An Ethogram for Ridden Horse Facial Expressions of Pain

The facial markers showing the greatest significant difference between lame and sound horses included ears back, tipping the head, eyes partially or fully closed, an open mouth with exposed teeth, and being severely above the bit, among others.

Photo: Courtesy Sue Dyson, MA, VetMB, PhD, DEO, FRCVS

New research by scientists at the Animal Health Trust (AHT) Centre for Equine Studies, in Newmarket, U.K., is aimed at producing a practical tool to help owners, riders, trainers, and veterinarians recognize signs of pain from a ridden horse’s facial expressions.

As TheHorse.com first reported in March 2017, owners and trainers don't widely undersTand facial expressions of pain in ridden horses. This means a horse’s health and welfare can be threatened, because veterinary assistance is not sought early enough, if at all.

Researcher Sue Dyson, MA, Vet MB, PhD, DEO, FRCVS, head of Clinical Orthopaedics at the AHT, has released two videos relating to that study. In the first video Dyson explained the common problems mistaken for pain, why the study is so important, and what it could mean for horses, owners, and vets in the future. It ignited a huge debate online about understanding equine behavior and body language. The video also prompted comments from owners who now feel guilty for not taking note of these facial expressions sooner to help their horse, and from other professionals agreeing that these expressions can be recognized, but are amazed at how often they are not.

The second video, now available online, provides individuals working with horses insight into how AHT researchers have developed an ethogram, how it was tested to ensure it could be applied by a broad range of people within the equine industry, and whether or not the ethogram is effective in not only helping recognise signs of pain, but could differentiate a lame horse from a sound horse.

The problem:

Evidence suggests that owners, riders, and trainers have a poor ability to recognize signs of pain seen when horses are ridden. As a result, problems are labeled as training-related, rider-related, behavioral, or deemed “normal” for that horse because “that’s how he’s always gone.” That means pain-related problems are often disregarded, the horse continues in work, and the problem gets progressively worse. If pain goes unrecognized and is not referred to a lameness specialist early enough, problems become too advanced to be resolved, or managed as well as they might have been if spotted sooner.

The aim:

Recognition of facial expression changes could potentially save horses from suffering and chronic injuries by enabling owners and trainers to recognize pain sooner, and get these horses the veterinary care that they need. Developing a practical tool for recognizing facial expressions, similar to that of a body condition score chart, could dramatically improve the health and welfare of all horses. This is something Dyson and her team at the AHT continue to work toward.

The ethogram:

The ethogram is a catalogue of facial expressions including the ears, eyes, nose, muzzle, mouth, and head position. Each body part can display an expression which may be normal, or reflect pain, conflict behavior or distress.

Developing the ethogram:

In its first stage of testing, the ethogram was successfully applied by a variety of people from different backgrounds, to a selection of photographs of horses’ heads while they were ridden. Using the ethogram these individuals could identify different expressions in each horse, such as ear position, eye changes, and muzzle tightness. The results were highly repeatable among the analysts proving that, with guidance from the ethogram, owners could potentially reliably recognize different expressions in their horse’s face.

Applying the ethogram:

Stage two tested if the ethogram could be used to distinguish between sound and lame horses. During this phase a pain score ranging from 0-3 was applied to each of the facial expressions (mouth, eyes, ears etc.), and then totaled to determine an overall pain score for each horse. Assessors viewed 519 photos of horses which Dyson had categorized as lame or sound. A total of 27,407 facial markers were recorded, with results showing that there was a scientifically significant difference in pain scores given by the assessor for clinically lame and sound horses. The facial markers showing the greatest significant difference between lame and sound horses included ears back, tipping the head, eyes partially or fully closed, tension around the eye, an intense stare, an open mouth with exposed teeth, and being severely above the bit.

To further prove the effectiveness of assessing pain in a horse with the facial expressions ethogram, a selection of lame horses underwent lameness assessment and nerve blocking (using local anesthetic solution), to alleviate the pain causing them discomfort when ridden. Comparison of their facial expressions before and after using local analgesia showed a significantly lower pain score once the pain causing lameness had been removed.

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