“There are but four venomous beats among the fauna of the United States. These are the rattlesnake, the copperhead, the moccasin and the spitz dog, and of the four, the latter is by far the most aggressive in its hostility to man.”
Again, the spitz:

the dachsund (during the height of WWI) the German Shepherd
the Doberman
the St. Bernard
...often w/ some dubious science abt how that type of dog was uniquely aggressive and resistant to pain.
The stigma around pitbulls is very similar — they have the most dangerous bite! they were bred to be killers — but the reason it's prolly stickier is its proximate to a hardy set of antipathies toward Black people.