Towards a Postural Indicator of Back Pain in Horses (Equus caballus)

Abstract

Postures have long been used and proved useful to describe animals’ behaviours and emotional states, but remains difficult to assess objectively in field conditions. A recent study performed on horses using geometric morphometrics revealed important postural differences between 2 horse populations differing in management conditions (leisure horses living in social groups used for occasional “relaxed” riding/riding school horses living in individual boxes used in daily riding lessons with more constraining techniques). It was suggested that these postural differences may reflect chronic effects of riding techniques on the horses’ kinematics and muscular development. In the present study, we tried to evaluate the interest of postural measures to assess welfare in horses. This study was separated into 2 parts. First, 18 horses coming from these 2 types of populations (leisure/riding school horses) were submitted to 2 back evaluations by 1) manual examination (experienced practitioner) and 2) sEMG measures along the spine. We then measured neck roundness on 16 of these 18 horses. The results highlighted high correlations between manual and sEMG examinations over the spine. sEMG measures at the different locations were strongly correlated all over the spine. Moreover, neck postures and muscular activities were strongly correlated, horses with concave necks having higher sEMG measures both at precise locations (i.e. cervical sites) but also when comparing neck postures to the whole spine muscular activity highlighting the functioning of horses’ back as a whole. Lastly, strong differences appeared between the populations, leisure horses being evaluated as having sounder spines, exhibiting lower sEMG measures and rounder neck than the riding school horses. sEMG measures and neck “roundness” seemed therefore to be reliable indicators of back disorders, easy to evaluate in field conditions. This highlights the accuracy of using postural elements to evaluate the animals’ general state and has important implications for animals’ welfare evaluations.

Risk factors associated with health disorders in sport and leisure horses in the Netherlands1

“…Instead, to reach large sample sizes most studies rely on questionnaires sent to owners or caretakers or self-reports (Hotchkiss et al, 2007;Murray et al, 2010;Ireland et al, 2012;Lesimple et al, 2012). However, several authors have shown that the effectiveness of this method is debatable since the response rate may be positively biased (e.g., toward less problems) and owner or caretakers may severely underestimate possible health and welfare problems.…”

“…Pathological or painful conditions such as lameness, sore mouth, and back pain can arise through injury associated with inadequate housing, management, activities, and equipment (Wyse et al, 2008;Lesimple et al, 2010;McGowan et al, 2010;Murray et al, 2010;Ireland et al, 2012;Lesimple et al, 2012). Lameness was a frequently reported health problem by owners of dressage horses in the study of Murray et al (2010): 33% of the horses were lame at some time during their career.…”

“…In the same study of Murray et al (2010), 25% of dressage horses were reported to have a back pain problem by their owners. Other studies estimate the prevalence of back disorders to lie between 3.9 and 22% using questionnaire surveys (Lesimple et al, 2012).…”

“…The resulting physical health issues, such as lameness, back pain, and too fat body condition have been reported in countries in which horses are mainly used for competition and for pleasure (Wyse et al, 2008;McGowan et al, 2010;Murray et al, 2010;Ireland et al, 2012;Lesimple et al, 2012). To ensure that there is an acceptable level of horse welfare, an objective assessment or monitoring system is warranted.…”

Invited

“…Their observations reveal potential « candidates » such as the quality of the human-horse relationship or the attentional state. More recently, studies by Fureix et al (2012Fureix et al ( , 2015, Lesimple et al (2012Lesimple et al ( , 2013Lesimple et al ( , 2014, Rochais et al (2016a,b) have led to the emergence of visible (behavioural and physiological) indicators that converge with evaluations of physiological and sanitary measures. Because the perception of situations is subjective, using such indicators, allow an animal-centered approach that can help identify the factors of influence and their relative weight in determining horse welfare, (Lesimple et al in revision).…”