A squirt from your water bottle works just as well. Assuming you can get the range with a water bottle.

I've been chased by my fair share of dogs, particularly in the hinterlands of Oregon where I grew up. What I've realized is most dogs are chasing you just because, well, you are moving. I think the mindset of the average dog is "moving thing, chase." It's the ones that KNOW what they are going to do when they catch you that worry me.

Mostly, I've learned not to pay them any mind. If they don't lose interest after an appropriate amount of time, I'll give them a shot of water.