An English breed, the Bullmastiff was a result of crossing old Bulldogs and Mastiffs to create a guard to protect against intruders. Activity level varies greatly among individual dogs. As with all mastiff and bull breeds, may be dog selective or dog aggressive. Requires a dedicated owner who can manage a strong, large dog with guard instincts. 100 - 130 lbs. #Bullmastiff #mastiff #large #dog