If the shoe fits...

24 June 2022 Written by Sarah Marinos

Well-fitted shoes can help prevent painful and costly injuries and ensure horses enjoy a longer racing life. Professor Chris Whitton and his colleagues are at the forefront of research into limb injuries.

At the University of Melbourne’s U-Vet Werribee Equine Centre, preventing and diagnosing lameness is a key focus for researchers like Professor Chris Whitton. The Equine Centre brings together research and cutting-edge diagnostic imaging facilities with a specialist referral clinic for the racing industry.

One of the most important areas of work so far has been identifying the types of exercise that are most damaging to bones and joints and highlighting the benefits that can come when horses are given periods of rest from high-intensity racing.

With funding from Racing Victoria, the Victorian State Government and international funding body the Grayson Jockey Club, Professor Whitton and his colleagues are also exploring new ways of assessing signs of injury in a horse’s stride. They are developing software that can assess limb injury risk in real time and are looking at how to improve on current diagnostic imaging methods.

The Equine Centre already has some of the most advanced imaging and diagnostic equipment, including a standing CT system that allows horses to be imaged standing while under sedation and without the need for anaesthesia. The system was the first of its kind in Australia and only the third in the world.

Professor Whitton says understanding the mechanics and loads generated in the lower limbs, particularly the fetlock joint, the surrounding tendons and the suspensory ligament, is key to helping horses in the racing industry avoid injury. Balancing the centre of pressure on the feet, with the help of well-fitted shoes, is part of this puzzle. 

“When you see videos of galloping horses, their fetlock is driving towards the ground and their pastern – the part of the leg between the fetlock and the top of the hoof – is almost horizontal. The only thing stopping it continuing to drive downwards are the tendons that wrap around the back of the foot and fetlock,” explains Professor Whitton.

“The further forward the centre of pressure, the greater the load on the joint and the centre of pressure is determined by the foot conformation. Reducing the load delivers the biggest bang for buck in reducing injury and to do that you need to keep a horse’s feet in good shape.”

Professor Whitton says vets will often work closely with a farrier to limit the risk of injuries to joints, tendons and ligaments. In general, joint injuries are more common in young horses while experienced racehorses are more likely to suffer damage to tendons and ligaments.

“Farriers will try and bring the centre of pressure of the foot back and they do that by reducing the toe length. They deal with heel collapse, which is an issue for a lot of thoroughbreds, by shoeing horses a bit wider and longer. Racehorses put a lot of stress on their heels,” explains Professor Whitton.

“The shoe itself is not that critical – it’s more to do with the trimming and maintenance of the foot shape that matters.”

The U-Vet Werribee Equine Centre is looking at how injuries can be spotted at an early stage to avoid further damage. Ultrasound and X-rays are more easily accessible and cheaper but advanced imaging, like CT scans and MRI, are more effective at monitoring joint health.

Last year, Racing Victoria introduced a Diagnostic Imaging Subsidy Program to help cover imaging costs. It covers MRI, standing CT scans and scintigraphy – a bone scan where a radioactive dye is injected into the horse and gamma camera records ‘hot spots’.

“Ultrasound is useful for tendon and ligament injuries. It creates an image of the soft tissue so you can see changes in the tendons and changes in the fibre pattern and see if that pattern is improving over time,” Professor Whitton said.

“The fetlock joint is challenging to monitor, but CT and MRI allow us to see pathology before it is too late. You can then modify a horse’s training program before it gets to the point of no return. Previously, we didn’t know an injury was there until it was quite severe. Now we can see what is going on much earlier and look at what training practice might predispose a horse to that injury.

“Bone injuries in joints are the most common injuries that cause poor performance or low-grade lameness and the serious fractures that can be fatal. So, we are doing imaging studies where we image horses at the start and end of a training program to understand how training practices affect the development of joint disease.”

Research has also shown that horses can begin to develop injuries before that injury becomes visibly apparent. Data suggests horses reduce their speed and stride length up to six races before developing an injury. While a number of factors can affect speed and stride length, such as the tempo of a race, the going and whether it is a sprint or long-distance race, Professor Whitton says sophisticated statistical analysis so far demonstrates a definite drop-off in performance prior to injury.

“We are also looking at the mechanics of the joint surface to better understand the structure of joints, how they behave mechanically and how resistant they are to loading so we will know the limits of the skeleton and not overdo the training and racing,” says Professor Whitton.

“The key to injury prevention is understanding that they come on gradually and there is an opportunity to prevent them – it’s not bad luck. We now have a lot of information that shows most injuries in racehorses are a result of accumulated damage over time. They get to a tipping point and that’s when we see the injury.

“We are looking at these issues at multiple levels with the ultimate aim of understanding how to train a horse safely so that it doesn’t develop injury. It’s a complex and challenging area and we are learning – but there is still a lot more to learn.”