Oh dear - such a familiar story especially with the collie types. But having said that when my first child was only about 18 months one of my Labradors flew across the room and went for him, scaring his face - nothing too dramatic but even so enough to still see the mark on him 40 years later!
We just muzzled her between his getting up time and going to bed, she settled to it beautifully and was an angel from them on, so long as she had the muzzle on. Some might think the muzzling cruel, we did not - the aternative was PTS as I would never pass on ANY breed of dog that has bitten a child, provoked or not.
Collies are a different matter altogether - in my opinion, any collie needs at best a days work to do, at the very least serious exercise every day, very few non working homes provide this, and that is when it all starts to go pear shaped. So sad you feel you have to rehome or PTS - but I do appreciate that even as a fanatical animal lover, even
my children came first!
The rescues are packed to the brim with every type and breed of dog with this background.....and because of the history many just go straight to the death chamber with no hope of reprieve....not having a go at you and your family in particular as I don't know the full background story but one does get rather exasperated by this continual flow of working type dogs that have found themselves shipped off to death row because their owners didn't realise what facilities needeto be in place to keep the type happy and healthy, physically and mentally.
Sad thread altogether.