I have a concrete slab with a covered 5x15 kennel/run for my two dogs. They are only in there while I am at work so they don't make to much of a mess, but I scoop up the poop, and put it in the garbage or with the lawn clippings. I found some stuff at petsmart called "Urine Destroyer." I put it in a spray bottle spray the slab down, let it soak for a minute and then hose it off. I have the slab surrounded by river rock that is 6-8 inches deep. Never had a problem with smell as long as I keep up on cleaning the slab. I try to pressure wash it once a month as well. Concrete is pretty porous.