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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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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.

References

This article includes 85 references
  1. Kleinginna PR, Kleinginna AM. A categorized list of emotion definitions, with suggestions for a consensual definition.. Motiv Emot 1981;5:345–379.
    doi: 10.1007/BF00992553google scholar: lookup
  2. Izard CE. The many meanings/aspects of emotion: Definitions, functions, activation, and regulation.. Emot Rev 2010;2:363–370.
    doi: 10.1177/1754073910374661google scholar: lookup
  3. Gendron M. Defining emotion: A brief history.. Emotion Review 2010;2:371–372.
    doi: 10.1177/1754073910374669google scholar: lookup
  4. Mendl M, Burman OHP, Paul ES. An integrative and functional framework for the study of animal emotion and mood.. Proc R Soc B Biol Sci 2010;277:2895–2904.
    doi: 10.1098/rspb.2010.0303pmc: PMC2982018pubmed: 20685706google scholar: lookup
  5. Cátia C, Kun G, Daniel M. Dogs and humans respond to emotionally competent stimuli by producing different facial actions.. Sci Rep 2017;7:1–11.
    doi: 10.1038/s41598-017-15091-4pmc: PMC5686192pubmed: 29138393google scholar: lookup
  6. Lansade L, Nowak R, Lainé A-L, Leterrier C, Bonneau C, Parias C. Facial expression and oxytocin as possible markers of positive emotions in horses.. Sci Rep 2018;8(1):14680.
    doi: 10.1038/s41598-018-32993-zpmc: PMC6168541pubmed: 30279565google scholar: lookup
  7. Lansade L, Lemarchand J, Reigner F, Arnould C, Bertin A. Automatic brushes induce positive emotions and foster positive social interactions in group-housed horses.. Applied Animal Behaviour Science 2022;246:105538.
    doi: 10.1016/j.applanim.2021.105538google scholar: lookup
  8. Zimmerman PH, Buijs SAF, Bolhuis JE, Keeling LJ. Behaviour of domestic fowl in anticipation of positive and negative stimuli.. Animal Behaviour 2011;81:569–577.
    doi: 10.1016/j.anbehav.2010.11.028google scholar: lookup
  9. Hansen SW, Jeppesen LL. Temperament, stereotypies and anticipatory behaviour as measures of welfare in mink.. Applied Animal Behaviour Science 2006;99:172–182.
    doi: 10.1016/j.applanim.2005.10.005google scholar: lookup
  10. Bremhorst A, Sutter NA, Würbel H, Mills DS, Riemer S. Differences in facial expressions during positive anticipation and frustration in dogs awaiting a reward.. Sci Rep 2019;9:1–13.
    doi: 10.1038/s41598-019-55714-6pmc: PMC6917793pubmed: 31848389google scholar: lookup
  11. Peters SM, Bleijenberg EH, van Dierendonck MC, van der Harst JE, Spruijt BM. Characterization of anticipatory behaviour in domesticated horses (Equus caballus).. Applied Animal Behaviour Science 2012;138:60–69.
    doi: 10.1016/j.applanim.2012.01.018google scholar: lookup
  12. Clegg ILK, Rödel HG, Boivin X, Delfour F. Looking forward to interacting with their caretakers: dolphins’ anticipatory behaviour indicates motivation to participate in specific events.. Applied Animal Behaviour Science 2018;202:85–93.
    doi: 10.1016/j.applanim.2018.01.015google scholar: lookup
  13. Van Den Bos R, Meijer MK, Van Renselaar JP, Van der Harst JE, Spruijt BM. Anticipation is differently expressed in rats (Rattus norvegicus) and domestic cats (Felis silvestris catus) in the same Pavlovian conditioning paradigm.. Behav Brain Res 2003;141:83–89.
    doi: 10.1016/S0166-4328(02)00318-2pubmed: 12672562google scholar: lookup
  14. van der Harst JE, Baars AM, Spruijt BM. Standard housed rats are more sensitive to rewards than enriched housed rats as reflected by their anticipatory behaviour.. Behav Brain Res 2003;142:151–156.
