawberry roan describes true or classic roan on a
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 ...
base coat. The mane and tail remain red or have only a few white hairs, while the body ranges from nearly chestnut to pinkish. Geneticists prefer the term "chestnut roan," but this term is not in common use. * Bay Roan is true roan on a bay coat. The particular shade depends on the underlying shade of bay; but the mane, tail, and lower legs are black, and the reddish body is intermingled with white hairs. The head is usually red. Formerly, bay roans were lumped together with chestnut roans and both called "red roans." * Blue Roan is true roan on a
black Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white have o ...
coat. The mane, tail, head, and legs remain black, while the body takes on a grayish or bluish appearance. Blue roans are sometimes mistaken for grays or
grullo Grulla or grullo, also called blue dun, gray dun or mouse dun, is a color of horses in the dun family, characterized by tan-gray or mouse-colored hairs on the body, often with shoulder and dorsal stripes and black barring on the lower legs. In t ...
s. However, Grays fade with age, while roans do not; and grullos are blue
duns Duns may refer to: * Duns, Scottish Borders, a town in Berwickshire, Scotland ** Duns railway station ** Duns F.C., a football club ** Duns RFC, a rugby football club ** Battle of Duns, an engagement fought in 1372 * Duns Scotus ( 1265/66–1308 ...
and possess dun markings but not intermingled white hairs. Any other coat color may also be affected by roaning. Few combinations have the same unique terminology applied to the common roan colors, although palomino roans are sometimes called ''honey roans''.


Roan mimics

A
varnish roan Varnish roan describes a horse with coloration similar to roan, but with some changes in color over the years, though not to the extreme of a gray. This type of roaning only occurs in conjunction with the Leopard complex. Varnish roans are born w ...
is not a true roan; it is actually one of the
leopard complex 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. ...
coat patterns associated with
Appaloosa The Appaloosa is an American horse breed best known for its colorful spotted coat pattern. There is a wide range of body types within the breed, stemming from the influence of multiple breeds of horses throughout its history. Each horse's colo ...
,
Knabstrupper The Knabstrupper or Knabstrup is a Danish breed of warmblood horse. It is principally a riding horse, but is also used as a harness horse and as a circus animal. It is broadly similar to the Frederiksborger, but often has a spotted coat. In ...
,
Noriker horse The Noriker horse, also called the Norico-Pinzgauer and historically known as the Pinzgauer horse, is a moderately heavy Austrian draught horse breed. The Noriker is considered indigenous to the central Alpine region of Europe, and is belie ...
and related breeds.
Rabicano Rabicano, sometimes called white ticking, is a horse coat color characterized by limited roaning in a specific pattern: its most minimal form is expressed by white hairs at the top of a horse's tail, often is expressed by additional intersperse ...
is a white pattern that falls into the category of ''roaning'' or scattered white hairs, the genetics of which are not yet fully understood. Sometimes called ''ticking'', rabicano is common even in breeds that do not have true or classic roan, including
Arabians The Arabs (singular: Arab; singular ar, عَرَبِيٌّ, DIN 31635: , , plural ar, عَرَب, DIN 31635: , Arabic pronunciation: ), also known as the Arab people, are an ethnic group mainly inhabiting the Arab world in Western Asia, No ...
and
Thoroughbred The Thoroughbred is a horse breed best known for its use in horse racing. Although the word ''thoroughbred'' is sometimes used to refer to any breed of purebred horse, it technically refers only to the Thoroughbred breed. Thoroughbreds are c ...
s. This pattern usually takes the form of scattered white hairs around the junction of the stifle and flank, and peculiar rings of white hairs near the base of the tail. This trait is called a ''coon tail'' or ''skunk tail''. Some forms of sabino, which is a
pinto Pinto is a Portuguese language, Portuguese, Spanish language, Spanish, Sephardi Jews, Jewish (Sephardic), and Italian language, Italian surname. It is a high-frequency surname in all List of countries and territories where Portuguese is an officia ...
pattern, have roaning along the edges of other white spots or markings A roan horse may not fit into any of the traditional categories as there is much still to be learned about the genetics of roan. The existence of other types of roaning conditions not covered by those mentioned here is possible and likely.


