My QH gelding is now 20, he has always been kind of a hard keeper, but always been pretty muscular. Lately, he has been losing a lot of his muscle on his topline along his back. You can see his spine quite a bit. He eats a ton - he's out on pasture about half the day, then gets a grass hay as well. He is not getting ridden much lately, so thought maybe that was why he is losing some muscle? The vet suggested a Vitamin E supplement...Anyone feed one or have experience with it?