Clean the wound. I haven't had to treat a chicken wound, but I have on my other animals. You can first clean the wound with peroxide, then with diluted betadine. I use a large syringe or squeeze bottle for the peroxide and betadine to give some gentle force to irrigate the wound. After cleaning and drying the wound, pack it with antibiotic ointment. Don't use the ointment with pain relief. You can also use saline solution to clean wounds. The wound doesn't appear to be large or too deep in the picture, so it should heal with no problems.