I had a chicken who got injured by a flockmate and ended up with an ~ inch diameter open gash in the skin on the back of her neck, almost up by her head. I sprayed it with Vetericyn to try and clean it, and just kept her isolated and the wound sprayed occasionally. It healed up, all her feathers grew back, and you'd never know she'd been injured. Every time she moved her head, it would open/close the wound, and there wasn't a good way to bandage it without her hurting herself more to get it off. Within a month it was gone. It looked really gnarly when it was trying to form a scab, and I had to stop spraying it for the scab to form as much as it could. I considered stitching it up, but I'm not good with that, and was afraid to trap dirt inside the wound or hurt her more.