Hi, my cat has started dragging her 6 week old kittens by the throat instead of the scruff of the neck and then she will bite their ears or face and try to drag them by this. The kittens don't scream or anything, but they freeze and then don't move for ages after my cat has let them go.

Is this normal? Do I need to watch out for anything? Other than this she seems to have been a fantastic mum...