A Neurologic Perspective of Equine Stereotypy

A novel approach to systematically compare behavioural patterns between and within groups of horses

“…Although many behavioural measures observed seem to confirm the grouping of calm and excitable horses, the figure highlights that heart rates and saliva did not fall in line with the interpretation that the excitable horses may be experiencing more 'stress' and calm horses possibly 'less stress'. This falls in line with research done on stereotypic behaviour which has identified different coping strategies dependant on neurophysiologic pathways, leading some horses to react in a more excitable and aroused manner, while at the other end of the spectrum some horses become withdrawn and quiet in response to repeated stressful situations with muted HPA-axis reactivity and dopamine pathways (Hall et al, 2008;McBride and Hemmings, 2009;Cabib and PuglisiAllegra, 1994). In future, measures such as spontaneous eye blink rate may be useful to establish dopaminergic function as a basic assessor of 'status' prior to selection of sample horses for behavioural studies (Colzato et al, 2009).…”

The physiological consequences of crib-biting in horses in response to an ACTH challenge test

“…Recently, Hemmann [43] found an unusually high prevalence of crib-biting in a small Finnhorse population, again suggesting that horses might inherit behavioral susceptibility to develop stereotypy. Other studies reported stress-induced alterations in the central nervous system (CNS) dopamine physiology in stereotypic animals [18,45,46]. This suggests that such alteration or sensitization in the CNS may be the result of chronic stress in combination with a genetic predisposition.…”

Cognitive differences in horses performing locomotor versus oral stereotypic behaviour

“…Weaving on the other hand is a locomotor stereotypy characterised by lateral movement of the head accompanied by contralateral shifting of weight on the forelimbs, with approximately 3-10% of horses performing this behaviour in the equine population (Cooper et al, 2000;Mcbride and Hemmings, 2009).…”

“…This is similar to that found in chronically stressed rodents, thus highlighting the potential effect of stress on striatal functioning, particularly of the ventral striatum (Cabib et al, 1998;Cabib, 2006;Dias-Ferreira et al, 2009). Therefore, it seems plausible that stress is linked to the receptor based changes recorded in the crib-biting horse (Mcbride and Hemmings, 2009). To date no similar neural investigations have been performed on horses prone to weaving.…”