Dun is a dominant gene that dilutes the color of body hair, leaving the points and head unaffected. Dun horses also show "primitive markings" consisting of a dark dorsal stripe, leg barring, shoulder stripes and concentric marks on the forehead (spiderwebbing, cobwebbing). The dorsal stripe appears to be a consistent feature of dun horses while the other "primitive marks" vary and may not all be present, or visible. The effect of the Dun gene on the base colors of chestnut, bay and black produces horses with shades that range from apricot, golden, dark gray, olive, and many, more subtle, variations. Dun is inherited independently of other coat color genes and can occur in combination with any other genes that modify the base colors. Dun dilution is present in many breeds of horses including Quarter Horses, Paints, Appaloosas, Icelandic Horses, Norwegian Fjords, Paso Finos, Peruvian Pasos and several of the pony breeds. The names assigned to the various Dun colors vary by breed. For additional information on Dun, D. Phillip Sponenberg's Equine Color Genetics has descriptions, names and photos for these colors.
Dun Zygosity TestingThe specific mutation that causes Dun has not yet been identified, and there is no direct test for the gene. VGL has identified DNA markers associated with Dun that can be used to determine if a horse has the Dun gene and how many copies. The Dun Zygosity analysis is not a direct DNA test, so the following additional materials should be included to provide the most complete analysis:
If a sample from a parent is not provided, the analysis may not be conclusive for the presence/absence of the Dun gene.
Note: The Dun zygosity test is not being offered at this time for PREs, Andalusians and Lusitanos. The marker association with the Dun gene in these breeds is still under research. Owners of Dun horses from these breeds interested in helping with the research should contact Customer Service.
For forms, pricing and mailing information please see the Submission Instructions.