Krud Kutter. Sold at Lowes, Home Depot, Wal-Mart... (You can also start with Spot Shot--this got red paint out of cream carpet for me, but it has a strong chemical smell; if you have urine in hardwood floors, Out!--usually found at Wal-Mart--works well.) It works on just about everything...except oil spills on concrete. I am a Jane-of-All-Trades (art, construction, automotive, anything, everything) and incredibly messy. Krud Kutter is amazing for laundry stains--removes blood, right before your eyes, with just a quick squirt. It doesn't bleach items AND is eco-friendly. I never dilute the stuff because I just like to go strong the first time around, but it IS a concentrated formula. I have a 12-year-old chihuahua that just loves to hike his leg on everything, and he also doesn't like to drink a lot of water; so, his urine is POTENT. I've used Krud Kutter on the diapers I now make him wear as well as in the carpet cleaner, and it is amazing. Best two cleaning products ever: Krud Kutter (comes in several iterations--I like the Tough Task) and Magic Eraser

I wish I would have timed how long it took me to read every single one of these posts. My beloved cats are destroying my house. I'm single, working, commuting, and losing my mind trying to clean it and get them to stop. I think that a fair number of these posts are written by SHILLS, which I find despicable. People like me are going through hell. Not only is there a mess, it's a smelly, toxic mess, and it's caused by my children. Yes, they are my children, and I can't just get rid of them. I, too, want to chime in and say that Nature's Miracle does NOT work. I'm fine with ripping up the carpet and starting over, but even that is going to be so incredibly difficult and time consuming. After reading all of this, and not having very nice carpet, I've decided to rip up my carpet, but I wish all of you cat lovers the best of luck in trying to eradicate the stains if you do want to keep your carpet. There isn't much on this thread about preventative measures to stop cats from doing this in the first place, but I encourage everyone to visit some reputable sites to deal with that as well. I've listed some below. Please don't ever think your cat is angry or vindictive or something like that. Cats don't have those types of emotions. Educate yourself and respond appropriately, but be careful of opinions in forums. Look to the experts for advice. I so very much appreciate the time people took to offer solutions. Thank you. I also want to recommend a money saving litterbox filler that will encourage you to keep up with cleaning it, as well as keep the smell at bay. My cats' issues have to do with new cats in the home, age and illness - not the use of this litter. I use plain wood pellets (no scent!), bought at Menard's or Fleet Farm type places. They're sold as woodstove fuel, as well as pet bedding. Way more economical that commercial litter and, I think, abate the smell much better. http://www.naturalcatcareblog.com/2011/06/cat-going-outside-the-litter-box-super-smart-behaviorists-share-their-tips/ http://catinfo.org/?link=litterbox http://www.littlebigcat.com/?s=litter+box One of the many posts on the brilliant Dr. Becker's site: http://healthypets.mercola.com/sites/healthypets/archive/2012/08/29/cat-litter-box-aversion.aspx http://www.naturalcatcareblog.com/2011/02/9-useful-sites-for-researching-cat-health-issues/

I am planning to replace the carpet in my living room, and have a similar problem, due to an elderly dog that just can't hold it the way he used to. I'm planning to have the carpet installers move my furniture and remove the old carpet, and will need to treat the concrete slab quickly before they start installing the new carpet. Does anyone know of anything that I can just spray on, that will dry quickly? Or is that just not realistic?

Thanks to all of you for the tips. I'll try the vinegar tomorrow. Pbrisjar--does it matter if it is white vinegar vs. the brownish cider vinegar? I sprayed the floor and all the walls with a peroxide and baking soda solution yesterday (recommended in a thread that I found on the flooring forum). That seemed to help at first, but I think the smell is coming back. It sounds like I will probably have to buy a lot of primer and seal the odor into the walls and/or the floor. I went to petsmart today and bought a blacklight; hopefully that will help me find the worst areas so that I know where to concentrate my efforts. I have a feeling the walls are worse than the floor; when applying the peroxide solution I noticed some discoloration and residue about 2 feet up from the floor on a few walls, so those may have been major spraying locations. I bought a large bottle of an enzymatic cleaner that sounded like it might help with older stains, but it was $35 and I know it won't be enough for the whole area, so if it's not much different from vinegar I may as well return it for a refund. Yes, I'm sure the prior owners knew about it. I have no idea how they managed to hide it every time that I came to the house (I have a sensitive nose), and it irks me that they did. If I'd known, I could have had a painter seal everything before I moved in, while it was still empty. At the closing, the owner mentioned that the cats had been "stressed" because of the move; I guess she knew that I would soon discover the smell. Thanks again!!