The Cavalier King Charles Spaniel is a small breed of Spaniel-type dog and is classed as a toy dog by most kennel clubs. It is one of the most popular breeds in the United Kingdom. Since 2000 it has been growing in popularity in the United States. It is a smaller breed of spaniel and Cavalier adults are often the same size as adolescent dogs of other spaniel breeds. It has a silky coat and commonly an undocked tail.