How about an air (BB) gun as an alternative weapon? Something like this: http://www.airgundepot.com/walther-cp99-compact.html The muzzle velocity would have to be high enough to really sting but not injure the animal. That should satisy the "moral" question you posed. I suppose the "stopping power" needed depends on the particular dog as well. Won't some breeds (i.e. pit bull) attack until death? It's not only cyclists who are at risk from killer dogs. In SC, it seems every couple of years there's a news story about some small child being mauled and killed by a pit bull. Senseless.