First of all, I'm NOT a dog lover. Never have been. It's probably due to some dog owners who are ignorant don't leash them, let them bark all night, etc. Anyway, I'm a runner and I constantly have to deal with dogs running up and almost tripping me because they're not on leashes or they are on leashes and people let them get to close anyway. As annoying and dangerous as that is, my main concern are the ones that growl and try to bite. Is pepper spray effective on dogs? I don't want to just scare them because that can make them more aggressive. (I have scars to prove that) I'd like to disable them long enough to get out of harms way
Nothing frustrates me more than irresponsible dogs owners, I'm a large breed dog owner of two Personal Protection security trained dogs. So if you are running in an area where it is not a designated off leash area then would I be wrong to assume that you may have similar laws to where I live and that it is against bylaw to have a dog off leash in a non off leash area? Where do you live?
Also, it is against the law here, even in an off leash area, for a dog to chase a member of the public in an aggressive manner.
If you are running it can trigger a prey drive in dogs so if you're running and a dog gives chase aggressively, for your own safety, stop running immediately.
CVW1004 has given very accurate advice on how to proceed.
It would be much more appropriate, and safe IMHO, that if such laws exist in your area to simply report the matter and have it dealt with legally, especially if this is happening with specific dogs and your post makes it sound like this is a regular occurrence.
As for 'disabling' a dog with pepper spray, please be aware (though as a non dog lover you might not be concerned) pepper spray can permanently injure a dog. So if you are running wielding an aerosol, I'd advise it only be used in the most dire of circumstances and not reactive to an irresponsible owner who's dog runs up to you and is of no imminent threat.
My friend's dog was sprayed as a joke whilst on his own acreage property by guys who were antagonizing him through the fence and it burned his eyes so badly it turned them white and nearly blinded him completely. The attached pic is of him after he was sprayed and the resulting damage.
So is it effective? Yes, you can potentially permanently blind them.
Will it disable them? It depends on your aim, also, be aware of wind direction and the potential to get dosed yourself or for you to harm people who are nearby.
My best advice is to deal with it legally, if this is indeed regular problem on your running route, as spraying someone's dog (especially a leashed dog) could rightly or wrongly lead to some aggressive owner confrontation.