It can't hurt, but you have to be very careful in applying it. You should dab it on, and make sure not to rub, because it can cause more damage.
Best of luck!
A good prevention tip- putting Vaseline on their combs in the daytime helps keep them frostbite-free at night.
I know some people believe this doesn't work, but I have seen great results with my chickens. I only do this a couple times a month, when I know that the temps are going to go way down...