I'd really hate to shoot someone's pet, especially if I had mistaken it's "friendly" intentions. With many publicized dog attacks and with just seconds to decide what to do, it can be a tough call. One skill that would be beneficial is reading the dogs body language. If a local dog has a bad reputation and he's loose and comes charging at you, that's getting pretty serious.........DOG BEWARE
If an unknown dog is running towards us, and not appearing vicious, I'd wait as long as I could. If children were nearby, and we didn't have time for higher ground, I'd make a move to attract the dog to me.