Cribbing or crib biting is an abnormal, compulsive behavior or stereotypy seen in some horses, and considered a stable vice. It involves the horse grabbing a solid object such as the stall door or fence rail with its incisors, then arching its neck, pulling against the object, and sucking in air. Windsucking is a related behavior whereby the horse arches its neck and sucks air into the windpipe without needing to grab a solid object. Windsucking is thought to form part of the mechanism of cribbing, rather than being defined as an entirely separate behavior. Cribbing and windsucking have been linked as a causal effect to colic and stomach ulcers.
A similar but unrelated behavior, wood-chewing or lignophagia, is another undesirable habit observed in horses, but it does not involve sucking in air; the horse simply gnaws on wood rails or boards as if they were food.
Cribbing and windsucking have been linked to a higher incidence of stomach ulcers and are also defined as risk factors for certain types of colic. Colic can also be a consequence of wood chewing due to the ingestion of wood splinters. Both cribbing and wood chewing can cause excessive wearing and deterioration of the teeth in severe cases. Horses displaying these behaviors may be less desirable to potential buyers and may be devalued as a consequence.
It has been anecdotally reported that horses can learn to copy these behaviors from other horses, although this has not been substantiated by scientific study. Wood chewing also is destructive to barns and fences, sometimes requiring costly repairs and ongoing maintenance.
Wood chewing has been linked with dietary deficiencies, and often can be remedied with a balanced diet or dietary supplementation. Some cases are thought to be linked to boredom or anxiety, often related to confinement. Boredom, stress, habit and addiction are also all possible causes of cribbing and windsucking. It was proposed in a 2002 study that the link between intestinal conditions such as gastric inflammation or colic and abnormal oral behavior was attributable to environmental factors.
Researchers now generally agree that cribbing and windsucking occur most often in stabled horses, although once established in an individual horse, the horse may exhibit these behaviors in other places. Recent studies indicate cribbing occurs more frequently in horses that were stable-weaned as foals than in those that were pasture-weaned. In the same study, feeding concentrates after weaning was associated with a fourfold increase in the rate of development of cribbing.
Cribbing and wind-sucking may cause a sensation of pleasure by releasing endorphins in the horse's brain. More recently, it has been suggested that the increase in saliva produced during wind-sucking could be a mechanism for neutralizing stomach conditions in stable-kept, grain-fed horses. Stereotypies have been defined as "repetitive, invariant behaviour patterns with no obvious goal or function", therefore, if cribbing and wind-sucking have one of the above possible functions, it may be inappropriate to label them as a stereotypy. However, as the causes and resulting reinforcement for these behaviors are probably multifactorial and they remain abnormal behaviors, this indicates that husbandry changes are needed for animals that exhibit cribbing or wind-sucking.
It has been shown that feeding cribbing horses an antacid diet can significantly reduce its frequency. Current research indicates that the prevention of cribbing and related behavior is based upon management conditions which allow daily free movement and feeding practices that provide higher amounts of roughage and limited amounts of concentrates. A growing body of work suggests that fat and fiber-based diets may also result in calmer patterns of behavior.
There are a number of traditional methods for minimizing or preventing cribbing, windsucking, and wood-chewing. However, the effectiveness of these methods is arguable since they do not address the underlying causal factors. One method involves the horse wearing a collar-like device that prevents it from arching and swelling its neck to suck in air. Covering exposed edges with metal or wire or painting surfaces with bitter substances such as carbolineum or a commercial "chew stop" product may reduce wood-chewing, though do not entirely prevent edges being gripped by the teeth. Other methods to prevent cribbing have included surgery, acupuncture, use of pharmaceuticals, operant feeding, and environmental enrichment.
- Malamed, R.; Berger, J.; Bain, M. J.; Kass, P.; Spier, S. J. (2010). "Retrospective evaluation of crib-biting and windsucking behaviours and owner-perceived behavioural traits as risk factors for colic in horses". Equine Veterinary Journal 42 (8): 686–92. doi:10.1111/j.2042-3306.2010.00096.x. PMID 21039797.
- Archer, D. C.; Pinchbeck, G. L.; French, N. P.; Proudman, C. J. (2008). "Risk factors for epiploic foramen entrapment colic in a UK horse population: A prospective case-control study". Equine Veterinary Journal 40 (4): 405–10. doi:10.2746/042516408X312149. PMID 18487105.
- Litva, A.; Robinson, C. S.; Archer, D. C. (2010). "Exploring lay perceptions of the causes of crib-biting/windsucking behaviour in horses". Equine Veterinary Journal 42 (4): 288–93. doi:10.1111/j.2042-3306.2009.00025.x. PMID 20525045.
- Green, P.; Tong, J. (1988). "Small intestinal obstruction associated with wood chewing in two horses". Veterinary Record 123 (8): 196–8. doi:10.1136/vr.123.8.196. PMID 3176272.
- Dixon PM, Dacre I.; Dacre I. (March 2005). "A review of equine dental disorders.". Vet J. 2005 Mar;169(2):159-61. 169 (2): 165–87. doi:10.1016/j.tvjl.2004.03.022. PMID 15727909.
- Hothersall, B.; Nicol, C.J. (2009). "Role of diet and feeding in normal and stereotypic behaviors in horses". Veterinary Clinics of North America: Equine Practice 25 (1): 167–81, viii. doi:10.1016/j.cveq.2009.01.002. PMID 19303558.
- Nicol, C. J.; Davidson, H. P. D.; Harris, P. A.; Waters, A. J.; Wilson, A. D. (2002). "Study of crib-biting and gastric inflammation and ulceration in young horses". Veterinary Record 151 (22): 658–62. doi:10.1136/vr.151.22.658. PMID 12498408.
- Waters, A. J.; Nicol, C. J.; French, N. P. (2002). "Factors influencing the development of stereotypic and redirected behaviours in young horses: findings of a four year prospective epidemiological study". Equine Veterinary Journal 34 (6): 572–9. doi:10.2746/042516402776180241. PMID 12357996.
- Mason, G.J. (1991). Stereotypies: a critical review. Animal Behaviour, 41: 1015–1037 
- Bachmann, I.; Audigé, L.; Stauffacher, M. (2003). "Risk factors associated with behavioural disorders of crib-biting, weaving and box-walking in Swiss horses". Equine Veterinary Journal 35 (2): 158–63. doi:10.2746/042516403776114216. PMID 12638792.
- McGreevy, P. D.; Nicol, C. J. (1998). "Prevention of crib-biting: a review". Equine Veterinary Journal 30 (27): 35–8. doi:10.1111/j.2042-3306.1998.tb05143.x. PMID 10485002.