Crib–biting is a stereotypic behaviour performed by approximately 5% of captive domestic horses. Dietary factors have been strongly associated with the development of oral stereotypies and risk factors for crib–biting, identified in recent epidemiological studies, include feeding high concentrate and/or low forage diets (Waters et al., 2002). Experimental work has shown that such diets are likely to result in increased gastric acidity (Murray and Eichorn, 1996; Nadeau et al., 2000). We therefore propose that young horses initiate crib–biting in an attempt to produce alkaline saliva to buffer their stomachs when alternative opportunities for mastication are limited. The aim of this study was to determine whether there was an association between crib–biting behaviour and stomach condition in foals.

Foals that had recently started to perform crib–biting were recruited into the study and compared with non–stereotypic foals. The stomachs of 15 crib-biting foals and 9 normal foals were examined using a video endoscope.