Our gelding horse, Sonny, has come down with Selenium Poisoning, not sure if I had mentioned this previously. Anyhow, the first clue was in August when his mane fell out, then in September when his tail fell out, also he was getting thin and laying down a LOT. Neither time the vet knew what was causing this. The Farrier came out in October and with one look immediately knew this was Selenium poisoning. The vet concurred. The Farrier told us that his hooves would be sloughed off and he'd have to grow new hooves before this was all done, about a year he told us. There was nothing to do but support Sonny the best we could be keeping his hooves trimmed up as much as possible to relieve any pressure as they came off, trying to keep his weight instead on his soles of his feet. So for a few months that is what we did.
Earlier this month we noticed Sonny getting VERY thin again, and so it was time for another Farrier visit. Last week he came out and told us Sonny was in the last stages of having hoof wall left and recommended we remove the rest of the hoof, and build a synthetic hoof for him. He called another Farrier, a national expert that lives in our area, and he also came out and the two set to work. They removed the remaining loose hoof and cut a piece of 3/4" plywood the size of his hoof for the bottom. This they epoxied on, gluing the wood to the new hoof which had grown about half way out. They also put a spongy material on the frog to give him some comfort and support. Then they screwed a smaller piece of 3/4" plywood onto the bottom, giving him the ability to rock a bit, instead of a completely flat bottomed foot.
They decided the back feet were doing well enough, so after taking off the old hoof on those they just left those alone. Sonny immediately showed signs of being more comfortable. If we can keep those on for 3 months or so we should be well on the way to recovery. Now he is moving around quite well like anyone learning to walk on inch and a half spike heels!