Elsevier

Journal of Veterinary Behavior

Volume 18, March–April 2017, Pages 7-12
Journal of Veterinary Behavior

Equine Research
Development of an ethogram to describe facial expressions in ridden horses (FEReq)

https://doi.org/10.1016/j.jveb.2016.11.005Get rights and content

Abstract

Many horses presumed to be sound by their riders are not. Facial expression ethograms have previously been used to describe pain-related behavior in horses, but there is a need for a ridden horse facial ethogram to facilitate identification of pain in ridden horses. The objectives of this study were to develop and test an ethogram to describe facial expressions in ridden horses and to determine whether individuals could interpret and correctly apply the ethogram, with consistency among assessors. An ethogram was developed by reference to previous publications and photographs of 150 lame and nonlame ridden horses. A training manual was created. Thirteen assessors (veterinarians of variable experience, n = 4; equine technicians, n = 3; equine studies graduates, n = 2; amateur horse owners, n = 2; equine veterinary nurse, n = 1; a British Horse Society Instructor, n = 1) underwent a training session and, with reference to the training manual, evaluated still lateral photographs of 27 training heads. Features were graded as Yes, No, or “Cannot see” (when it was not possible to determine the presence or absence of a feature). The ethogram was adapted, and after further training, the assessors blindly evaluated 30 test heads from nonlame and lame horses. Intraclass correlation (ICC) and free-margin kappa tests were used to assess consensus among assessors. For the training heads, single ICC matrix among observers resulted in an overall ICC of 0.50 (95% confidence intervals, 0.40-0.62). Four assessors consistently scored differently from the others, with ranges of ICC of 0.20-0.50 (mean, 0.41). There was no difference in assessors' scoring related to their professional backgrounds. For the test heads, mean interrater agreement among assessors was 87%. Two assessors still scored consistently differently (0.28-0.50 ICC agreement; mean, 0.40) from the remaining 11 assessors (0.44-0.69 ICC agreement; mean, 0.56). The mean percentage of overall agreement was 80%, and the mean free-marginal kappa value was 0.72, standard deviation (SD) ± 0.22. The large SD was the result of inconsistency in assessments of the eyes and muzzle. It was concluded that the developed ethogram could reliably be utilized to describe facial expressions of ridden horses by people from different professional backgrounds. Future work needs to determine if nonlame and lame horses can be differentiated based on application of the ethogram.

Introduction

There are many horses that appear sound in hand but have underlying pain-related musculoskeletal problems which are evident to a trained observer in ridden horses (Dyson 2016a) but which may go unrecognized by owners, riders, trainers, or a less-experienced veterinarian. Horses that experience musculoskeletal pain on the lunge and when ridden show a variety of gait modifications in an attempt to reduce pain. These include reducing the range of motion of the thoracolumbosacral spine (Greve et al., 2016a, Dyson, 2016a, Dyson, 2016b), taking shorter steps, alteration of limb flight, and increasing body lean (Greve et al., 2016b). It has been observed that owners, riders, and trainers appear to have a poor ability to recognize signs of pain seen when horses are ridden (Dyson and Greve, 2016). In a study of 506 sports horses in normal work and presumed to be sound, 47% were overtly lame or had other pain-related gait abnormalities (e.g., stiff, stilted canter), thus highlighting the size of the problem (Greve and Dyson, 2014). As a result, problems are labelled as training related, rider related, behavioral, or deemed “normal” for that horse because “that is just how the horse has always gone.” Consequently, pain-related problems often get progressively worse, and if ultimately presented for investigation to an experienced lameness specialist, the problems are often too chronic and advanced to manage satisfactorily. Inability to perform satisfactorily may result in a decline in value of the horse and the standards of care (McLean and McGreevy, 2010a, McLean and McGreevy, 2010b). Improved pain recognition will enhance equine welfare.

