In some countries dogs are considered a delicacy. In others, they are treated like vermin.
I've been bitten twice while riding, chased inumerable times. The chasers I don't mind are the "regulars". I know where they are, how fast they can run, and what gear I need to be in when the sprint starts - also, it's fun to screw with riding buddies that aren't familiar with the suprise sprint. Still pisses me off somewhat.
The stealth chasers and biters are a different story. I will defend if I must, just as I would an aggresive driver. But you gotta pic your fights. The two giant wolfhounds in one incident were actually dragging the lameass owner by their leashes on a dirt road as they chased me. I was pulling a trailer so my sprint was weak and one got me on the thigh. I did not stop as these dogs were out of control.
My biggest pet peeve is dog owners that are blind to dog ****. Ever run over one of these obstacles? High speed, knobby tires, and dogs inevitably result in flying dog****. Not a problem on the road, but the last couple of rides I've had to pick the **** out of my tires, brakes, drivetrain, and HELMET! I hate recycled dog food.