I like the "call the vet" advice. It is always better to be safe.
On the other hand, remember that Yorkies are terriers and were bred to hunt rodents. I do hope that everyone has thanked their Yorkies for the good hunting. The only house cat we had was a fierce hunter. I had to "thank" her regularly for bring "fresh" meat to me. Several times the "fresh meat" was still alive and was doctored and released
