Exercised to help my TB slow down. Poles make him faster and its canter that he need to work on. Maybe an exersise that will help him become stronger in canter if that makes sense?
I have a lot of experience with TB, OTTBs especially and the best thing to do is a TON of transition work, think less about “slowing him down” and more about controling his speed! Once you have done enough transition work you can focus on collecting and further controling the gait, hope this helps:)