The weakest part of a dog is the back legs. If you can wrap your legs around the dog (if bigger), or somehow get to the back legs and pull them sharply, they will come out of socket, especially on German Shepherds. Fight over. Stomp the dog to death after that.
That seems like a lot of work while getting bit. I’m adverse to physical exertion while having my skin and muscle ripped apart, call me lazy, but I’ll stick to a firearm.