MFT Color Panel

"What Color is Your Horse"?

Part 8

"SPOTS OR WHAT"

This 8th article in our series will deal with the various patterns of white that are often referred to as "spotted." The four identified spotting genes are Tobiano, Frame, Splashed White and Sabino. All four of these genes exist in the foxtrot breed. For many years only two types of spotted horses were recognized; Tobiano (still called Tobiano) and Overo (now further divided into Frame, Splashed White, and Sabino). The Tobianos were pretty self-evident and any spotted horses that did not have the criteria to qualify as a Tobiano were referred to as Overo. Many breeds and breeders still recognize only the two old classifications of spotted horses – Tobiano and Overo.

Today, spotted genes are broken down into four known spotting patterns (this DOES NOT include the appaloosa spotting patterns) and all four of these genes are considered dominant – although they can be so minimally expressed that identification is tricky. What was once called Overo has now been broken down into three genetic patterns; Frame, Splashed White and Sabino.

When a spotting gene is added, color expression is blocked on some areas which creates the white portions of the pattern.

Spotted horses come in all base colors (sorrel, black, bay) and can be passed in addition to dilutions (Cream, Dun, Champagne) or modifiers (Grey, Roan). Any type of spotting gene is in addition to the base color genes of the horse. A horse may possess one, two, three or even all four spotting genes at one time and such a horse could pass any one or combination of the genes to their offspring. For example you could have a horse that is a black/white Tobiano that also carries the Sabino and Grey genes. This horse would probably appear solid Grey as an adult, but could easily reproduce spots.

Tobiano - Body ANY solid color with white spots and typically all four legs are white. Spots are usually regular and rounded with even borders and usually cross over the back somewhere between the ears and the tail. The Tobiano gene tends to leave the head dark (blazes are not uncommon) and it is also common for Tobianos to have white in the tail. The Tobiano gene can be minimal expressed where the indications are high white stockings and a small spot in the mane, tail or on the body. A maximum Tobiano may be mostly white with only a few colored body areas – but would probably still retain the dark head The commonly seen and easily identified Tobiano pattern is a 50-50 mix of dark and white, commonly with a white tail and white in the mane.

There is a test for the Tobiano gene; this test identifies a marker commonly seen with the Tobiano gene, not the gene itself, so it is not 100% accurate. The test is commonly used to determine if a Tobiano horse is homozygous for the Tobiano spotting gene (2 doses of the gene and will therefore always pass on one copy of it and the offspring will always be Tobiano spotted) or heterozygous (1 dose of the gene and 50% of the offspring should be spotted).

Current studies show that the Tobiano gene is closely linked to either black or red. For example if you have a stallion that has the Tobiano gene linked to black, he will pass the black gene and the Tobiano gene together. Assuming he is heterozygous for black (can produce both black and red foals) then when bred to sorrel mares he could produce foals that are black/white Tobiano, bay/white Tobiano and solid sorrel (NO White). If the stallion had the Tobiano gene linked to red, he would only pass the Tobiano gene with red.

If a black and white horse is homozygous for Tobiano, that does not mean that the black is homozygous as well. A horse can be homozygous for Tobiano, but have one red and one black gene. In this case he can produce black/white, bay/white (if the mare carries the agouti gene that restricts black to the points) and red/white foals. A red and white homozygous Tobiano will always produce red and white foals when bred to sorrel mares (other color mares could contribute other colors to produce a variety of colors with the spots).

Splashed White - White spotting that usually comes UP from the legs, looking as though the animal has splashed paint up from below. Maximum expressed Splashed Whites almost always have white legs. White does not usually cross the back, and bald faces and blue eyes are common.

Minimum and Moderate Splash markings

Splash can be minimal, i.e. a horse that has a bottom heavy blaze, one that begins in the middle of the face and gets heavier and wider as it goes downward, or maybe only a white nose that looks as though the horse has a huge snip. Many times the Splash becomes LOUDLY evident when 2 minimal Splashes are bred together. Since there is no test for this gene, one has to go by breeding records and offspring, plus appearance. Deafness has also been associated with some families of Splashed White horses, but many Splash horses have no hearing problems.

Splashed White can be very minimal, and only express itself loudly when two Splashed White horses are bred together. Splashed white does not typically create the white ticking or "roaning" appearance throughout the body as Sabino often does.

