Flora has frostbite on her beautiful (largest in the flock) comb. Greta has a little spot, too. I'd been told not to worry about the cold here (Oregon) and that frostbite occurs due to lack of ventillation in the coop. Our coop is very airy. It is a converted wood store, about 60sq. ft. for three chickens and, in addition to the official ventillation with the chicken wire and hardware cloth, there are lots of holes and cracks. I've put some shea butter (don't have bag balm or vaseline) on all their combs. Should I do it regularly until the weather warms? Is it preventive as well as curative?