Bulldog,  also known as the British Bulldog or English Bulldog, is a medium-sized dog breed. Bulldog,  also known as the British Bulldog or English Bulldog, is a medium-sized dog breed. It is a muscular, hefty dog with a wrinkled face and a distinctive pushed-in nose. The Kennel Club (UK), the American Kennel Club (US), and the United Kennel Club (US) oversee breeding records. 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.