Dog Repellant Experience?
Maybe just carry a 6' hickory walking stick. Most dogs will stop in their tracks and think twice when they see you raise that into a swinging stance. It's pretty hard to empty a can of bear spray at close range and not end up shellacking yourself in the process if the wind's in your face. I always carry beef jerky in my vest for such occasions. Haven't met a dog yet that would rather sink his teeth in me than a good chunk o' jerky. Made a lot grumpy dog friends that way.
Possibly bear spray. It seems pretty strong, and comes in big sizes. It also sprays far.
there are IoS apps that are available that send ultrasonic sounds that would prevent dogs from coming close to you. I tried it on my cats and dogs and you notice that their tails go between their legs and they look uncomfortable when I turn it on so I know that it is working.
I found my machete to be a pretty effective tool the one time in 33 years i needed to use it.
If all of the above fail, there's always this: