I've had 3 dog encounters and I don't ride on the road very often. I've only been on the roads since this spring.
All 3 were when I was climbing a hill. One very slow and steep hill, and the other two, hill shallow enough that I could stand up and motor away, but only for a short bit.
First was a German Sheppard. This was on the slow hill, I'm talking my speed is about 3-4 mph. He came out of a driveway and half heartedly trotted while barking behind me up the hill. He gave up when I went beyond his territory of what I could tell was the property line.
Second was a Golden Retriever. Same as the first, just trotted along within the yard along the road barking at me. If any dog is not going to attack a human, I think this is the dog. I was concerned though of it entering the road, catching me and knocking me down, then drowning in its slobber while it greeted me with its tongue.
Third was some sort of dashhound or something. I don't know dogs very well to know what they are. All I know is it flew out of the yard (while the big dog stopped before the road) and must have put its heart and soul into catching me. I could see it in my mirror and those poor little legs were a blur as it tried to chase after me.
Now the one I worry about. There is a road that I come out at a T to another road after my biggest climb. I'm exhausted only having about 30 seconds of recovering after the climb where directly across the road I'm exiting is a very large Pit Bull. He looks to be nothing but about 120 pound muscle. He's tied up to a box right at the road (amongst a mass of junk, this would be what we call Boofers here in rural western Pennsylvania, junk cars, junk tractors, and a dog tied up amongst 3 foot tall uncut grass.) As soon as he sees me, he lunges out of the box and flips upside down when he reaches the end of the short chain. Not sure what's going to happen if he ever busts off the chain.