Evaluation of the practical clinical use of the Horse Grimace Scale translated into French



      To assess the reliability of a French version of the Horse Grimace Scale (HGSfv).

      Study design

      Prospective, randomized, clinical study.


      The operated (OP) group included 13 horses undergoing elective surgery. The positive (PC) and negative control (NC) groups included seven colicking horses and eight exercising sport horses, respectively.


      Photographs were extracted from videos of the horses’ heads. Videos were taken before and immediately after surgery in OP, on arrival of the horse in PC, and at rest in their stalls in NC. Pictures were evaluated by three anaesthetists [Diplomates (DIPs)] and four riders (RIDs) using Horse Grimace Scale translated into French (HGSfv) at two points, 2 weeks apart (E1 and E2). Each evaluator gave each image a score (1–3) for six identified facial action units. The scores given by DIPs and RIDs were compared using a Wilcoxon test. Intra- and inter-evaluator reliability were assessed using Spearman correlation tests (rs) and intra-class coefficients (ICCs), respectively.


      RIDs and DIPs gave significantly higher scores in the PC group than in the NC group [RIDsE1PC 5.0 (4.2–9.8) versus RIDsE1NC 2.2 (0.0–6.5), p = 0.02; RIDsE2PC 5.2 (3.2–9.5) versus RIDsE2NC 2.0 (0.2–5.8), p < 0.01; DIPsE1PC 4.0 (1.3–6.3) versus DIPsE1NC 2.2 (1.0–4.7), p = 0.04; DIPsE2PC 2.7 (1.0–6.0) versus DIPsE2NC 1.0 (0.0–2.3), p = 0.03]. Scores given by RID or DIPs 2 weeks apart were highly correlated [rs (RIDsE1, RIDsE2) r = 0.86, p < 0.0001] and [rs (DIPsE1, DIPsE2) r = 0.81 p < 0.0001]. The ICC between RIDs and DIPs in E1 and E2 was 0.94 (0.92–0.95) and 0.91 (0.89–0.93), respectively. The specificity and sensitivity of the HGSfv was 94% and 43%, respectively.

      Conclusions and clinical relevance

      Using the HGSfv, knowledge of horses rather than specialization in veterinary anaesthesia and analgesia appears to differentiate horses with visceral pain from those assumed to be pain free.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Veterinary Anaesthesia and Analgesia
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Ask K.
        • Rhodin M.
        • Tamminen L.M.
        • et al.
        Identification of body behaviors and facial expressions associated with induced orthopedic pain in four equine pain scales.
        Animals. 2020; 10: 2155
        • Dai F.
        • Leach M.
        • MacRae A.M.
        • et al.
        Does thirty-minute standardised training improve the inter-observer reliability of the Horse Grimace Scale (HGS)? A case study.
        Animals. 2020; 10: 781
        • Dalla Costa E.
        • Minero M.
        • Lebelt D.
        • et al.
        Development of the Horse Grimace Scale (HGS) as a pain assessment tool in horses undergoing routine castration.
        PLoS One. 2014; 9e92281
        • Dalla Costa E.
        • Pascuzzo R.
        • Leach M.C.
        • et al.
        Can grimace scales estimate the pain status in horses and mice? A statistical approach to identify a classifier.
        PLoS One. 2018; 13e0200339
        • Dalla Costa E.
        • Stucke D.
        • Dai F.
        • et al.
        Using the Horse Grimace Scale (HGS) to assess pain associated with acute laminitis in horses (Equus caballus).
        Animals. 2016; 6: 47
        • de Grauw J.C.
        • van Loon J.P.
        Systematic pain assessment in horses.
        Vet J. 2016; 209: 14-22
        • Dyson S.
        • Berger J.M.
        • Ellis A.D.
        • Mullard J.
        Can the presence of musculoskeletal pain be determined from the facial expressions of ridden horses (FEReq)?.
        J Vet Behav. 2017; 19: 78-89
        • Gleerup K.B.
        • Forkman B.
        • Lindegaard C.
        • Andersen P.H.
        An equine pain face.
        Vet Anaesth Analg. 2015; 42: 103-114
        • Goodwin D.
        The importance of ethology in understanding the behaviour of the horse.
        Equine Vet J. 1999; 31: 15-19
        • Mustajoki M.
        • Forsén T.
        • Kauppila T.
        Pain assessment in native and non-native language: difficulties in reporting the affective dimensions of pain.
        Scand J Pain. 2018; 18: 575-580
        • Rashid M.
        • Silventoinen A.
        • Gleerup K.B.
        • Andersen P.H.
        Equine Facial Action Coding System for determination of pain-related facial responses in videos of horses.
        PLoS One. 2020; 15e0231608
        • Van Dierendonck M.C.
        • van Loon J.P.
        Monitoring acute equine visceral pain with the Equine Utrecht University Scale for Composite Pain Assessment (EQUUS-COMPASS) and the Equine Utrecht University Scale for Facial Assessment of Pain (EQUUS-FAP): A validation study.
        Vet J. 2016; 216: 175-177
        • van Loon J.P.
        • Van Dierendonck M.C.
        Monitoring acute equine visceral pain with the Equine Utrecht University Scale for Composite Pain Assessment (EQUUS-COMPASS) and the Equine Utrecht University Scale for Facial Assessment of Pain (EQUUS-FAP): A scale-construction study.
        Vet J. 2015; 206: 356-364
        • van Loon J.P.
        • Van Dierendonck M.C.
        Monitoring equine head-related pain with the Equine Utrecht University scale for facial assessment of pain (EQUUS-FAP).
        Vet J. 2017; 220: 88-90