The term stereotype derives from the Greek words στερεός (stereos), "firm, solid" and τύπος (typos), "impression," hence "solid impression".
Stereotypic behaviour, for example crib biting, is characterised by being undesirable, abnormal or a stable vice where a horse performs an anomalous repetitive behaviour (Budd, 2000; Fraser 1992; McGreevy, 2004). Crib biting has not been observed in feral horses, only horses within a domestic environment (Wickens and Heleski, 2010). Although this statement proposes the need to carry out research on stabled horses which crib bite to expose the causes, to date there have been no studies on crib biting as a stereotypic behaviour within the field; likely due to the cause of crib biting being in the stable. It is vital for stereotypical behaviours, such as cribbing to be explored due to underling health risks such as predisposing them to colonic obstructions and other types of colic, worn down incisors, an inability to put weight on and gastric ulcers (Litva et al, 2010; Hannes, 2008; Nicol et al, 2002). The purpose of this study is to observe a crib biter in the stable and in the field and compare the duration and frequency of the bouts of stereotypical behaviour; the aim being, to see whether the horse shows more of the stereotypical behaviour in the field than the stable.
Crib biting is a well recognised oral stereotypical behaviour occurring in horses (Ledbelt et al, 1998) which involves the horse to grasp a hard object, such as a stable door or fence post with its incisor teeth, contract its neck muscles while pulling back in conjunction with making a grunting noise (Ledbelt et al, 1998; Worthington, 1998). Although some studies believe the grunt to signify air passing into the oesophagus and thus into the stomach (Fraser, 1992 and 2010; Frape, 2010), others do not. In order for the horse to truly swallow, the tongue must be raised tip first against the hard palate of the mouth (in order to push the food bolus towards the phalanx) (Frandson et al, 2009). A Study by McGreevy et al (1995) captured the image of the upper digestive tract of a crib biting horse. The images showed the tongue was not seen to move during bouts of crib biting - instead air was observed returning through the cranial oesophageal sphincter muscle into the pharynx instead of following the tract down into the stomach. McGreevy et al (1995) continued the study further by the use of fluoroscopy and endoscopy to observe the pharyngeal and oesophageal tissues and of the air column, following observations of the images, the results concluded that air is not passed into the stomach during bouts of crib biting behaviour (McGreevy, 2004; McGreevy et al, 1995).
Crib biting, being abnormal, appears to have no goal or function but It has been suggested by many that the cause relates to a low forage or a high-starch diet and as cribbing incorporates the use of the lips and teeth it may help to satisfy the lack of foraging opportunities...