As a runner, dog trainer and owner of three herding breed dogs, I just want to interject a little in this thread.
If you are running and a loose dog charges you, stopping and turning to face the dog without making eye contact is usually your best bet. Also, say SIT or NO is a firm, deep voice. The vast majority of dogs will at least stop at this and you can turn and walk away. If they follow, turn around and repeat the NO or tell them to GO HOME. If you keep running, they will keep chasing. I would rather stop and face a dog I don't know than continue to provoke its prey response.
Of course, this won't stop a truly vicious dog but lets face it, 95% of us aren't going to outrun a truly vicious dog either and most of the dogs we meet on the road are not intent on doing serious bodily harm to runners. They are over stimulated and out of control. Stopping helps to diffuse the situation and significantly reduces the chance that a dog will nip or bite.
Should you have to stop? No of course not! Dogs should be onleash, behind a solid fence or under voice control. But in a less than ideal world, runners should be prepared to act constructively in these situations. I just wanted to add this for those runners who may not be dog people - mostly I lurk here.
Lisa
PS - Being a herding breed is not an excuse. It's simply a set of genetic predispositions that require appropriate training to control and direct. It's no more appropriate for a herding breed dog to chase people than any other breed. She is chasing, not herding. Herding instincts are only a modification of prey drive and without appropriate channelling will quickly get a dog in trouble.