RE: German Shepherd
MossyOak, I have a 6 y/o german shepard (Boone) that has picked up just about anything I have ever tried to teach him. Rolling over is the only exception. I bring him pheasant hunting with me, no, he doesn't retrieve for crap, but he loves to be an extra pusher and will stay between 2 people and flush birds that he smells. I bring him elk hunting and use him as a pack mule. I've also trained him to find metal ammo boxes for when we are out geocaching.
I have no doubt that you can teach him to track a blood trail. Make it a game for her and she will catch on.