The Bulldog is a British breed of dog of mastiff type. It may also be known as the English Bulldog or British Bulldog. It is a medium-sized, muscular dog of around . They have large heads with thick folds of skin around the face and shoulders, and a relatively flat face with a protruding lower jaw. The breed has significant health issues as a consequence of breeding for its distinctive appearance, including brachycephalia, hip dysplasia, heat sensitivity, and skin infections. Due to concerns about their quality of life, breeding Bulldogs is illegal in Norway and the Netherlands.
The modern Bulldog was bred as a companion dog from the Old English Bulldog, a now-extinct breed used for bull-baiting, when the sport was outlawed in England under the Cruelty to Animals Act. The Bulldog Club (In England) was formed in 1878, and the Bulldog Club of America was formed in 1890. While often used as a symbol of ferocity and courage, modern Bulldogs are generally friendly, amiable dogs. Bulldogs are now commonly kept as pets; in 2013 it was in twelfth place on a list of the breeds most frequently registered worldwide.
The first reference to the word "Bulldog" is dated 1631 or 1632 in a letter by a man named Preswick Eaton where he writes: "procuer mee two good Bulldogs, and let them be sent by ye first shipp". In 1666, English scientist Christopher Merret applied: "Canis pugnax, a Butchers Bull or Bear Dog", as an entry in his Pinax Rerum Naturalium Britannicarum.
The designation "bull" was applied because of the dog's use in the sport of bull-baiting. This entailed the setting of dogs (after placing wagers on each dog) onto a tethered bull. The dog that grabbed the bull by the nose and pinned it to the ground would be the victor. It was common for a bull to maim or kill several dogs at such an event, either by goring, tossing, or trampling over them. Over the centuries, dogs used for bull-baiting developed the stocky bodies and massive heads and jaws that typify the breed, as well as a ferocious and savage temperament.