Researchers at the Animal Health Trust Equine Clinic have developed an ethogram to help veterinary surgeons, owners and riders identify when a horse is in pain, from its facial expressions when being ridden.
According to the AHT, there is undisputed evidence 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'.
This, says the AHT, means pain-related problems are often disregarded, the horse continues in work, and the problem gets progressively worse.
Dr Sue Dyson, Head of Clinical Orthopaedics at the AHT, believes it may be easier to educate riders and trainers to recognise changes in facial expression and behaviour rather than lameness. So she and her team set out 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 consistently.
At this stage in the project, they concluded that their ethogram could reliably be used to describe facial expressions of ridden horses by people from different professional backgrounds (full paper here: http://www.journalvetbehavior.com/article/S1558-7878(16)30184-8/fulltext).
In the next stage of the project, Sue and her team sought to demonstrate that the ethogram could be used to identify lameness.
The ethogram was applied blindly by a trained analyst to photographs (n=519) of the head and neck of lame (n=76) and non-lame (n=25) horses acquired during ridden schooling-type work at both trot and canter. These included images of seven lame horses acquired before (n=30 photographs) and after diagnostic analgesia had abolished lameness (n=22 photographs).
A pain score (0-3; 0=normal, 1-3=abnormal) was applied to each feature in the ethogram, based on published descriptions of pain in horses.
A total of 27,407 facial markers were recorded, with those giving the greatest significant difference between lame and sound horses including ears back, eyes partially or fully closed, an open mouth with exposed teeth and being severely above the bit.
Pain scores were higher for lame horses than non-lame horses (p<0.001). Total pain score (p<0.05), total head position score (p<0.01), and total ear score (p<0.01) were reduced in lame horses after abolition of lameness.
Severely ‘above the bit’, twisting the head, asymmetrical position of the bit, ear position (both ears backwards, one ear backwards and one to the side, one ear backwards and one ear forwards) and eye features (exposure of the sclera, the eye partially or completely closed, muscle tension caudal to the eye, an intense stare) were the best indicators of pain.
The researchers concluded that application of the ethogram and pain score could differentiate between lame and non-lame horses. Assessment of facial expression could potentially improve recognition of pain-related gait abnormalities in ridden horses (full paper here: http://www.journalvetbehavior.com/article/S1558-7878(17)30019-9/fulltext)
Sue and her team are now working on the development of a whole horse ethogram and its application to non-lame and lame horses, to help to differentiate between manifestations of conflict behaviour, in response to the demands of the rider, and pain. They are also working towards the development of a practical tool for recognising facial expressions, similar to that of a body condition score chart, which they say could dramatically improve the health and welfare of all horses.