    doi: 10.1016/S0166-4328(02)00403-5pubmed: 12798276google scholar: lookup
  15. Dolensek N, Gehrlach DA, Klein AS, Gogolla N. Facial expressions of emotion states and their neuronal correlates in mice.. Science 2020;368:89–94.
    doi: 10.1126/science.aaz9468pubmed: 32241948google scholar: lookup
  16. Battini M, Agostini A, Mattiello S. Understanding cows’ emotions on farm: Are eye white and ear posture reliable indicators?. Animals 2019;9:1–12.
    doi: 10.3390/ani9080477pmc: PMC6720764pubmed: 31344842google scholar: lookup
  17. Lundblad J. Changes in facial expressions during short term emotional stress as described by a Facial Action Coding System in horses.. 2018.
  18. Lundblad J, Rashid M, Rhodin M, Andersen PH. Facial expressions of emotional stress in horses.. Animal Behavior and Cognition 2020.
    doi: 10.1101/2020.10.19.345231google scholar: lookup
  19. Carmo LG, Werner LC, Michelotto PV, Daros RR. Horse behavior and facial movements in relation to food rewards.. PLoS ONE 2023;18:1–14.
    doi: 10.1371/journal.pone.0286045pmc: PMC10259797pubmed: 37307268google scholar: lookup
  20. Mullard J, Berger JM, Ellis AD, Dyson S. Development of an ethogram to describe facial expressions in ridden horses (FEReq).. Journal of Veterinary Behavior 2017;18:7–12.
    doi: 10.1016/j.jveb.2016.11.005google scholar: lookup
  21. Minton JE. Function of the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system in models of acute stress in domestic farm animals.. J Anim Sci 1994;72:1891–8.
    doi: 10.2527/1994.7271891xpubmed: 7928769google scholar: lookup
  22. Valenchon M, Lévy F, Moussu C, Lansade L. Stress affects instrumental learning based on positive or negative reinforcement in interaction with personality in domestic horses.. PLoS ONE 2017;12:1–16.
    doi: 10.1371/journal.pone.0170783pmc: PMC5419560pubmed: 28475581google scholar: lookup
  23. Strzelec K, Kankofer M, Pietrzak S. Cortisol concentration in the saliva of horses subjected to different kinds of exercise.. Acta Vet Brno 2011;80:101–5.
    doi: 10.2754/avb201180010101google scholar: lookup
  24. Schmidt A, Aurich J, Möstl E, Müller J, Aurich C. Changes in cortisol release and heart rate and heart rate variability during the initial training of 3-year-old sport horses.. Horm Behav 2010;58(4):628–636.
    doi: 10.1016/j.yhbeh.2010.06.011pubmed: 20600048google scholar: lookup
  25. Witkowska-Piłaszewicz O, Grzędzicka J, Seń J, Czopowicz M, Żmigrodzka M, Winnicka A. Stress response after race and endurance training sessions and competitions in Arabian horses.. Prev Vet Med 2021;188:105265.
    doi: 10.1016/j.prevetmed.2021.105265pubmed: 33497894google scholar: lookup
  26. Horváth Z, Dóka A, Miklósi Á. Affiliative and disciplinary behavior of human handlers during play with their dog affects cortisol concentrations in opposite directions.. Horm Behav 2008;54:107–14.
    doi: 10.1016/j.yhbeh.2008.02.002pubmed: 18353328google scholar: lookup
  27. Fortin M, Valenchon M, Lévy F, Calandreau L, Arnould C, Lansade L. Emotional state and personality influence cognitive flexibility in horses (Equus caballus).. J Comp Psychol 2018;132:130–140.
    doi: 10.1037/com0000091pubmed: 29517248google scholar: lookup
  28. Forkman B, Boissy A, Meunier-Salaün MC, Canali E, Jones RB. A critical review of fear tests used on cattle, pigs, sheep, poultry and horses.. Physiol Behav 2007;92:340–74.
    doi: 10.1016/j.physbeh.2007.03.016pubmed: 18046784google scholar: lookup
  29. Wascher CAF. Heart rate as a measure of emotional arousal in evolutionary biology.. .
    pmc: PMC8237168pubmed: 34176323
  30. Briefer EF, Maigrot A-L, Mandel R, Freymond SB, Bachmann I, Hillmann E. Segregation of information about emotional arousal and valence in horse whinnies.. Sci Rep 2015;4:1–12.
