The Cavalier King Charles Spaniel is a small spaniel classed as a toy dog by The Kennel Club and the American Kennel Club. It is one of the most popular breeds in the United Kingdom, where it also originated. Since 2000, it has grown in popularity in the United States and ranks as the 18th most popular pure-breed in the United States (2013 Registration Statistics). It has a silky, smooth coat and commonly a smooth undocked tail.