Oh wow - I am so sorry that happened to you - scary!! 
 
I always wonder what I would do...  Most of the time any dog that approaches us is coming to "say hi" - and the owners simply can't hold them back...  Sometimes they are offleash though, so, if I can't get away without yanking Welsey out of the way, I just give as much slack as there is, to put them on "equal ground" and say happily "hi puppies" or something and then move off as fast as I can...  I am trying not to tense up and pull everytime a dog runs at us, since I think that will probably make Wes's reaction worse, no??