My Cat Got Into A Fight!

It sounds like the cut is infected. If it is still open, try to keep it open so it can drain. Also, if you have a thermometer, you can take your cat's temperature (it should be under 102.5 to be considered normal). If it's high, he may have a fever as a result of an infected wound and should see the vet right away to be put on antibiotics. You can use warm compresses to bring the infection to the surface and to keep the wound from healing over and sealing in the bacteria. Be very careful with the hydrogen peroxide--you don't want it to get into his eyes. You can also flush the wound with saline solution (like the stuff they sell for human eye care), which may be safer on that part of the body as it's less abrasive. Check the antibiotic ointment to make sure it does NOT have a pain reliever (some do, like Neosporin Plus). A little bit of plain old Neosporin is probably okay as long as it doesn't seal the wound completely--again, you don't want to seal in the bacteria. He really should see a vet on Monday at the latest but I would call the ER vet immediately if he has a fever, stops eating or drinking, or isn't using the litter box.