The Shetland Sheepdog, often known as the Sheltie, is a breed of herding dog that originated in the Shetland Islands of Scotland. The original name was Shetland Collie, but this caused controversy among the Rough Collie breeders of the time, so the breed's name was formally changed. This hard-working small dog is intelligent, vocal, excitable and willing to please. This breed was formally recognized by The Kennel Club (UK) in 1909. Shelties have a double coat, which means that they have two layers of fur that make up their coat. The long, rough guard hairs lie on top of a thick, soft undercoat. It is hard to tell, without actually breeding, whether a dog is white-factored or not, though dogs with white going up the stifle (the front of the hind leg) are usually assumed to be white-factored. Breeding two white-factored dogs can result in color-headed whites — Shelties with colored heads (sable, tricolor, bi-black, or blue or sable merle) and white bodies.