Dog urine hardwood floors with Pictures - Suggestions requested

[Chris Pasternak]

Hi all,

Couple pictures of hardwood floor sin my rental that I'm turning over now.  Floors have been my biggest issue thus far.  I have a few options to go through and the last thing I want to do is paint over these. 

What do you guys think of these floors?  The top picture is more closely what it looks like now, except more grey and less black. 

So far I've done multiple doses of hydrogen peroxide and a few rounds of sanding in between.  Odor gone.  Need to figure out best way to restore floor ideally, if its too far gone, what do you suggest?

Thank you