I usually bring them in and thaw then out a little. I wasn't doing anything to prevent it as none of them seemed to be getting any but I may have to start trying some stuff...Oh bummer. Do you do anything for it? I might try to use coconut oil tonight if i get a chance on one of my hens that got it too. Or maybe all? I'm still not sure if I think it's necessary. There's so much info out there...