The coats of domestic dogs are of two kinds: "double" being widespread in dogs (in addition to wolves) originating from colder climates, built up of the coarse guard hair plus a tender down hair, or "single", with the topcoat only. Breeds may have an occasional "blaze", stripe, or "star" https://social-media-traffic22098.thezenweb.com/the-main-principles-of-dogs-69794114