I used to carry a collapsible baton until they became illegal in this state—not to hit the dog, but to push it away or give it something to grab. Rarely encounter dogs on my rides these days, but I've had experiences. Dogs are "hard wired" to chase and catch. As far as I'm concerned, any dog chasing me or coming at me is a threat, even if its intentions are entirely benign. Even a five pound dog under or in a wheel is going to be bad news for both of us.
Maybe I should consider "bending the law," with the baton, but I don't like the idea. Perhaps I should get some pepper spray.