If you can't find blood or lose the blood trail, get a couple of friends and do a grid search. I think that most fatally hit deer die within 200yds of the shot - check out to at least 400yds for added insurance.
A trained dog will beat all the lights, sprays, grid searches, and whatever else you have hands down. Dogs are useful even if it has rained (up to 0.5") or snowed on the trail. I just started using Ruby last season. ... Go to the UBT website(
http://www.unitedbloodtrackers.org/) to find volunteer trackers. If dog trailing is not legal in your state, join UBT and start writing letters...
-fsh
