bulldog, breed of thick-set nonsporting dog developed in the British Isles many centuries ago. It stands from 13 to 15 in. (33-38.1 cm) high at the shoulder and weighs from 40 to 50 lb (18.1-22.7 kg). Its short, straight, flat-lying coat is a glossy brindle, white, red, or fawn in color. The low-slung body, broad chest, large skull, and undershot jaw of the bulldog give it an appearance of stubbornness and defiance, two qualities necessary to its original role as a bullbaiter and pit fighter. These "sports" also required a high degree of ferocity, but after 1835, when such contests were made illegal, viciousness and intractability were progressively eliminated from the breed. Today the bulldog makes a gentle, devoted companion and pet. See dog.