Others here mentioned Zebralight for headlamps. The models that made them famous, with the natural white LED, impressive specs, and ran on a AA, is discontinued.
I'll agree, the white LEDs seem to work better for bloodtrailing.
But, last year I bought a Fenix E11 that runs on a AA with 2 brightness settings. I love that damn thing. I walk in and out of camp in the dark a lot. Usually I put my headlamp on low, so I can see 30 yards out or so, and keep the Fenix in my pocket and use it to flood areas well ahead of me to avoid confusion
I haven't had a chance to use it on a blood trail yet, but it's white enough that I don't see how it wouldn't work.