Keep then out of wet areas
I use thrush buster and it's amazing
You can't beat picking out the hooves a couple times a day. The thrush meds can also do wonders along with moving the horse to a dryer area if possible.
"Thrush off" is great but quite pricey, make sure to keep your horses stall free from urine and keep his feet dry.
I use a brand called "no thrush!" And it's a powder that treats thrush and is a preventative! It works so well!