YOU might think it would be easy to spot when a horse is going lame. But an inability to walk, trot, canter or gallop with a regular motion on all four hooves can produce subtle or intermittent symptoms, making it hard to decide whether a valuable racehorse or showjumper needs treatment. Now a sensor more often found in smartphones could help provide an early diagnosis.
The use of technology to study equine locomotion has a distinguished history. Back in 1877, the photography pioneer Eadweard Muybridge used a high-speed camera to show that a galloping horse at times has all four hooves off the ground. The new scheme aims to detect incipient lameness by focusing on the movement of a horse when it is trotting.
鈥淎n objective measure of lameness is needed because it鈥檚 not always obvious visually,鈥� especially in the early stages of a condition, says of the large animal sciences unit at the University of Copenhagen in Denmark. So Thomsen and his colleagues have turned for help to the miniature accelerometers that were originally developed for use by the cellphone industry.
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At the heart of these devices are three piezoelectric cantilevers, set at right angles to each other. Each one produces a voltage when it is compressed by forces due to acceleration or gravity, so the three together can detect forces in three dimensions. Phones use these signals to orient information displayed on the screen, or to produce a response when the user shakes the device.
Thomsen knew that when a horse is about to go lame it starts to move with an asymmetric gait as it trots, and reasoned that such an accelerometer, mounted on the animal鈥檚 back above its centre of gravity at the base of the neck, might be able to detect this.
In a set of preliminary tests on 12 healthy trotting horses they found that the accelerations detected by the device were, as the team expected, symmetrical (Journal of Biomechanics, DOI: 10.1016/j.biomech.2010.05.004).
鈥淎ll we need to do is check vertical accelerations of the trunk during trot, because the symmetry decreases with lameness,鈥� says Thomsen. The team now plans to conduct further tests on lame horses to see if deviations from the 鈥渟ymmetry indices鈥� they have drawn up can help predict the onset of lameness.
The Danes will have their work cut out, says equine surgeon of the University of Bristol in the UK. Many biomechanical systems have been proposed for lameness detection, he says, 鈥渂ut none has been translated into practical aids鈥�.
That said, Tremaine reckons Thomsen鈥檚 results are encouraging because the accelerometer seems well able to monitor movement of the animals鈥� centre of gravity 鈥� so it may be able to help diagnose problems in other gaits, too. 鈥淲e will have to wait for their subsequent studies to see if they get consistent, clinically useful results,鈥� he says.