Roan dogs

The genetics behind roan dogs are still unclear, and at present candidate genes have been ruled out. There remains a great deal of ambiguity in terminology regarding mottled dogs, which are called ''roan'', ''ticked'', ''mottled'' and ''belton'' depending on the context. The roan or ticked color is described in many breeds of
gundog Gun dogs, or bird dogs, are types of hunting dogs developed to assist hunters in finding and retrieving game, usually quail, dove, or duck. Gun dogs are divided into three primary types: retrievers, flushing dogs, and pointing breeds. Types ...
s such as
English Cocker Spaniel The English Cocker Spaniel is a breed of gun dog. It is noteworthy for producing one of the most varied numbers of pups in a litter among all dog breeds. The English Cocker Spaniel is an active, good-natured, sporting dog standing well up at ...
s,
American Cocker Spaniel The American Cocker Spaniel is a breed of sporting dog. It is a spaniel type dog that is closely related to the English Cocker Spaniel; the two breeds diverged during the 20th century due to differing breed standards in the US and the UK. In th ...
s,
English Springer Spaniel The English Springer is a breed of gun dog in the Spaniel group traditionally used for flushing and retrieving game. It is an affectionate, excitable breed with a typical lifespan of twelve to fourteen years. They are very similar to the Wels ...
s, Field Spaniels and Brittanys,
German Longhaired Pointer The German Longhaired Pointer (GLP) is a dog breed, breed of dog. Developed in Germany, it is used as a multipurpose gundog. It is closely related to its cousins, the German Shorthaired Pointer (GSP), the German Wirehaired Pointer (GWP) and the L ...
s,
German Shorthaired Pointer The German Shorthaired Pointer (GSP) is a medium to large sized breed of pointing dog developed in the 19th century in Germany for hunting. A versatile hunting breed, being an all-purpose gun dog suitable for both land and water, they are streaml ...
s, Bracchi Italiani, Spinoni Italiani, Lagotti Romagnoli,
English Setter The English Setter is a medium-size breed of dog. It is part of the setter group, which includes the red Irish Setters, Irish Red and White Setters, and black-and-tan Gordon Setters. The mainly white body coat is of medium length with long si ...
s,
Small Münsterländer The Small Münsterländer (also SM or Kleiner Münsterländer) is a versatile hunting-pointing- retrieving dog breed that reached its current form in the area around Münster, Germany. The Large Münsterländer is from the same area, but was ...
as well as
Border Collie The Border Collie is a Scottish breed of herding dog of medium size. Widely considered to be the most intelligent dog breed, they are descended from landrace sheepdogs once found all over the British Isles, but became standardised in the Angl ...
s and many other breeds. In dogs, roan manifests itself only in unpigmented areas, the presence and shape of which are determined by other genes. This is in stark contrast to true roan horses and roan cattle, which are roan only in pigmented regions of their coat and may have white markings. Instead, dogs with roaning or ticking are born with clear, open white markings which begin to fill in with flecking in the subsequent weeks and continue to darken with age. Most breed standards use the terms "ticked" and "roan" interchangeably, with the former referring to clearly defined flecks on a white background and the latter to flecks so closely spaced that the mixture appears even. The terminology that relates the underlying coat color with the roan modifier is often breed-specific, but most standards call a black dog with roaning ''blue''. In breeds that are characterized by roaning and ticking such as the Large Munsterlander, clear white-marked individuals may be called ''plated''. The term ''belton'' is reserved for
English Setter The English Setter is a medium-size breed of dog. It is part of the setter group, which includes the red Irish Setters, Irish Red and White Setters, and black-and-tan Gordon Setters. The mainly white body coat is of medium length with long si ...
s. In 1957, Little suggested that roan and ticking were controlled separately, and postulated that roan may have been homologous to "silvered" coat in mice. This condition in mice is actually homologous to
merle Merle may refer to: People *Merle (given name), a given name used by both men and women *Merle (surname), a surname of French origin Others *Merle (dog coat), a pattern in dogs’ coats *Merle (grape), another name for the wine grape Merlot *Akaf ...
, which might be described by some as "roan." In 2007, the gene responsible for roan cattle (KITLG) was refuted as a possible cause of roan in dogs. Neither roan nor ticking, if they are independently caused, appear to be recessive.


Roan cattle

Breeds of
cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...
known for roans are the
Belgian Blue The Belgian Blue (french: 'Blanc-Bleu Belge', nl, 'Belgisch Witblauw', both literally meaning "Belgian White-Blue") is a breed of beef cattle from Belgium. It may also be known as the , or nl, dikbil, label=none (literally "fat buttocks" in ...
and
Shorthorn The Shorthorn breed of cattle originated in the North East of England in the late eighteenth century. The breed was developed as dual-purpose, suitable for both dairy and beef production; however, certain blood lines within the breed always emp ...
. Among the former, coat color may be solid black, solid white, or blue roan; the latter may be solid red, solid white, or red roan. Belgian Blues also typically exhibit spotting patterns, which are genetically separate from roan. As a result, most roan cows exhibit blotches of clearly colored and clearly white hair, with roan patches. Some "cryptic" roan cattle appear solid, but upon close inspection reveal a small roan patch. Roan cattle cannot "breed true" but breeding white cattle to a solid mate will always yield a roan calf. The white color typical of Charolais and
White Park White Park may refer to: ;Places: * White Park Bay, in County Antrim, Northern Ireland, UK * White Park, County Antrim, a townland in Northern Ireland, UK * White Park (Concord, New Hampshire), a public park in Concord, New Hampshire, US * White Pa ...
breeds is not related to roan.Seitz, Schmutz, Thue & Buchanan: "Although both Charolais and White Park could be classified as white phenotypically, all typed r/r homozygous colored) at the MGF locus. Alternative loci must be responsible for these forms of white, as has been suggested previously (Olson and William 1982)." Roan in Shorthorns and Belgian Blues is controlled by the ''mast cell growth factor'' (MGF)
gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
, also called the ''steel locus'', on bovine
chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
5. Part of the
KIT ligand Stem cell factor (also known as SCF, KIT-ligand, KL, or steel factor) is a cytokine that binds to the c-KIT receptor ( CD117). SCF can exist both as a transmembrane protein and a soluble protein. This cytokine plays an important role in hematopoi ...
, this region is involved in many cell differentiation processes. Mast cell growth factor promotes
pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...
production by
pigment cells Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and heart. M ...
, and without it, skin and hair cells lack pigment. With two functional MGF genes (
homozygous Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mo ...
dominant), cattle are fully pigmented; without any functional MGF genes (homozygous
recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...
), they are white. MGF-controlled roan occurs when cattle possess one functional and one non-functional MGF gene (
heterozygous Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mo ...
), resulting in a roughly even mixture of white regions and colored regions. The reproductive condition "White Heifer Disease," associated with the MGF gene, is characterized by
homozygous Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mo ...
MGF-white heifers with incomplete reproductive tracts.


