I had a run-in with a Patou sheepdog just west of Riez, France last year, frightened the life out of me! I was walking along a flat section of the GR4, saw a flock of sheep ahead but didn't really take much notice. Suddenly the flock parted and this enormous white Patou dog came charging at me, barking, slobbering and looking for blood!!!
I stopped dead in my tracks and started to walk backwards and luckily this 'saved' me! The dog stopped, it kept barking and slobbering though so I walked back a few more paces. The dog then decided to return to the flock, I didn't move for a while, I just waited until the flock drifted away from me and the path and then strolled on. I felt lucky!