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Find information on animal health topics, written for the veterinary professional.

Behavior Modification in Horses

By Karen L. Overall, MA, VMD, PhD, DACVB, ABS Certified Applied Animal Behaviorist, Research Associate, Psychiatry Department, Center for Neurobiology & Behavior, University of Pennsylvania

The most commonly used techniques to modify animal behavior include habituation, extinction, desensitization, counterconditioning, and shaping. A behavior modification technique called flooding (see Behavior Modification in Horses) is not used very often because it has the potential to make most animals worse. While it is claimed that punishment is frequently used with varying degrees of success, few people correctly employ punishment. For punishment (for example, screaming at the horse) to be successful, it must occur sufficiently close to the onset of the behavior. Most punishments are inappropriate in context, duration, or time of application.

Most of the passive, or positive techniques involved in behavior modification are not hard to learn and are successfully employed as preventive techniques. They do require a regular investment of time and effort, however. The following is a short review of the basic principles involved in the techniques, and their associated strategies.

Habituation is an elementary form of learning that involves no rewards. It is merely the ending of or decrease in a response to a stimulus that results from repeated or prolonged exposure to that stimulus. For example, horses placed in a pasture bordering a road may at first run away when traffic passes, but eventually learn to ignore it. A horse that habituates to one type of sound does not, as a consequence of this habituation, become habituated to other sounds. Habituation is distinct from failing to respond to stimulation as a result of fatigue or injury. The effects of habituation are generally long lasting. If a horse is repeatedly exposed to a potentially harmful stimulus (such as to a predator) without being harmed, habituation does not generally occur. Responses to dangerous stimuli seem to have an inherited resistance to habituation.

Spontaneous recovery is associated with habituation. If there is a long time between when a horse has experienced an event to which it had habituated and re-exposure to the same event, the horse may again react.

Conditioning refers to associations between stimuli and behavior. For example, a horse that touches an electric fence will receive a painful shock. It will quickly learn to avoid touching the fence. The sight of the fence itself will then become associated with the shock.

Reinforcement is any event that increases the chance that a certain behavior will be repeated. When positive reinforcement (such as a reward) is used in training, there is a positive relationship between the behavior and its consequences. The more the horse does a behavior, the more it gets positive reinforcement and what it gets is good. This makes that behavior increase. A negative reinforcement (which is mistakenly thought of as punishment by many people) is something unpleasant that increases a behavior when it is removed. For example, most horses find the application of spurs to be painful. When the horse starts moving, the spurring stops. This reinforces the behavior the rider wanted. Over time, the horse will start moving as soon as the spurs are applied.

Second-order reinforcers are signals that can be used at a distance to let the horse know that the reward is coming. Commonly used second-order reinforcers are words, such as “good girl,” hand signals, and whistles. By carefully pairing these with a primary reward (such as food), second-order reinforcers can elicit the same response that the reward would.

Extinction is a response that stops when the reward is removed. For example, if a horse was used to getting a carrot as a treat for coming up to the fence of a paddock, but then the owner stopped giving it a carrot, the horse would eventually stop coming over to the fence. The more valuable the original reinforcer, the longer the reinforcement has been continuing, and the more uncertainty there is about whether the reward has been truly removed, the greater the resistance to extinction.

Resistance to extinction can also occur even without reinforcement if the reward was good enough and was tightly linked to the behavior. Because there is often an association between getting the reward and the intensity of the behavior, the intensity or frequency of the behavior you are trying to eliminate usually increases at the beginning of extinction. In other words, a behavior you are trying to extinguish may get worse before it gets better. It is critical that you do not give in. Giving in will only make extinction more difficult. The horse will learn that, although your threshold has increased, the horse can override it by working harder.

Overlearning is the repeated performance of an already learned behavior. It is frequently used in training for specific events. Overlearning accomplishes 3 things: it delays forgetting, it increases the resistance to extinction, and it increases the chance that the response will become an automatic or “knee-jerk” response in similar situations. This aspect can be useful in teaching a horse to overcome fear or anxiety.

Shaping is a training technique that works well for horses that do not know what response is desired by the trainer. Shaping works through gradual approximations and allows the horse to be rewarded initially for any behavior that resembles the desired behavior. For example, when teaching a horse to load on a trailer, at first you might praise and stroke the horse for just taking 1 or 2 steps toward the trailer’s ramp. Next, you would reward it for walking calmly up to the ramp. Finally, the horse would be rewarded only for completely entering the trailer.

Avoidance is essential until you can seek qualified help, particularly in the case of an aggressive horse. With treatment it may be possible to desensitize the horse to circumstances in which aggressive behavior occurs, but avoidance is the key in minimizing danger. Avoidance does not mean that the horse has control, or that the owner is giving in. Rather, it means that the horse is not being given the chance to exert control in its usual manner. Every time a horse becomes aggressive, it learns that aggression may help it cope with the situation, thus reinforcing the problem.

Desensitization is a way to teach a horse to tolerate a situation by exposing it to the problem in a series of small steps. For example, a horse that is fearful of having its hooves picked may need to be desensitized to having its feet handled. This could be started by first rubbing and massaging the upper leg, then gradually working down to the hoof. The leg could also be picked up and held for a few seconds, gradually increasing that to several minutes over a series of training sessions.

Counterconditioning is a method for reducing undesirable behavior by teaching the horse to replace it with another more favorable behavior. In the hoof-picking example, the horse will learn faster if it is first taught to stand calmly and relax in exchange for a treat. The horse must be absolutely quiet and calm, and convey by its eyes, body posture, and ear position that it is not alarmed. Once this behavior is learned, the desensitization is added by handling the leg closer and closer to the hoof. If at any time the horse starts to become anxious or agitated, the trainer should handle a higher part of the leg until the horse relaxes again. There is no point in forcing the horse to submit to handling if it is clearly distressed. Relaxation is the first step to changing the behavior. Counterconditioning coupled with desensitization is a time-consuming technique. The exercises must be repeated often so that the fearful response decreases until it disappears.

Flooding is prolonged exposure to a stimulus until the horse eventually stops reacting. This is the opposite of the approach taken in desensitization. It is far more stressful than any of the other treatment strategies and if not used correctly could make things worse. This technique should be used only by a professional and only as a last resort.

Punishment is also known as aversive conditioning. It is any unpleasant event that lowers the chance that a behavior will be repeated. Punishment is not the same as negative reinforcement (see Behavior Modification in Horses). To be most successful, punishment must occur as early as possible (within a few seconds of the start of the behavior), and it must be consistent and appropriate. Critical factors in punishment include timing, consistency, appropriate intensity, and the presence of a reward after the undesirable behavior ends. This is the most frequently ignored part of treatment for people whose horses have behavior problems. Owners often resort to physical punishment as the first choice, but punishment does not need to be physical. Furthermore, punishment is just as hard to use correctly as counterconditioning and desensitization. Punishment is never an “easy out” and has a high chance of failure. It can also lead to other negative consequences, such as increased fear or aggression.

Use of Medication to Treat Behavior Problems

Your veterinarian may, in some cases, prescribe medication to help treat a behavior problem in your horse. Drug treatment for almost any behavior change is most useful when combined with behavior modification (see Behavior Modification in Dogs : Use of Medication to Treat Behavior Problems).