Many advances in health and welfare of equine athletes would not be possible without the support of donors and people working on the front lines of the racing industry, Ontario Veterinary College (OVC) researchers said recently.
“All of the equine research funding that we receive through Equine Guelph comes from the horse industry,” Dr. Jeff Thomason, co-chair of the Equine Guelph research committee, said at the Research Update event held at Woodbine Racetrack on May 22.
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Dr. Jeff Thomason
Thomason said equine industry support allows Equine Guelph is able each year to fund seven or eight projects by OVC researchers each year. Proposals are vetted by a diverse committee that includes members of the racing community and to ensures that the research is built on good science and is relevant to the industry.
Sponsored by Woodbine Entertainment Group and the Horsemen’s Benevolent Protective Association of Ontario (HBPA), the event was an opportunity for OVC researchers to reach out and thank the “backstretch family” of trainers, riders, jockeys, grooms, veterinarians and others who contribute to the health and well-being of racehorses.
“We need your ideas and your feedback to tell us if we’re on the right track and to help us interpret the data,” Dr. Peter Physick-Sheard told the audience of about 40 people as the event wrapped up.
The day featured posters by OVC graduate students as well as brief talks by researchers including Thomason and Physick-Sheard as well as Drs. Luis Arroyo, Thomas Koch and Judith Koenig.
Thomason opened the program with a discussion of his findings on the impact of racetrack design and construction on injuries and death rates in horses. A biomechanics and anatomy professor in OVC’s Department of Biomedical Sciences, Thomason’s research has focused on how the horse’s feet and legs move and how different track types affect that movement.
He said that just as in human high-performance athletes, there are many factors involved when race racehorses are injured or come up lame. With respect to track surfaces, consistency seems to be more important than whether the track is dirt, hard-surfaced, turf or synthetic. There is still a lot we don’t know, and track designers need to take what we do know about the horse into account when developing their ideas, he said.
“A perfectly designed track and surface will never prevent all injuries, but we can minimize the damage.”
Koch and Koenig talked about regenerative medicine and the potential of stem cells derived from cord blood to heal tendon injuries and join inflammation in horses. They lead a team of scientists and clinicians that recently treated a racing thoroughbred and a breeding stallion that had suffered what appeared to be career-ending injuries. The horses were treated using allologous (also known as allogeneic) stem cells that were banked and transplanted from an unrelated donor horse – a medical first in Canada and among only a handful of cases reported worldwide.
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Drs. Judith Koenig and Thomas Koch answer questions following their talk.
Koenig said the results have been very promising so far, and the Thoroughbred in particular has shown remarkable improvement. But more clinical cases must be evaluated before these stem cells can be offered as a proven effective treatment for tendon lesions, she said.
The hope is that allologous stem cells will offer at least one key advantage over autologous therapy in which the patient’s own cells are used: time. Other studies have shown that horses with tendon injuries are more likely to re-injure the same tendon if they are not treated within 44 days.
“We have the advantage of time with these cells,” said Koch, who was the first to establish a protocol for collecting and differentiating stem cells from equine cord blood, a process that is non-invasive and simple compared to obtaining cells from embryos or bone marrow.
From frozen cell stock these cells can be in the hands of the treating clinician within a few days. The cells can be stored for future “off the shelf” use and they can also be screened and categorized into cells with optimal properties for treating various conditions.
“My hope is that clinicians and scientists and the equine industry can come together to support our work and help put Ontario and Canada on the map as leaders in this important and exciting area of research,” Koch said.
The audience also heard about OVC cardiovascular research that may shed light on the causes of sudden deaths in racehorses. About 150 horses die at racetracks each year; about half the deaths are associated with fractures, but in about one-quarter of the remaining cases, experts can’t pinpoint the cause of death.
Part of the answer may lie in arterial calcification, or hardening of the pulmonary artery, said Arroyo, a large animal medicine specialist in the Department of Clinical Studies who began looking into the problem during his PhD research in 2006.
Arroyo identified the build-up of hard, brittle plaque lesions in major blood vessels during post-mortems of horses sent to OVC under the Ontario Racing Commission’s death registry program. The lesions build up in the middle layer of the arterial walls, particularly in the pulmonary artery, causing it to lose the elasticity that normally allows it to handle the massive changes in pressure as it carries blood from the heart to the lungs.
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Dr. Luis Arroyo
Working with U of G engineering professor John Runciman, Arroyo studied artery biomechanics and found changes in the behaviour and structure of artery walls that may help explain what causes the hardening.
To help understand the clinical significance of the hardening, and perhaps find ways to prevent it, Arroyo’s future plans include using new intravascular ultrasound equipment to provide imaging of the blood vessels from the inside out.
Sudden deaths in horses may also be linked to disturbances in heart rhythm that occur during and after racing. In separate studies, Physick-Sheard’s research team monitored the heart rates and rhythms of hundreds of standardbreds and thoroughbreds during normal scheduled racing at Mohawk and Woodbine. The horses were monitored using an ECG (electrocardiogram) monitor attached to their harnesses before, during and after racing.
Horses are creatures of habit, so in order to try to understand cardiac responses to racing, it was vital to study them under “live” racing conditions, he said.
“In truth, we really don’t know what normal is,” Physick-Sheard said. “And we don’t know what normal is during racing. Perhaps it’s better if we use the term ‘usual’ instead of ‘normal’. ”
The researchers have found that complex arrhythmias are fairly common in standardbreds during the cool-down period after racing, which is also the time when they are at the greatest risk of sudden death. Their heart rate slows unevenly in a step-wise fashion, dropping off sharply, then speeding up, then dropping off and speeding up again, in a pattern that continues throughout the early recovery period. Despite experiencing what appeared in some cases to be potentially serious arrhythmias during this process, none of the horses in the standardbred study died and all returned to normal sinus rhythm, leaving researchers to wonder what triggers a fatal response.
“It may be that the occasional horse gets into this pattern of disturbance and can’t recover.”
In the thoroughbreds, the research team found heart rates initially showed the same drop-off as in the standardbred study, but then climbed and stayed higher during the recovery period. The thoroughbreds did not show the same rhythm disturbances, yet they are much more susceptible to sudden cardiac death.
The study also found wide variations between individual horses in terms of heart rate (and thus cardiac output) and responses at different stages of the race and in association with a variety of other factors such as the track surface and the gender of the trainer.
“There are huge differences between horses and we don’t know yet how to interpret these data,” Physick-Sheard said.
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The day included poster presentations by graduate students.
