What are horse stereotypies?
In the course of doing research in 1991, Mason described horse stereotypic behavior as "any repetitive behavior performed with no obviously discernible function." In addition, most researchers see stereotypies as abnormal behaviors that are detrimental to the health or performance of the horse. In some cases, they have been likened to the repetitive motoric movements of autistic children, such as rocking, swaying, or head banging.
During the past two decades, much research has been done concerning why horses develop these repetitive behaviors and what can be done to prevent actions that may have a detrimental effect on the horse's health and welfare.
Originally considered to be "vices" by many horse people because of the seemingly devilish attitude of horses engaged in these behaviors, most animal researchers and horse owners now prefer the term "stereotypies."
In general, stereotypies fall into three groups: oral; locomotion; and other. Oral stereotypies are usually identified as cribbing or wind sucking, wood chewing, bed eating, dirt eating or coprophagy, and mane and tail chewing. Locomotion stereotypies include stall walking, weaving, circling, pawing or digging, stall kicking, and head shaking.
"Other" stereotypies are not as well-defined and usually encompass natural horse behavior carried to the point that it becomes problematic, such as bucking, barn sour, or prancing. Whether these are true stereotypies is questionable since they are not repetitive behaviors engaged in for an extended period of time. In many cases, they are bad habits picked up by the horse as a result of poor training or interactions with people and other horses.
For example, if the horse pins its ears back and bites at the person getting ready to mount, it may get away with not having to take that person for a ride. In this case, the threatening attempt to bite becomes more of an avoidance behavior than a stereotypy.
What conditions lead to horse stereotypies?
- Unnatural feeding schedules and too much processed feed
- Stall confinement
- Lack of exercise
- Lack of socialization
- Genetics and/or temperament
- Fear and/or frustration
- Sudden change in routine
In fact, stereotypic behaviors are often seen as safety valves that allow the horse to survive stressful conditions. Horses that live in circumstances similar to those of animals in the wild seldom, if ever, develop stereotypies.
Most research indicates that when these behaviors reach the point of becoming stereotypies, this abnormal behavior can be equated with poor welfare on the part of the animal. This not only affects the health and well-being of the animal, but also affects performance. When conditions are corrected, the horses usually show a reduction in the occurrence of stereotypical behavior and an increase in performance level.
Keeping these facts in mind, all horse management should take into account the needs of the horse. Feed should be varied, and nutrition adequate, with as much foraging allowed as possible.
Housing for horses should provide sufficient opportunity for movement and a variety of stimulating activities. Social contact between horses should be maximized, with horses being kept in groups whenever possible.
Oral stereotypies are those repetitious movements the horse makes where the mouth and muzzle are involved.
Cribbing or Wind Sucking
Cribbing occurs when a horse bites down on an object, flexes its neck, then pulls back with its teeth while swallowing air. Some research indicates that the horse receives an euphoric feeling or a sense of well-being from these actions. Unfortunately, cribbing can lead to weight loss, colic, and excessive tooth wear. Causes of cribbing are usually thought to be boredom, confinement, and lack of exercise.
Wind sucking is similar to cribbing except that the horse does not necessarily bite down on an object. It flexes the neck and sucks air down into its lungs and/or stomach with a distinctive grunt after the inhalation of the air.
This behavior becomes compulsive, and if allowed to continue over a period of time, may lead to malnutrition, weight loss, and colic. Excess confinement and lack of exercise resulting in boredom are considered the main causes of wind sucking.
Wood chewing is a common occurrence in horses that spend most of their time in stables and are given limited opportunities for foraging in pastures where long-stemmed vegetation is available. Researchers have documented that a horse or pony can eat up to two pounds of wood daily, leading to damaged stalls, fences, and feeders.
Ingestion of slivered wood sometimes results in gastrointestinal irritation or obstructions. Often, simple management changes that include providing horses with plenty of roughage and adequate socialization with other horses, especially in a pasture setting, will help stop this behavior.
Research shows that the more time a horse spends eating, the less likely the horse is to engage in wood chewing. Lack of exercise -- leading to the need for a release of nervous energy -- is often seen as a factor in wood chewing.
Reducing tension, eliminating boredom, providing adequate exercise, and furnishing feed with a good amount of roughage often result in the elimination of wood chewing.
Coprophagy or Dirt Eating
Ingestion of fecal matter or dirt by a foal is considered to be a temporary behavior that helps establish a normal population of microorganisms necessary to gastrointestinal health. In addition, the mare's feces supply vitamins and minerals that might be lacking in the foal's diet.
When a horse begins repetitive eating of manure or dirt, it may be because of a nutritional deficiency of protein, minerals and/or fiber in the diet. Or it may be a developing stereotypy resulting from confinement, boredom, lack of exercise, or a change in the horse's daily routine causing excess nervous energy.
If the cause is lack of adequate nutrition or foraging time, a change in the diet and in the way feed is supplied will often correct the problem. If the coprophagy or dirt eating has developed into a stereotypy, it usually indicates that confinement, lack of exercise, and lack of socialization with other horses are the causes.
