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White Hair Patterns TOBIANO - The white pattern Tobiano is the most common pinto pattern in horses. It is often characterized by the horse having four white stockings, white extending up the shoulder and over the wither and sometimes neck, white on the croup and sometimes the top of the tail, and at times the white will extend over the length of the horse’s back. Tobiano patterns have crisp, clean edges and often horses that are Tobiano do not have much white on their face. Tobiano is represented by “T” or “To” and can be found in breeds such as American Paint, American Saddlebred, Mustang, Oldenburg, Swedish Warmblood, Gypsy Vanner, etc. Tobiano is a dominant gene and can sometimes be expressed slightly different in homozygous form. Heterozygous Tobiano’s (Tt) will have a 50% chance of producing Tobiano patterned foals. Homozygous Tobianos (TT) will always produce Tobiano foals. Homozygous tobianos can sometimes express a little roaning from the edges of the white, and “cat tracks” or “ink spots”. These are small patches of the horse’s body color within the white areas. However not all Homozygous Tobiano horses have these characteristics. Tt: Heterozygous Tobiano. 50% of foals will be tobiano, while the rest will be solid. TT: Homozygous Tobiano. All Foals will be tobiano colored. 
RABICANO - Rabicano is a type of Roaning pattern but is genetically separate from Roan. There is no test for Rabicano, but it is a very distinct white hair pattern. Typical characteristics of Rabicanos are roaning in the flank area, and white bars or horizontal stripes at the base of the tail. Horses with extensive Rabicano Roaning will have roan hairs that seem to wrap around the barrel of the horse, and sometimes cause vertical “Striping” of the roaned hairs along the sides.  They will also usually have a “skunk tail”; white hairs at the base of the tail that reach down both sides leaving a strip of colored hair in the middle of the tail. Rabicano can be found in Arabians, Throughbreds, Quarter Horses, Warmbloods, etc.
COLOUR - PG 3
FRAME OVERO - Frame overo is represented by “O” and is most commonly found in American Paint horses. It is also known as Lethal White Overo. This is because in homozygous form (OO) the Overo pattern produces an all white or nearly all white foal, however the foal will soon die or need to be euthanized, therefore the gene is “lethal” when homozygous. This is because the colon is not properly developed resulting in the foal being unable to pass waste and will eventually become impacted and colic if not humanely euthanized. Heterozygous frame overos (nO) however have no health complications and it is in this form that it manifests itself as a pinto pattern. Overo’s rarely have white extending over their top line, most of the white is in patches on the sides of the horse and on the side of the neck giving it a “Frame” of the base color around the white. Overos often have bald faces, dark tails and sometimes blue eyes. Usually an overo will not have white on their legs, although sometimes they can have the odd sock or stocking. The edges of the white are usually jagged and rough looking and can give a “patchy” appearance. nO: Heterozygous Tobiano. 50% of offpring will be Overos. Solid colored foals may still carry the overo gene. OO: Homozgyous Overo. Foal will be completely or nearly all white. All foals will have Lethal White Overo Syndrome and will have to be humanely euthanized.
SPLASHED WHITE - This pattern is often classified as an “overo” pattern by most registries; however it is separate from the overo gene. There are three known versions of Splash: SW1, SW2, and SW3. Common characteristics of Splashed White horses are four socks or stockings of relatively equal length, “Apron Face” or bald face and blue eyes and sometimes white starting at the bottom of the horse’s tail extending up. Most have described the gene as looking like the horse had been dipped in paint from the feet up. The edges of this pattern are crisp and clean like the Tobinao pinto pattern. Splash can be found in Trakheners, Morgans, American Paints, Quarter Horses, Miniatures, Gypsy Vanner, etc. Splashed White is linked with congenital deafness, although not all Splashed white horses are deaf. SW1 - This version of Splashed White is the most common and expresses itself the least out of the three types. A horse that is heterozygous SW1 (nSW1) can have minimal expression of the gene such as four socks and a blaze, or it may have four stockings and a blaze, apron face or bald face and sometimes blue or partially blue eyes. A Homozygous SW1 (SW1SW1) may have white extending all up the legs to the belly, sometimes seeming to wrap around the barrel of the horse, a bald face with the white extending to the jowls and blue eyes, or it may look like the horse has been “dipped in paint”. Whether the Splash gene is a dominant or an incomplete dominant gene is up for discussion as there has been documentation of horses that have no white markings on them at all carrying one SW1 gene. nSW1: Heterozygous Splash-1. Horse may or may not have white markings and blue eyes. 50% of offspring will receive a Splash-1 gene. SW1SW1: Homozygous Splash-1. Horse will usually exhibit extensive white markings and blue eyes. All offspring will be Splash-1 carriers. SW2 & SW3 - There seems to be no visual difference between the three versions of Splash, however SW2 and SW3 have only been found in certain bloodlines of Quarter Horses and Paints. There is also speculation that SW2 and SW3 in homozygous form is lethal resulting in a non-viable embryo. nSW2: Heterozygous Splash-2. Horse may or may not have white markings and blue eyes. 50% of offspring will receive a Splash-2 gene. SW2SW2: Homozygous Splash-2. Thought to be lethal in this form which results in a non-viable embryo. No live horses have been documented homozygous Splash-2. nSW3: Heterozygous Splash-3. Horse may or may not have white markings and blue eyes. 50% of offspring will receive a Splash-3 gene. SW3SW3: Homozygous Splash-3. Thought to be lethal in this form which results in a non-viable embryo. No live horses have been documented homozygous Splash-3. Horses may also carry two different splash genes resulting in a homozygous splash horse. For example, a horse can carry both a SW1 gene and an SW2 gene and all offspring will be either SW1 or SW2 carriers. SW1SW2: Homozygous Splash. Horse will usually exhibit extensive white markings and blue eyes. 50% of offspring will receive a SW1 gene, and 50% will receive a SW2 gene. All foals will be splash carriers. SW1SW3: Homozygous Splash. Horse will usually exhibit extensive white markings and blue eyes. 50% of offspring will receive a SW1 gene, and 50% will receive a SW3 gene. All foals will be splash carriers. SW2SW3: Homozygous Splash. No horse has been recorded carrying both SW2 and SW3 genes so there is no way of knowing if these two genes combined result in a non-viable embryo.
