talesin-I have a multi-cat household and live way out in the country where inhumane people dump off their unwanted pets, when my cats insist on going out, they sometimes end up beaten up by the dumped cats...too many puncture wounds. My vet told me to open up their wounds (pick off the scab-nasty, yes) to let it drain, then use hydrogen peroxide on the wound to clean it and ALSO to prevent it from healing too fast. It heals on the outside, but continues to fester and rot on the inside and you want healing from the inside first. Hence, the peroxide to slow the outside from healing first.
I hope your dear kitty gets better soon.
CJ