As has already been explained, you can use neosporin, but need to do so sparingly to prevent poisoning your cat. One thing that will help is to apply the ointment, apply a small sterile pad, then wrapping the area with stretchable self-adherent bandage wrap. This is the wrap that is used to keep a sterile pad in place after you get your blood drawn. It comes in a variety of colors, but your cat probably won't care about that. This way, your cat won't be able to lick away the neosporin.