The King Charles Spaniel (known as the English Toy Spaniel in the U.S. an Canada) is a breed of small dog in the spaniel category. The Cavalier King Charles Spaniel is a different breed, although it is sometimes referred to as a King Charles Spaniel. The Cavalier is more closely related to Cocker Spaniels in appearance, while the King Charles Spaniel is more closely related to the Pug.