soak it in cold water, use grandmas stain cleaner
take cat to vet, UTI it sounds like
then use BIZ on the spot and scrub with a toothbrush
that cant be used for anything else
wash well
see if you can smell it after it dries
if so rewash
so NOT DRY IN A DRYER
until it is smell free (if itsnt ever smell free, replace fabric and batting in that area) sorry