You need to treat it like any other 'water' stain. What finish do you have on your wood floor - oil, wax, lacquer etc?
I'd suggest talking to someone who is experienced with your material and or googling same, your local fitter or showroom might be able to help if it's a modern floor. Wooden floorboards in a period home might be more forgiving but either material will show a mark if the urine has really penetrated the wood unless you opt to completely sand and refinish. The finish will determine your stain removal options but you could try the
For Dummies site -
How to Remove Water Stains from Wood Furniture Another option that grandmothers and housekeepers everywhere will recognise is the iron and brown paper routine. Whether this is an old wives tale or not it gets retold to each new generation and must have some merit. However I can't remember exactly what problems it's supposed to work on! Perhaps you could google that too :)
Good luck. I'm about to fit a wooden floor so it's good to know what I should be aware of (sorry!)