The bullmastiff and rottweiler mixed breed dog is referred to as a mastweiler, according to Designer Mixes. They can grow up to 130 pounds and are recognized by the Designer Breed Registry and the International Designer Canine Registry.
Mastweiler dogs are mellow and playful and interact with children well. Typically, they are well behaved, low shedding and easy to train. While they don't bark much, they can howl and growl. Mastweilers need exercise daily. They don't run fast, and they tire easily, but they can jump very well. Mastweilers live about 10 years and are not prone to health problems, aside from a predisposition to ear infections.