We moved into a house last year where the previous owner had left her dogs and cat in the basement a lot. The carpets were completely stinky and the enzyme stuff as well as professional cleaning didn't do away with it. After a few months we ended up ripping out all the carpet. The paneling on the walls was so soaked with dog urine that it was coming delaminated. So that got pulled out as well. Now we have nicely painted drywall, cork floors, and no money. But also no stink!

Give up. Rip it out and start over. This one is bigger than you.