A long time ago a friend showed me a trick to repel aggressive security dog(s) at residences, commercial properties, or on the street. When a dog STARTS to get aggressive bend down and pretend to pick up a rock and motion as if you are throwing it at them. For some odd reason they run away, as if they have been hit before. The downside - if the owner THINKS you are harming their dog you may get your ### kicked. Or if this trick doesn't work you will get your ### kicked by the dog.

Please, NEVER actually throw anything at an animal or person.