I had made the decision on my own after seeing Izzy doing back flips in his small paddock. I decided that controlled exercise is better than what he was doing on his own. I feel much better with the vet's endorsement however.
I used my thick cotton lunge line for the work. It's a round rope that is soft, heavy enough for rough play, and long enough to let him make wide circles.
When he was with "the trainer" up north, I worked him in the round pen a few times, but he was pretty tense up there, and I still didn't get to see a nice forward trot or canter.
When I put him on the lunge line for some walk and light trot work, I got all giddy inside. He didn't offer a beautifully lifted back or anything, but he did show me a glimpse of the nice movement that I knew he had.
I had him walk for a few minutes, and then I sent him into a quiet trot. I laughed out loud when I saw how slow and easy he moved out. Right from the start his trot showed rhythm and balance. He didn't pull or lean on the lunge line, and he was quick to look to me for a whoa cue. In fact, I had to do a fair amount of kissing and clucking to keep him going. I don't think he's much of a bolter.
Now that we can officially work on the lunge line at all three gaits, I can help him burn off some of that extra energy by long lining him and maybe putting him in the side reins. The bridle and saddle are not far behind.