Should I wash my dog?

so recently I was playing around with a black light and I saw a spot where my dog peed that id never noticed. you can’t tell when it’s dry, and I assume the accident happened weeks or months earlier, if not more. But my dog does like to lie down in that spot, yet there is no wetness, smell, or anything to give it away. so my question is if I should still wash her and/or the things she’s been laying on since? its been dry for a very long time, but I’m not sure how residue works. Thanks!