Horses and People

Horses, as flight animals, instinctively remain silent in the face of pain, but a new study, recently published in Equine Veterinary Education, shows they have a ‘voice’ if observers are trained to ‘listen’. The study confirms that if vets are trained to use a Ridden-Horse-Ethogram they are better able to recognise pain-related behaviour in horses, which may reflect lameness or back or sacroiliac pain. This should in turn help them to communicate potential performance problems more effectively with their clients.¹

Led by Dr Sue Dyson, Head of Clinical Orthopaedics at the Centre for Equine Studies at the Animal Health Trust in Newmarket and her team, the study compared the real-time application of the Ridden-Horse-Ethogram with analysis of video recordings of the horses by a trained assessor and determined whether veterinarians, after preliminary training, could apply the ethogram in real time in a consistent way and in agreement with an experienced assessor.

A Ridden-Horse-Ethogram is a catalogue of observable behaviours, for example, head tilting, intense stare, tail swishing, toe dragging, etc… (see below the list summary).

Twenty horse and rider combinations were used for the study. The horses were in regular work and were capable of working ‘on the bit’. They were assessed by a chartered physiotherapist and then a Society of Master Saddlers (SMS) qualified saddle fitter checked the fit, placement, balance and suitability of each horse’s saddle. Eleven horses were found to have ill-fitting saddles and 14 had back muscle tension or pain but these did not influence the behaviour scores.

The horses were also assessed by an independent lameness expert. Sixteen showed low-grade lameness or abnormalities of canter, which were likely to be pain induced but did not prevent the horses from being used for the study.

All 20 horses were given a 15-minute ridden warm-up before executing an 8-minute purpose-designed preliminary level dressage test. During each dressage test a team of 10 equine vets, who were selected from 40 volunteers and given preliminary training, applied the Ridden-Horse-Ethogram. They assessed each horse for the presence of a total of 24 behaviours that occur more commonly in lame horses compared with non-lame horses. It has previously been shown that the presence of 8 or more behavioural markers is likely to indicate the presence of musculoskeletal pain.

The following is a summary of the Ridden Horse Ethogram from previous studies by Dr Dyson and her colleagues:

Repeated changes of head position (up/down)
Head tilted or tilting repeatedly
Head in front of vertical (>30°) for >10 s
Head behind vertical for (>10°) >10 s
Head position changes regularly, tossed or twisted from side to side, corrected constantly
Ears rotated back behind vertical or flat (both or one only) >5 s; repeatedly lay flat
Eye lids closed or half closed for 2–5 seconds
Sclera exposed
Intense stare for 5 s
Mouth opening shutting repeatedly with separation of teeth, for >10 s
Tongue exposed, protruding or hanging out, and/or moving in and out
Bit pulled through the mouth on one side (left or right)
Tail clamped tightly to middle or held to one side
Tail swishing large movements: repeatedly up and down/side to side/circular; during transitions
A rushed gait (frequency of trot steps >40/15 s); irregular rhythm in trot or canter; repeated changes of speed in trot or canter
Gait too slow (frequency of trot steps <35/15 s); passage-like trot
Hindlimbs do not follow tracks of forelimbs but deviated to left or right; on three tracks in trot or canter
Canter repeated leg changes: repeated strike off wrong leg; change of leg in front and/or behind; disunited
Spontaneous changes of gait (e.g. breaks from canter to trot or trot to canter)
Stumbles or trips repeatedly; repeated toe drag
Sudden change of direction, against rider direction; spooking
Reluctant to move forward (has to be kicked verbal encouragement), stops spontaneously
Rearing (both forelimbs off the ground)
Bucking or kicking backwards (one or both hindlimbs)

The assessments were made in walk, trot and canter and on the left and right reins. A total behaviour score of 8 or more (out of 24) is likely to indicate the presence of musculoskeletal pain.

All behaviours were scored as present or absent. The ethogram was also applied to each horse by an experienced trained assessor (Dr Dyson) and the tests were filmed so that the experienced assessor could make a comparison between her real-time behaviour assessments and video analysis.

There was good agreement between the expert’s scores and the volunteer vets’ scores and excellent consistency in overall agreement among the volunteers. The scores also reflected the volunteers’ capacity to use the ethogram to identify lameness status, with higher scores awarded to the lame horses compared with the non-lame horses.

There was no significant difference in real-time scores and video-based scores for the experienced assessor, verifying the reliability of the system.

“The study confirms that with basic training veterinary observers can use the ridden horse ethogram with consistency as an effective tool to help identify musculoskeletal pain which could reflect lameness or back or sacroiliac pain,” said Dr Dyson. “The volunteers were unanimously positive about the potential value of the ethogram in helping them to determine the presence of musculoskeletal pain in horses performing poorly or at pre-purchase examinations.”

The study abstract can be found here. It is titled: Can veterinarians reliably apply a whole horse ridden ethogram to differentiate nonlame and lame horses on live horse assessment of behaviour? Authors: S. Dyson, K.Thomson, L. Quiney, A. Bondi and A.D. Ellis.

The following images are supplied by AHT to illustrate some of the Ridden-Horse-Ethogram pain-related behaviours.

Image A (below): Front of head (profile) is more than 30 degrees in front of the vertical; ears behind vertical for 5 seconds; intense stare; bit pulled through

Image B (below): Front of head (profile) over 30 degrees in front of the vertical; ears behind vertical for 5 seconds; intense stare; hindlimb toe drag; tail swishing.