The Bullmastiff with a proper temperament should not be aggressive and guard all the time. The lovely thing about this breed is that the dogs have a "live and let live" attitude. Unless something is wrong, you should not see these dogs in their working mode. The Bullmastiff is perfectly content to watch TV with the children, sleep on his back with his feet in the air, play with family members or other family dogs, or just find his favorite spot to lie down where he can get a clear view of the goings-on in the house or yard. The Bullmastiff can go from lying perfectly still, completely at ease, to moving full speed in a matter of seconds. If something needs his attention he'll be there. The Bullmastiff is very discriminating. He can tell who is legitimately on your property and who is trespassing. He knows the difference between someone you let into your house and someone trying to come in through a window or over a fence
Our Bullmastiffs are loyal and loving. They will give everything for those they love. In return it is only fair for them to receive respect and love from those he/she lives with.