Don't know what he did. Was chasing his ball. Next time I threw it, his rear end wouldn't run correctly, he just tried hopping along. He's walking very stiff on the left hind in particular. Bearing weight on both okay. I'm giving him couple days of rest and then seeing where we are. He took a small divot out of a toe too, so I think he really stoved himself, but am not sure if the leg, hip, or back is bothering him.