Dr Sue Dyson: Reading a horse’s facial expressions
Dr Sue Dyson, is a world-renowned expert in equine orthopaedics, with a particular interest in lameness and poor performance in sports horses. Sue’s recent study proves that horses demonstrate pain through their facial expressions and it will help us to spot underlying pain and issues, she explains the study and her findings on the #HorseHour Podcast.
Having trained horses and competed at Advanced level eventing and Grade A showjumping, Sue has a passionate interest in sports horses and an in-depth knowledge and understanding of performance problems in horses from all disciplines. She is highly skilled in the diagnosis of both subtle and complex lameness cases. She is also an expert in diagnostic imaging, including radiography, ultrasonography, scintigraphy and magnetic resonance imaging.
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There is undisputed evidence to show that owners, riders and trainers have a poor ability to recognise signs of pain seen when horses are ridden. As a result, problems are labelled as training-related, rider-related, behavioural, or deemed ‘normal’ for that horse because ‘that’s how he’s always gone’. Unfortunately that means pain-related problems are often disregarded, the horse continues in work, and the problem gets progressively worse. If pain goes unrecognised 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.
Recognition of changes in facial expression could potentially save horses from needless suffering and chronic injuries, by enabling owners and trainers to recognise pain sooner, and get these horses the veterinary care that they need. Developing a practical tool for recognising facial expressions, similar to that of a body condition score chart, could dramatically improve the health and welfare of all horses – which is something Sue and her team at the Animal Health Trust continue to work towards.
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 behaviour 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 positions of the ears, changes in the eyes, and tightness in the muzzle. The results were highly repeatable among the analysts proving that, with guidance from the ethogram, owners could potentially reliably recognise 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 from 0 – 3 was applied to each of the facial expressions (mouth, eyes, ears etc.), and then totalled to determine an overall pain score for each horse. 519 photos of horses which had been categorised by Sue to be lame or sound were assessed. An amazing 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 anaesthetic 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.
For Sue and her team the study does not end here, with the next exciting stage of the project already underway with the development of a whole horse ethogram – keep a look out for the next stage (and for your horse’s expression!)