Whatever you do, DO NOT USE A BLACKLIGHT in your bathroom!
It will of course show human urine as well as pet fluids. I thought it would be fun to use the blacklight in the one bathroom my family of four shared. I still have nightmares, knowing there are more splatters and drips than you could imagine.
There are some things you just don't need to know.
Oh, and I have a carpet steam cleaner, and the detergent I use in it also "glows" under the blacklight. So if you didn't know that, you'd think my entire carpet was full of urine since it all glows! It does seem to be a different color (the detergent vs urine), though.