Horse Communication
Here is a page all about how horses communicate!
     Smell: Horses have a very good sence of smell. With their sence of smell, they can recognize both human and animal friends. Horses can also smell the fear scent that is given off by humans. This explains the tension that is communicated when a rider exhibits fear.
Body and Facial Language: Body and facial language is an important way of communicating for horses. Fear, curiosity, and aggression are often displayed in this manner. When horses are scared, they often flare their nostrils and flatten their ears against their heads. Aggression can produce similar facial expessions but should not be mistaken for fear. Aggression normaly be accompained by a clamped down tail, an open mouth, or a raised leg.
Oral Communication: Physical expressions are often used with oral communication. Snorting, associated with a long stare, is how a horse tells its peers there is danger or asks if they are under threat. Horses determine wheather an intruder is a friend or foe by a large blow through the nostrils, similar to a snort. Nickering is a friendly type of communication used between horses or to humans that they see as friends. A squeel or scream is a warning sign and may mean that a fight is about to start. A horse uses a neigh to locate other horses or announce its own presence.
Horses comminicate using touch, smell, body and facial language, and oral communication. Touch: Horses use touch to communicate with each other and humans. This is why the horse responds to leg and seat preasure of the rider. Horse's whiskers are used to touch and feel objects, mainly  food. Horses groom each other as a form of bonding. They also nuzzle each other as a sign of friendship.