Horse Facts & Trivia # 2:
In the wild a horse uses body language to communicate with the rest of the herd. The instinct in a domestic horse sometimes will be the same. A horse confronted by something frightening or potentially dangerous will analyze the threat and respond accordingly to the perceived seriousness of the danger.
1. Startle Response: The horse raises its head to look and listen intently. It pricks up its ears and points the forward, flares its nostrils to take in any potentially informative smells and opens its eyes to see as much as possible. If it perceives a threat, it may back off in a nervous way and begin pawing at the ground while still trying to find out what is going on. It may also snort, raise its tail and prance about then either wheel around on its hind legs in a defensive posture or stand and face the threat
2. Display of Aggression: If the treat is another horse it may display aggression. This involves thrusting its head forward, with its ears back, nostrils wrinkled up and back, and in rare cases baring its teeth. If the threat remains, the horse will normally move or lunge forward, with its head low and neck stretched out, ready to lunge at the treat if necessary.
3. Attack: If the horse or intruder does not withdraw, a fight may ensue. The horse will bite at another horse anywhere within reach. Males, in particular, often rear up with flailing forelegs, trying to come down on the back of his opponent in an attempt to get them on the ground where they can trample and kick them. Some horses, particularly mares, may also back into each other, kicking out with their hind feet.