    doi: 10.1038/srep09989pmc: PMC4404681pubmed: 25897781google scholar: lookup
  31. Leiner L, Fendt M. Behavioural fear and heart rate responses of horses after exposure to novel objects: Effects of habituation.. Appl Anim Behav Sci 2011;131:104–9.
    doi: 10.1016/j.applanim.2011.02.004google scholar: lookup
  32. Visser EK, van Reenen CG, van der Werf JTN, Schilder MBH, Knaap JH, Barneveld A. Heart rate and heart rate variability during a novel object test and a handling test in young horses.. Physiol Behav 2002;76(2):289–296.
    doi: 10.1016/S0031-9384(02)00698-4pubmed: 12044602google scholar: lookup
  33. van der Harst JE, Fermont PCJ, Bilstra AE, Spruijt BM. Access to enriched housing is rewarding to rats as reflected by their anticipatory behaviour.. Animal Behaviour 2003;66:493–504.
    doi: 10.1006/anbe.2003.2201google scholar: lookup
  34. Dudink S, Simonse H, Marks I, de Jonge FH, Spruijt BM. Announcing the arrival of enrichment increases play behaviour and reduces weaning-stress-induced behaviours of piglets directly after weaning.. Appl Anim Behav Sci 2006;101:86–101.
    doi: 10.1016/j.applanim.2005.12.008google scholar: lookup
  35. Anderson C, Yngvesson J, Boissy A, Uvnäs-Moberg K, Lidfors L. Behavioural expression of positive anticipation for food or opportunity to play in lambs.. Behav Processes 2015;113:152–158.
    doi: 10.1016/j.beproc.2015.02.003pubmed: 25659525google scholar: lookup
  36. Anagnostaras SG, Josselyn SA, Frankland PW, Silva AJ. Computer-assisted behavioral assessment of Pavlovian fear conditioning in mice.. Learn Mem 2000;7:58–72.
    doi: 10.1101/lm.7.1.58pmc: PMC311321pubmed: 10706603google scholar: lookup
  37. Phelipon R, Ascione A, Ruet A, Bertin A, Biau S, Arnould C. Differences in behaviour, facial expressions and locomotion between positive anticipation and frustration in horses.. Applied Animal Behaviour Science 2024;274:106262.
    doi: 10.1016/j.applanim.2024.106262google scholar: lookup
  38. Corr PJ. Approach and avoidance behaviour: Multiple systems and their interactions.. Emot Rev 2013;5:285–290.
    doi: 10.1177/1754073913477507google scholar: lookup
  39. Moe RO, Bakken M, Kittilsen S, Kingsley-Smith H, Spruijt BM. A note on reward-related behaviour and emotional expressions in farmed silver foxes (Vulpes vulpes)—Basis for a novel tool to study animal welfare.. Applied Animal Behaviour Science 2006;101:362–368.
    doi: 10.1016/j.applanim.2006.02.004google scholar: lookup
  40. Lambert H, Carder G. Positive and negative emotions in dairy cows: Can ear postures be used as a measure?. Behav Processes 2019;158:172–180.
    doi: 10.1016/j.beproc.2018.12.007pubmed: 30543843google scholar: lookup
  41. Dalla Costa E, Minero M, Lebelt D, Stucke D, Canali E, Leach MC. Development of the Horse Grimace Scale (HGS) as a pain assessment tool in horses undergoing routine castration.. PLoS ONE 2014;9:e92281.
    doi: 10.1371/journal.pone.0092281pmc: PMC3960217pubmed: 24647606google scholar: lookup
  42. Trindade PHE, Hartmann E, Keeling LJ, Andersen PH, Ferraz GDC, Paranhos da Costa MJR. Effect of work on body language of ranch horses in Brazil.. PLoS ONE 2020;15:1–22.
    doi: 10.1371/journal.pone.0228130pmc: PMC6986720pubmed: 31990951google scholar: lookup
  43. Christensen JW, Jensen D, König von Borstel UU. Conflict behaviour in Icelandic horses during elite competition.. Applied Animal Behaviour Science 2024;271:4–9.
