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PloS one2025; 20(5); e0319315; doi: 10.1371/journal.pone.0319315

Characterisation of facial expressions and behaviours of horses in response to positive and negative emotional anticipation using network analysis.

Abstract: The welfare of an animal is closely linked to their emotional experiences, making it essential to identify reliable indicators of these emotions. This study aimed to identify behaviours and facial movements in horses experiencing contrasting emotional valence, triggered by the anticipation of a positive condition (going to pasture) or a negative condition (going alone to a novel environment). Twenty horses were daily trained to wait in a starting box before being exposed to these two conditions. After one week of positive training or negative training, we analysed horses' behaviours, cortisol variations, and facial movements while they waited in their starting box. First, we confirmed that the two conditions induced contrasting emotional valence, as evidenced by the shorter time taken to approach in the positive condition compared to the negative, and by the higher maximal heart rate and cortisol variation in the negative condition. Then using the Equine Facial Action Coding System (EquiFACS) and network analysis (NetFACS) we revealed distinct behaviours and facial expression profiles. In positive anticipation, the horses exhibited a greater range of behaviours, including shaking their heads from side to side, stepping back, sniffing, and pawing at the ground. Additionally, two distinct facial expression profiles were identified as specific to positive and negative anticipation. In positive anticipation, the horses displayed a higher neck, accompanied by a greater frequency of half-blinks and mouth movements. Conversely, in negative anticipation, the horses exhibited a medium neck, with ears backward accompanied by more flattened ears and expressed more nostril movements. The findings highlight the importance of these indicators in characterising horses' emotions and emphasise their significance for assessing equine welfare.
Copyright: © 2025 Phelipon et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Publication Date: 2025-05-14 PubMed ID: 40367029PubMed Central: PMC12077714DOI: 10.1371/journal.pone.0319315Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research article explores how horses’ emotions can be identified by studying their behaviours and facial expressions when they anticipate positive or negative conditions. A comparison was made between their responses to going out to pasture (positive condition) and going alone to a new environment (negative condition).

Study Design

The study involved:

  • Training twenty horses to wait in a starting box before exposing them to both positive and negative conditions.
  • Conducting one week of positive training and subsequently one week of negative training.
  • Observing the horses’ behaviours, changes in cortisol (a hormone associated with stress), and facial movements during their waiting time in the starting box.

Key Findings

The research findings showed that:

  • Contrasting emotional valence (the value assigned to a stimulus in terms of its attractiveness or averseness) was induced by the positive and negative conditions. This was corroborated by observable differences in the horses’ behaviours, cortisol variations, and approach time towards the stimulus condition.
  • Distinct behaviours and facial expression profiles were found between positive and negative anticipation using the Equine Facial Action Coding System (EquiFACS) and network analysis (NetFACS).
  • In positive anticipation, horses exhibited a wider variety of behaviours, such as shaking their heads from side to side, stepping back, sniffing, and pawing at the ground.
  • Two specific facial expression profiles were identified – one for positive anticipation, characterised by a higher neck position, more frequent half-blinks and mouth movements; and another for negative anticipation, which involved a medium-height neck position, backward-facing ears, flatter ears, and increased nostril movements.

Significance of the Research

  • The research helps in the identification of reliable emotional indicators in horses.
  • The ability to distinguish between positive and negative emotional experiences in horses is vital for ensuring their welfare.
  • The distinct behaviours and facial expressions observed in the study could help equine caregivers understand their horses’ emotional states better, potentially leading to more appropriate care strategies.

Cite This Article

APA
Phelipon R, Bertrand L, Jardat P, Reigner F, Lewis K, Micheletta J, Lansade L. (2025). Characterisation of facial expressions and behaviours of horses in response to positive and negative emotional anticipation using network analysis. PLoS One, 20(5), e0319315. https://doi.org/10.1371/journal.pone.0319315

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 20
Issue: 5
Pages: e0319315
PII: e0319315

Researcher Affiliations

Phelipon, Romane
  • INRAE, CNRS, Université de Tours, PRC, Nouzilly, France.
Bertrand, Léa
  • INRAE, CNRS, Université de Tours, PRC, Nouzilly, France.
Jardat, Plotine
  • INRAE, CNRS, Université de Tours, PRC, Nouzilly, France.
Reigner, Fabrice
  • UEPAO, INRAE, Nouzilly, France.
Lewis, Kate
  • Department of Psychology, Centre for Comparative and Evolutionary Psychology, University of Portsmouth, Portsmouth, United Kingdom.
Micheletta, Jérôme
  • Department of Psychology, Centre for Comparative and Evolutionary Psychology, University of Portsmouth, Portsmouth, United Kingdom.
Lansade, Léa
  • INRAE, CNRS, Université de Tours, PRC, Nouzilly, France.

MeSH Terms

  • Animals
  • Horses / physiology
  • Horses / psychology
  • Facial Expression
  • Behavior, Animal / physiology
  • Emotions / physiology
  • Hydrocortisone / metabolism
  • Hydrocortisone / analysis
  • Male
  • Female
  • Heart Rate / physiology

Conflict of Interest Statement

The authors have declared that no competing interests exist.

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