Treating pet odors is what I do for a living and I see situations like this on a daily basis. I am going to asume your basement subflooring is concrete which is porous and will absorb urine and its odors. Bleach is the strongest household disinfectant you can use to kill germs and odors and it will do good as a initial clean-up on the surface which is the key word. After the bleach has dried the concrete still has wet urine and odor below the surface that is still off-gassing. The next step is get the concrete as dry as possible by using air movers and dehumidifiers together this equipment will also dry the walls if the cats have been spraying on them. Finally we use a industrial sealer that has a moisture barrier and a odor barrier once applied we guarantee you will never smell any pet urine odor from any area we treat. Kills is designed for smoke odors, as cat and dog urine acids will eventually weaken the product and the urine odor will be back. Enzymes are temporary fixes or are for minor problems per the manufacturers instruction the area has to stay wet for up to 3 weeks for best results and @$20-40 gal do the math bleach is better and stronger. Besides you have already cleaned the area now you have to get it sealed. Oh! and toss the carpet It would cost you more for a pet odor treatment then replacement. Here is a link that might be useful: thepetodorspecialist.com

I had a bad situation in my master closet with pet urine and vomit in the carpet padding (sick pet, kept climbing into the darkest corner and letting loose.) I tried every product under the sun to get the odor out - various pet odor solutions, Nature's Miracle, etc, and NOTHING worked. It still reeked. Then I remembered my "skunk potion". We live in skunk central, so I keep the ingredients on hand to shampoo the dogs if one of them gets sprayed in the spring. I know for a fact that it completely disappears even horrible skunk spray, so I figured what the heck, I'll try it. Pee can't be worse than skunk, right? It worked, though I had to do it twice for carpet padding. The odor is completely gone. I poured it on and just let it sit for about an hour or 2, soak in really good, then steam cleaned it back out. Here's the recipe: I 32 oz bottle hydrogen peroxide (fresh and unopened is best) 1/2 cup baking soda 1 tsp dishwashing soap (Dawn, Ivory, whatever) It will foam up, and has to be used immediately - it can't be stored. You may want to try this before you go painting or varnishing an entire floor.

I learned this the hard way, but it is good to.know. I purchased a 100% wool 10 x 13 rug for my living room. One of my cats did not like the.other using the litter box so she started going on the rug. I found a recipe online to remove the odor. It helped a lot but didn't stop.the cat. Each time I saw a,wet place I blotted.it, then literally poured whire vinegar and hydrogen peroxide on the spots. I had to put something under afterwards to.dry the floor and absorb liwuid from the rug. Then when I had my upholstery cleaned, I had them clean the rug. Only after I paid them did I ask how they clean wool.rugs (my sister pays souch to.have hers picked up, cleaned and returned.in place. WELL, I was completely shocked to.learn the carpet cleaners WASH WOOL.CARPETS. So after that did what they said they do. My husband took ut out to the drive way, and I washed it front and back. It has to be turned to dry thoroughly, but don't leave the top with direct sun for several days like I did. I had a bit of fading. So, you do have this option if you really like the warmth and feel of carpet under your feet. Not all wool rugs are as expensive as some pay for the orientals. Mine was 900. compared to almost 4000. ,my sister paid. Hers has to be a lifetime.purchase. Mine does not, thankfully. Also,.in.my bedrooms, I bought the padding that has the liquid barrier layer. Also, another tip I got :, If you do decide on carpet, before installing, wash your subflooring (if not particle board) with white vinegar and hydrogeox peroxide,,When dry sprinkle combo of baby powder and baking soda. Sweep that up so to leave sime in the wood grain. Then again sprinkle a light layer.all.over and install carpet over it with.the pet type padding or the fur babies will.smell where they went before. It will be chore with 4 of them, but u k buy baby diapers and cut a hole for the tail. Then u should take all if them.out together removing the duapers at the doggie door and coax them out with a treat. When u take off the diapers, note which.one already wet their diaper. Then as each goes you should praise them by name and give another treat. You can reuse the dry diapers using painters tape wrapped as round. The orig tape wint endure. You may find by checkin who.used the diaper that all 4 ate not the culprits. I.have two dogs, two cats and all but the newest puppy rings a bell hanging.on the door to.let me know. Then they all go out together. But that puppy comes running to.me to see if I am coming, so she's om her way. I do also have a doggie door, but.only..one cat uses it. I also.keep a pee pad on the bath floor for when I am gone. I.learned a long tome ago, you have to use some of your not really free time to train puppies /dogs. Skip.one tome taking them out on a schedule (for a while) and you are causing the problem. The become accustomed.to going at certain times. You have to.gradually extend it from every hour until a couple of times a day. Hope ALL this helps some.

Thanks for the replies and advice:) To Embothrium: In hindsight, the bedding used to soak up the pet urine most likely soaked up the water in the soil, wicking away water from the tree roots. That's my hunch since the trees deteriorated in the same manner as when irrigation is turned off in this desert climate that I live in. And you're right, if it ain't broke... but because the soil in that part of the garden usually runs really dry, I somehow thought the bedding would help retain more moisture. Duh, what was I thinking?!?!?! To rifis: In the desert where I live, it takes forever for anything to decompose if I don't water it. Hmmm, I wonder what mobster treasures have been found in the desert out here? :) Anyhow I agree with you. Manually removing 30 cubic feet of bedding with or without the soil will be a lot of work but it might be the most effective option (if the seeds don't grow per toxcrusadr's advice). It took me 30 minutes today to sift a gallon's worth of soil with minimal results. No can do but seeing the rate of (non)decomposition of the bedding and the time-consuming task of sifting, I might have to remove the soil and start over as Embothrium suggested. To toxcrusadr: I live in Henderson, Nevada, an extremely dry desert climate. The bedding contained duckling urine and feces, so I'm guessing it was high in nitrogen. The leaves turned yellow and brown and new growth stopped altogether by next season even after I hand-watered throughout the spring and summer months. I dug through the soil today- dry but bedding is still intact and moist (irrigation has been turned off for a year and last precipitation was 2 weeks ago). I will take your advice and do a test run of the soil with some seeds and will post the results. That's great advice, btw!