Thanks to the seminal work of Robert Sapolsky, in “Why Zebras Don’t Get Ulcers,” we now have a much better understanding of the disparity between the way animals in their natural environment handle stress and the way humans do.

As a result of this intensive study, we can also ascertain that both the value of identifying and responding to, the physiological triggers of alarm. And with all that being said, one would not be stretching too far to hypothesize that horses also do not get ulcers. However, nothing could be farther from the truth.

Horses, like zebras, live in a natural environment. That is, roaming wild and fending for themselves. Yet, on the other hand, a vast number of horses do not enjoy this lifestyle. And here, we have a very interesting study. The truth is, not one case of ulcers in wild horses has been found. On the other side of the equation, racehorses, whose lifestyle is extremely demanding exhibit ulcers in 1 out of every 5 horses at the track.

Looking at the difference in the life of a wild horse, which is relatively serene, with healthy social group dynamics, and allows for freedom of response, and that of a racehorse, which is intensely demanding both physically and mentally, is lived in near complete isolation, and restricts freedom of movement, it is not hard to understand why these numbers would be so far apart. It is, indeed, a bit like comparing life in rural Colorado to downtown New York City.

But why then, do some racehorses get ulcers, and some do not? Well this phenomenon is best explained by the same principle that explains why some people suffer mental illness and others do not, when raised in similar environments. Called the “diathesis stress model,” this theory states that some people have a genetic predisposition for certain mental illnesses, and with enough environmental stress, theses conditions will develop. Therefore, in turn, we can say that some horses are predisposed to develop ulcers, but require the right situational conditions to do so.

So how do the ailments caused by stress affect the horse when engaged in equine therapy? Well for one thing, the horse’s natural ability to deflect stress, and therefore remain calm, is disrupted. Essentially what this means is that the horse is sort of chronically wired, or high strung.

When interacting with a novice horseperson, as most equine therapy patients are, this horse is actually likely to induce more anxiety in the person, and more to the point, the kind of anxiety that cannot be resolved through the relationship with this particular horse. Even worse, the person’s response of fear may aggravate the horse’s already disrupted physiological system, which then exacerbates the person’s worry as well. Essentially, the two are fused in physiological escalation that can’t be easily resolved.

This is a bit like an already anxious mother trying to calm her child without attending to her own out of control anxiety. The child is triggered by the mother, which sets off her anxiety even more, and the two soon relate almost exclusively through the anxiety. In this way, the anxiety becomes the glue in the relationship and the two know no other way to relate.

In order to disrupt this cycle then, and provide for a healing experience for both the horse and the person, the horse depends on a trained horseperson to help mitigate and recover from the effects of stress. Once the horse again realizes his own natural ability to offset stress, he may then be ready to perform equine therapy.