Sadly, it's heard all too often about people who own dogs, even guardian breeds, who are attacked while with the dog, and the dog does nothing.

It happens all the time.

Plus, and I'm not downing German Shepherds at all, but poorly bred shepherds are notorious for tucking tail and running when the going gets tough. I used to petsit for someone who owned German Shepherds, and they were the biggest chickens in the world. If you said "Boo" they ran.

I've had the unfortunate chance to find out that my great dane will not only menace someone who is threatening me, but will engage them as well. Not all dogs will do this, despite the scary growling/showing teeth display. That's just a warning. When push comes to shove, a lot of dogs will back down and flee.