Validation of a fear test in sport horses using infrared thermography

The aim of our research was to assess feasibility and validity of a fear test in adult sport horses and to investigate if the exposure to a fearful stimulus induces a change in eye temperature. Fifty horses aged 14±6 years of different breed and gender entered the study. A novel object fear test (NOT), modified from Górecka-Bruzda (Górecka-Bruzda et al. 2011, Appl Anim Behav Sci 133:207–15), has been selected to examine fearfulness. For each horse, a caretaker was asked to fill in a validated temperament questionnaire. In order to assess discriminant validity of the NOT three human-animal relationship tests were performed on the same horses. Temperature of the lacrimal caruncle was measured pre-test and post-test on 22 horses, representative of the whole sample. Data were analysed with descriptive, non-parametric and multivariate statistic methods. No significant differences were found between female and geldings for any of the measured variables. Horses that were described by caretakers as more prone to panic, vigilant, excitable, skittish and nervous (p < 0.001), needed significantly longer time to approach the novel object (p < 0.01). Eye temperature was significantly higher after the NOT compared to basal (p < 0.01), with subjects who did not re-approach the novel object tending to present larger increases (p < 0.1). Horses showing more fear related responses to the NOT did not show more negative reactions to humans during the human-animal tests. These results suggest that, to some extent, the NOT predicts horses’ behaviour in real on-farm situations. Our findings reject the hypothesis that reactivity to humans and general fearfulness belong to the same basic feature of temperament. Importantly, infrared thermography proved to be useful to assess physiological reactions of fear in horses.