Frame - Solid color topline, dark legs. White patches, usually irregular, are often on the sides of the body and appear as though "framed" by the dark areas. Can have blue or brown eyes. Most frames have extensive facial white. Many frames have a solid color on the upper lip, even when a wide blaze is present. This is called a "mustache." Many frames also have blue eyes, even when a colored patch surrounds the eyes. Frame is a very unique and striking pattern when in its maximum form. Minimal frames can be deceptive, where a horse can carry frame but only have a minimal amount of white, such as a star. Frame in the homozygous state is always lethal; this is known as Lethal White Overo syndrome. Foals are born completely white, and die within a few days of birth.

If there is a chance that a horse may be Frame, or has frame ancestors, it is HIGHLY suggested that the horse be tested before breeding. The test is simple hair test and is available through the University of California Genetics Testing Laboratory as mentioned in our last article. This test is very important, since breeding a Frame horse to another Frame will produce a Lethal White foal 25% of the time. By testing all horses with any Frame ancestry for the gene, breeding Frame to Frame can easily be avoided.

Sabino - White lacey patches, especially on the legs, face and under jaw, and belly. Scattered white hairs throughout the coat that appears roan-like but do not have the dark face and legs of the true roan. Usually having high white jagged stockings that are higher on the front of the leg than the rear of that leg. Body, mane and tail may be any color although many Sabinos have a somewhat lighter mane and tail than their body color. Sabino itself does not cause blue eyes, but blue eyes may result when other genes are also present.

Minimal and Maximum Sabino markings

Minimal Sabinos can go unnoticed with maybe only a small chin spot or one rather odd short stocking as illustrated by the photo on the left. Maximums can be quite "loud" in appearance and may appear completely white. These should NOT be confused with Lethal White foals (homozygous Frame). Maximum Sabinos do NOT have the problems associated with the Frame gene. Usually those that appear completely white will have some tiny dark spots on their otherwise pink skin ("tea leaf" markings), or in the coat (small uneven spots of mixed dark and white hair that are easily missed). Dominant White (W gene) another gene that can produce a solid white coat, has not been documented within the fox-trot breed to our knowledge, although we welcome possible horses for evaluation. Currently there is no test for the Sabino gene (or genes). It is theorized that Sabino may be "polygenic", meaning there may be several genes effecting the amount and level of expression of the Sabino spotting pattern

Multiple Spotting Genes - When a horse carries multiple spotting genes it becomes very difficult to determine which genes the horse actually has.

Sabino and Tobiano can both make the legs white, a Splash horse may have a bald face, but a Sabino or Frame can also have a completely white face. In many cases the only way to know which genes are carried by a horse that appears to carry multiple spotted genes is by studying his ancestry or looking at the progeny.

Tovero - Many horses have more than one spotting gene; a horse that is primarily Tobiano in appearance can have additional spotting genes.

These horses are referred to as Tovero, meaning Tobiano, plus any one (or more) of the three genes referred to as Overo. Tobianos almost always have 4 white socks, but adding the Frame gene seems to cause one or more leg to stay dark.

Of the above genes, Tobiano and Frame may be tested for through the use of a DNA based hair test. It should be noted that that DNA hair color tests from UC Davis are different from DNA tests conducted through Stormont lab, the latter are the only DNA tests that are entered into the MFTHBA books.

The cost at UCDavis is $50.00 for one color test, $25.00 for each additional test of the same hair sample. More information can be obtained on the Internet by visiting http://www.vgl.ucdavis.edu/horse/coatclr.htm or by contacting Veterinary Genetics Laboratory, University of California, One Shields Ave, Davis, Ca. 995-616-8744.

As always, the Color Panel welcomes your pictures and questions. Thank you for your time and interest in our series of articles. If you have any questions, or pictures that you would like an opinion on, they may be sent by e-mail to the Colorpanel@mfthba.com, or mailed directly to the Color Panel, at P. O. Box 1027, Ava, Missouri, 65608 . There is no cost for this opinion and you are not required to abide by it, it is for information purposes only. Any color changes that anyone may wish to make to their horses registration papers after receiving the Color Panel’s opinion would be a the expense of the owner. Happy Fox-Trotting!!