The dun gene changes where the pigment is most concentrated on the hair shaft. This causes some hairs to look much lighter then normal. All dun horses will have a clear dark stripe down the spine called a dorsal stripe. If a horse is missing this they are not duns. Duns will also have dark legs that may include horizontal stripes. Other markings that duns can have include darker faces, dark ear tips sometimes with a secondary stripe, darker marks on withers and a whole range of mottling and smokey markings. Dun can be difficult at times to detect and sometimes even experts can misidentify it. On a dun horse the dark areas always show the “true” color of the horse while the light areas are the diluted color.
The dun gene is located but no paper has yet been released on it’s exact location.
Located on chromosome 8.