Equines as prey animals are afraid of lots of things like bears, 2 foot rocks, charred tree stumps, backpackers especially if they are uphill, llamas, loud wind noises, gunshots, etc. "All equines are time bombs just waiting to go off." (Lee Roeser, 2nd generation packer).

This is their fatal flaw that makes horses, mules, and donkeys in descending order of flight response dangerous. They aren't afraid of being hurt, they are afraid of being killed. I would still love to go on a long hiking trip sometime with two good donkeys, and lead them from the ground.