    doi: 10.1016/j.applanim.2024.106166google scholar: lookup
  44. Ricci-Bonot C, Mills DS. Recognising the facial expression of frustration in the horse during feeding period.. Appl Anim Behav Sci 2023;265:105966.
    doi: 10.1016/j.applanim.2023.105966google scholar: lookup
  45. Waller BM, Julle-Daniere E, Micheletta J. Measuring the evolution of facial “expression” using multi-species FACS.. Neurosci Biobehav Rev 2020;113:1–11.
    doi: 10.1016/j.neubiorev.2020.02.031pubmed: 32105704google scholar: lookup
  46. Ekman P, Friesen WV. Facial action coding system.. Environ Psychol Nonverbal Behav 1978.
  47. Wathan J, Burrows AM, Waller BM, McComb K. EquiFACS: The equine facial action coding system.. PLoS ONE 2015;10:1–35.
    doi: 10.1371/journal.pone.0131738pmc: PMC4526551pubmed: 26244573google scholar: lookup
  48. Lewis K, McBride SD, Micheletta J, Parker MO, Rincon AV, Wathan J. An ethogram of facial behaviour in domestic horses: evolutionary perspectives on form and function.. PeerJ forthcoming.
  49. Hintze S, Murphy E, Bachmann I, Wemelsfelder F, Würbel H. Qualitative Behaviour Assessment of horses exposed to short-term emotional treatments.. Appl Anim Behav Sci 2017;196:44–51.
    doi: 10.1016/j.applanim.2017.06.012google scholar: lookup
  50. Tomberg C, Petagna M, de Selliers de Moranville L-A. Horses (Equus caballus) facial micro-expressions: insight into discreet social information.. Sci Rep 2023;13:1–15.
    doi: 10.1038/s41598-023-35807-zpmc: PMC10224940pubmed: 37244937google scholar: lookup
  51. Mielke A, Waller BM, Pérez C, Rincon AV, Duboscq J, Micheletta J. NetFACS: Using network science to understand facial communication systems.. Behav Res Methods 2022;54:1912–27.
    doi: 10.3758/s13428-021-01692-5pmc: PMC9374617pubmed: 34755285google scholar: lookup
  52. Mielke A, Carvalho S. Chimpanzee play sequences are structured hierarchically as games.. PeerJ 2022;10:1–29.
    doi: 10.7717/peerj.14294pmc: PMC9675342pubmed: 36411837google scholar: lookup
  53. Muschinski J, Mielke A, Carvalho S. A network-based analysis of signal use during approach interactions across sexes in chacma baboons (Papio ursinus griseipes).. Animal Behavior and Cognition 2023.
    doi: 10.1101/2023.02.04.527103google scholar: lookup
  54. Kremer L, Klein Holkenborg SEJ, Reimert I, Bolhuis JE, Webb LE. The nuts and bolts of animal emotion.. Neurosci Biobehav Rev 2020;113:273–286.
    doi: 10.1016/j.neubiorev.2020.01.028pubmed: 31982603google scholar: lookup
  55. Phelipon R, Hennes N, Ruet A, Bret-Morel A, Górecka-Bruzda A, Lansade L. Forage, freedom of movement, and social interactions remain essential fundamentals for the welfare of high-level sport horses.. Front Vet Sci 2024;11:1504116.
    doi: 10.3389/fvets.2024.1504116pmc: PMC11615640pubmed: 39634765google scholar: lookup
  56. Krueger K, Esch L, Farmer K, Marr I. Basic needs in horses?—A literature review.. Animals (Basel) 2021;11:1–16.
    doi: 10.3390/ani11061798pmc: PMC8235049pubmed: 34208615google scholar: lookup
  57. Janczarek I, Stachurska A, Kędzierski W, Pawlak EW, Wilk I, Zyglewska K. Heart rate variability in Konik and purebred Arabian horses in response to different predator vocalisations.. Animal 2021;15:100045.
