Radiographic and endoscopic study of horses performing an oral based stereotypy.

This research investigates the phenomena of oral based stereotypies in horses, such as cribbing or wind-sucking, using radiographic and endoscopic methods. It reveals that these behaviors do not correlate with swallowing, no air reaches the stomach, and the characteristic noise occurs during the intake of air through towards the cricopharynx.

Understanding Oral Based Stereotypies in Horses

• This paper investigates the misunderstandings in the veterinary literature about oral based stereotypies, including crib-biting and wind-sucking, in horses. Stereotypy is a repetitive behavior that doesn’t serve an apparent purpose, and often includes mannerisms like cribbing (biting a fixed object and arching the neck while sucking in air) or wind-sucking (similar behavior but without biting onto an object).

Methods and Observations

• The research used fluoroscopy and endoscopy, imaging techniques that allow the study of organ movement and functioning, to observe the horses’ behavioral sequence during crib-biting or wind-sucking. This made it possible to understand how the tissues in the pharynx (back of the throat) and oesophagus (connecting path from throat to stomach), and the column of air within, behaved during these stereotypic acts.

Key Findings

• The observations revealed that crib-biting or wind-sucking actions in horses are not related to deglutition, the process of swallowing. This goes against previous perceptions.
• It was noted that the characteristic noise associated with wind-sucking happens when the air rushes into the cricopharynx, a part of the pharynx, not when it is swallowed to the stomach as previously assumed, because no air was observed to reach the stomach.
• The study also saw transient dilation (temporary expansion) of the upper oesophagus during these stereotypic behaviors.

Proposed Mechanism

• A proposal in the paper suggests that the contraction of the neck’s strap muscles during these behaviors may create a pressure gradient in the surrounding soft tissues, which induces the movement of air from the pharynx into the oesophagus.

Implications and Suggestions

• The research helpfully sheds light on the mechanics of these behaviors, which have been poorly understood and misrepresented in veterinary literature. It suggests the need for revising the definitions related to these stereotypies particularly in the context of horse sales, where misunderstanding could impact the accurate determination of a horse’s condition and value.