I've always had good luck using "Halt" pepper spray. It's made for cyclists and postal carriers. It seems to work adequately and all dogs. The last ocasion I had to use the Halt, my wife and I were riding in unfamiliar territory when a large dog came after us. A loud shout to "git" didn't work, so when he got within 5 feet of my bike, I gave him a taste of pepper spray, which sent him into the grass with his muzzle on the ground like he was mowing the grass! A couple of weeks later we found ourselves in the same area, and the same dog barked at us and started out of the yard towards us on a dead run until he saw me come up with my can of Halt, and halt he did! He just sat there quietly and watched us ride by. Guess he didn't like the taste of hot pepper!