    doi: 10.1016/j.animal.2020.100045pubmed: 33516023google scholar: lookup
  58. von Borell E, Langbein J, Després G, Hansen S, Leterrier C, Marchant J. Heart rate variability as a measure of autonomic regulation of cardiac activity for assessing stress and welfare in farm animals - A review.. Physiol Behav 2007;92:293–316.
    doi: 10.1016/j.physbeh.2007.01.007pubmed: 17320122google scholar: lookup
  59. Friard O, Gamba M. BORIS: a free, versatile open-source event-logging software for video/audio coding and live observations.. Methods Ecol Evol 2016;7:1325–30.
    doi: 10.1111/2041-210X.12584google scholar: lookup
  60. Altmann J. Observational study of behavior: sampling methods.. Behaviour 1974;49:227–266.
    doi: 10.1163/156853974X00534pubmed: 4597405google scholar: lookup
  61. Core RT. R: A language and environment for statistical computing.. 2019.
  62. Landis JR, Koch GG. The Measurement of Observer Agreement for Categorical Data.. Biometrics 1977;33:159.
    doi: 10.2307/2529310pubmed: 843571google scholar: lookup
  63. Hartig F. DHARMa: residual diagnostics for hierarchical (multi-level/mixed) regression models.. R Packag Version 020 2018.
  64. Fox J, Weisberg S. An R Companion to Applied Regression.. SAGE Publications 2018.
  65. Smith AV, Proops L, Grounds K, Wathan J, McComb K. Horses give functionally relevant responses to human facial expressions of emotion: a response to Schmoll (2016).. Biol Lett 2016;12:20160549.
    doi: 10.1098/rsbl.2016.0549pmc: PMC5046936pubmed: 27624798google scholar: lookup
  66. Reid K, Rogers CW, Gronqvist G, Gee EK, Bolwell CF. Anxiety and pain in horses measured by heart rate variability and behavior.. J Vet Behav 2017;22:1–6.
    doi: 10.1016/j.jveb.2017.09.002google scholar: lookup
  67. Schmidt A, Möstl E, Wehnert C, Aurich J, Müller J, Aurich C. Cortisol release and heart rate variability in horses during road transport.. Horm Behav 2010;57:209–215.
    doi: 10.1016/j.yhbeh.2009.11.003pubmed: 19944105google scholar: lookup
  68. Sikorska U, Maśko M, Ciesielska A, Zdrojkowski Ł, Domino M. Role of Cortisol in Horse’s Welfare and Health.. Agriculture 2023;13:1–17.
    doi: 10.3390/agriculture13122219google scholar: lookup
  69. Massányi M, Halo M, Mlyneková E, Kováčiková E, Tokárová K, Greń A. The effect of training load stress on salivary cortisol concentrations, health parameters and hematological parameters in horses.. Heliyon 2023;9:e19037.
    doi: 10.1016/j.heliyon.2023.e19037pmc: PMC10457446pubmed: 37636408google scholar: lookup
  70. Hernandez CE, Thierfelder T, Svennersten-Sjaunja K, Berg C, Orihuela A, Lidfors L. Time lag between peak concentrations of plasma and salivary cortisol following a stressful procedure in dairy cattle.. Acta Vet Scand 2014;56:61.
    doi: 10.1186/s13028-014-0061-3pmc: PMC4194406pubmed: 25297979google scholar: lookup
  71. Cook CJ, Jacobson LH. Salivary cortisol as an indicator of stress in sheep (Ovis ovis).. N Z Vet J 1995;43:248–248.
    doi: 10.1080/00480169.1995.35902pubmed: 16031862google scholar: lookup
  72. Chmelíková E, Bolechová P, Chaloupková H, Svobodová I, Jovičić M, Sedmíková M. Salivary cortisol as a marker of acute stress in dogs: a review.. Domest Anim Endocrinol 2020;72:106428.
    doi: 10.1016/j.domaniend.2019.106428pubmed: 32213439google scholar: lookup
  73. Cockrem JF. Individual variation in glucocorticoid stress responses in animals.. Gen Comp Endocrinol 2013;181:45–58.
    doi: 10.1016/j.ygcen.2012.11.025pubmed: 23298571google scholar: lookup
  74. Lansade L, Bouissou M-F, Erhard HW. Reactivity to isolation and association with conspecifics: A temperament trait stable across time and situations.. Applied Animal Behaviour Science 2008;109:355–373.
