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"Animal behaviorists say it's really no mystery but rather instincts, and virtually every dog has them. But when those predatory behaviors are exhibited by the larger, more powerful breeds, such as Rottweilers or pit bulls, serious injury or even death can occur."- On the contrary, any dog of any size, breed, or tempermant can inflict serious injury that can lead to death.
"But when Ashlynn's mother, D'ette Browning, looked out to check on her daughter, she saw the girl on the ground and one of the dogs standing nearby."
Here is the exact issue at hand, why in the world was a 4 year old playing outside alone? With or without dogs present. Do not leave young children alone with any dog of any breed or size.