title: Development of the Horse Grimace Scale (HGS) as a pain assessment tool in horses undergoing routine castration.
abstract: BACKGROUND
  The assessment of pain is critical for the welfare of horses, in particular when pain is induced by common management procedures such as castration. Existing pain assessment methods have several limitations, which reduce the applicability in everyday life. Assessment of facial expression changes, as a novel means of pain scoring, may offer numerous advantages and overcome some of these limitations. The objective of this study was to develop and validate a standardised pain scale based on facial expressions in horses (Horse Grimace Scale [HGS]).
  
  
  RESULTS
  Forty stallions were assigned to one of two treatments and all animals underwent routine surgical castration under general anaesthesia. Group A (n = 19) received a single injection of Flunixin immediately before anaesthesia. Group B (n = 21) received Flunixin immediately before anaesthesia and then again, as an oral administration, six hours after the surgery. In addition, six horses were used as anaesthesia controls (C). These animals underwent non-invasive, indolent procedures, received the same treatment as group A, but did not undergo surgical procedures that could be accompanied with surgical pain. Changes in behaviour, composite pain scale (CPS) scores and horse grimace scale (HGS) scores were assessed before and 8-hours post-procedure. Only horses undergoing castration (Groups A and B) showed significantly greater HGS and CPS scores at 8-hours post compared to pre operatively. Further, maintenance behaviours such as explorative behaviour and alertness were also reduced. No difference was observed between the two analgesic treatment groups.
  
  
  CONCLUSIONS
  The Horse Grimace Scale potentially offers an effective and reliable method of assessing pain following routine castration in horses. However, auxiliary studies are required to evaluate different painful conditions and analgesic schedules.
authors.affiliation: Università degli Studi di Milano, Dipartimento di Scienze Veterinarie e Sanità Pubblica, Milan, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Dalla Costa
authors.affiliation: Università degli Studi di Milano, Dipartimento di Scienze Veterinarie e Sanità Pubblica, Milan, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Minero
authors.affiliation: Pferdeklinik Havelland / Havelland Equine Hospital, Beetzsee-Brielow, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Lebelt
authors.affiliation: Pferdeklinik Havelland / Havelland Equine Hospital, Beetzsee-Brielow, Germany.
authors.forename: Diana
authors.initials: D
authors.lastname: Stucke
authors.affiliation: Università degli Studi di Milano, Dipartimento di Scienze Veterinarie e Sanità Pubblica, Milan, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Canali
authors.affiliation: Newcastle University, School of Agriculture, Food & Rural Development, Newcastle upon Tyne, United Kingdom.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Leach
mesh_terms: D000700:Analgesics / Q000627:therapeutic use; D000818:Animals; D002369:Castration / Q000009:adverse effects*; D003002:Clonixin / Q000031:analogs & derivatives / Q000627:therapeutic use; D006736:Horses; D010146:Pain / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology; D010147:Pain Measurement / Q000379:methods*
chemical_list: D000700:Analgesics; C014557:flunixin; D003002:Clonixin