I have a friend who is a letter carrier. She always has some dry dog food in her pocket to offer to loose dogs.

Once I was walking to church when a large aggressive dog shot out a screen door and across the street right at me. I had no doubt this dog meant to attacj me. When she was about three feet away, I said in the sweetest, most affectionate voice I could, 'Hi, doggie.' (dragging it out in a coo, the way we speaks to upset babies) The dog didn't bite me, simply settled for slamming herself against my legs. Then she shot back home.

I learned later that she had a litter of puppies. I have no idea why she saw me a threat. I had been carrying a bright red bag, and maybe that bag was the problem.

I'm not saying that rocks etc, are wrong. (I have no sympathy for people who let dogs run loose.) It's just that other things might work too.