I was at a tack shop pricing saddles, and the owner was talking with someone about thrush. He was advising the horse owner to inject the hoof with formaldehyde. He said a farrier had shown him about it. He swore that it immediately healed the thrush, that thrush would never ever come back, and the hoof would be so healthy and also so hard, that you would never need to put shoes on your horse. It could ride on any surface and never need shoes.
Uhhhh, to me that sounds dangerous. I don't know about the claims of what all it will do for the horse's hoof, but isn't formaldehyde unsafe to be injecting into the sole of a horse's hoof? For good gosh, that is used for embalming bodies!