She was a perfectly normal little mare with no serious vices--until the accident that literally peeled the hide from her chest. Two hours of surgery and many stitches later, she was sentenced to stand cross-tied for two weeks while the wound healed. Although we walked her as much as possible and kept a hay bag full of fresh hay within reach at all times, Peppi found the enforced confinement stressful and boring. Eventually, she began to crib.

The reason horses crib, or windsuck, is an ongoing debate. Is it a stable vice? A result of confinement, boredom, stress? Obsessivecompulsive behavior? An addiction? Is it dangerous? How can it be controlled or better yet, cured? The answers are varied and often controversial, with different experts having diverse and sometimes conflicting ideas, beliefs, and experiences.

Because of its undesirability, cribbing is considered a stable vice by some; however, there is more to this behavior than training and discipline can correct. Is it caused by confinement, boredom, and/or stress? In many cases (as with Peppi), the answer is a definite yes. But, why in a barn of many horses does only one or two learn to crib, while the rest seem perfectly happy?

Finally, could cribbing be an addiction? Or perhaps a mysterious affliction known as obsessive-compulsive behavior? To answer these questions, we must first understand the definition of these disorders, and what happens mentally and physically when a horse plants his teeth on a solid object and proceeds to suck air.

Research has shown that when a horse cribs, natural pleasure-inducing endorphins are released into the brain, thus making the act of cribbing pleasant for the horse. One pleasurable episode leads to repeat performances and soon the behavior becomes entrenched-a habit is formed.

This follows the natural pattern of how horses learn. Behavior reinforcement is the basic premise in most training philosophies. The whole concept of pressure and release training is to present an uncomfortable stimulus until the horse responds appropriately, then provide a reward by stopping the stimulus. Repeating the stimulus, then releasing for the same desired result, teaches the horse to search for the reward-a habit is formed.

This analogy is not exactly accurate, for while the learning premise is the same, the differences are significant. Proper training is beneficial for the horse and most do not go around repeatedly sidestepping without an outside stimulus. The habit of cribbing goes much deeper than a simple learned behavior pattern. It pushes into the realm of abnormal behaviors in that, while creating a pleasurable sensation, the behavior damages the horse both physically and, if severe enough, mentally. (Some horses actually prefer cribbing to eating).

In humans, the dysfunction of obsessive-compulsive disorder (OCD) involves recurrent and persistent thoughts, impulses or images that areintrusive and inappropriate and that cause marked anxiety or distress (DSM-IV). This is a simplified description of obsession, and may be irrelevant to this discussion because we have no way of knowing exactly what the cribbing horse is thinking.

However, the next part of this disorder, compulsion, is described in the DSM-IV as :

(1) repetitive behaviors (e.g., hand washing, ordering, checking) or mental acts (e.g. praying, counting, repeating words silently) that a person feels driven to perform in response to an obsession

(2) the behaviors or mental acts are aimed at preventing or reducing distresshowever these behaviors or mental acts either are not connected in a realistic way with what they are designed to neutralize or prevent, or are clearly excessive.

There are other and more in depth criteria for a human diagnosis of OCD, but what is recorded here is sufficient to understanding this line of reasoning when applied to cribbing. Seeking release from boredom, stress, etc, the horse becomes driven to repeat a behavior that does not relieve the boredom, stress, etc., but instead becomes detrimental to the horses overall well-being.

A simpler, more direct explanation (and one I endorse) is that cribbing is an addiction to an endorphin thrill, similar to that created by sexual stimuli. Some synonyms for addiction include habit, compulsion, dependence, need, craving, and infatuation. Addiction and OCD are similar disorders and both are being defined in relation to human beings, and therefore are not fully accurate in this context. However, they do provide a workable analogy for understanding cribbing.

But why only certain horses? What initiates cribbing in one horse, but not others in similar circumstances? There is no easy answer. Even in humans, the exact causes of mental and addictive disorders are not fully understood. Genetic predisposition (not born with, but subject too) combined with environmental situations can create unhealthy responses and outlets in some individuals.

Cribbing may be one method by which stressed, bored, nervous, or ill horses find an outlet for their pain. Biting, nibbling, tasting, and chewing on available objects leads to an intake of air that produces pleasure. Repetition develops into an annoying and dangerous habit that, without early and consistent intervention (which is often not successful), becomes a lifelong addiction.

Next time: Cribbing, Part II Prevention and Control

Note: The DSM-IV is the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision of the American Psychiatric Association.