'The real need is to predict injury before it occurs': The New Zealand vet shaping the future of injury prevention

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“The real need is to predict injury before it occurs,” is how Dr Wayne McIlwraith sees the future of equine orthopaedic research. Many of the projects the pioneer of equine orthopaedics is now involved in revolve around prediction and prevention of injury.

In 50 years since the first equine arthroscopy, McIlwraith hasn’t observed any big trends with the type of injury he sees on the racetrack, but he believes we seem to see more now because we are paying greater attention.

“That’s associated with better diagnostics,” he said. “You haven't got crappy radiographs where you have to spend time dipping the film in a bath and so on. You’ve got digital radiographs. The world has changed a lot as far as diagnostic standards (are concerned).”

The development of digital radiographs provided much better detail of both normal joints, as well as better clarity of disease and injury. There are times when less experienced vets on the track pull the proverbial trigger, he said, and point out something that may not truly affect the horse, but that learning curve comes with time and guidance from more experienced racetrack vets - and is far less of a problem compared to before the dawn of digital radiography.

The same can be said for surgery.

“To become a good surgeon, you need the caseload,” he said. “That can be difficult, as our field is driven by economics. The two questions I am always asked are, ‘how much? And what is the percentage chance of that horse racing back to its previous level?’ We have the data on that now.”

Making strides with sensors

Data is at the heart of a research project launched in February of this year, where more than 700 juvenile racehorses will wear a sensor from one of six brands whenever undergoing fast work.

The project, overseen by the American Association of Equine Practitioners, will run for the rest of 2025 and aims to pinpoint changes in movement patterns that might precede musculoskeletal injury. Over US$1 million ($1.54 million) has been contributed to the project by industry groups.

“It’s very neat, the sensors are the size of a cellphone, so it’s not a weight problem for the horse,” McIlwraith explained. “All the horses that train with Aidan O’Brien at Ballydoyle go out with these sensors in the morning. However, what the sensors detect is a work in progress in terms of technologic development, as well as convenience of use."

The sensor manufacturers taking part in the study are Alogo Analysis, Arioneo, Equibase (Stable Analytics), Equimetrics, Garmin, and StrideSAFE - some of which will already be familiar to Australian and New Zealand trainers. Information on stride length, frequency, and pattern will be uploaded to cloud storage from each individual horse’s workout, and then the analysis will begin in earnest.

McIlwraith explained that Dr Chris Kawcak, he, and Colorado State University are partnering directly with Equimetrics - founded and developed by Annemarie O'Brien with Tom and Shay Curtis at Ballydoyle - in Ireland. He explained that Kawcak is the brains and leader on their end of the partnership, and the project was a major team effort. Kawcak has also recruited additional expertise for the project, bringing on board Dr Steve Simski as well as the team at the Sothwest Institute.

Undertaking the analysis for the project will most likely employ cutting edge artificial intelligence to help sort through thousands of workouts' worth of data, but “those fine details are out of my league to explain. I’m just the old guy hanging out, adding some experience, and trying to keep up with younger minds and what the team is doing!”

The idea of what the sensors will look for is, fortunately, more straightforward.

“The idea is that by putting a sensor on an individual horse, they'll establish the horse's individual (movement) signature. One day, the horse may come back with a totally different signal to what you've had in the last 10 breezes, so that means that something's changed in that horse's gait, and then you're going to do more diagnostics. That’s when you can say to the owner, 'look, you've got to get a CT’.

“The hope is that it will be a step up from other diagnostic techniques, such as serum biomarkers, that in previous work we have found in collaboration with Southern California Thoroughbred trainers and racetrack veterinarians to be useful in detecting early change.

“And then ultimately, the dream is that we will be able to do what we started talking about 30 years ago; being able to detect sunchondral bone microdamage. You'll likely see a change in the CT image that may show as a specific lesion, or perhaps a non-specific change that reflects early microdamage, and then that way, if there’s a change in a horse, you know it needs to be scratched.”

Further characterisation of the change on CT (computerised tomography) can be done using PET (positron emission tomography) CT imaging to define size and location of bone change that could have led to a catastrophic event.

The technology is currently far from perfect, McIlwraith admits, but this widespread study is a big step in the right direction towards developing the perfect sensor.

Since 2023, all horses starting at Churchill Downs have worn StrideSAFE sensors during races as part of raceday protocol. Last month, Churchill Downs trainer Dale Romans wrote in TDN about how the technology had caught changes in the movement pattern of one of his horses while race, and how diagnostic imaging confirmed bone changes that led to the horse being sent for a break.

The potential is certainly there, with the right application of data. “It's kind of the great hope for predicting injury,” McIlwraith said. “But we're not there yet.”

