Brains and speed. I once saw a TV show where a dog pound dog had been trained to sniff out cancer cells and a collie could detect the smell of oncoming seizures in her owner. If these dogs who aren't bred for nose can smell these minuscule scents, then hog dogs have no excuse for not smelling hogs. The brain comes in because I want a dog to know with certainty that their only job in life is finding hogs for me. Screw his agenda or the day, he works for me.
T-Bob, I believe that quite a few dogs have a good nose. The difference I believe has more to do with genetics. Some dogs do not respond to a 6 hour track and yet others do. Something in the brain has to trigger for the dog to respond.MO