The exact reason horses crib remains unknown. The most prevalent belief is that cribbing horses have unmet dietary or management needs. Some researchers also suspect a link between trace element deficiencies resulting in oxidative stress and the stereotypy.

Because trace elements such as selenium, zinc, manganese and copper protect the body from oxidative stress, one research group in Iran recently explored the hypothesis that oxidation status may contribute to cribbing. To test this theory, they collected blood samples from horses during or immediately after an episode of cribbing and when cribbers were resting. Control horses with no known history of cribbing were also tested. Then they analyzed the samples for various markers of oxidation.

The most important finding in this study was that blood serum selenium concentration was significantly lower in cribbing horses than in controls, with the lowest levels measured while horses were actually cribbing. Based on these data, the researchers concluded “that alterations in serum selenium, an important component of the antioxidant system, may play a role in the pathophysiology of cribbing behaviour in horses, adding further evidence to the theory that cribbing may be related to increased oxidative stress and alterations in essential trace elements.”

Management also plays an important part in minimizing stereotypic behaviours. Strategies such as providing environmental enrichment tools, offering free-choice hay or prolonged grazing, and allowing direct visual contact or prolonged turn out time in groups are thought to improve the welfare of affected horses.