One of my young hens at one time had an entire flap of skin hanging off one of her sides. The rooster did it with his spur. I took her to the vet, thought she could stitch it up, but no, she said she'd cut the skin off and I'd periodically bring her back to have the edges 'etched' for new growth. 200 bucks each time 4 or 5 times. Um...no.
I came here and got advice and was told chickens do heal very well and 'grow new skin' but you have to keep it clean. The only good thing that came out of the vet visit, was that she gave me some Chlorhexadine solution 2%. Mix with water till you get a light sky blue color. Use this to keep the wound clean.
She said DO NOT use betadyne or hydrogen peroxide. It will hinder the healing process and can cause necrosis.
After bringing her home I was really befuddled about the flap of skin. I mean it was 'still alive' and viable. Why didn't she stitch it for me! She said she worried about infection and the skin dying regardless.
I got some advice here, and was given confidence of how resilient chickens are to wound healing. So I got out a little plastic bottle -
hygiene bottle with spray tip - mixed up the
Chlorhexidine solution. And, I'm sorry but I had to find the smallest sewing needle and just do something about this flap of skin. I knew I could not sew it all the way around but one area NEEDED a stitch or two. She did give me some Metacam too. So I gave her Metacam and an hour later put some stitches to an area that allowed this flap of skin to hang on to something. I used dental floss!! She hardly even winced when I did this, thankfully.
As the days went on, I routinely cleaned the wound. Paper towels and squirt bottle. I made sure all the dirt was out. I would use a tiny 1ml syringe to suck out any excess solution down in the corner where I stitched it. All that skin survived and did reattach but that flap eventually did dry up, turned black and died off. I did have to cut it where it dried out. But don't cut off any live skin. As the days passed, a scab appeared initially and that scab eventually turned into skin! I was literally amazed how well it did heal up and I'm pretty sure the diluted Chlorhexidine solution is the best stuff to assist in healing and avoid irritation. No peroxide, no betadine, and no epsom salt.
Here is the thread of mine when Sweet Pea's skin ripped off. If you don't have Chlorhexidine on hand, buy some ASAP on Amazon, or see if a farm store has it. Maybe a local vet can sell you some?
Best wishes to your hen