SABINO - Sabino is another pattern that is often described as “overo” by registries and like Splashed White it is genetically separate from Frame Overo. Sabino horses can be similar to Splashed White horses in that they usually have four white stockings and belly spots, however, a horse that is carrying a Sabino gene will have very jagged, roaned out edges and sometimes white flecking or spotting around the edges. Sabinos will also usually have a white lower lip and/or chin and sometimes white extending under the jowls.  Sabino can be found in Thoroughbreds, Arabians, Shires, Clydesdales, Paint and Quarter Horses, etc.  There is a test for Sabino (designated Sb1) however there have been horses that exhibit patterns very similar to Sabino and tested negative Sb1 so there is debate on whether there is more than one type of Sabino, just as there is more than one type of Splashed White, which have yet to be found. Sabino is an incomplete dominant gene. This means that, like Cream and Pearl, it expresses itself differently in heterozygous form (nSb1) and homozygous form (Sb1Sb1). In heterozygous form the horse will have the recognizable white legs, belly spots, rough, roaned edges on the white and flecking or spotting near the edges. In homozygous form the horse will be nearly all white with a few tuffs of colored hair along the topline or in the mane. This is also called a Maximum Sabino.   nSb1: Heterozygous Sabino. Horse will have white legs, belly spots and roaned edges on white markings. 50% of offspring will receive a Sabino gene. Sb1Sb1: Homozygous Sabino. Horses are usually nearly all white. All offspring will be Sabino.
DOMINANT WHITE - Dominant White is exactly as it sounds; a Dominant gene that produces a horse with a white pattern or is completely white. Dominant White is NOT an albino. Albino horses do not exist. Dominant White is a White pattern that can manifest itself as looking very similar to Sabino, with white legs, white running up the underside of the horse, rough edges, etc. Or it can make the horse appear to be completely white. These horses will still have dark brown eyes unless the horse is carrying another gene that would change its eye color (such as Splash, Cream, or Champagne). Dominant White horses base coat color is not White, however if the horse is completely white it will be impossible to know what the base color is without testing. Dominant white is thought to be lethal in homozygous form, producing a non-viable embryo. There are 20 known versions of Dominant White: W1: Most horses are completely white; sometimes have small amounts of colored hair that will whiten over time W2: Horses are completely white; this mutation has been found in Thoroughbreds W3: Most horses have some coloration; this mutation has been found in Arabians W4: Horses are completely white, or have small amounts of color that whitens over time W5: Can range from Sabino-like patterns to completely white; this mutation has been found in Thoroughbreds. W6: This mutation was seen in only one Thoroughbred who was nearly all white W7: This mutation was seen in only one Thoroughbred who was nearly all white W8: This mutation was seen in an Icelandic Pony that had markings resembling Sabino W9: This mutation was seen in one Holsteiner who was completely white W10: Can range from small amounts of white on the legs to nearly completely white; this mutation has been found in Quarter Horses W11: This mutation was seen in a German Draft bloodline; horses were nearly completely white W12: No known confirmation of this mutation has been found but it was thought that a young Thoroughbred colt carried this mutation. He passed away at a young age. W13: This mutation was seen in one Quarter Horse/Peruvian Paso cross who was completely white W14: This mutation was seen in a Thoroughbred who was completely White W15: This mutation has been seen in Arabians who expressed Sabino-like patterns W16: This mutation has been seen in Oldenburgs who were completely white W17: This mutation has been seen in Japanese Draft horses who were completely white W18: This mutation has been seen in Swiss Warmbloods who express Sabino-like patterns W19: This mutation was seen in a Partbred Arabian who was about 50% white W20: This mutation has been seen in Thoroughbreds who have simple leg and face markings.
ROAN - Roan is a gene that evenly distributes white hair throughout the body of the horse, excluding the head (although sometimes the roan hairs can spread to the jowls) and legs. Roan is a dominant gene and is represented by “Rn”. There is no visual difference between Heterozygous Roan (Rnrn) and Homozygous Roan (RnRn). It used to be thought that Homozygous Roans were lethal and were aborted during early pregnancy, however this has since been disproved as there are documented Homozygous Roan horses with no known health issues. Roan is separate from Grey in that the horse does not loose pigment over time. There are varying degrees of roan, from just a few scattered white hairs along the body to a horse that’s body is nearly white with a colored head, mane & tail and legs.   Some examples of colors that include roan are: Blue Roan (Black + Roan); this is called “Blue” roan because the mixture of white and black hairs in the coat gives the horse a “blue” look. Red Roan (Chestnut + Roan); this is sometimes called “strawberry roan” as the mixture of white and red hairs can give the horse a “pink” appearance. Bay Roan (Bay + Roan); Bay roans can sometimes look “purple” in certain light depending on the base color of the body. This is usually with darker bays.
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