I used to enjoy my local MUP on weekends (which is officially a "hike and bike" trail) until I came upon a woman and her off-leash dogs. She had headphones on, so I approached from behind at near-walking pace, and of course one of her dogs ran across my path and I barely managed to get my foot out of the pedal and did the awkward low side squat--not quite falling down. She was genuinely apologetic and said she hadn't heard me coming. I bit my lip as I reckoned she had learned her lesson. The MUP is great during commuting hours though, since it's practically just us friendly cyclists.