I would clean the wound well with warm water and betadine.
then spray with hydrogen peroxide.
apply the antibiotic ointment (no pain reliever)
if you haven't been trained to give injections, i don't recommend experimenting. get someone to show you exactly where and how deep. if you do this yourself, my best advice is make sure it is in the muscle to the left or right of the sternum, try to get the needle to the middle of that muscle (visualize - not too deep or shallow) and ASPIRATE the needle before injecting, if any air or blood comes into the needle, pull out and try again. this is the most important thing. alternate sides when you give the injections. it has been a long time since i've seen anyone use penecillin but maybe that is wise advice, i don't know.
I think an oral antibiotic could also be used here, which would be safer if you haven't done injections before. I have used bactin before but not sure it's approved for meat if you plan on eating him.
hydrogen peroxide is GOOD to use especially if you have flies around. after you clean, spray some on the wounds, it will kill any larva (MAGGOTS), then put the ointment.
good luck!!!