My friends and I went to a couple of rides, that had several mule wagons. The horses were wth! But they soon got use to them, I had mine follow right behind, beside and in between the wagons several times, to help her get use to them for the future. My friends mare HATES mules. She would see one, her ears would pin, her mouth would open as large as she could get it, and lunge for those mules, she really had to watch her around the wagons, along with the mule riders. It was almost comical watching her, but could be serious if left unchecked.