The Bullmastiff is an English dog breed of mastiff type and large size with a solid build and a short muzzle. It was originally developed by British gamekeepers in the mid-19th century to guard country estates from poachers. The breed is a cross between the English Mastiff and the now-extinct Old English Bulldog, with a ratio of approximately 60% Mastiff and 40% Bulldog. The Bullmastiff's purpose was to track and overpower poachers without mauling them, earning it the nickname "Gamekeeper's Night