B.Sorrells dogs, Boyels (Dirty maria), Frisco/Lee ling.....hell i have seen Skull dogs that where smarter then the average bear Boo Boo "who bred them and why". Any line has the potential to produce inteligent dogs some more consistant yes but it can start with just one super smart dog that can pass that attribute. Along with some well thought out selective breeding followed by selective inbreeding on the desired trait trial and error. Man it sounds so easy

RoughNeck