Written by Laurie Goldstein
We regularly see recommendations for home-made formulas to clean cat urine stains here on the forums of TheCatSite.com. These formulas are widely circulated on the Internet, and typically include either vinegar or hydrogen peroxide and baking soda. Of course, many people unfamiliar with the problem of cleaning cat urine
stains simply try to clean up cat pee as they would any other stain, only to find out later it didn’t work. In fact, using traditional household cleaners on cat urine actually “sets” the stain. This makes the stain even more difficult to remove with proper enzyme cleaners.
There is a strong, legitimate, and chemically important reason to use an enzyme cleaner to clean cat urine stains. Home-made mixtures, vinegar, baking soda, or typical household cleaners simply do not contain the required ingredients to remove ALL the components of cat urine. Vinegar and baking soda work to neutralize the odor temporarily, and hydrogen peroxide is 30% more oxidizing than chlorine. But cat urine is composed of things that REQUIRE enzymes to break down the chemical bonds.
Cat urine is composed of:
- Uric Acid
- Other electrolytes
- Bacteria - typically 5 different strains.
When cat urine dries, the urea is broken down by the bacteria. This is what makes it smell like ammonia. As it decomposes further, it releases thiols that make the odor worse. (It is the thiols in skunk spray that make it SO potent and difficult to remove).
The urea and urobilin/urobilogin are not hard to clean. Urea is water soluble, and urobilin is the pigment that causes the color. Traditional household or carpet cleaners will deal with these, and this is why hydrogen peroxide, vinegar, and/or baking soda also appear (initially) to be effective at eliminating the problem. But the problem has not been solved! Uric acid and its salts have been left behind. Uric acid is not water soluble and bonds tightly to whatever surface it touches.
The vinegar and hydrogen peroxide/baking soda mixtures (or traditional household cleaners) do not - are not chemically capable of - removing the uric acid and its salts. They only temporarily make the smell go away, because they do clean up the other components of the cat urine. But when exposed to humidity, the salts cause
the uric acid crystals to reform, and they start to release the smell again; not always at levels detectable to the human nose, but the cats’ more sensitive noses can smell it. And the scent of their urine outside of the litter box encourages them to continue urinating outside of the box, with their families left scratching their heads wondering why.
Notably, because of the uric acid component of cat urine, cat pee has a half-life of six years. This is why it is absolutely essential to use a cleaner that can break down the uric acid. Soap, vinegar, baking soda, ammonia, chlorine, and hydrogen peroxide (to name the most common cleaners) are not chemically capable of breaking down the uric acid in cat pee.
The ONLY thing that will break down the uric acid to PERMANENTLY remove the smell is an enzyme cleaner. Enzymes are the only thing that will break down the uric acid. The enzymes break down uric acid into carbon dioxide and ammonia, both gasses that then easily evaporate. This is why it is also essential to allow the enzyme cleaner to air dry. It needs the “natural” drying time to break down the uric acid salts and allow the resulting carbon dioxide and ammonia to evaporate.
Not all enzyme cleaners are equally effective. Good enzyme cleaners are expensive. Cheap ones will work, but need to be reapplied over and over (and probably end up costing as much as the expensive enzyme cleaners). Enzyme cleaners that work well and reliably, as tested by members of TheCatSite.com include Nok Out, Urine Off, Anti-Icky Poo, and Stink Free.
Of course ANY cleaner needs to be used properly. Most enzyme cleaners come in a spray bottle. This is deceptive, because just spraying a light layer of enzyme cleaner over a urine stain will not result in complete cleaning of that spot. Cat pee wicks, and unless the enzyme cleaner completely envelopes all of the cat pee, even it won’t work. "Spraying" doesn't work. DOUSING, POURING, and SOAKING are required when cleaning up cat urine.
To properly use an enzyme cleaner on a fresh stain:
- Blot up as much of the urine as you can before applying anything.
- Soak the affected area with the enzyme cleaner.
- Let the enzyme cleaner sit for 10 to 15 minutes.
- Blot up as much of the enzyme cleaner as possible.
- Leave the enzyme cleaner to air dry.
Covering the area with something is always a good idea. This will not only help prevent the cat from attempting to pee on the same spot while the enzyme cleaner does its work; it will stop family members from stepping or sitting on the wet spot. Some people lay aluminum foil down over the area; other recommendations have included an upside down laundry basket or an aluminum baking sheet.
The same basic procedures apply for an old stain. But be aware that an old stain may require two or three full cycles of enzyme cleaner application (allowing it to completely dry between applications) in order to completely clean the stain.
Cushions and mattresses CAN be cleaned! SOAK the affected area of the cushion. As mentioned earlier, cat pee wicks, and you must get the enzyme cleaner to wick to all of the same places the cat pee did or it won't work. When one of our cats peed on the couch, we took the cushion outside, blotted up as much of the cat urine as possible, then we soaked the cushion by very slowly pouring the enzyme cleaner on/around the affected area, giving it time to really soak through the cushion. We let it sit for 15 minutes, and squished out as much of the excess enzyme cleaner as possible, then blotted up what we could (with a lot of towels). If sunny, we left it outside as long as we could to dry. We then laid aluminum foil down over the couch, put the cushion down, put aluminum foil over the top of the cushion, and a throw blanket on that. Before bed, we'd remove the throw blanket so the aluminum foil was left, discouraging the cat from peeing on it until it had the chance to dry.
To treat the mattress, we used essentially the same process, only we did not remove it from the bed. We slowly poured the enzyme cleaner on/around the affected area, ensuring it had the chance to really soak in thoroughly. We let it sit for 15 minutes, then blotted up what we could with a lot of towels. We then laid down several layers of clean towels over the area, and made the bed. Just swap out those clean towels each day (if done properly it will take days to dry). We took a very large box, cut it down, and laid it over the top of the bed during the day. This prevented the kitty from wanting to pee on the bed while the enzyme cleaner did its work.
Thick cushions and mattresses may require several applications to completely remove the cat urine. The thickness is the issue, and getting the enzyme cleaner to all the same spots the cat pee went is more difficult on the thick things. But rest assured, your couch or your mattress is not ruined if your cat pees on it. You will be able to clean it!
Laurie Goldstein is a CFA Charterholder. In addition to her work as an equity analyst, she applies her research skill to all things cat, focusing on nutrition and advocacy for feral cat management via trap-neuter-return (TNR) and educational research on cat predation. Learn more about feral cats on her website http://www.StrayPetAdvocacy.org.
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