You know it's really no surprise, it's incredible how much stress these top horses go under. Horses are not meant to be pushed so hard. Wouldn't be surprised if something else happened to that poor guy.
I really hope that he has a speedy recovery and is fine....sad part is that in a couple more years he will be useless as a race horse. Hopefully he can win big and retire with all the ladies he can service!
Be strong and courageous, and do the work. Don't be afraid or discouraged by the size of the task, for the Lord God, my God, is with you. He will not fail you or forsake you.