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Does Cat Pee Glow Under a Black Light? Science-Based Facts & Tips

Written by: Rachael Gerkensmeyer

Last Updated on June 3, 2024 by Catster Editorial Team

Black light illuminating cat urine markings on a wall

Does Cat Pee Glow Under a Black Light? Science-Based Facts & Tips


Dr. Paola Cuevas Photo


Dr. Paola Cuevas

MVZ (Veterinarian)

The information is current and up-to-date in accordance with the latest veterinarian research.

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Cats can easily be trained to use a litter box because they are generally clean animals and prefer keeping their bathroom contained and separate from their living spaces. However, sometimes, cats can have accidents in the house. It could be that their litter box is too dirty for their taste, they have health problems, or they simply made a mistake.

Whatever the reason, the scent of a cat’s urine can really stink up the place, especially if you can’t find the stain to properly clean it up and neutralize the odor. So, if you’re smelling cat urine in your home, you are probably wondering how to find the stain so you can get rid of the smell once and for all. We have the solution for you: a black light!

Here’s what you should know about how black lights can find and make cat urine glow and how to use one to find urine in your home.

cat paw divider

How Does a Black Light Find and Highlight Urine Stains?

The wavelengths that black lights emit interact with the phosphorus and proteins in urine, making them glow under the light. Any cat urine stains in your home that have not been cleaned with a bio-enzyme cleaner likely harbor phosphorus and/or protein even long after they have dried up. Therefore, black lights can usually pick up old cat urine stains when you’re hunting for them.

The longer the wavelengths that a black light emits, the more powerful and effective it will be when looking for urine stains.

How to Use a Black Light to Find Cat Urine Stains

Black light UV LED Flashlight
Black light UV LED Flashlight (Image By: DanceWithNyanko, via Wikimedia Commons CC BY-SA 4.0)

Utilizing a black light to find cat urine stains in your home is as simple as ensuring that the room is dark, then holding out the light and slowly moving it around. The room that you’re working in needs to be dark enough to see the black light illuminating. If it’s too bright in the room and you can’t clearly see the black light stream, you likely won’t find any urine stains even if they’re right in front of your face.

When a cat urine stain is present, it will glow bright yellow (sometimes with a greenish tint) under the black light.

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Top 3 Tips for Finding Cat Urine Stains

While the process of finding cat urine stains with a black light in your home is easy in general, there are a few things that you can do to make it even simpler and more satisfying overall.

Tip #1: Know That the Darker the Room Is, the Better

The darker the room that you’re working in is, the easier it will be for you to see urine stains with your black light. Therefore, it’s a good idea to close the curtains and turn off all the lights (aside from the black light) while you work. If necessary, you can turn on a nightlight for safety reasons.

Tip #2: Pay Close Attention to the Nooks and Crannies

Cats can spray the corners of rooms and right at the edges of furniture. If you’re just checking the floor, you could be missing a few stains. Take the time to inspect the corners, around the furniture, and even under the rugs while you’re working with your black light.

dry cleaning of an old white mattress
Image By: Olga Aniven, Shutterstock

Tip #3: Mark the Stains That You Find

When you find a urine stain with your black light, mark the place with tape or string so you can go back to the stain and clean it after you turn the lights back on. This will help ensure that you know exactly where you need to clean. Consider surrounding the stain with the marking material so you don’t clean too little or too much surface area.

cat paw dividerWhat to Do When You Find Old Cat Urine Stains

Once you identify and mark the cat urine stains, you can get rid of lingering odors and stains by utilizing a bio-enzymatic cleaner. It contains good bacteria that work to “digest” and neutralize odors and stains. It doesn’t just cover up the smell; it will get rid of the phosphorus and proteins so absolutely no odor or stain is left behind when all is said and done.

Follow the directions on the product that you decide to invest in to get the best results.

close up of woman in rubber gloves with cloth and derergent spray cleaning carpet at home
Image Credit: Ground Picture, Shutterstock


Final Comments

Cat urine stains can be a pain, but they don’t have to be everlasting with the help of a black light and a bio-enzymatic cleaner. If your cat tends to have accidents, even if just occasionally, in your home, it’s a good idea to check for stains once a month or so.

Featured Image Credit: In The Light Photography, Shutterstock

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