If you find out let me know. As far as I know the only way is to replace the sections damaged. You can lay laminate on top but you must get the smell out before-hand otherwise moisture will cause a stink.

Enzyme treatments(Nature's Miracle is one) will chemically alter the urine and destroy the odor. We just bought a foreclosed house and one reason we got it was that there were pet urine stains in every room(house had been carpeted) and the previous occupants had at least three inside dogs---as well as four outside dogs(from tie out patterns). The carpet was removed, the floors treated with an enzyme and I installed new unfinished hardwood flooring. (And finished it)

If the stains in the floors in your rental are too deep to sand out, the only solution would be to flood the stains with enzyme and either cover or replace the flooring.

Installing laminate will be more expensive, but much cleaner and faster. Sanding floors takes a couple of days---and sanding dust will be EVERYWHERE(you would need to move out for about a week) plus the time needed for three coats of finish.

The biggest problem with installing laminate over hardwood is the height on the floors in referrence to entry doors. There is quite often too little room to install laminate without reinstalling the front/back/side entry doors. That can be done, but is additional expense.

Or, the hardwood in place could be removed and new fl;ooring installed.