This is a personal account of my experiences with frostbite.
*Warning for those with weak stomachs—graphic images ahead*
I live pretty far north, where frostbite is constantly lurking around the corner. The best thing you can do to prevent it is open up the coop. It seems counterintuitive but nothing else is going to work. For temperatures in the neighbourhood of -5*F or below you probably want to close up some ventilation to keep drafts away from your birds, but DON'T seal the coop up entirely! I can repeat that if needed... lol. Humidity is your enemy here. I have about 40 square feet of ventilation (some in soffit vents, some in windows) and I reduce it to maybe 10 square feet in winter? Works well for me and this is the arrangement by which I get the least bird damage.
If I have single combed roosters, they are going to get frostbite. There is no way around it, I refuse to bring 10 roosters in the house all winter and heating doesn't work for my situation. If you have valuable showbirds then the electricity bill might be worth it but for a regular backyarder it isn't. Having the foresight to choose the breeds with combs better suited for your climate will go a long ways towards reducing the headache that comes with monitoring frostbitten cockerels. I am in the process of switching over to just Chanteclers and Ameraucanas.
A side note: dubbing might be useful in preventing it. I am not experienced enough to safely attempt it but if you can find a mentor it's certainly a viable option.
As for what I do with "treating it"—I don't. Thawing and maybe saving some of the comb/wattles just means he gets to go through it again. I leave the bird outside and will continue to do so unless I see signs of infection. Be careful if you do bring the bird inside; warmth increases swelling and so might inflate throat/wattle frostbite to dangerous levels.
I don't have many pictures of roosters with frostbite because my camera stays inside in winter. I did find this one, though, of a cockerel that was almost done healing from frostbite. There's only a little chunk left of the frostbit parts.
If you are getting hens with frostbite, then that usually (assuming you do not have weather colder than -40*F) means you're doing something wrong. Open up the vents more and make sure they're in a place where they won't blow on the roosts. I have Leghorn hens right now and they don't get anything more than the tips turning a bit white even in some pretty cold weather. If you are unlucky and have high humidity outside along with cold temperatures then there isn't really much you can do.
That's all for frostbite on combs and wattles. Frostbite on legs and feet does require treatment and is a real headache. I have only dealt with it once and that was when I foolishly hatched in late August and the pullets (bantams) weren't ready for the cold. I won't do that again.
Here's a picture of the frostbit bantam. She lost all the skin off her feet, a toe or two, and all her toenails. Her feet are stiff to this day.
Because of how much swelling there was, I popped the blisters on the bottom of her feet with a needle. That way she could walk instead of tumbling around like those blow up punching bags. Then I slathered antibiotic ointment on the feet and bandaged with a cotton pad and vetwrap. After a few months she was good to go.
Oh, I just remembered. Chrissy, a Welsh Harlequin duck, also lost a foot to frostbite after a mink attack left her unable to pull her web under her in the December chill. That was different in terms of treatment—it shriveled and dried without swelling or pus, so I didn't do anything with it. I just changed her bedding frequently, gave her baths, and it fell off on its own. She recovered well from that, but later she lost her life after another accident which I won't go into.
Foot after it fell off. Rather neat in a sick way, eh?
Here's the stump that was left. No infection, just healthy tissue. I bandaged this up with antibiotic ointment and vetwrap & changed the dressing daily.
That's all for now. If you have any questions or comments, let me know.