You didn't say what is wrong with your horses hooves, but I would guess thin walls. In addition to what the previous posters have said, I would suggest applying Keratex to the hooves. Be sure to read the directions. Also, to help strengthen the hooves while your horse is wearing shoes, and to grow out a stronger hoof, you could add 1 packet of gelatin 2 times per day for 30 days to the feed, then drop to 1 packet per day.
Hope this helps. We have one horse with thin walls to his hooves also.