Why is Cat Pee So Tough to Clean?

Why is Cat Pee So Tough to Clean?

Cat urine is a notorious, odorific, stain. It is estimated that more than 99% of all humans have suffered the pungent odor of cat urine. Cat urine like human urine is inherently ‘stinky’ and is a liquid by-product of metabolism. Urea, uric acid, and creatinine are by-products of metabolism that are nitrogen-rich and need to be expelled by mammals to keep the body oxygen-rich. These chemicals are soluble in water and thus are easily rinsed away as urine, which is the nitrogen-rich, pungent, odor we all love. A large quantity of human urine is ‘rinsed’ down the drain via toilets and plumbing. This urine is not allowed to dry or oxidize so the smell can be reasonably mild compared to cat urine exposed to air.

Cat lounging on a couch

So … we know urine stinks in general, but what makes cat urine so much worse?

Cat urine is inherently more odorific than human urine. One of the main reasons for this are high levels of 3-mercapto-3-methylbutan-1-ol, which is often called MMB. This is a volatile pheromone that we most identify with cat urine. And it gets more interesting… There is a carboxylesterase called Cauxin. A carboxylesterase is an enzyme, but unlike enzymes that are used in cleaning (see Phytolase®), a carboxylesterase (or carboxylic-ester hydrolase) converts water and esters into an alcohol and carboxylate. Esters with low molecular weight are commonly used as fragrances and found in essential oils and pheromones
Cauxin only exists in the urine of one mammal…cats. Cauxin hydrolyzes 3-methylbutanol-cysteinylglycine (3-MBCG) to make Felinine. Felinine is a sulfurous odorific compound, which then degrades (gets smellier over time) into MMB. Human urine generally does not contain any sulfur. Cat urine does.
Bunch of asparagus
Fun fact: This is what happens when you eat asparagus.  Asparagusic acid is converted into sulfur-containing compounds.  Asparagus makes human urine smell more like cat urine.

How to remove cat urine from fabrics and garments. 

  1. Thoroughly rinse the garments with water to the utmost degree. If the garment is water-safe, you want to dilute the cat urine oils and alcohols as much as possible (in this case… the solution is dilution) The urine will also crystallize making it even harder to remove, so you can potentially dissolve this or at least physically remove it. 
  2. Remember how we said enzymes (like Cauxin) are responsible for converting esters (odorific compounds) to make Felinine and its ultimate byproduct, i.e. the ultimate urine odor, MMB!  It just so happens that enzymes can also reverse this reaction in more ways than one.
  3. Uric acid is very non-polar (oil-loving), so even though maximizing the water solubility/dilution is important to removing what you can… ultimately, you’ll need a detergent (e.g. Dirty Labs Bio Laundry Detergent) and enzymes like protease to break down the peptide bonds (e.g. Phytolase)
  4. Enzymes will not only convert the MMB, felinine, and other esters and ketones into less odorific, less recognizable compounds, but also, they will hydrolyze the urea, which breaks it up into carbon dioxide and ammonia (also stinky, but this is not harmful beyond the general hazard of cat urine and all urine being technically toxic). It is ideal for this decomposition to take place in the laundering process where it can dissolve readily as polar (water-loving) molecules into the water.
  5. Wash your clothes with a triple-boost (heaping capful) of Dirty Labs Bio Laundry Detergent and use hot water if your garments are safe for hot water, if not, try to use Warm. No matter how good your detergent is… cat urine is exceedingly difficult to remove, so the heat can help even if it’s not the most energy efficient thing for regular use (*this is a special case!).
  6. Inspect your garment with your nose when it comes out. It should be good! If not, rewash again (repeat…) and you will have a better chance of success. 

    Kitten looking sad

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