A look at grullo horses around the world and on a variety of different breeds.
The dun dilution on a black base has a variety of names depending on the breed and location, including black dun, blue dun, grullo/grulla, slate dun and lobo dun. This combination creates a smoky blue color that ranges from light mouse grey to a deep slate grey and is often prized as the rarest of the dun shades. Mane, tail, points and primitive markings remain black.
