Dun is the only coat colour dilution for which there is, as yet, no genetic testing available. Dr. Gus Cothran of Texas A&M is conducting a study into the dun gene, and is requesting blood samples from dun horses. Here’s what’s needed:
1) A sample consists of 2 large (7 or 10 mL) yellow or purple top vacutainer tubes. They do not need to be kept refrigerated.
2) With your samples, please include a pedigree with colors. He mainly needs the color of the sample horse and its parents.
3) Label tubes and pedigrees with the horses name (registered name is suggested) and your name.
4) I would include your email address/phone number, too, as you may then be given the results of test results if/when he gets to the point of developing a test.
E. Gus Cothran, Ph.D.
Equine Genetics Lab.
Texas A&M University
College Station, TX 77843-4458
Not sure if your horse is dun or not? Dun Central Station is a great resource; although it focuses on Morgans, colour genetics are the same across all horse breeds. There’s a “field guide” to identifying dun characteristics, and a page of great photos showing horses which some think are dun, but are not. Buckskin and dun are NOT the same thing, and a dorsal stripe by itself means little. Arabs and Thoroughbreds do not have dun in their gene pools (the only dilution gene TBs are known to carry is cream, and even that’s pretty rare) so you can rule them out. Remember too that a horse must have at least one dun parent in order to be dun; it doesn’t skip generations, although it may be hidden by other factors, such as grey.
I’m thinking a tutorial on horse colours might be in order…