a.k.a. Cribbing / Windsucking. An example of abnormal stereotypic behavior sometimes called a stable vice. Crib Biting is characterized by the horse first grasping a solid object with the incisors whilst at the same time flexing its neck muscles and drawing air into the oesophagus with a characteristic grunting sound. Windsucking is similar but does not necessarily require the gripping of an object by the teeth first. The movement is repetitive and apparently performs no useful function. It may be learned early in life and follow on from wood chewing. Approximately 4% of all horses will crib bite and the behavior can become dominant, happening hundreds of times daily. It is more common but by no means confined to stabled horses and may reduce in severity or disappear when horses are turned out to pasture. It is not known in wild horses.
Recently there have been suggestions that oral stereotypies like crib biting may be an attempt to increase saliva production for its buffering activity on stomach acid and related reduction in the discomfort caused by stomach ulcers. EGUS should probably be considered as a potential predisposing cause of the condition and treated if present. Cribbing horses have a distinctive gut microbiome but whether that is cause or effect is yet unknown. Deterrents like throat straps with metal inserts, neck cradles and radical neck surgery (Forcells operation) are no longer seen as appropriate.