The horse and rider will often communicate anxiety, or even outright fear, to each other. The handler must realize that the horse uses fear to protect himself in his wild environment. One horse in the group senses danger and they all immediately become alert and ready to flee.
Fear is something which a vervous rider can easily convey to a horse.
Just about anyone who has been around horses for very long recognises this. What many people don't realize is that horses can teach humans how to master fear. Prey animals can't spend their entire lives in terror, so they have to be able to manage this emotion. We can learn from them in this regard. Dan was hitched alongside a large and very experienced wheel horse named Prince.