Jim Schaafsma of ArrowFive Outfitters in California has developed an incredible breed of dogs specifically for trailing wounded deer. They are a small terrier mix. Very friendly, active dogs that have trailed deer as far as is needed. If they don't find the deer, it isn't going to be found.
You would really be remiss in your search if you didn't at least talk with Jim.
Since the dog is only trailing the deer, and not dragging it to the ground, a small dog works great, and eats a lot less!
That said, I have an airedale that is extremely smart and friendly, and loves to hunt about anything, and wth very little training does a fair job at trailing deer. He'll retrieve ducks, hunt pheasants and grouse, roust out rabbits, kill coons, possums, skunks, and porcupines, and trail deer - then sleeps about 20 hours a day (though he's getting old now). A great thing about airedales is they hardly shed - most of the other breeds, especially the terriers, leave hair everyplace they go.