There seem to be a lot of stories about dogs chasing bikes, but not attacking, so, it would seem that they are just playing, or protecting their territory.
From what I have read in the replies a lot of cyclists have attacked, or would attack, dogs, which surprises me, as I thought that regular cyclists were generally peaceful people.
As there is no evidence of dogs bitting cyclists, don't you think the best bet is to continue on your way and ignore them.
However, I have found a friend who has an electronic device for scaring dogs and I am going to try it out next weekend. Just in case...