I've put on a lot of miles and have yet to encounter any dog that was dangerous to me.
Perhaps I've just been lucky, and I know many of you have stories to the contrary, but my advice is to keep the halt, mace, wasp spray, bear spray and anything else that will get you in trouble at home.
99% of the time the dog is protecting her territory by chasing you. When you stop, the dog stops. That's your sign that you are not being attacked. If they're persistent, a good squirt with a water bottle will send them home. If the dog is actually acting aggressive toward you, keep your bike between you and make a lot of noise.
A premature blast of mace that sends the dog squealing and writhing in the grass is not a pretty sight, and one that tends to get pet owners all riled up. i prefer to avoid that confrontation.
You say this dog is supposedly friendly. There's a difference between an "annoying chaser" and one that will hurt you. I would try to not overreact in these situations.