We have a large Rottweiler dog who serves as an effective way to discourage missionary boys wearing white shirts and ties, door to door sales people, and uninvited visitors in the middle of the night. We have signs on our gates and front door. By the way Brody has been known to open the front door to receive guests if we do not lock the door with the deadbolt. He knows how to open doors with latches and knobs. Brody is a very good dog.