I don't find dogs to be much of an issue while on tour. In ~13K miles I only remember being in fear twice and they both occurred on my tour this summer in South Dakota. One dog stopped when he reached the end of his fence (even though he was outside of it) and the other stopped when my yelling alerted its owner who came outside and gained control of the dog. If I'm passing a house where I suspect aggressive dogs might be and I can see there's no traffic in either direction I'll cross the road and ride as far away as I can.

I did use bear spray on a dog on a local ride once. Bet he never did it again