I fooled with Blackmouth Curs for quite a few years and never messed with one that wouldn't trail up wounded deer naturally.
Through observation, I've come to believe that wounded animals give off a trauma scent and it is that, rather than blood, that dogs trail.
Now they CAN and will zero in on a bloodied deer when brought up from downwind, but as far as trailing one up that is wounded, it is the trauma scent they are following. That's why they will pay no attention to trails left by other, unwounded, deer.
I expect any breed of dog can smell it, but some are not inclined to follow it.
My dogs would trail elk that were not wounded or bloodied.
I do believe deer would be a little more difficult.
