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 40–55 lb (18–25 kg). 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 brachycephaly, hip dysplasia, heat sensitivity, and skin infections. Due to concerns about their quality of life, breeding Bulldogs is illegal in Norway and the Netherlands.

A mastiff is a large and powerful type of dog. Mastiffs are among the largest dogs, and typically have a short coat, a long low-set tail and large feet; the skull is large and bulky, the muzzle broad and short (brachycephalic) and the ears drooping and pendant-shaped. European and Asian records dating back 3,000 years show dogs of the mastiff type. Mastiffs have historically been guard dogs, protecting homes and property, although throughout history they have been used as hunting dogs, war dogs and for blood sports, such as fighting each other and other animals, including bulls, bears and even lions.