Glad he is on the rebound. My dog just had her rear leg operated on a few days ago. those bullys have so much muscle and often not enough bone & tendon so they end up trashing their hind ends. so 4400 bucks later, she has bionic rear legs like the now old lab chow mix that we have. Give the used dog some rimadyl, it should ease his pain.
How does she get around? That must be rough. I'll have the Used Dog send happy thoughts. Maybe he's doing so now. He's snoring.