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A bay-and-white, or skewbald, tobiano-patterned horse
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A black-and-white, or piebald, tobiano-patterned miniature horse
Tobiano horses

Tobiano is a spotted color pattern commonly seen in pinto horses, produced by a dominant gene. The tobiano gene produces white-haired, pink-skinned patches on a base coat color. The coloration is almost always present from birth and does not change throughout the horse's lifetime, unless the horse also carries the gray gene. It is a dominant gene, so any tobiano horse must have at least one parent who carries the tobiano gene.


Other spotting patterns seen in pinto horses include frame overo, splashed white and sabino. In the United Kingdom, tobianos are frequently referred to as "coloured" or as "pied": piebald if black and white, skewbald if white and any base color other than black. Sometimes "painted" is also used. [1] Bay and white tobiano horses are also referred to as tricoloured.


Shah Jahan on a piebald tobiano. "Shah Jahan on Horseback", Folio from the Shah Jahan Album MET COVERr5 98M.jpg
Shah Jahan on a piebald tobiano.

Tobiano traits generally include the following:

The word tobiano is of Portuguese origin, first used in Brazil to describe horses brought to Farroupilha's War by Brigadeiro Rafael Tobias de Aguiar. (HOUAISS, A. VILLAR, M. de S. Dicionário Houaiss da Língua Portuguesa. Rio de Janeiro: Objetiva, 2001. p. 2727). [1]


Tobiano is a dominant gene, designated TO. [2] Therefore, one parent must be a tobiano for the pattern to occur, and the coat pattern will occur with a single copy of the tobiano gene present (i.e. the horse is heterozygous for tobiano). Furthermore, when a horse is homozygous for tobiano coloring, all of that horse's offspring will be spotted, with only a few exceptions: if either parent passes the dominant gray gene to the foal, then its spots will be visible while it is young, but will gradually become lighter until finally, as the gray gene acts upon all coat colors, the entire horse's coat fades. In the case of horses that are born tobiano but turn gray, the skin will retain pigmented and unpigmented skin beneath its hair that may produce "ghost" markings. A homozygous tobiano that also carries a dilution gene, such as a pinto with a base color of palomino or buckskin, may not reliably produce spotted offspring if bred to another horse with a dilution gene, as a double-dilution may "wash out" the base color.

The tobiano gene itself is not linked to lethal white syndrome. However, some tobiano horses may be carriers of the gene if they have overo ancestors, and thus have produced affected offspring when bred to another horse that is also a carrier. [3] In some cases, a horse which carries both tobiano and overo genetics may display white markings that combine both patterns, and are referred to as toveros.

DNA testing

Tobiano occurs due to a chromosomal inversion on ECA3 where the gene order of a section spanning nearly one-third of the chromosome "flipped" during a genetic recombination event. It is thought to be an ancient gene among domestic horses, about 3500 years old, and is widely distributed across many breeds in the world. [1]

Genetic testing is available to help determine the presence of the tobiano gene. Originally, there was no direct test for tobiano; the early tobiano tests utilized six genetic markers, including a marker on the KIT gene on horse chromosome 3, which were closely linked to tobiano but could not be used to officially prove homozygosity. [4] After some years of research from the University of Kentucky, in 2008 the chromosomal inversion that affects regulatory regions of the KIT gene was discovered. [5] This inversion was finally mapped for genetic testing and is now offered by several laboratories. [1] Testing is most often intended to determine homozygosity, but is also useful in cases where a horse has grayed, or if a horse has an unexplained loss of pigmentation.

See also

Related Research Articles

<span class="mw-page-title-main">Roan (color)</span>

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.

<span class="mw-page-title-main">American Paint Horse</span> American breed of horse

The American Paint Horse is a breed of horse that combines both the conformational characteristics of a western stock horse with a pinto spotting pattern of white and dark coat colors. Developed from a base of spotted horses with Quarter Horse and Thoroughbred bloodlines, the American Paint Horse Association (APHA) breed registry is now one of the largest in North America. The registry allows some non-spotted animals to be registered as "Solid Paint Bred" and considers the American Paint Horse to be a horse breed with distinct characteristics, not merely a color breed.

