I don't personally have a Shih Tzu, but my office neighbor at work does and she brings her to work with her every day like I do Scooter. She's his favorite playmate. Since your Yorkie is about 9 pounds, I don't think there would be a problem. We have to watch my friend's Shih Tzu around Scooter so that they don't get too rough, because she's 9 pounds and Scooter is only 4 pounds (he can completely disappear underneath her). Anyway, I think your baby would be fine.
