I was bit by a Great White Pyrenees last year . I was rolling up to a blind country stop sign. Trees blocking east, west view 55 mph highway. Hidden in the bushes to my left were two Pyrenees I didn't see. I hear a growl and in a flash, had his fang into my calf before I could blink. I drove my fist down on his head and they both ran back into the bushes. The dog fence was dead I later learned. Don't think for a moment you'll always have time for a defense, you won't.