Roan guinea pigs

The roan coloration of
guinea pig The guinea pig or domestic guinea pig (''Cavia porcellus''), also known as the cavy or domestic cavy (), is a species of rodent belonging to the genus ''Cavia'' in the family Caviidae. Breeders tend to use the word ''cavy'' to describe the ani ...
s is linked to microphthalmia. The allele that controls roaning in guinea pigs is
incompletely dominant In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...
: an animal with one copy of the allele will have varying amounts of white hair scattered through its coat, particularly on the back and sides. About 25% of guinea pigs born to two roans are ''completely white'', having two copies of the "roan" allele, and may have a constellation of
deformities A deformity, dysmorphism, or dysmorphic feature is a major abnormality of an organism that makes a part of the body appear or function differently than how it is supposed to. Causes Deformity can be caused by a variety of factors: *Arthritis an ...
associated with "lethal white syndrome", although this condition has no relation to overo
lethal white syndrome Lethal white syndrome (LWS), also called overo lethal white syndrome (OLWS), lethal white overo (LWO), and overo lethal white foal syndrome (OLWFS), is an autosomal genetic disorder most prevalent in the American Paint Horse. Affected foals are bo ...
in horses or double merle syndrome in dogs. Lethal white guinea pigs ("lethals") often die shortly after birth or at
weaning Weaning is the process of gradually introducing an infant human or another mammal to what will be its adult diet while withdrawing the supply of its mother's milk. The process takes place only in mammals, as only mammals produce milk. The infan ...
age, but with hand-feeding and regular dental care, lethals may live 2 to 3 years. Some lethals have reportedly lived to 6 or 7 years. It is worth noting that, unlike anophthalmic
hamster Hamsters are rodents (order Rodentia) belonging to the subfamily Cricetinae, which contains 19 species classified in seven genera.Fox, Sue. 2006. ''Hamsters''. T.F.H. Publications Inc. They have become established as popular small pets. The b ...
s, guinea pigs with the condition are not
sterile Sterile or sterility may refer to: *Asepsis, a state of being free from biological contaminants * Sterile (archaeology), a sediment deposit which contains no evidence of human activity *Sterilization (microbiology), any process that eliminates or ...
, but females may be unable to deliver live young. Lethal white syndrome symptoms include: * Partial or complete
blindness Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment ...
* Partial or complete
deafness Deafness has varying definitions in cultural and medical contexts. In medical contexts, the meaning of deafness is hearing loss that precludes a person from understanding spoken language, an audiological condition. In this context it is written ...
* Microphthalmia or
anophthalmia Anophthalmia, (Greek: ἀνόφθαλμος, "without eye"), is the medical term for the absence of one or both eyes. Both the globe (human eye) and the ocular tissue are missing from the orbit. The absence of the eye will cause a small bony orbi ...
* Unpigmented eyes * Missing or deformed
incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, whe ...
s * Deformed
molars The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...
* Elongated
tooth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...
roots * Malabsorption in the small intestine, due in some cases to lack of
intestinal villi Intestinal villi (singular: villus) are small, finger-like projections that extend into the lumen of the small intestine. Each villus is approximately 0.5–1.6 mm in length (in humans), and has many microvilli projecting from the enterocyte ...
* Increased susceptibility to
illness A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that ar ...
Roan coloration is not to be confused with the "
magpie Magpies are birds of the Corvidae family. Like other members of their family, they are widely considered to be intelligent creatures. The Eurasian magpie, for instance, is thought to rank among the world's most intelligent creatures, and is one ...
" coloration of guinea pigs, which is a brindle color lacking red pigment due to the "
chinchilla Chinchillas are either of two species (''Chinchilla chinchilla'' and ''Chinchilla lanigera'') of crepuscular rodents of the parvorder Caviomorpha. They are slightly larger and more robust than ground squirrels, and are native to the Andes mount ...
"
allele An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...
, an allele also responsible for self white and silver agouti coloration.


See also

*
Equine 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 ...
*
Equine coat color genetics 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. The "base" colors of the horse are determined by the Extension locus, which in recessive form (e ...


References


External links


Photos of roan English Cockers
{{DEFAULTSORT:Roan Horse coat colors Dogs Cattle