I have an 8 year old Shih Tzu and I have to say.. Chester (our Bully)..is the most laid back dog. It's our shih tzu (Milo) that will nip at his face and growl at him. I have never heard Chester growl and he is over 10 months old. When they are playing, Chester can't really keep up with Milo - Chester is too bulky and slow, but if he does catch him somehow, he won't do anything but nudge him with his head. Chester is a "gentle giant".