Abstract
Although stereotypic behaviors are a common problem in captive animals, why certain individuals are more prone to develop them remains elusive. In horses, individuals show considerable differences in how they perceive and react to external events, suggesting that this may partially account for the emergence of stereotypies in this species. In this study, we focused on crib-biting, the most common stereotypy displayed by horses. We compared how established crib-biters (“CB” = 19) and normal controls (“C” = 18) differed in response to a standard “personality” assessment test battery, i.e., reactivity to humans, tactile sensitivity, social reactivity, locomotor activity, and curiosity vs. fearfulness (both in novel and suddenness situations). Our analyses showed that crib-biters only differed from control horses in their tactile sensitivity, suggesting an elevated sensitivity to tactile stimuli. We suggest that this higher tactile sensitivity could be due to altered dopamine or endogenous opioid physiology, resulting from chronic stress exposition. We discuss these findings in relation to the hypothesis that there may be a genetic predisposition for stereotypic behavior in horses, and in relation to current animal husbandry and management practices.
Highlights
Stereotypies are defined as repetitive and invariant behaviors, which are thought to be a consequence of suboptimal environmental or housing conditions
There were no differences between groups CB and C in their time spent interacting with the person (“Conth”), standing attentive (“Att”), standing while resting (“Sr”) and standing while exploring the ground (“Sexpl”)
There were no differences between groups CB and C in their time spent interacting with the unknown object (“Conto”), standing attentive (“Att”), and standing while exploring the ground (“Sexpl”) (GLMM: effect of Group CB-C on Conto, X12 = 0.30, p = 0.58; effect of Group CB-C on Att, X12 = 0.67, p = 0.41; linear mixed-effects models (LMM): effect of Group CB-C on Sexpl, X12 = 0.67, p = 0.41)
Summary
Stereotypies are defined as repetitive and invariant behaviors, which are thought to be a consequence of suboptimal environmental or housing conditions. Stereotypies include locomotor (e.g., “pacing”) and oral (e.g., “sham chewing”; “crib-biting”) behavioral abnormalities, which can be debilitating for individuals, especially if they are expressed extensively. The causal factors and neurobiological mechanisms underlying stereotypic behaviors are only partially understood [2]. A recurrent hypothesis is that sustained “stress” or chronic stress, mainly in the form of restricted and suboptimal living conditions, can lead to the development of stereotypic behaviors in animals [2]. The idea is that if animals are prevented from executing some behaviors, this can facilitate the development of alternative behaviors such as stereotypies, via sensitization of the underlying neural systems involved [3]. The basal ganglia are thought to constitute the location where neural alterations might
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
