Aggression in Horses
Dr. Linda Aronson
Aggression is a natural and necessary trait for horses. It has enabled them, over many generations, to fend off predators, protect their young and maintain the integrity of their bands. While horses are not generally territorial, protection of food and other valued items does occur in domestic horses. In addition, humans have selected aggressive horses to be bred for war. To this day, certain breeds and lines of horses are far more aggressive than others. Mime bite – a head swing with the neck extended and a slightly opened mouth or nipping, directed towards the adversary's forelegs, head, shoulder or chest
For an animal, like the horse, that relies on his speed and endurance to escape prey species, fighting is a potentially life-threatening proposition, even for the victor. Injuries sustained during fighting can debilitate a horse to the extent that he becomes easy prey the next time. It also inhibits finding adequate food and water or from keeping up with his herd. For this reason the horse, like most other species, has developed a panoply of behaviors and expressions to convey his intentions to other horses so that actual fights can be avoided.
Many of the problems humans encounter in dealing with horses or other species could be avoided if we learned to recognize what they were "saying" to us. We will examine signs of aggression, dominance and submission in the horse, as well as the types of aggression seen in horses that stem from natural behaviors. Finally, we will look at physiological problems that can cause horses to act aggressively.
What is He Saying?
The horse is superbly equipped for visual communication, which is probably the primary mode for expressing feelings. The first clue to his level of excitement comes from his posture. In most situations, either both his head and tail will be up or they will be down. Rarely do the two extremes of his anatomy move in opposite directions. With increasing excitement, both head and tail tend to become higher. The submissive horse has a lowered head and tail and he will seem to be trying to slink along as low to the ground as he can. The more aggressive and dominant a horse feels, the higher the tail and head will be carried and the more confident he will appear. A somewhat elevated head, with a tucked or partially raised tail, may accompany a defensive threat. However, a sleepy horse will drop his head and tail, while a horse that is excited, eager to check out a new environment, or one that is moving at a faster pace than a walk, will also have an elevated head and tail carriage, so context is also important in judging posture.
The next set of clues to a horse's mood come from his facial expression, particularly the movements of his ears, mouth and nose. There are 13 pairs of muscles adjusting the position of each ear and 10 pairs moving the nostrils, mouth and lips. The aggressive horse's ears are laid back against his head, pushed flat against the skull. His eyes will be wide open and generally focused on the object of aggression, his body lining up to follow the forward-facing eyes. His nostrils will also be dilated drawing in air in case he is called upon to take further action. His mouth may be open and if he intends to bite, or threatens to do so, the incisor (front) teeth will be seen. If a bite or bite threat is being made, the head will drop and be extended – giving the neck a snake-like appearance.
The submissive horse's ears tend to spread out to the side or they are held backwards but not pinned against the head. In young horses in particular, a behavior that is usually described as jaw snapping signals submission. The head is extended with the mouth open and the lips drawn back. The jaws are then opened and closed, usually without the lips or teeth making contact. There may be a slight sucking sound as the tongue hits the roof of the mouth. This appeasing behavior has been variously described as either a ritualized grooming or eating display, both of which could be construed as calming, non-aggressive gestures.
The tail can also tell us a lot about a horse's intentions. The dock of the tail is tensed in the aggressive horse so that the tip of the tail flows further out behind as the tail itself is raised. If the horse is slashing his tail forcefully from side to side, or even more dramatically up and down, there is a good chance he will kick or lash out. This contrasts to the more leisurely tail swishing associated with brushing off flies.
Other signals that can help us judge a horse's intentions would include the way he orients his body. If he turns his quarters towards the object of his attention, or pushes at it with his shoulder, this would indicate either a dominant display or mild aggression. A submissive horse will try and scoot his lowered quarters away from the other animal or human. The tail will tuck under and the hindquarters will drop, while the head will deflect to the side so he is not looking directly at the other animal. If possible, the submissive horse will probably try to back away slowly. As aggressive displays intensify, a horse will:
Start striking – raising one or both forelegs off the ground or stamping hard - pounding his feet on the ground
Kick – vigorous tail switching accompanied by lifting one or both hind legs and extending both hind feet out behind.
At this level, it is clear from the lack of effort behind the motion that the movements are threats rather than intentional attacks. As antagonism increases, these movements will become more forceful.
In general, auditory behaviors tell us more about the level or arousal/excitement of the horse and less about his aggressive tendencies. Certainly high-pitched squeals may accompany aggressive displays or attacks, while throaty low-pitched nickers would be more appropriate for the horse that wishes to appease others.