Argentinian Dogo's are pretty incredible dogs. This is all rumors but I've heard they were bred to hunt bears or chase down escaping slaves and stuff, which is pretty cool. (not the slavery part, but the hunting of man part) Obvgiously personality is dog specific but of the few dogo's I've known they've all been pretty mellow. They were deliberately bred maybe 100-200 years ago mixing america bull dogs, grey hounds, big mastiffs and all sorts of other big dogs.