The coats of domestic dogs are of two kinds: "double" currently being common in dogs (along with wolves) originating from colder climates, built up of the coarse guard hair along with a smooth down hair, or "one", Using the topcoat only. Breeds may have an occasional "blaze", stripe, or "star" https://jaredrxzba.madmouseblog.com/12227860/not-known-facts-about-dogs