Shouldn’t happen. On shared space the cyclist should stop. Loose dogs are more unpredictable but most owners with retractable leads will bring the dog under control. I’m scared of dogs but haven’t had any real issues. I’ve had to stop 3 times so not to risk hitting a loose dog. Only one owner didn’t apologise - it was one of those tiny things in a jumper, more rat than dog and was at great risk of getting trodden on as she was walking it through a busy shared space.