Qualitative Behaviour Assessment of horses exposed to short-term emotional treatments

Assessing emotion in animals is fundamental to the study of animal welfare with methodologies for reliable and valid assessments being highly desirable. Qualitative Behaviour Assessment (QBA) is based on the assumption that human observers are capable of integrating details of animals’ behavioural expressions using descriptors (e.g. calm, playful) that reflect the animals’ putative emotional experiences. Our study aimed at assessing how treatments assumed to induce different short-term emotional states of both positive and negative valence would affect the observers’ judgements of horses’ behavioural expressions. To this end, 16 horses were each exposed to two positive (grooming, food anticipation) and two negative treatments (food competition, waving a plastic bag) while being video-recorded. Using a Free Choice Profiling methodology, fifteen observers who were blind to treatment were asked to describe and score the horses’ behavioural expressions based on 45 s long video clips. General Procrustes Analysis revealed consensus between the observers’ judgements. Three main dimensions of behavioural expression were identified, explaining 84.7% of the variation between horses. Dimension 1 (D1) was positively associated with the terms ‘calm/relaxed/content’ and negatively with the terms ‘nervous/stressed’, whereas dimension 2 (D2) was described as ranging from ‘irritated/impatient/angry’ to ‘frightened/insecure’, and dimension 3 (D3) was labelled as ranging from ‘curious/interested’ to ‘aggressive/irritated’. Linear mixed-effect models revealed an effect of treatment on the horse scores on all three dimensions (D1: F4,60 = 86.90, p