Coat (dog)A dog's Coat is its fur. A dog can be double coated—that is, having both a soft undercoat and a coarser topcoat. Some dog breeds are single-coated—having only one type of coat or the other, more often only the topcoat. The state of the coat is considered an indication of the animal's breeding and health. Newfoundland lying next to its combed-out seasonal undercoat. Most dogs