In recent years it has become clear to veterinarians and researchers studying injury rates in racehorses that serious injuries probably don't happen out of the blue. Major injuries are now commonly believed to be the result of minor injuries going undetected until they accumulate or worsen. One of the reasons those minor issues can easily go unseen is that the first defense for soundness monitoring for most horses is still a visual exam from a trainer or veterinarian or an assessment from a seasoned rider. Horses are very good at compensating for minor problems however, and small changes in their movement can often be imperceptible to the human eye.
Some experts are hopeful that sensor systems may help pick up what the human eye cannot. At a special virtual edition of the annual Tex Cauthen Memorial Seminar held on Jan. 24, several veterinarians provided updates on research into the use of data from systems like the Lameness Locator and StrideMASTER on the racetrack.
So far, the consensus seems to be that both systems provide veterinarians useful information but they're still learning how to contextualize that information.
Dr. Abigail Haffner presented data from a recently-concluded study at Thistledown Race Course which is still being analyzed. Researchers placed Lameness Locator sensors on horses and watching them jog about 25 strides in hand. The Lameness Locator uses sensors on the horse's head, pelvis, and right front pastern which contain accelerometers and gyroscopes. Together, the sensors develop a sense of the horse's “gait signature” or its normal way of going.
The study measured 73 horses weekly over several weeks, with a total of 1,663 exams performed. The horses were selected based on voluntary participation of their trainers, which also meant that horses dropped out of the study for reasons that weren't always known to the study team – like whether the horse had left the barn because it was claimed, or because it had developed an injury and been sent for lay-up or retirement.
None of the horses in the study suffered fatal injuries.
What Haffner and her team learned was that the process of using the system in a practical, racetrack setting is pretty easy – each reading takes three to four minutes and the sensors were simple to apply correctly.
She is hopeful the data may tell her more about how good the system is at noticing changes that were indicative of impending injury. Due to conformational differences, horses may not always move in a perfectly symmetrical way without an injury actually being present, which can sometimes complicate lameness exams.
Dr. Kevin Keegan, professor of veterinary medicine and surgery at the University of Missouri, said he's hopeful for the system's potential to help horses, but does admit it has limitations.
When used for these repeated measurements over time, the Lameness Locator is best at showing existing asymmetries of movement and changes to the horse's movement — but it can't tell you why those asymmetries exist.
“We are measuring a clinical sign, not a disease,” said Keegan “You can define lameness as a movement that's different from normal … lameness may have many causes, but the cause we're most interested in is physical pain.”
Read more about the Lameness Locator in this 2020 Paulick Report feature.
If it's put on a horse who already has mild underlying lameness, it will show areas where the horse's body travels asymmetrically but the interpreter won't know if that's a horse's pain-free, normal way of going or if there's an underlying problem.
A horse demonstrates the bonnet portion of the Lameness Locator, which has a sensor at the poll to detect head movement
Bilateral lameness, or lameness occurring in two legs at a time, is even more difficult to capture with the human eye than lameness in a single leg. Keegan says it's possible for the Lameness Locator to detect this, although it is more challenging. Many people assume that a horse will swap weight evenly between the left and right limbs in a bilateral lameness to avoid pain, but it's usually not that precise. Keegan said that sooner or later, the sensors are going to pick up changes in the head and pelvic movements that will point to that swapping.
The process of studying systems like this one has also shown veterinarians that the current way of doing pre-race lameness exams can be less than ideal. Horses are walked or jogged without a rider on board, and can often be fractious, which interferes with their movement. Keegan pointed to Mongolian Groom as a classic example of the variability you could have between multiple exams conducted at the barn versus on the track. He believes a sensor on the ill-fated colt during a jog on the track may have provided a different set of information than the vet checks the horse passed at the barn before the 2019 Breeders' Cup Classic.
Dr. Bronte Forbes, veterinarian with the Singapore Turf Club, said the Lameness Locator has been used in that country to assess poor performers post-race, helping officials flag which ones need further assessment.
“If you're going to consider using this technology as a regulatory tool, everyone has to buy into it,” Forbes said.
Horsemen really believed in the technology in Singapore, Forbes said, and would sometimes request a reading if they had a horse they were worried about.
Still, Forbes said, he has concerns about the best way to work the technology into a regulatory system. He worries that a pre-race use of the technology could lead to a liability issue if it records asymmetry that the trainer or veterinarian believes is just a horse's gait signature, and the horse subsequently breaks down. Likewise, if a horse breaks down in a jurisdiction where the technology is used post-race, many people may have legitimate questions as to why it wasn't used as a screening tool.
Also, Forbes agreed with Keegan, the sensors provide information, but not context, and veterinarians must be aware of the difference.
“It's a measure of asymmetry, and there is no line in the sand currently that determines whether that horse is lame or whether that horse is going to sustain an injury or not – and that's especially true for a one-off assessment of the horse,” he said. “We've all seen very sound horses injure themselves and lame horses not injure themselves. I think we'll establish a welfare level of 'It's not acceptable to send this horse out there.'”
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