Many members of the veterinary profession have had little training in pain recognition and assessment of behavior and have had limited education in identification of low-grade lameness and recognition of musculoskeletal pain as a cause of poor performance. Behavioral changes related to experimentally induced orthopedic pain in horses have been described (Bussières et al., 2008, Lindegaard et al., 2010), but the features described, such as pawing the ground, are generally not applicable to ridden horses. The most recent advance in the recognition of subtle behavioral changes associated with pain is the investigation of facial expressions (Gleerup and Lindegaard, 2016). The spectrum of facial expressions exhibited by normal horses under nonridden circumstances has been described in detail (Wathan et al., 2015). An “equine pain face” was developed to describe facial features of horses with induced limb pain at rest (Gleerup et al., 2014). A Horse Grimace Scale, consisting of 6 features (the ears held stiffly backwards; orbital tightening [the eyelid is partially or completely closed]; tension above the eye; the mouth strained with a pronounced chin; the nostrils strained with flattening of their profile; and prominent strained chewing muscles) at 3 levels (not present, moderately, and obviously present) was developed to categorize the facial expressions of horses undergoing routine castration (Dalla Costa et al., 2014). However, it has been suggested that posture changes and overall body tension in resting horses may confound results and that further research is required to test for reliability of “pain grimace” measures (Hausberger et al., 2016). The Equine Utrecht University Scale for Facial Assessment of Pain (EQUUS-FAP) was developed to assess facial pain expressions in horses with or without colic and used a 3-point system from “normal = 0” to “maximal visible pain” for 9 facial parameters, to derive an overall pain scale (van Loon and Van Dierendonck, 2015). This system showed good reliability among 4 veterinary students and 2 veterinarians when looking at 10-minute video recordings of stabled horses. However, for working horses, the rider or trainer should be able to assess animals and recognize facial expressions overall.

An initial outline of a scheme to assess some aspects of facial expression in ridden horses has been described (Hall et al., 2014); however, a detailed description of the results was not documented. Head movement, ear position, teeth grinding, and lip movements were described in a study comparing 2 groups of young horses (3.5 years of age) when first lunged under a saddle and first ridden at a trot following either a “conventional training approach” or a “sympathetic training approach” (Visser et al., 2009). A comprehensive method for describing facial expressions in ridden horses, potentially to determine the presence of pain, has not been reported previously.

The aim of the present study was to develop and test an ethogram to describe facial expressions in photographs from ridden horses and to determine whether individuals could interpret and correctly apply the ethogram, with consistency among assessors. The objective was to look at ridden facial expressions in general, rather than an immediate focus on pain which may introduce an observer bias. The results can then be applied in future studies to assess photographs and video recordings of ridden horses and to test for differences in expressions due to pain or stress.

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Materials and methods

The study was approved by the Clinical Ethical Review Committee of the Animal Health Trust (AHT 29 2015).

Ethogram development: Training heads

The results and discussion with observers highlighted that certain behaviors were difficult to identify on the photographs. Forty-five percent of the behaviors were scored as “Cannot see” for >25% of the observations (Figure 2). However, for 65% of the individual behaviors which were scored, there was an average median assessor agreement of ≥70% for all horses.

All related behaviors were compared for consistence. For example, the head positions of relaxed and tight were scored fairly

Discussion

An ethogram was developed to describe facial expressions in ridden horses which, after adaptation and training, was adequately interpreted by assessors from different professional backgrounds, with reasonable consistency for most observations. Observations relating to the eye and muzzle were the least consistent, with κ values ranging from 0.25 to 0.42. Results for the test heads were superior to the training heads, following additional training and adaptation of the ethogram. The proportion of

Conclusions

An ethogram for facial expressions in ridden horses has been developed, which can reliably be utilized by people from different professional backgrounds. This novel work is the first step toward assessing pain in ridden horses other than through obvious gait changes or physiological posture. Future work needs to determine if pain-free and lame horses can be differentiated based on application of the ethogram (in still and moving pictures) and if key markers can be identified, so that the

Acknowledgments

The study was generously supported by World Horse Welfare and the Saddle Research Trust. The sponsors had no role in any aspect of the study. The authors thank the assessors: Karena Bean, Anne Bondi, Julie Breingan, Siobhan Gilligan, Laura Jones, Melissa Lockwood, Claire Martin, Abbi McGlennon, Jenny Routh, Heather Stephenson, Karen Sweet, and Lisa Zimmerman.

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