Horses are large and powerful
They create a natural opportunity for some to                       overcome fear and develop confidence
The size and power of the horse can be naturally                   intimidating to many people.
Accomplishing a task involving the horse, in spite of
         those fears, creates confidence and provides for                   wonderful metaphors when dealing with other                       intimidating and challenging situations in life.
Horses are very much like humans in that they are               social animals. They have defined roles within their               herds.
They would rather be with their peers.
Horses have distinct personalities, attitudes, and                 moods.
An approach that seems to work with one horse,                  does not necessarily work with another.
Horses like to have fun. In other words, horses                     provide vast opportunities for metaphorical learning. 
Horses have the ability to mirror exactly what human            body language is saying

A Lesson to be learned is that if they improve or change themselves, the horses respond differently. Horses are honest, which makes them especially powerful messengers.
Why Horses?