Changes in management of the horse's daily activities that allow plenty of exercise and socialization, plus the addition of either more foraging time or coarser hay often deter this behavior.
If coprophagy or dirt eating are allowed to continue over a period of time, the horse may become prone to colic, gastrointestinal ulcers, and other digestive disorders -- especially if the dirt eating results in ingestion of foreign objects, such as rocks, plastics, or other indigestible materials.
Mane and Tail Chewing
As foals mature, they often engage in some mane and tail chewing. In the cases of foals and younger horses, mane and tail chewing is often a result of playfulness or a way to relieve boredom.
In young horses, this chewing sometimes results in a less than attractive mane or tail. Some horse owners use commercial or homemade concoctions that contain cayenne pepper or other foul-tasting ingredients to discourage this behavior.
When an older horse begins routinely chewing either its own or other horses' manes and tails, it is cause for concern because of the potential for gastrointestinal obstructions or other digestive problems, particularly if the behavior develops into a stereotypy.
In addition, competition or show horses that engage in this behavior are at a disadvantage in the grooming category. Although deficiencies in diet may be a factor in a small number of cases, most cases are thought to arise from confinement and boredom.
Sometimes, simply changing to straw as a bedding material results in improvement in this behavior because the horse can engage in chewing activity that relieves boredom and provides an outlet for nervous energy. In other cases, a change in activity level and the addition of more fiber or roughage in the diet help deter this behavior.
Stereotypies rarely occur in horses living in their complex natural environments where a wide range of active behaviors occur. But in more confined environments, repetitive behaviors involving locomotion are seen as abnormal and indicative of welfare problems for the horse displaying them (Lawrence and Rushen, 1993).
Stall walking by stabled horses is a rather common occurrence and is usually the result of being confined in a small area, often a box stall, with insufficient exercise. In stall walking, the horse moves around the perimeter of the stall, eventually wearing down the flooring.
In some cases, the horse walks slowly, but in other cases, the walking is rapid and the horse appears agitated, often defecating and flicking the ears as it walks aggressively around the stall. Not only is this behavior destructive to the flooring of the stall, but it can also result in hoof and limb problems.
When stall walking takes up much of the horse's time and attention, it can lead to dehydration and loss of weight resulting from lack of interest in eating and drinking.
When a horse engages in weaving, it stands in place rocking back and forth in a repetitive fashion. Animals that have a tendency to be nervous or those that are confined to their stalls for long periods of time without contact with other horses are prone to weaving. Uneven hoof wear and lameness are common occurrences when a horse engages in weaving behavior. In addition, the horse may lose weight and become dehydrated if it engages in this activity to the exclusion of eating and drinking properly.
Some research shows that weaving increases with aging of the horse, especially if the horse tends to bedistressed or nervous.
Circling is similar to stall walking in that the horse circles around the stall compulsively, either slowly or in an agitated fashion, depending on the temperament of the horse and the amount of energy expended. Weight loss and lameness often become components of a circling stereotypy.
Pawing and Digging
In the horse's repertoire of movement, pawing has a number of meanings and uses. When pawing develops the repetitiveness of a stereotypy, it often reflects the horse's frustration or impatience with its environment and may be done with such a fervor that the horse seems unaware of its surroundings and becomes totally engrossed in the pawing action.
The pawing may take place in the stall, the trailer, or the paddock. The pawing leads to digging and can create deep holes depending on the surface where the horse is pawing. Pawing can result in abnormal hoof or shoe wear or to loss of shoes, and can lead to lameness and weight loss.
Stall kicking can be a vicious stereotypy depending on the energy level of the horse. Little anecdotal evidence supports the idea that most stereotypies are mimicked or copied from other horses; however, stall kicking is an exception, possibly because it may become a means of communication among horses.
Repeated stall kicking damages the horse's hooves and limbs and can cause serious injury. In addition, stall walls and doors are damaged and need constant repairs. As with other locomotion stereotypies, research shows that increased exercise and less confinement and more pasture time will decrease the amount of time a horse spends kicking at stall walls and doors.
Some head shaking is common for most horses and may be caused by a variety of factors, such as eye, ear, or tack problems, allergies, sensitivity to light, insects, and other irritants. When the horse's head shaking becomes a stereotypy, it usually begins as a habitualized response to stress and occurs in a repetitive fashion on a regular basis.
In fact, careful observation of the horse may show that the repeated head shaking has an almost drug-like effect on the horse, since the behavior triggers the release of endorphins in the brain, causing the animal to feel better.
If the head shaking takes place at events or while being ridden, it can affect performance. If it occurs only while the horse is in the stall, it is an indication of boredom and lack of sufficient socialization with other horses.
In some cases, head shaking occurs only with certain types of bits or tack, and if this is the case, it may be the result of discomfort, and once the discomfort is alleviated, the behavior stops.