The dun gene is a dilution gene that affects the red and black pigments in a horse’s coat color. The dun gene lightens most of the body while the original mane, tail, feet and markings remain shaded with the undiluted base color. A dun horse always has a dark dorsal stripe down the center of the back, usually has a darker face and legs, and may have horizontal stripes on the shoulders or horizontal stripes on the back of the front legs. The body color depends on the genetics of the underlying coat color. A classic “Bay Dun” is a golden gray or tan characterized by a sandy yellow to reddish brown body color. Chestnut-based duns may appear tan, and black-based duns are steel gray. Manes, tails, primitive markings and other dark areas are usually shaded with the undiluted base color. The dun gene can interact with all other coat color alleles.