People who say dog attacks are 'not the dog, but the owner' are wrong.
It absolutely is the dog, every single time without exception, and for one very simple reason - dogs do what dogs do, and there are no, that is NO exceptions.
Dogs are pack animals, and they operate on a status and pecking order system.
In a wild pack, the biggest strongest dog leads the pack, and stays leader until one of the lower dogs decides to take a chance and challenge for leadership.
This goes one of two ways - if the pack leader is still strong enough, he will vanquish his opponent, who, if he survives, remains in his place to fight another day.
If the upcoming dog wins, the leader is deposed, the new leader takes over, and so on, until someone catches him on the day when he is too old or ill to win, and he loses his pack as well.
Elsewhere in the pack, there may be other fights for position, with a younger dog taking on an older, in order to move up the pack, and eventually challenge for the top job.
Transmit that system to a family, and you have the dominant adult, usually the male, and the rest of the pack, including the children, and the dog.
Even though the dog is brought up with children, and never even looks sideways at them, his pack instinct is still there, because it's bred into all dogs.
And although the dog is likely to be too intimidated by the sheer size of the adult human to challenge for the top job, the leader, there is nothing at all stopping them from moving up the pack, especially if the next up in line is small enough for them to have a go at.
That is one of the main reasons why family pet dogs attack children without warning, it's time for a change in the pack order, and the dog fancies a chance to move up, by asserting its superiority over the next in line, and there is only ever one way to do that.
No matter how loving and well trained your pet is, that instinct is primal, and unchanging, and any dog, from the biggest to the smallest, can feel the urge to move up the line, and do something about it, with no prior warning whatsoever.
Of course, the vast majority of dogs live happily in their pack, and stay in their position.
But that's luck, not training, or breeding, or anything else.
If the dog is big enough to harm or kill a child, its instinct has horrific consequences - and of course he's 'never done that before ...' - the first time is the last time.
I would never have a dog of any size around children, it's simply not worth the risk of expecting a dog not to do what dogs do.