Hair Shaft Changes Causing Colour Effects
This page is under construction. It will contain extensive information on the horse colours Dun and Satin. We are looking for pictures of horses that are representative of the various shades in each colour. For a photo to be chosen the horse must be clean, unclipped, and standing in a conformation type stance that best shows off the colour. We have provided information on these colours in an unfinished format for your initial learning enjoyment, with more to follow as the page evolves.
Dun (D): A dominant gene that affects both black and red pigment. Colour ranges from light yellowish, through tan, sandy
yellow, grey-gold, steel-grey and reddish-brown, generally with a flat yellow cast to the coat. Dun is associated with primitive markings; a dark
dorsal stripe is always present and typically the mane, tail, face and legs are darker than the body like a Buckskin (E-A-CRcr). Face cobwebbing and
horizontal stripes on the back of the front legs are common but can be faint. Least commonly seen is shoulder blade striping and fish boning (barb like
lines coming out of the dorsal stripe). Dun creates its look of diluted colour because the pigment in each hair shaft is actually on only one side
so there is a translucent side. Ancestrally Dun is the first dilution gene found in horses.
Red base: referred to as red dun
Black base: referred to as blue dun, mouse dun, grulla, black dun
Bay base: referred to as classic dun, bay dun, zebra dun
Genetics: The Dun dilution gene, TBX3 (T- box 3) is located on chromosome 8 and has 8 exons.
NCBI: Gene ID: 100056019; Location: Chr 8 NC_009151.2 (18208462…18221192); Length: 12,731 bp
Ensembl: Gene ID: ENSECAG 00000012861; Location: 18209492…18218248; Length: 8,757 bp
Breeds: Quarter Horse, Paint Horse, Appaloosa, Icelandic Horse, Norwegian Fjord, Paso Fino, Peruvian Paso, many pony breeds, etc
Akhal-Teke Metallic/ Satin: A brilliant metallic looking coat that sparkles like metal in the sun, not just “shiny” or “glossy”. The Akhal-Teke Association of America has the best explanation of the change to the hair structure: “the opaque core is reduced in size and in some areas may be absent altogether. The transparent part of the hair (the medulla) takes up this space and acts like a light pipe, bending light through one side of the hair and reflecting it out the other side, often with a golden cast.” The shine is different than what occurs with champagne or pearl horses, and the Akhal-Teke breed does not have these dilutions. Heartridge Performance Horses in Sherwood Park, Alberta, Canada have a buckskin Appendix Quarter Horse broodmare named King Bar Razzle (2005) who seems to have the same metallic hair coat as an Akhal-Teke. Her foals are born with a “pinkish” sheen to the foal coat and then shed to the metallic shine. At this time the claim is unable to be scientifically validated. Similar mutations have been found in cats, rats, hamsters, guinea pigs, and mice so far and are referred to as Satin or Glitter (cats).
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