The English Cocker Spaniel is a breed of gun dog. It is noteworthy for producing one of the most varied numbers of pups in a litter among all dog breeds. The English Cocker Spaniel is an active, good-natured, sporting dog standing well up at the withers and compactly built. There are "field" or "working" cockers and "house" cockers. It is one of several varieties of spaniel and is the foundation of its American cousin, the American Cocker Spaniel. The English Cocker is closer to the working-dog form of the Field Spaniel and the English Springer Spaniel. English Cocker Spaniels are also known as the "Merry Spaniel" due to their constantly wagging tail. Outside the US, the breed is usually known simply as the Cocker Spaniel, as is the American Cocker Spaniel within the US. The OED states that the word cocker is derived from the fact the breed was used to flush woodcocks.