Are the horse's feet soft because they are thrushy or is he thin soled? Coppertox is fine as a antifungal/antibiotic. I have suggested to people to paint the white line with coopertox or thrushbuster if the horse is at risk for white line disease. If he has sensitive soles I have had good results with venice turpentine (use it on the thin soled tb types that have had their racing plates pulled and are on turn out only to take the "sting" out for the first few days. I don't think coppertox would have the same affect.