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PloS one2023; 18(6); e0286045; doi: 10.1371/journal.pone.0286045

Horse behavior and facial movements in relation to food rewards.

Abstract: Food rewards are believed to have a positive valence in horses. The aim of this study was to assess the effect of food rewards on horse behavior before entering a horse chute, and behavior and facial movements while restrained in it. Thirteen female adult horses were brought once daily to an animal handling facility for three weeks. In week 1, baseline period, no reinforcement was applied. In weeks 2 and 3, experimental phase, half of the horses received positive reinforcement treatment after entering and remaining in the chute; the remaining horses were considered as controls (no positive reinforcement applied). There was a cross-over between the groups during the experimental phase. Horses were individually brought to the restraining chute and videos recorded during 60-sec. The duration and number of entries into the area close to the gate leading to the chute were measured before restraining and body posture, neck position, and tail swinging were recorded in the chute. Facial movements were also recorded and scored using EquiFACS methodology. Multilevel linear and logistic models were built to assess behavioral changes from baseline to the treatment phase and between phases (control and positively reinforced). Horses did not change their body posture or tail swings across the different phases (P > 0.1) and were less likely to show lowered neck during the positively reinforced phase (OR: 0.05; CI95%: 0.00-0.56; P = 0.05) compared to baseline. The likelihood of a lowered neck did not differ between the positive reinforcement and control phases (P = 0.11). In the positively reinforced phase, horses seemed to be more attentive (ears forward) and active (less eye closures, more nose movements) than in the control phase. A three-day positive reinforcement phase did not elicit major changes in body behavior in the chute but affected the facial movements of group-housed mares.
Copyright: © 2023 Carmo 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: 2023-06-12 PubMed ID: 37307268PubMed Central: PMC10259797DOI: 10.1371/journal.pone.0286045Google Scholar: Lookup
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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 paper explores the impact of food rewards on horse behavior and facial movements. It found that positive reinforcement didn’t significantly alter their physical behavior, but it did cause noticeable changes in their facial expressions.

Objective and Methodology

  • The goal of the study was to assess the impact of food rewards on horse behavior and facial movements, particularly before entering an enclosure (a chute), and during confinement within it.
  • Thirteen adult female horses were used in the experiment, which spanned three weeks. The horses were divided into two groups: a control group that received no rewards, and a test group that was positively reinforced with food after entering the chute.
  • The first week served as the neutral period wherein no reinforcements were given, while the second and third weeks constituted the experimental phase in which food rewards were administered. There was a cross-over between the two groups during the experimental phase.
  • Horses’ body postures, neck positions, tail swings, and facial movements were analyzed and recorded using videos captured during 60-second periods.
  • The researchers applied the EquiFACS methodology to score the facial movements of the horses.
  • The researchers used multilevel linear and logistic models to evaluate behavioral changes from the initial stage to the treatment phase and across the different phases.

Findings

  • The researchers found no significant alteration in body posture or tail swings across the different phases of the study.
  • However, horses displayed less likelihood of showing lowered neck during the positively reinforced stage compared to the baseline period.
  • The chance of a lowered neck did not vary noticeably between the positive reinforcement and control phases.
  • During the positive reinforcement stage, horses appeared to be more aware and active, indicated by more forward ear movements, lesser eye closures, and more nose movements than in the control phase.
  • Although the three-day positive reinforcement phase did not incite significant changes in body behavior in the chute, it effected visible changes in the facial movements of the group-housed mares.

Conclusion

  • The research indicates that while food rewards (positive reinforcement) do not significantly affect horses’ body behavior, they do influence facial movements, making horses more attentive and active.
  • Such findings could be beneficial in further understanding horse behavior, especially in response to positive reinforcement.

Cite This Article

APA
Carmo LG, Werner LC, Michelotto PV, Daros RR. (2023). Horse behavior and facial movements in relation to food rewards. PLoS One, 18(6), e0286045. https://doi.org/10.1371/journal.pone.0286045

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 18
Issue: 6
Pages: e0286045
PII: e0286045

Researcher Affiliations

Carmo, Laize G
  • Graduate Program in Animal Science, School of Medicine and Life Sciences, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil.
Werner, Laís C
  • Graduate Program in Animal Science, School of Medicine and Life Sciences, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil.
Michelotto, Pedro V
  • Graduate Program in Animal Science, School of Medicine and Life Sciences, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil.
Daros, Ruan R
  • Graduate Program in Animal Science, School of Medicine and Life Sciences, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil.

MeSH Terms

  • Female
  • Horses
  • Animals
  • Reward
  • Movement
  • Face
  • Reinforcement, Psychology
  • Posture

Conflict of Interest Statement

The authors have declared that no competing interests exist.

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Citations

This article has been cited 4 times.
  1. Jardat P, Yamamoto S, Ringhofer M, Tanguy-Guillo N, Parias C, Reigner F, Calandreau L, Lansade L. Emotional contagion of fear and joy from humans to horses using a combination of facial and vocal cues. Sci Rep 2025 May 21;15(1):17689.
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  2. da Fé VCS, Dos Santos VMO, de Lima ACB, Hernandes MSP, Caldara FR, Gomes MNB. Auditory enrichment on facial and physiological responses of Pantaneiro geldings and mares under short-term stress. PLoS One 2025;20(5):e0323649.
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  3. Phelipon R, Bertrand L, Jardat P, Reigner F, Lewis K, Micheletta J, Lansade L. Characterisation of facial expressions and behaviours of horses in response to positive and negative emotional anticipation using network analysis. PLoS One 2025;20(5):e0319315.
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  4. Phelipon R, Lansade L, Razzaq M. Using deep learning models to decode emotional states in horses. Sci Rep 2025 Apr 23;15(1):13154.
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