we have 120lb pit and we trained him by shaking a can when he was bad. Just a monster can full of pennys or something metal. That works well, and using conditioning you train him to tolerate people. When he barks or get aggressive you shake the can as you get on them until he stops. Eventually they learn. We never hit the dog, I think there was one time where he bit Daniel and Dan wacked him one, never happened again. Now if you just shake the can a little he ducks his head and runs outside.