Dogs are wired to eat small and/or helpless things.
Even my saint..I had to teach him not to hold my daughter down by the back of her head...if the kids were running and he was loose, that's what he would do! He'd run over her, knock her down, then grab the back of her noggin and not let her up. He did it 2x and he doesn't do it anymore, but how quickly that could go bad!
I STILL don't leave my children home alone with all three of my dogs...I have the pit, the saint, and a terrier....and they are not physcially capable of restraining them, so I NEVER leave them alone with the big boys. They're fine with one, or the other...but never both. The dogs act differently when they are together, and my 11 and 10 year olds are not capable of commanding respect or physically restraining the dogs. So I never leave them alone. At night, I sleep with my door open, so I can exert control over the dogs. The pit usually sleeps with my daughter, adn the saint in my room or the living room..if he gets up and walks into the girl's bedroom, I make him get out. Because dogs interact with other dogs in a way that is different from the way we interact with them. One dog with my daughter views her as something to protect...two dogs might just view her as a toy.
You got that right...my last two Shepherds were brother and sister. Each on their own were mild-manned, quick to obey a command, and generally pleasant around strangers. But together out in public? LUNATICS!

Once my gal and I came out of a store I'd parked in front of and the two of them had their heads out the car windows (rolled down half way) snarling and growling at passersby to the point small groups had formed in each direction afraid to pass by them.
Since I rarely miss an opportunity to grandstand, I pretended we didn't know the dogs. I asked aloud how so many could be afraid of a couple dogs cooped up inside a car....most of them looked down at their shoes. So I had to walk over to the car, tell them to "LAY DOWN" in a forceful voice, which of course they did, and we walked away to finish the stunt. I heard one guy say "that guy's got some balls on him alright"....