My horse has four white socks and typically has very sensitive pink skin under said white socks. He got mud fever at the beginning of the summer (6 months ago) and I had tried everything known to man to get rid of it, but for some reason, this bout didnt wanna go away, it got infected at one point and required anti B's. By this time, he had it on three legs, one of which, his off hind, was infected almost up to his hock. The anti B's helped, but then I tried Mud Guard feed supplement and that was two weeks ago, and guess what? It gone! completely! In all my years of working with horses, I have never known anything so effective on mud fever. It not particularly cheap but who cares if it qworks so well. Just wanted to pass on the info as this time of year is ripe for it.