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.