Cat pee glows under a black light.

Cat pee glows under a black light.

In fact, if you can smell cat urine in your house but can't find the stain, you should use a black light to locate the stain to treat it. You should make sure to do this. Even if you can't find the cat urine, your cat will. He's more likely to pee in the same spot again if it still smells like pee.