I know that someone has been having a problem with her thoroughbred and I have just met a special horse pharmacist who gave me these ideas which could help
I suggest that you try a liver tonic, because sometimes during racing and the damage that comes prior, the liver can become very sensitive
or, try some pro-biotics, this will most likely make him digest his food 100 times better (remember that you should leave them on this for the rest of their lives - it will only do wonders for him and is not dangerous or damaging in any way - and buy a good quality type)