Characterisation of facial expressions and behaviours of horses in response to positive and negative emotional anticipation using network analysis.
Authors: Phelipon Romane, Bertrand Léa, Jardat Plotine, Reigner Fabrice, Lewis Kate, Micheletta Jérôme, Lansade Léa
Journal: PloS one
Summary
# Editorial Summary Emotional anticipation shapes equine welfare significantly, yet reliable indicators of positive versus negative affective states remain poorly characterised. Researchers conditioned twenty horses daily to either anticipate positive (pasture access) or negative (isolation in a novel environment) outcomes, then analysed behavioural, physiological and facial responses during the anticipation phase using the Equine Facial Action Coding System (EquiFACS) and network analysis. The two conditions produced measurably different affective states: horses demonstrated faster approach times, lower maximal heart rates and reduced cortisol elevation when anticipating positive outcomes, with distinct behavioural profiles emerging—positive anticipation elicited head-shaking, stepping back, sniffing and ground-pawing, whilst negative anticipation produced ear retraction and increased nostril flaring. Clinically, this work establishes specific facial and postural markers (elevated neck with frequent half-blinks for positive states; medium neck with backward ears and nostril movement for negative states) that practitioners can use to assess emotional state and welfare status during routine handling and training. These findings provide an evidence-based framework for identifying emotional distress or contentment in individual horses, enabling more nuanced welfare monitoring and management adjustments across farriery, veterinary, physiotherapy and coaching contexts.
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Practical Takeaways
- •Use observable facial and behavioural markers—ear position, neck height, nostril movements, and blink rate—as practical on-farm indicators of emotional state and welfare without requiring equipment or blood sampling
- •Recognize that restricted behaviour repertoire combined with backward ear position and increased nostril flaring indicates negative anticipation/stress; conversely, head shaking and pawing with raised neck suggests positive emotional states
- •Incorporate these standardized facial and behavioural observations into regular welfare assessments and handling protocols to identify anxious or distressed horses early and adjust management accordingly
Key Findings
- •Positive anticipation triggered increased behavioural diversity including head shaking, stepping back, sniffing, and pawing, while negative anticipation showed restricted behaviours with backward ears and increased nostril movements
- •Positive anticipation was characterized by higher neck posture with frequent half-blinks and mouth movements; negative anticipation showed medium neck posture with flattened ears
- •Negative anticipation induced significantly higher maximum heart rate and cortisol variation compared to positive anticipation, confirming physiological stress response
- •Network analysis of facial expressions and behaviours revealed distinct profiles specific to positive versus negative emotional valence that can be used as welfare indicators