<span class="mw-page-title-main">Lethal white syndrome</span> Medical condition

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 born after the full 11-month gestation and externally appear normal, though they have all-white or nearly all-white coats and blue eyes. However, internally, these foals have a nonfunctioning colon. Within a few hours, signs of colic appear; affected foals die within a few days. Because the death is often painful, such foals are often humanely euthanized once identified. The disease is particularly devastating because foals are born seemingly healthy after being carried to full term.

<span class="mw-page-title-main">Piebald</span> Animal with white markings on a darker coat

A piebald or pied animal is one that has a pattern of unpigmented spots (white) on a pigmented background of hair, feathers or scales. Thus a piebald black and white dog is a black dog with white spots. The animal's skin under the white background is not pigmented.

<span class="mw-page-title-main">Skewbald</span>

Skewbald is a colour pattern of horses. A skewbald horse has a coat made up of white patches on a non-black base coat, such as chestnut, bay, or any colour besides black coat. Skewbald horses which are bay and white are sometimes called tricoloured. These horses usually have pink skin under white markings and dark skin under non-white areas. Other than colour, it is similar in appearance to the piebald pattern. Some animals also exhibit colouration of the irises of the eye that match the surrounding skin. The underlying genetic cause is related to a condition known as leucism. The term is also used to describe spotting patterns in various other animals, such as goats.

<span class="mw-page-title-main">Tricoloured horse</span>

Tri-coloured refers to a horse with three different coat colours in a pinto spotting pattern of large white and dark patches, usually bay and white. This colouring is also commonly called skewbald. In modern usage in British English, skewbald and piebald horses are collectively referred to as coloured, while in North American English, the term pinto is used to describe the colour pattern.

<span class="mw-page-title-main">Bay (horse)</span> Hair coat color of horses

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.

<span class="mw-page-title-main">Gray horse</span> Coat color characterized by progressive depigmentation of the colored hairs of the coat

A gray horse has a coat color characterized by progressive depigmentation of the colored hairs of the coat. Most gray horses have black skin and dark eyes; unlike some equine dilution genes and some other genes that lead to depigmentation, gray does not affect skin or eye color. Gray horses may be born any base color, depending on other color genes present. White hairs begin to appear at or shortly after birth and become progressively more prevalent as the horse ages as white hairs become intermingled with hairs of other colors. Graying can occur at different rates—very quickly on one horse and very slowly on another. As adults, most gray horses eventually become completely white, though some retain intermixed light and dark hairs.

<span class="mw-page-title-main">Equine coat color genetics</span> Genetics behind the equine coat color

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) creates a solid chestnut or "red" coat. When dominant (E), a horse is black. The next gene that strongly affects coat color, Agouti, when present on a horse dominant for E, limits the black color to the points, creating a shade known as Bay that is so common and dominant in horses that it is informally grouped as a "base" coat color.

<span class="mw-page-title-main">Pinto horse</span> Horse with coat color that consists of large patches

A pinto horse has a coat color that consists of large patches of white and any other color. The distinction between "pinto" and "solid" can be tenuous, as so-called "solid" horses frequently have areas of white hair. Various cultures throughout history appear to have selectively bred for pinto patterns.

<span class="mw-page-title-main">Overo</span> Group of colouration patters of horses

Overo refers to several genetically unrelated pinto coloration patterns of white-over-dark body markings in horses, and is a term used by the American Paint Horse Association to classify a set of pinto patterns that are not tobiano. Overo is a Spanish word, originally meaning "like an egg". The most common usage refers to frame overo, but splashed white and sabino are also considered "overo". A horse with both tobiano and overo patterns is called tovero.

<span class="mw-page-title-main">Tovero</span>

The Tovero coloration is a mix of tobiano and overo colorations in Pinto horses and American Paint Horses. The genetics of pinto coloration are not always fully understood, and some horses have a combination of patterns that does not fit cleanly in either category.

<span class="mw-page-title-main">Equine coat color</span> Horse coat colors and markings

Horses exhibit a diverse array of coat colors and distinctive markings. A specialized vocabulary has evolved to describe them.