It's in the blood

Despite officially “retiring” from the University in 2020 as a University Distinguished Professor and his primary surgical practice in Southern California in 2023, McIlwraith remains incredibly active at the Orthopaedic Research Center (ORC) at Colorado State University. McIlwraith founded the ORC in 1994, and was Director of it from 1994 until 2020. Back home in New Zealand, he is an Adjunct Professor at his alma mater Massey University and also has been Chair of the New Zealand Equine Trust (that funds equine research and associated equine endeavours) since 2009.

His endeavours were recognised in the New Years Honours list at the beginning of 2025, where he was made an Officer of the New Zealand Order of Merit for services to veterinary medicine and the equine industry.

Microdamage is something that McIlwraith recognised early on as an area in dire need of research; microdamage is an inevitable part of training, but if a horse isn’t sufficiently rested to heal that damage, they are on a slippery slope to a fracture.

“In 1995, Dr Chris Kawcak completed his PhD with us at CSU that showed that every horse that went on the treadmill for 6 months developed microdamage and micro cracks over time in the subchondral bone. This damage can potentially progress to more severe macrodamage and fracture, and that is the beginning of nearly all catastrophic fractures.

“Basically, it's the beginning of all the joint fractures that we get, but these changes can only be definitely 'diagnosed' at post mortem with special staining to show this early microdamage.”

While most microdamage is undetectable on radiographs, CT has greatly improved our ability to visualise damage and is currently the gold standard for looking for it. However, rapid prediction of microdamage as a screening technique requires a true standing CT and portability.

A current study based in South California racing Thoroughbreds led by Drs Dave Frisbie and Mcilwraith is nearly complete, and is looking at the use of metabolomics as signals of stress or damage in a joint. McIlwraith is hopeful it will become another tool in predicting injury. Metabolomics looks at the presence and levels of proteins and metabolites produced by disease in the bloodstream, and it could in time be that early indicator of microdamage.

“The hope is that it'll be practical enough that we can take a blood sample every month, and if something looks wonky, then that horse will go and get a CT,” he said. Much in the vein of existing blood tests that look for abnormal levels, the study will be looking for an unnatural increase in metabolites to indicate the presence of disease.

“You can’t isolate the location with the biomarkers, but we would say that you have subchondral bone disease - that means that under the cartilage, you have these microfractures (that precede a major fracture) and 95 per cent of the time, they are in the fetlock joint. That’s where we get the majority of catastrophic fractures.”

A new way to screen

One of the projects McIlwraith is most passionate about is further developing CT machines to speed up the process of screening horses for injury. CT utilises a thin computerised x-ray beam that is rotated quickly around the patient’s body or limb, creating a series of cross sectional images of the patient that can give a clinician more detail or depth than a single radiograph or ultrasound image. The images can also be stacked together to create a three dimensional rendering of the location scanned on the animal.

One of the greatest limits in equine screening technology right now is the time and space constraints taken up by the available equipment.

“If you have a horse that you saw something suspicious on and you do a CT which involves putting the horse's leg in a ring, so you either do it under anesthesia or heavily tranquilised,” McIlwraith explained. “You’re using it for diagnostic purposes, not screening, and the big need we have at the moment with imaging is a screening tool.”

McIlwraith and Kawcak, a Professor of Orthopaedics and an integral part of the research team, have been working towards what McIlwraith calls a “true standing CT”.

“We’re getting there, all we need to do is make it smaller,” McIlwraith said. “​​There’s no ring. The horse will just be able to stand on a pad, and then paddles come in and take an image.

“The CT is very quick, it only takes 20 seconds. That's why it's replaced MRI for these problems that we want to detect in the horse. An MRI can take 45 minutes (to take an image), but in 20 seconds in a CT, we can get an image of the whole 360 degree view of the fetlock, for example.”

The overall concept of Kawcak and McIlwraith is for it to be walk in, walk out for easy screening in the run up for big race days. McIlwraith’s model would also be cheaper than what is currently available, with the hope that it will be commercially viable for veterinary practices to purchase, as well as having them available at all racetracks.

“We have developed a prototype that takes good images,” McIlwraith said. “But we want it to be much smaller. Chris and I are working with a company in italy to achieve that.”

It would negate the need for sedation or the stand down time associated with nuclear imaging (scintigraphy), both major concerns that have been raised by owners and trainers alike targeting the G1 Melbourne Cup with international raiders.

“To have it as a screening tool (would mean) that it can be used right before the Melbourne Cup, or before the Breeders’ Cup, or the Kentucky Derby when the horses are on the grounds. The vision is that can just have these horses walk through and get screened very quickly.”