I'm new to this board, and I think I originally posted this question in the wrong place.

I bought a 50 year-old house 4 years ago. I immediately took up the wall-to-wall carpet to find beautiful hardwood floors in pristine condition. I had the floors professionally sanded and polyurethaned. Now 4 years later I have 5 or 6 dark urine stains from my new dog. How can I remove these stains. I don't want to just cover them with carpet or scatter rugs. Can anybody help me?