My approach when faced with a possibly dangerous dog in my path is to aim the front wheel at the dog's torso - I'd rather go over an aggressive dog and cause it some damage then go around it and be leaped upon by a dog in full health...
So far the dog always blinked first.
Any long absences on my part in future may suggest it hasnt worked and I'm in hospital.
In an ideal world I'd have a sword on my bike and kebab the thing. Its always f***ing staffys and similar things. They should all be destroyed.