Legging horses back up in there early teens to finish and run. Anyone done this and had success. 

My stallion Zan became a land whale while I was hurt and during my surgery and healing time several years ago. He was 13 when the injury happened. I started legging him up again when he was 15. He ran his 15 and 16yo year great and set his personal best times in several arenas as a 17yo.