Oh my!! How scary!! We had a similar incident when I was a teenager and we were at a park playing horse shoes. We had a toy poodle named Peppy who was really my mother's baby. She didn't know he was there and she swung her arm back and hit him with the horseshoe. He was knocked silly too and taken to the vet but had no permanent consequences.
I am glad to hear it ounds like Bowzer is feeling better.
How big a yorkie is he?