field spaniel, breed of medium-sized sporting dog developed in England from crosses between cocker spaniels and Sussex spaniels. It stands about 18 in. (45.7 cm) high at the shoulder and weighs about 40 lb (18.1 kg). Its medium-length, silky coat is flat or wavy and usually solid black in color, although it may be liver, golden liver, or mahogany red. Its tail is docked. Although the field spaniel is relatively slow, it has great endurance and can be trained as a bird hunter. It is not a common breed in the United States. See dog.