There may be no choice but to also treat the floor joists.  The bacteria that causes that odor is not cured by clorox.  It takes a special enzyme treatment that neutralizes the bacteria. 

I wouldn't sell that house.  The odor, if not completely eliminated will keep coming back.  Concrete is pourous too.  If they have a basement, it's probably there too. 

What a shame.  Their age has nothing to do with it. They are just immune to the odor. 

I'm older than dirt and I can smell that mess before the front door is opened. 

Good luck... I wouldn't haven't even gone there...the wood on the floors will have to be replaced...as well as the dry wall where the animals might have urinated... If they are putting travertine, and have not replaced the wood...you will never get rid of the smell...Well, good luck, hope it works...

I think you would have to remove the smell by airing out the house.

Don't laugh but my brother, an attorney, says he has heard in cases where the bodies are left for a long period and the smell is terrible that mouthwash (don't ask me what brand) is put in cloths all through the property and left until it absorbs the odor.......on another note, I have sealed concrete before replacing carpet and pad and never had complaints later......

Vinegar perhaps to neutralize the odor? or Baking soda maybe.

Sometimes the natural remedies work better.  After the vinegar smell disapates it's supposed to take the odors along with it.

Try an electronic air purifier. They work wonders and I know there are companys that will rent them for a few days. Might be something worth checking into.

I just got a puppy, and we're keeping him in a tiled area until we get him house trained.  Like Lenn said, concrete is porous, and so is grout.  Once the animals have spotted that area, it's there to stay.  I would recommend doing everything that you can to correct the situation, keep strong odor eliminators in the affected rooms, lower the price to reflect the situation, and most importantly -disclose it! 

I know servepro and servicemaster both offer services that will get the smell out. If they are in your area check them out, they are known for mold removal but also handle animal smells. Good luck!

I would advise painting the entire "cat room with Kilz primer and then repainting.  They need to have at least one litter per 2 cats and scoop twice daily, and use a quality clumping litter.  Good luck!!

Kilz the floors and walls before putting down new flooring and repainting. Also use odorexit. These two things work wonders. We used both to deal with a house that had been a pitbull dog fighting farm. It worked wonders!!!!

Mary, once that smell gets in my nose I can't shake it.  Maybe hiring a professional floor person/cleaner to come in? I'm real sensitive to odor, so I probably would have turned around on the sidewalk and headed home! LOL

I'm sure that once you get the odor out of the house it will sell quickly for you!

If the animals are going on the carpet, walls then there is a big problem and, no matter what is replaced, they will just keep ruining furnishings, walls, carpets. On the other hand, I have been in houses with cats that were going in the litter, but nobody cleaned it. So, even though they were not fouling the home, the slovenly home owner created the stench by not cleaning litters. You need to figure out which. If they just flat cannot, or will not, clean the litter, get them to hire someone else to do it till the house sells. If the animals are fouling the carpet, floors then it is way more complex. If a carpet can be saved, you use an enzymatic cleaner. You can get them at janitorial stores. The problem is, if the pad or the underlayment below the carpet is stained, then you need to cut that out where it is fouled and put in a new piece. In other words, you can get the carpet so it does not stink probably, but the floor below will stink. Also, while these enzymatic cleaners dry, the stench is worse. As for walls, if they are going there, then you could try the cleaner but might have to replace heavily soiled areas. I know some people have had results with products like Kilz and paint. To isolate problem areas, you can get a black light at a pet store for about $20.00. It will illuminate way more than you want to see.

Natures Miracle seems to work but the real problem is going to be getting a place to keep the pets so that the home does not get smelly again.

I don't think I would have taken the listing because frankly, I wouldn't know how to help.  Sounds like you've done a great job so far.  But is the smell in the walls, fabrics etc?  I hope you let us know how this one concludes.

Hi Mary, sounds like you have quite a little challenge on your hands.  You've got a lot of advice here, let us know if anything works!