Pet odor removal

Question
My daughter has found a wonderful place to rent, HOWEVER, it wreaks of pet urine in hardwood floors.  I've tried a couple of pet odor removal products and haven't made much headway.  Is there something I'm missing?  It's as if someone locked up either cats, dogs, or both in that duplex and let them have at it.  It really smells badly.  What can we do to make it liveable, if anything?

Answer
Hi Cheryl..well two things. first of all, if they are wood floors, then the smell has soaked in and it is probably not fixable. the floors will need to be torn up and replaced. But i did want to share with you that i went to someone's house recently for that reason and to try and help them. We found out that the previous renters had allowed their animals to go potty in the house so much, that the urine had gotten in the baseboards of the walls. Someone had to come tear those up to. If she is renting, i would tell the landlord.  good luck and sorry i cant help fix it.