You can train a dog to do as much as you have time for, and their ability.
I don't know how to train a dog to blood trail, but my last dog would scent trail. I would just point to the last know spot and command "search" and he'd run down the duck, goose, ground hog or deer to it or the hole or last spot he could find scent. Made it easy to find downed deer, real easy to what hole the ground hog ran too that you saw, ect.
"If you can't have fun doing it, it ain't worth doing, or you're just doing it wrong."
River hunting in my Wilderness Systems Kayaks; Commander 120 and Ride 135
My Blog archeryrob.wordpress.com Confessions of a fisherman, hunter and tinkerer