Eh... no. ALL dogs have an instinct to "cull the weaking" as part of pack behavior. This is unlikely to be triggered if there's just one dog, but with two or more (and it does not matter what breed) -- ANYTHING that
goes down and screams is liable to trigger this "culling" behavior. Kill the rabbit, kill the weakling, put the injured pack member out of its misery. At that point species, breed, temperament, and training are no longer relevant. Even the mildest-natured, best-trained dog can be involved.
This is why serious dog attack incidents generally start with someone tripping and falling down, or a child falling and screaming, and why the owners cannot understand why their otherwise-meek dogs attacked granny or chewed little Johnny.
And pitbulls are not involved any more often than other breeds, but the media has a habit of calling any solidly-built dog a "pitbull" because that's where the Scare Factor is today, so that's what garners more eyeballs. (A generation ago it was Dobermans; before that it was German Shepherds; and in the Prohibition era, the scary dog was Collies.)
Incidentally, pitbulls were developed to fight each other, NOT to attack man; in fact one that bit its handler would get a bullet and be out of the gene pool. Conversely, German Shepherds (and Boxers, and a few other breeds) were developed specifically as a mankiller, and it's only through later breeding efforts that they became at all suitable as pets.
At any rate, don't be afraid of some specific type of dog; rather, exercise sensible behavior around any dog. You're in charge, not the dog. And don't leave little kids or anyone unstable on their feet alone with any animal, that's just common sense. Most of the time nothing will happen, but dogs are dogs, not humans. They react as dogs.
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I mentioned "you're in charge, not the dog". This is probably the biggest problem I see in "dog training" today -- the owner fails to be in charge, and dogs, not being wired to take over that position, will bully instead of leading. Training with treats exacerbates this (in nature, the underling gives the bribe to the boss -- you can see the problem!). I've been in dogs over 40 years and when I started, we never had the kind of behavior problems I see with today's "feelgood" training.
Koehler was right.