When I was growing up, it was German Shepard until the late 70s and early 80s, and then it was the Doberman Pincher, and then Rottweiler (sp) and then the Pit Bull. It cycles through to the vogue dog of thugs and mindless power junkies (rednecks, gangsters, etc.) The history of dog-of-the-moment can probably easily be tracked by grindhouse flicks.