A cat standing inside a black and white litter box.

Why Cat Urine Smells (And What to Do About it)

If your cat has an “accident” in the house, there’s no doubt what the pungent smell is. So what makes cat urine soooo smelly compared to dog urine? And what’s the best way to remove the smell — for good?

The Chemistry Behind the Smell

Normal cat urine is mostly water (about 95%), but it also contains urea, ammonia, uric acid and creatinine, which are natural waste products of protein breakdown and contribute to its distinctive, acidic smell. The urea is broken down into ammonia by bacteria in the environment, which is why it’s important to scoop the litter box every day to avoid a strong ammonia stench emanating from the box. Cat urine tends to be more concentrated than dog urine (meaning it has a higher density or specific gravity), which contributes to making the urine smellier. But that’s not the only difference.

The Felinine Factor

Another reason cat urine smells different to dog or human urine is the felinine factor. Felinine is a sulfur-containing amino acid that is only found in the urine of domestic cats and their close relatives (e.g., bobcats and lynx). You can’t actually smell felinine (it’s odorless) but it breaks down into highly volatile, stinky compounds. Unneutered male cats have much higher concentrations of felinine which, along with testosterone, typically makes their urine the stinkiest.

When the Smell Is Different

You probably try to avoid smelling your cat’s urine, but it’s important to pay attention (particularly if they also went outside the litter box) because a change in smell could be due to a health issue. An abnormal urine odor could be from an infection, cystitis, dehydration or diabetes. So it’s best to contact your veterinarian if your cat’s urine smells a little different than usual.

Cat urine doesn’t contain bacteria (unless your kitty has an infection), but when your cat urinates, bacteria from the surrounding skin and fur can contaminate the urine. That’s why, if your veterinarian needs to collect a urine sample to confirm an infection, it needs to be done using a “clean” method that will avoid contamination from the environment.

Deodorizing the Odor

If your cat has urinated outside the litter box, the first (and best) thing to do is clean it up straight away. The stain will be harder to remove and the smell will become more concentrated the longer the urine is there. Also, if your cat can smell the urine, they will continue to use that spot. So if you see it, clean it.

The Ohio State University Indoor Pet Initiative has some great tips on getting different floor surfaces clean and making sure your cat doesn’t start a new habit. Here’s a summary of OSU’s cleaning tips.

Carpet: Blot the area with paper towels, then stand on a towel or stack of paper towels to continue soaking it up. Use a carpet cleaner or a few drops of dish detergent and water to saturate the area, and let it sit for one or two hours. Rinse by gently blotting and using a sponge with tap water, then soak the area with club soda for 10 minutes. Blot with paper towel again, then use a pile of paper towels or a towel weighed down with something heavy overnight. Finally, spray the area with an enzymatic cleaner — don’t use ammonia or ammonia-based products as this may attract your cat to the area and they may do it again.

Linoleum: Wipe up the urine with a paper towel or a mop soaked in soapy water. Rinse with warm water, then wipe with a sponge moistened with white vinegar and let the floor air dry.

Hardwood: Blot the urine, then use an enzymatic cleaner (that’s safe for hardwood floors). If the stain/smell stays, you may need to sand, bleach and refinish the floor.

Laundry: Wash using one cup of white vinegar only then run the washing machine again with detergent.

Find the Cause of Urinary “Accidents”

If your cat has decided the living room rug is a better place to urinate than the litter box, it’s important to find out why — before it becomes the new norm. There are many reasons cats break their litter box habits, including health issues, litter box aversions, behavioral or social problems and territory marking. This post can help you get to the bottom of the litter box problem, or for further advice, talk with your veterinarian. The quicker you can address the problem, the easier it will be to get your cat back on the right path (to the litter box).


RELATED POST: How to Manage Inappropriate Cat Urination

The information in this blog has been developed with our veterinarian and is designed to help educate pet parents. If you have questions or concerns about your pet's health or nutrition, please talk with your veterinarian.


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