Reports from the world of equine research.
Gait analysis in the field.
A gait analysis system initially developed for the Great Britain dressage team is now available to all.
Haydn Price, farrier to the British Olympic team, started using video recordings in his work in 1999. Initially, he had only a hand-held camera, but it allowed him to record the way the horse moved. He could then examine more closely any areas of concern.
But he wanted something more objective. “I could never prove that what we had done had helped the horse. I could see the effect, the owner could feel the effect, and the horse performed better. But I couldn’t prove it.”
To find a solution he turned to Professor John E Davies, consultant Physician in Sports Medicine at Guys Hospital, London. Together they developed a portable gait analysis system (“Equinalysis“).
As the only equipment needed is a video camera and a laptop computer, the system is readily portable, making it possible to use it “in the field”. A standard protocol has been devised.
Markers are placed at specific points of the horse’s limbs - mainly over joints. The horse is walked and trotted in hand past the camera. A video recording is made from in front and behind and from both sides. This can then be slowed down, examined and analysed.
What does Price look for in a recording? “The video clips should show clearly two full strides from a lateral view. The handler should not influence the horse, at both walk and trot, in any way. Of course the horse must move in a straight line.”
The computer software records the movement of the markers, and produces data that can be analysed to give information on factors such as the range of movement, the angle, and degree of flexion of joints.
What are the most common reasons for examination? “The usual request is either poor performance or intermittent lameness” Price reports. “ But also and interestingly, that the rider “feels something” but nothing clinical can be diagnosed at veterinary inspection ”
“We have used the system to measure the effects immediately after the shoeing process has been executed, with some very interesting findings! This has highlighted the effects (or in some cases not!) of recognised treatment plans for specific conditions, such as rolled toe and raised heel.”
“We can accurately measure differences in stride patterns and isolate it to particular segments of the limb”
Martyn Elliot, a farrier in Nottinghamshire, has been using the Equinalysis system since early 2006. “Most of the gait abnormalities can be identified by playing the video slowly“ he explains. “But for complicated cases you can refer to the biomechanical measurements for interpretation.”
“The big advantage to a farrier using this equipment is they can cut out the middle man. They can analyse, identify the problem, suggest a remedy, try it and reassess to see if it has had the desired effect.”
He describes a Pony Club dressage horse that was referred to him by another farrier because of abnormal wear of the shoes that he could not explain. The video showed that the horse was markedly over-tracking - the hind foot would land three foot lengths in front of the fore foot. By studying the video, Elliot was able to see that the horse twisted the stifle in and the hock out just before breakover, at the end of the weight-bearing phase of the stride. So he shod the horse with a squared toe with plenty of support at the quarters. Afterwards the horse moved much better. The rotation was much less marked and the overtracking was reduced to about one foot length.
Although the system was originally conceived as a means of assessing the effect of shoeing on the horse’s gait, it has other applications. It can be used to assess other interventions such as manipulation, and can provide a record of the horse’s action.
“We are about to train a chiropractor who wishes to measure the effects of treatment“ Haydn Price explains. Indeed Martyn Elliot has already measured a horse following manipulation”
Haydn Price sees a place for the system as part of the prepurchase examination. “Some vets would prefer to incorporate it as part of the vetting procedure whilst others may prefer to use the facility afterwards. Just remember that the system does not diagnose and therefore can only be accurately used alongside present veterinary practices. Equally the information from the screening can assist in acting as benchmark in the same way as x-rays or scans.”
“We are collecting data from our business partners and from veterinary practices” he explains. “Whilst it is too soon to give statistical information, some very interesting findings are now beginning to appear. For example, with Equinalysis, I can prove that moving the front of the shoe back by 3mm results in a 6-degree difference in knee flexion.”
Price concludes “ With Equinalysis we can optimise the trimming and shoeing so that the horse can move in the most efficient way. This should limit the strain on the joints, promote better performance and may delay the onset of degenerative joint disease.”
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© Copyright Equine Science Update 2006