As I wrote in my most recent 'your ride today' post, it's 'funny' (good word, funny - can mean anything from entertaining through puzzling straight to tragic) how dogs try so very hard to imitate and take a lead from their owner. They know no better.
Most dogs want to see its owner as the pack leader and 'instructor' if you like; with the best will in the world in this recent tragedy the owners had apparently 'bought' the dog a week ago so the predominant 'model' for the dog's ingrained behaviour would have been the seller - if indeed the seller was indeed the real previous 'owner' of the dog etc etc - and/or its previous owner/s.
And yes, to leave any dog - let alone a newly-purchased, and presumably adult, dog - with any child who is any of the following - unable, or possibly unable, to react appropriately to the dog/liable, or possibly liable, to react inappropriately to the dog /unaccustomed to said dog/unaccustomed to dogs in general/fearful of dogs and a whole host of other situations, for even the briefest of moments, is deliberately putting the child at HUGE risk and the height of irresponsibility. The less you know about the dog, the greater the risk ...
Yet most of us have at least read of - and I personally have experienced - dogs being the most wonderful protectors of 'their' pack, be they adult or child
TL; DR:
There are dogs which will warn of impending epileptic and diabetic episodes and I personally knew a working border collie which tugged and tore at a child's clothing while barking whenever it could, in order to hold back a small child from wandering onto a railway line. The child was not even one of its own 'pack' but had toddled out from the traveller encampment which was on the old brickworks next to the railway line. The dog had darted away from its owner (the farmer who neighboured the brickworks) as he was checking his own boundary fences (because of his 'new neighbours'); he must have sensed or been alerted to something 'not right' in some way. The family of the child were searching on the other side of the encampment, where it abutted onto the canal, thinking that water would be the temptation rather than scrubland leading to a railway line ...
When I was a child, my family took in a wandering mongrel which just 'turned up' one day; we called him Charlie and he was a very sociable dog. He used to play with us kids all day long when we weren't at school. One day we were playing in the woods, and the dad of one of the kids turned up with ropes and tools to build us a proper swing near our 'den'. It was soon finished and we all wanted 'first go'. After my friend Andrea had had a turn, Mr Martin lifted me onto the swing ; I screamed in excitement and as I screamed, Charlie hurled himself at the one he perceived as 'attacking' me ie Mr Martin. He put me down and Charlie was all waggy tail as he licked me as if to check I was OK. Then Mr Martin said to Andrea, if I lift you onto the swing again, will you scream like Norah did? I want to see if Charlie will protect all of you little girls. So they did, and Charlie did - not with quite the same degree of aggression as he had when it was me screaming but ... Mr Martin made sure that Andrea and I knew what a good dog Charlie was (I was trying to tell him he was a bad dog for attacking Mr Martin) and said he would tell our dads what a good dog he was, in case they got hold of the wrong bit of the story.
So I am inclined in favour of dogs and their responsible ownership, rather than opposed to them - but you know what, I think dogs should be removed forcibly and physically from those owners or keepers who do not take their responsibilities seriously.
There are very few inherently bad dogs - they are made so by irresponsible humans, and as such we humans should take full responsibility for their behaviour.