I’ve discovered a wonderful product that eliminates pet urine odor, even in concrete. It’s called “Urine Gone!” and comes in 24-ounce spray bottles. I bought mine at Bed Bath & Beyond, for $9.99. It is an enzyme-action product that breaks down the urine into components that do not have an odor. You have to completely soak the area so the product penetrates into all areas where the urine has penetrated.
I bought my first bottle when my male cat decided the fireplace was reasonably similar to his litter box, and could be used when he was too lazy to go to the other room. The Urine Gone! seemed to do the trick, but I wasn’t sure until I went on a one-week trip in late spring. I left the house closed up, with the thermostat set on 80 degrees to save electricity. If any urine odor remained, I would have smelled it the minute I entered the house. What a surprise–no odor at all!
If you are interested, HERE is an article that explains why these types of products work, and why simple cleaning with detergents, vinegar, hydrogen peroxide, bleach, etc., will not do the job.
This also works on mattresses, carpeting, and fecal stains. Just be sure to soak the area so the product penetrates to all places reached by the urine, and then let it air-dry to give it time to “do its thing.”