This question is for Chetco (you other guys can answer too though)!?

Chetco, you seem so smart, always out-doing me in answering questions, well i've got a question for you, i have a puppy, he is 11mos old, and a chow something mix. we are not 100% sure of what he's mixed with, but we think it might be pit, because of his facial shape and demeanor. He is totally adorable, and absolutely sweet, but there is one big problem. we also have two japanese shih-tzu's (purebred), and he bullies them. I mean he treats them bad, i know how dogs act when they are gaining dominance, (i have four male dogs), but he don't do that, he takes it to a whole nother level, the level of being an absoulute bully, he'd get total submission from one of the dogs, and he'll still grab them by the neck (or sometimes collar) and drag 'em round the yard. he acts as if it is a game, but the other dogs don't enjoy it, not at all. and i am afraid that he might accidentally hurt one of my smaller dogs. what should i do?!!!