Physical contact with other horses is vital to the mental well-being of your horse. A horse's sense of smell is far more acute than that of a human being. They're much easier to correct if you know their origin. Understanding herding instincts will help you interpret your horse's behavior. About Horses human and animal, by smell alone.
Horses are also able to smell the fear scent that is given off by humans.
This explains the tension that can be communicated when a rider or handler exhibits fear. Body and facial language are primary communication tools for horses, with fear, curiosity and aggression often being displayed in this manner. In the case of fear, horses often flare their nostrils and flatten their ears against their heads. Aggression, which can produce similar facial expressions, on the other hand, should not be mistaken for fear. Such expressions of alarm would normally be accompanied by a clamped down tail and in more defensive stages, by an open mouth and a leg being raised.