Dun gene

The dun gene is responsible for the coat color seen in wild equines, which was lost in most domestic horses. A dun horse has a lightened color over most of the body while leaving the points darker. Both red and black pigment are affected. A dun horse always has a dark dorsal stripe down the middle of its back, usually has a darker face and legs, and may have transverse striping across the shoulders or horizontal striping on the back of the forelegs. Body color depends on the underlying coat color genetics. A classic "bay dun" is a gray-gold or tan, characterized by a body color ranging from sandy yellow to reddish brown. Duns with a chestnut base may appear a light tan shade, and those with black base coloration are a smoky gray. The mane, tail, legs, and primitive markings are usually the same color seen on non-dun horses. Interactions with other coat color genes can result in a wide variety of possible colors.