First, get rid of the cat. Then mop on bleach, mixed 1-2 parts water to one part bleach. (Others swear by vinegar). Then paint with a good oil or shellac-based paint designed to cover stains and...
Lightly spot sand and apply an appropriate finish to "hide" the blemish. If unsatisfactory, consider reappling the finish to the entire floor. If severe you may have to sand the spot down to bare...
Non-acetone polish remover (or rubbing alcohol) worked great with a cotton ball. For slightly more set-in stains, let it sit for a short time. --- Try toothpaste! Believe it or not, it works great on...