Sorting Out Abnormal Oral Behaviors

As a species, horses have an interesting repertoire of unusual oral behaviors. The most common of these behaviors are cribbing (also called crib-biting), wind-sucking, and wood-chewing.

Cribbing This behavior is characterized by the horse grasping a fixed object with the incisors, bearing down on the object with an arched neck, and drawing air into the cranial esophagus, which causes the distinctive grunt. Once a horse begins cribbing, the behavior seems to be permanent, though severity or intensity differs among horses. Close observance of one foal found it cribbed 50% of its day. In another study, researchers found that a group of confirmed cribbers engaged in the vice an average of 1,470 times during a 22-hour stabled period.

Domestication and captivity seem to incite the behavior, as cribbing has not been reported in feral horses, though it has been observed in captive Przewalski’s horses. Diet seems to play a role in the development of cribbing, as it seems to increase in those horses fed a low-forage or high-concentrate diet. The behavior is also associated with gastric ulceration. Though stress has been advanced as a cause of cribbing, studies have been inconclusive.

Wind-sucking Though the terms are often used interchangeably, cribbing and wind-sucking are not identical. While the two behaviors are similar, horses engaged in wind-sucking do not set their teeth against an object.

Wood-chewing Cribbing and wood-chewing are two distinct behaviors. Horses that wood-chew often engage in the vice in a variety of postures rather than the familiar arched-neck pose of cribbers. Posture typically depends on the location of the object being chewed. Most importantly, there is no sudden intake of air associated with wood-chewing. Though wood-chewing is a separate behavior, it often coincides with or precedes cribbing.