I have a UV flashlight I was given as a gift some years ago. Thus far I have not used it to actually do a tracking, but I did try it under a hanging moose at camp, and the blood glowed fairly brightly. I think yes it would be an aid. But it must be dark, or at least dusk, it would be pretty useless in daylight.
Blood does fluoresce nicely with a UV, just like it does on TV for all those cop shows.
My son has a cat, so I took and shone it around his apartment. He was not amused when it lit up everywhere the cat has sprayed. Also highlights over spray around the toilet.