Hi Ljohn it sounds like your horse has stressed tendons and would benefit from a pack of support boots all 4 professional choice is the best company for support boots the design and thickness of the boot helps protect and support tendons that are weak. Any time you work your horse you should use them his weak tendons are probably the reason he was taken off the track. Hell be an awesome horse and you can start training him right away just with all 4 protective boots even if you are just turning him out to play. Reason being is because if he overstresses his tendons he can acctually bow a tendon and if that happens the casing that holds the tendon in will rip and let it out and are lame for months and need to be wrapped with a cotton wrap every day. It happens a lot to horses off the track. My grandma grew up on track.. Her father was a trainer so she saw a lot of these problems. But if you keep support boots on him when you get him out he should be fine just check with your vet if you think hes bowed a tendon. Good luck.