Cat Urine 100+ Year old Hardwoods

[Lucy Lewis]

Looking for some input on which route to go here.  We're under contract on our first investment property, a duplex built in 1900 and it has the original hardwoods.  The upstairs unit is in good shape with a little cleaning, but downstairs a previous tenant clearly had a cat with a tendency to spray in the house.  Not a "cat house" by any means, but certainly a pungent odor.  There is no visible evidence that we can find.  Do you think that we will be able to fix this problem by sanding and sealing the floors or in your experience is a tear out necessary?  We're planning to replace the baseboards and most of the lower 1/3 of the walls' drywall for other reasons, and obviously a good thorough cleaning and painting throughout.  We'd love to salvage these old floors if possible, both for cost and charm...but cat pee is not very charming.