Dogs can definitely be a problem.

I notice when I ride the bike paths that any loose dogs encountered tend to be a non-issue. This is the exact opposite of dogs encountered on the road who come flying out of their yards. Obviously it's a territorial thing with them.

I've found a few tricks that may help. The one that seems to work best is ignore dog, look away from it and pedal as if it isn't there. Another good one, especially when startled, is to yell a loud "No!" They all know that word. Sometimes it stops them in their tracks.