Personally, I would never do it. Some people will tell you they have no problem and that it's just the way they're raised, but it is more than that. You cannot erase ancestry and genetics and while I have nothing against these dogs, I would never risk my yorkie. The worry just isn't worth it. I have read too many horror stories over the years and some have involved yorkies. It is illegal to own one in our county. Have you read the latest thread:
http://www.yorkietalk.com/forums/mem...n-one-day.html
Then there is another thread where a member's sister's dog was attacked by a pit. It is a decision only you can make. You can never leave them out alone together and is that really fair to your little one? It's your decision.