A full tick panel would be a waste of money, but a $2000 MRI isn't? It's not a classic tick symptom, but for my peace of mind, I think I would do it anyway. That said, Fletcher has had arthritis with intermittent limps since he was 5, but he doesn't hop. But, he didn't have a broken hock, either. I also would try acupuncture. It is terrible to see them in pain and not be able to fix it