I will give you my experience...........with a kitten. She showed up at my house, very lethargic and with a large, gaping wound on her shoulder. The wound was infested with maggots. It was horrendous. We poured peroxide in the wound and dug all of the critters out with tweezers. We then cleaned with saline wound wash and betadine. I dressed it with neosporin and a non stick gauze pad and wrapped her in vet wrap. We cleaned it twice a day for probably two weeks. The cat is perfectly fine and now lives at our house After a couple of days, I did read a suggestion to open an antibiotic capsule (from leftover human antibiotics) and sprinkle it on the wound. I figured we had nothing to lose, so I checked that the med was safe for cats and we put it on the wound with the neosporin. I don't know if it helped, but her woulnd was as large as your chickens and you can't even tell where it was now.
If you are keeping the chicken outside, I would definitely cover the wound with a gauze pad and vet wrap. Good luck!
If you are keeping the chicken outside, I would definitely cover the wound with a gauze pad and vet wrap. Good luck!