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A scientists' journey: cutting-edge research into lameness in horses

by
01 July 2017, at 1:00am

Dr THILO PFAU of the RVC Equine Hospital explains what his unit has been doing to create a tool which will help clinicians to diagnose and treat lameness effectively by isolating specific causes and effects

AS EVERY HORSE OWNER AND VET will know only too well, lameness can be a very serious issue for horses. It has been identified as the most common reason for older horses to be put down and can affect the health and well-being of horses of any age. The Royal Veterinary College’s Equine Hospital is a leader in its field and helps to treat lameness as well as many other ailments that can afflict horses. But across the way from the emergency room, there is a research centre at the RVC that goes to the heart of this issue, and conducts cutting-edge research that is expanding our body of knowledge and understanding into the causes, diagnostics and treatment of lameness. It is known as the RVC’s Structure and Motion Lab, a world-renowned research facility for investigating locomotion in animals, led by Professor Alan Wilson, where I have had the pleasure of working for nearly 10 years. Primarily, we use technological aids to reduce the subjectivity of lameness examinations, as well as to enhance our understanding of the biomechanics of lameness. As a number of our early studies into the limits of human perception of lameness showed, you might be surprised how difficult it is to detect small movement asymmetries with the untrained eye, and how much goes into the mechanics of horse movements that we can barely see. Considering my academic background in computer science, it was a natural next step to bring technology to bear where the eye fails. We sought to scientifically investigate the biomechanics of movement of healthy and lame horses, to better understand the underlying mechanisms in every movement. Using six degrees of freedom inertia sensors (that detect movement on all three axes) as well as more classic 3D motion cameras, and even the sensors found in mobile phones, we have been able to construct the most precise analysis yet of the interactions between different anatomical parts in lame horses, ranging from almost imperceptible asymmetries to extreme limps. More recently, a collaboration with likeminded researchers at the Swedish University of Agricultural Sciences in Uppsala has allowed us to significantly increase the sample sizes of some of our studies. Recently-published research into lameness in sport horses has suggested that many racehorse owners do not consider their horses lame despite experts being able to spot, by eye, movement deficits that are consistent with lameness. Fuelled by this observation, we have set about providing measurable evidence about movement asymmetry parameters in “normal” horses – so horse owners can compare movements to what they “should” be. This, we believe, is an essential step towards evidence-based assessment of movement deficits in horses and has formed the basis of other studies at other research facilities relating to diagnostics and treatment of lameness, such as a study quantifying the effect of administering non-steroidal antiinflammatory drugs. We have also conducted studies into methods that might allow horse owners to improve their lameness detection skills, and have found that a simple video-based approach can help.

Removing the bias

A crucial element of our research in these areas is to remove the bias inherent in human decision-making. By putting into numbers what can be observed by the naked eye, we aim to remove the subjective element that can lead to disagreement between experts – as well as giving tools to those who are not experts. But the effects of our research can go so much further than that. It can
provide essential progress towards evidence-based decision-making – helping clinicians to diagnose and treat lameness effectively by isolating specific causes and effects.

Observing phenomena

During a lameness examination, we observe lots of phenomena in horse movement – head nod, hip hike, movements of the withers, length of stride, etc. – all of different magnitudes and intensities, and all affected by the horse’s pain. It is clear that people struggle with conscious optimal decision-making when faced with so many parameters. Increasingly, we are conducting research using technical aids and keeping parameters limited in number, to work out the exact impact of certain clinical interventions (e.g. numbing the pain – known as diagnostic analgesia) on a limited number of parameters (e.g. quantifying head nod and hip hike only). We are also measuring other parameters that go beyond those currently understood as the main criteria for lameness and can relate to things sometimes more difficult to perceive by eye. Measuring more than just the head nod and hip hike can be useful. For example, we have recently found that by measuring movement asymmetry in the withers, we can detect a difference between horses with induced forelimb lameness and horses with induced hind limb lameness. Encouraged by this finding, a largescale study in racing thoroughbreds – funded by the Horserace Levy Board at the Singapore Turf Club – showed that this new parameter provided new quantitative information in support of the “rule of sides”. This rule helps veterinarians to determine the affected limb in multilimb lame horses. Vets will now have another tool at their disposal to detect this by measuring movement in the withers.

Complete transformation

In time, this research could lead to a complete transformation of lameness diagnostic examination – where a specific effect will very precisely and confidently be linked to a specific cause – due to our expanded collective body of knowledge in this area and our deeper understanding of all related causal relationships. My scientific journey over the last 10 years has been a transformative one, allowing me, significantly helped by the undergraduate and postgraduate students and in collaboration with clinicians and researchers both at the RVC and elsewhere, to apply my background and skills in computer science to the complex, real-life task of detecting and quantifying lameness in horses. There are still many questions left unanswered; however, I am optimistic that continuing progress will be made and that the work of researchers
around the globe in this fascinating area is helping veterinarians to make confident decisions, particularly when faced with “tricky” horses presenting with subtle lameness and performance issues.