A year or so ago, we took the kitty kids in to get them neutered. On the way home one of Havoc's incisions opened, and bled all over the towel I had in the crate for him. We found this when we got home, which by then it had stopped bleeding. I kept an eye on this for a few days.
One day I was looking at it, and the sac looked puffy. I picked just a bit at the scab, and pussy blood drained from the wound. After getting as much gunk out of the wound as possible, I put a couple drops of peroxide in the wound, just to do the final clean up. That did NOT make him very happy. Thankfully, though, that cleared up the infection, and it healed up nicely.