Every new dog that comes to the house is subjected to growling, snarling and teeth-baring from Popeye. He doesn't attack them, just makes a lot of noise if they deign to come near him. It usually takes him about a week to get over it. We have a record with Pip though--Popeye started playing with him on the first night. Of course, by the next morning, Popeye was back to the snarling and barking.