Generally speaking, it's a bad idea to run from carnivors (dogs, lions, tigers, bears, oh my). That just turns you into a prey animal, AKA Dinner. Dogs really can't help it, that's just the way they are made.

They are pack animals, though, so what I do is the Alpha B**ch thing. I make myself as big as possible and give a good low menacing growl: "Don't you even think about it" or a commanding bark: "NO! Get back!" has worked so far.

That being said, I have Halt and if I ever need it, I will not hesitate.