Horses have a sophisticated language of communication, which involves physical and tactile signals, or body language, such as the laying back of their ears and mutual grooming. Smell is also an important form of communication: the animals produce and receive pheromones, smell messages, which are produced by the skin glands.
Foals instinctively recognize the smell of their dams. Members of a group are identified by what may be a corporate odor. Smell also plays a significant part in sexual behavior. The pheromone sent by a mare in estrus (season) is a clear message to the stallion that she is ready to mate. She also sends physical messages, the flashing of the vulva, for example, and the adoption of the mating posture when she holds the tail to one side. She communicates just as clearly if she is not ready to accept the stallion's attentions, by baring her teeth and attempting to bite or kick him. She may further indicate her displeasure vocally by squealing. Though horses are not as territorial as other animals, stallions do scent-mark their territory with urine over the urine or feces of mares within his group, sending a clear message to outsiders that the mares are part of his harem.
Stallions check the reproduction cycle of mares by sniffing their vulva and urine. As the mare approaches estrus, the stallion becomes excited and indulges in a form of foreplay. He licks the mare and engages in tactile stimulation, which may be accompanied by flehmen, the curling back of the lip. Flehmen is not always associated with sexual excitement. It can be provoked in both sexes by strong and unusual smells and tastes, such as garlic, lemon or vinegar.
Horses can communicate vocally. Squeals and grunts are usually signs of aggression or excitement. Snorts are made when horses see or smell something that interests them or something that is potentially dangerous. Horses whinny for separated companions, and may whinny out of excitement. A mare will whicker softly to reassure her foal, and both sexes make the same noise in anticipation of being fed or receiving a snack. Some horses even learn to attact human attention by whinnying loudly if their feed is delayed.
It seems certain that humans do communicate unconsciously with horses by the smells they exude. Frightened people and even aggressive ones too, give off odors that reveal their state of mind to the hypersensitive equine, either causing it to become apprehensive or aggressive, depending on whether the animal is of a recessive or dominant nature. Old-time horsemen smeared their hands in aromatic fluid when dealing with young or difficult horses. The saying "a bold man makes a bold horse" is revealing of the horse's hypersensitivity and another example of communication between the species. Horses sense their rider's moods and react accordingly.
Horses also communicate through the closely related senses of taste and touch. They do so when they groom each other, thus creating a friendly relationship. Humans seek to communicate or introduce themselves by touching and patting horses. In fact, it might be more effective to do as horses do and blow into the nostrils. Grooming is another way to communicate with horses and it builds up a relationship between the two.
It is not difficult to understand that a horse standing with a hind hoof rested, head down, ears held slightly back, lower lip hanging and eyes partially closed, is in a relaxed state. The posture of tension is equally easy to interpret. Horses that turn their quarters to humans who enter their stalls are sending an unmistakable message. Stamping a hind leg, shaking the head and/or swishing the tail are signals of irritation.
Horses' ears give crystal clear messages. Enormously mobile, they can be rotated at will, controlled as they are by 13 pairs of muscles. Their positions reveal the horse's state of mind. Pricked firmly forward, they indicate a strong interest in some object and a corresponding lack of attention to the rider. When relaxed or dozing, the horse lowers the ears and allows them to become flaccid. When laid hard back, they indicate displeasure, temper or aggression. Twitching, mobile ears are comforting to a rider for they assure him that the horse is attentive.
