How can I best treat a hardwood floor damaged by dog urine?

Oh my gosh I am so sorry that happened :( Here's a tutorial on how to (hopefully) take care of that! https://www.northsidefloors.com/remove-urine-hardwood-floors/

If the sections are blackened, that section will have to be sanded down past the black portions - it can even necessitate having that section cut out, and redone.

Vinegar And bicarbonato de soda whit Dish And peróxido Ang whas

I had the same problem (blackened). I poured peroxide on the stain and just left it. It completely bleached out without any further treatment !

Sand lightly and buy the special wood bleach at a hardwared store. Very strong so make sure you use rubber gloves as the product is very harsh. Follow directions on the can. It will pull out the black but if the dog used this spot over a long period the only remedy is to take up and put new boards down. Jo

Tsp trisodium phosphate buy it at any big box hardware

Here is an article that might help - http://www.dogingtonpost.com/what-to-do-about-dog-urine-on-your-hardwood-floors/

Do not use a rotating brush or any attachment that may scratch the wood. Mix warm water and white vinegar in a cup at a ratio of 1:1. Dampen a soft towel with the solution, wring well and wipe the affected area to remove as much lingering odor as possible. Wipe the spot with clean water and dry very well with a towel.