I was attacked by several dogs.
I have heard that yelling “no” will usually stop a dog because that is something most dogs (and small children 
) understand. Sometimes that works. I have been successful with out-racing small dogs.
I would not attempt to mace or tazer a dog while riding my unicycle. I have found that a quick dismount and using the unicycle as a shield is most effective. It prevents injury to the rider and lawsuits from the dog owner. The dog usually starts backing off as soon as I start coming down off the unicycle.
My most recent dog experience was with a yappy poodle. The dog’s owner was on the other end of the leash and she just laughed while the dog almost got caught in my Coker wheel. 