Okay as a former nurse and current Vet Tech student, this is my suggestion: I wouldn't do anything to it but observe the wound and the cat's behavior. Animals will hide the fact that they are in pain as a survival strategy. If the cat becomes aggressive or starts to limp, then the wound needs some immediate attention. Watch the wound for any signs of infection: Redness, drainage, usually cloudy in color or pus filled, bleeding etc. The cat will keep the wound clean by licking it and he/she will do it as often as it needs to be done.