Horses bite one another to communicate.
If you have been around horses for any length of time and had the opportunity to watch them interact with one another, you may have noticed that they have a tendency to bite one another on the necks. This neck biting is part of the way horses communicate with one another. You often have to take into consideration other body language as well as the situation to determine what message the horses are trying to convey to one another.
Self-Biting
If a horse is biting its own neck, chances are it is doing it for one of two reasons: either it is scratching an itchy place on its neck or it is attempting to rid itself of a bug or other irritant that is touching or biting its neck. Horses do not have hands and hooves do little when it comes to scratching an itch on the top half of the body, so horses do most of their grabbing and scratching with their mouths, often giving the impression of biting.
Grooming
Herd members in the pasture will often be seen chewing and nibbling on themselves and one another as a form of grooming. Mutual grooming allows horses in a herd to bond with one another. This is part of the reason many equine experts recommend riders groom their horses to aid in developing the bond between them. The bites horses give one another, often on the withers or neck area, are not intended to do any damage. They are more likely to be the equine equivalent of scratching an itch for a companion. Mutual grooming is easily identifiable by the relaxed behavior of the horses. Their ears will be up or sideways and their behavior will seem friendly and comfortable.
Dominance
Horses are herd animals, and every herd has dominant and submissive members. Horses often bite as a part of establishing this dominance. Biting another horse on the neck can be a way of guiding the other horse or establishing that the horse doing the biting is the boss horse. You may notice mares nipping at their foals in this manner. Biting is a way dominant horses deal with misbehaving herd members. Dominance nipping rarely does any damage and the horses may seem slightly irritated or aggravated, but not outwardly aggressive.
Aggression
Some horses do bite due to aggression. Horses will lay their ears flat back, stomp hooves, rear and generally give a number of physical signals of attacking before they do so. Stallions will do this in the wild to establish alpha horse dominance over the herd. In captivity, food aggression is one of the most common types of aggressive biting, with the aggressive horses attacking horses and other beings that come near its food while eating.
Playing
Horses that are playing will often nip and bite at one another. You will see this fairly often in younger herdmates. They will bounce, rear, kick and bite but typically do not do any actual damage to one another. Their body language will be largely friendly.
Tags: bite another, with another, another often, biting neck, body language