This is a stub for Practical equine psychology. Currently, material is being moved from horse breaking that may need further editing.
Horses, unlike domestic animals like cats and dogs, have never formed a voluntary symbiotic relationship with their human keepers. Horses are prey animals, which run in herds, and have a highly developed flight instinct in order to avoid becoming food for predators. Nonetheless, because their physiology is peculiarly suited to the accomplishment of a number of human-related jobs and entertainments, humans have domesticated horses and pressed them into service for centuries.
The clearest and most fundamental pecking-order relationship in horse herds is that between mare and foal. Foals and young horses display subservience and a "don't hurt me - I'm harmless" message to other members of the herd by drawing the corners of their mouth back and open - creating an almost "keyhole" effect at the corners of the mouth, chewing dramatically, and lowering their head. Mares exhibit this same behavior (among others) to signal acquiescence to a breeding stallion. In mature horses, a less dramatic chewing motion, lowered head, and cautious approaching walk signals simple acquiescence. A mare will discipline and reassert her dominance over a misbehaving foal by raising her head and tail, and moving aggressively toward it. If it fails to retreat, she may make eye contact as a further threat, bite it at the rump or withers, or even resort to a mild kick. She will keep the foal at a distance and keep it moving away with these actions until it offers to return meekly with lowered head and chewing motions, indicating submission. She will in turn accept the contrite foal with her own lowered head, turning sideways, and perhaps engaging in mutual grooming. The pecking order is firmly established when she moves slowly away and the foal follows at her shoulder no matter which way she turns. Roberts calls this point in the relationship "join up."
A senior mare or "herd mare" will assert her dominance over the other mares in the herd in much the same way.
