ISES Day 2: Feeding Horses Naturally, Footing Issues, and New Research Goals

    Press/Media: Press / Media


    Indicators on the inside; physiology and equine quality of life

    H. Randle1, C. Henshall1, C. Hall2, G.Pearson3, L. Preshaw4, N. Waran5 

    1School of Animal and Veterinary Science, Charles Sturt University, Wagga Wagga, 2678, NSW, Australia

    2School of Animal, Rural and Environmental Sciences Nottingham Trent University Brackenhurst Campus Southwell Nottinghamshire, NG25 0QF, UK

    3The Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9R, UK

    4The Horse Trust, Slad Lane, Princes Risborough, HP27 0PP, UK

    5Eastern Institute of Technology, Hawke's Bay, New Zealand


    *Corresponding author:


    Horse welfare is coming under increasing scrutiny worldwide.  Recently there has been a move away from the resource-based assessment of welfare exemplified by the Five Freedoms towards an animal-based framework such as the Five Domains Model.  This has highlighted the need to develop an Equine Quality of Life (EQoL) assessment framework and identify evidence-based, observable equine behaviours that reliably reflect underlying emotional state.  This Systematic Review aimed to identify potential physiological indicators of equine emotional states. Online database searches using two Boolean strings incorporatingemotion*/affective/cognit*/behav*/welfare/physiol*/horse/equid/equine/stress/respons*/behav* terms yielded 1600+ publications.  After application of predetermined selection criteria 124 were retained for analysis.  Heart rate (HR), heart rate variability (HRV) and cortisol are the most commonly measured physiological indicators of equine emotion.  However, the effects of negative and positive stimuli are not consistently reported across studies.  Additionally, these measures are at risk of confounding by physical exertion. HR is considered a reliable indicator of equine emotional state due to changes being rapid and sensitive to the intensity of the experience.  Increases are reported with arousal, pain, novelty, anticipation and exercise, whilst decreases occur during allogrooming and habituation.  HRV has been considered a more sensitive indicator of emotional state encompassing parasympathetic and sympathetic nervous system activity, however a variety of methodological and interpretive questions about its reliability remain.  There is inconsistency in cortisol studies and a lack of association between behaviour and cortisol results is not uncommon.  Cortisol increases due to acute stress, anticipation, stereotypy prevention and physical exertion are reported, whereas it decreases in chronic stress.  The modifying effects of factors such as physiological habituation, coping style, past experience and individual variability remain unknown.  Other suggested correlatesof emotional state include eye temperature, ACTH challenge, haematological, immunological, neurological factors, respiratory rate and salivary alpha amylase but many of these lack validation in relation to association with emotional state.  Methodological problems exist with all physiological measures, ranging from lack of standardisation of reporting and interpretation, calibration and validation difficulties, confounding effects of ‘outlier’ values and erroneous use of human baseline data when deriving equine HRVs.  Valid interpretation of the contribution of physiological data in relation to emotional state requires an understanding of the context in which the data are measured.  Consequently, physiological data alone is an unlikely candidate for assessing EQoL.  A more comprehensive set of measures are needed to assess equine emotional state and consequently EQoL.


    Lay person’s message

    Horse welfare is coming under increasing scrutiny worldwide.  An individual horse’s welfare relies on more than just having food, water and an appropriate place to live.  The mental health of the horse is now also being investigated, including his/her emotional states and positive/negative (affective) experiences.  A review of 124 research papers focussing on physiological measures of equine emotion (e.g. heart rate) revealed that these may have limited use when assessing horse welfare.  A comprehensive set of measures that takes into account the horses experiences at any one time is needed to assess equine welfare and his/her overall quality of life.

    Key words: Equine; welfare; emotion; affective state; physiological indicator; quality of life

    Period21 Aug 2019

    Media coverage


    Media coverage


    TitleInternational Society for Equitation Science
    LocationUniversity of Guelph, Guelph, Ontario, Canada
    Period19 Aug 2019 → 21 Aug 2019


    • Equine
    • Welfare
    • Behaviour
    • Quality of Life
    • Emotion
    • Horse
    • Indicator
    • Affective state
    • Positive
    • Systematic Review