It’s an undisputed fact: horses crib to deal with stress and loneliness. It is, therefore, little wonder that horses, in especially intensive training, are known to crib more commonly than leisure horses.
Cribbing is a stereotypical equine reaction to stress and isolation. Long term stress inhibits the release of dopamine (Dopamine is a neurotransmitter that helps control the brain's reward and pleasure centers.) Cribbing stimulates the release of dopamine which creates a feeling of well-being, calm and increased capacity for learning.
A group of Swiss researchers found that cribbers who were allowed to crib during training had lower stress levels than those who were prevented from cribbing. In other words, there is something about the act of cribbing that alleviates stress.
The researchers took a sample of 19 cribbers and 18 non-cribbers and asked them to perform five simple spatial reasoning tests. There were no significant differences in performance or learning time between the cribbing and non-cribbing horses during the tasks. Earlier, comparative studies had suggested that cribbers take longer to learn that the food has been moved to a different bucket, (in what is known as a “reversal” test,) but this was not observed in this study. What was observed was that, despite the lack of differences in learning new tasks, there were notable differences in the cortisol levels measured between the cribbing and non-cribbing horses, when the cribbers were not allowed to crib during training. However, when the cribbers were allowed time to crib during training, their cortisol levels decreased and ultimately matched the levels of the non-cribbers.
Cortisol is the “stress hormone,” which can be measured through saliva testing. During the test, the horses who normally crib were allowed access to a piece of wood which was designated specifically for them to crib. When horses cribbed during the tests, their salivary cortisol levels dropped to that of non-cribbers. The research team stated that the study categorically demonstrated that horses who crib experienced greater stress while learning and that it could be counterproductive to prevent them from cribbing during periods of learning. Due to the impact of stress on the body, it could be detrimental to prevent a horse from cribbing when their stress levels are raised during training.
It is interesting that horses have adopted cribbing as a way to deal with stress levels. This research is a good starting point for more research into stress and its management in horses. One consideration for trainers, owners and riders is to monitor stress levels and try to minimize the amount of stress that horses are put under. It is apparent that to deal with stress, some horses resort to behavioral issues, and with that in mind, it may be useful to consider characteristics of a horse when planning a new training programs so as to not overstress the horse.
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