    doi: 10.1016/j.applanim.2007.03.003google scholar: lookup
  75. Visser EK, Ellis AD, Van Reenen CG. The effect of two different housing conditions on the welfare of young horses stabled for the first time.. Appl Anim Behav Sci 2008;114:521–533.
    doi: 10.1016/j.applanim.2008.03.003google scholar: lookup
  76. Young T, Creighton E, Smith T, Hosie C. A novel scale of behavioural indicators of stress for use with domestic horses.. Applied Animal Behaviour Science 2012;140:33–43.
    doi: 10.1016/j.applanim.2012.05.008google scholar: lookup
  77. Saslow CA. Understanding the perceptual world of horses.. Appl Anim Behav Sci 2002;78:209–24.
    doi: 10.1016/S0168-1591(02)00092-8google scholar: lookup
  78. Lesimple C. Indicators of Horse Welfare: State-of-the-Art.. Animals (Basel) 2020;10(2):294.
    doi: 10.3390/ani10020294pmc: PMC7070675pubmed: 32069888google scholar: lookup
  79. Fureix C, Hausberger M, Seneque E, Morisset S, Baylac M, Cornette R. Geometric morphometrics as a tool for improving the comparative study of behavioural postures.. Naturwissenschaften 2011;98:583–592.
    doi: 10.1007/s00114-011-0803-2pubmed: 21573691google scholar: lookup
  80. Lundblad J, Rashid M, Rhodin M, Andersen PH. Effect of transportation and social isolation on facial expressions of healthy horses.. PLoS ONE 2021;16:1–17.
    doi: 10.1371/journal.pone.0241532pmc: PMC8177539pubmed: 34086704google scholar: lookup
  81. Humphrey T, Proops L, Forman J, Spooner R, McComb K. The role of cat eye narrowing movements in cat–human communication.. Sci Rep 2020;10:1–8.
    doi: 10.1038/s41598-020-73426-0pmc: PMC7536207pubmed: 33020542google scholar: lookup
  82. Heleski CR, Shelle AC, Nielsen BD, Zanella AJ. Influence of housing on weanling horse behavior and subsequent welfare.. Applied Animal Behaviour Science 2002;78:291–302.
    doi: 10.1016/S0168-1591(02)00108-9google scholar: lookup
  83. Pavlov IP. Conditioned reflexes: An investigation of the physiological activity of the cerebral cortex.. Ann Neurosci 2010;17:136–41.
    doi: 10.5214/ans.0972-7531.1017309pmc: PMC4116985pubmed: 25205891google scholar: lookup
  84. Hausberger M, Muller C. A brief note on some possible factors involved in the reactions of horses to humans.. Applied Animal Behaviour Science 2002;76:339–344.
    doi: 10.1016/S0168-1591(02)00016-3google scholar: lookup
  85. Fureix C, Bourjade M, Henry S, Sankey C, Hausberger M. Exploring aggression regulation in managed groups of horses Equus caballus.. Appl Anim Behav Sci 2012;138:216–28.
    doi: 10.1016/j.applanim.2012.02.009google scholar: lookup

Citations

This article has been cited 3 times.
  1. Górski K, Kondracki S, Kępka-Borkowska K. The Complexity of Communication in Mammals: From Social and Emotional Mechanisms to Human Influence and Multimodal Applications. Animals (Basel) 2026 Jan 15;16(2).
    doi: 10.3390/ani16020265pubmed: 41594455google scholar: lookup
  2. Smith R, Perkins L, Pinchbeck G, Ireland J. Owners' everyday interactions with their horse: Pain-related issues and those of veterinary concern. Anim Welf 2025;34:e62.
    doi: 10.1017/awf.2025.10036pubmed: 40988863google scholar: lookup
  3. Roth LSV, McGreevy P. Horse vision through two lenses: Tinbergen's Four Questions and the Five Domains. Front Vet Sci 2025;12:1647911.
    doi: 10.3389/fvets.2025.1647911pubmed: 40895790google scholar: lookup
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