Perseverative responding and the aetiology of equine oral stereotypy

Crib-biting horse required significantly more unreinforced trials (P < 0.01) and overall button presses (P < 0.01) to reach extinction criterion compared to control animals. Thus, crib-biting horses demonstrated characteristics of increased perseveration suggesting alterations in basal ganglia physiology. These results tend to dissuade from the hypothesis that crib-biting is a method of producing additional saliva to ameliorate visceral discomfort, but studies combined might suggest that visceral discomfort has an important role to play in the alteration of basal ganglia activity that then manifests itself behaviourally as oral stereotypy.