This would probably cause me stop riding!
Seriously, while I do have issues with the locals in my town who never walk their dogs on leash, it hasn't seemed to be much of an issue when riding, except in my own neighborhood. I've had one nasty encounter with my next door neighbor's dog, as did my DH. I attribute this to owner stupidity. If I had to prepare so much for a ride, in fear of a dog attack, the fear would stop me. I am not an animal lover and it is very hard for me to understand why people put up with poorly behaving pets. I mean, I don't like it when a dog even comes near me under any circumstance, let alone riding. During the one incident I had, I stopped the bike, on a hill no less, put it between myself and the dog and yelled like hell, "go home." I was ready to squirt my water bottle when it left.