<span class="mw-page-title-main">White horse</span>

A white horse is born predominantly white and stays white throughout its life. A white horse has mostly pink skin under its hair coat, and may have brown, blue, or hazel eyes. "True white" horses, especially those that carry one of the dominant white (W) genes, are rare. Most horses that are commonly referred to as "white" are actually "gray" horses whose hair coats are completely white. Gray horses may be born of any color and their hairs gradually turn white as time goes by and take on a white appearance. Nearly all gray horses have dark skin, except under any white markings present at birth. Skin color is the most common method for an observer to distinguish between mature white and gray horses.

<span class="mw-page-title-main">Black horse</span> Horse coat color

Black is a hair coat color of horses in which the entire hair coat is black. Black is a relatively uncommon coat color, and it is not uncommon to mistake dark chestnuts or bays for black.

<span class="mw-page-title-main">Sabino horse</span> Color pattern in horses

Sabino describes a distinct pattern of white spotting in horses. In general, Sabino patterning is visually recognized by roaning or irregular edges of white markings, belly spots, white extending past the eyes or onto the chin, white above the knees or hocks, and "splash" or "lacy" marks anywhere on the body. Some sabinos have patches of roan patterning on part of the body, especially the barrel and flanks. Some sabinos may have a dark leg or two, but many have four white legs. Sabino patterns may range from slightly bold face or leg white markings—as little as white on the chin or lower lip—to horses that are fully white.

<span class="mw-page-title-main">Rabicano</span> Horse coat colors and patterns, such as white ticking or roaning

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 interspersed white hairs seen first at the flank, then other parts of the body radiating out from the flank, where the white hairs will be most pronounced. Rabicano is distinct from true roan, which causes evenly interspersed white hairs throughout the body, except for solid-colored head and legs.

A cropout, crop-out or crop out is a horse with body spots, including pinto or leopard complex spotting, or "high white" horse markings, with a sire and dam who both appeared to have been solid-colored. There are several variations in the definition, depending on the breed registry involved. There are multiple genetic reasons that may cause a horse to be a cropout. Sometimes solid-colored horses throw cropouts because some spotting patterns are recessive genes that are not necessarily expressed unless the relevant allele is inherited from both parents. Other times a gene may be a dominant or incomplete dominant but so minimally expressed that the horse looks solid but can pass flashy color on to its offspring.

<span class="mw-page-title-main">Dominant white</span> Horse coat color and its genetics

Dominant white (W) is a group of genetically related coat color alleles on the KIT gene of the horse, best known for producing an all-white coat, but also able to produce various forms of white spotting, as well as bold white markings. Prior to the discovery of the W alllelic series, many of these patterns were described by the term sabino, which is still used by some breed registries.

<span class="mw-page-title-main">Roan (horse)</span> Horse coat color pattern characterized by an even mixture of colored and white hairs on the body

Roan is a horse coat color pattern characterized by an even mixture of colored and white hairs on the body, while the head and "points"—lower legs, mane, and tail—are mostly solid-colored. Horses with roan coats have white hairs evenly intermingled throughout any other color. The head, legs, mane, and tail have fewer scattered white hairs or none at all. The roan pattern is dominantly inherited, and is found in many horse breeds. While the specific mutation responsible for roan has not been exactly identified, a DNA test can determine zygosity for roan in several breeds. True roan is always present at birth, though it may be hard to see until after the foal coat sheds out. The coat may lighten or darken from winter to summer, but unlike the gray coat color, which also begins with intermixed white and colored hairs, roans do not become progressively lighter in color as they age. The silvering effect of mixed white and colored hairs can create coats that look bluish or pinkish.


  1. 1 2 3 4 Bailey, Ernest; Brooks, Samantha A. (2013). Horse genetics (2. ed.). Wallingford: CABI. pp. 56–59. ISBN   9781780643298.
  2. "Introduction to Coat Color Genetics" from Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis. Web Site accessed January 12, 2008
  3. Paul D. Vrotsos RVT and Elizabeth M. Santschi DVM. University of Minnesota Genetics Group. "Stalking the Lethal White Syndrome" Archived 2008-10-26 at the Wayback Machine . Paint Horse Journal. July 1998.
  4. "Tobiano" from Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis. Web Site accessed January 13, 2008
  5. "DNA Testing for Tobiano" from Animal Genetics Incorporated

Further reading