In many ways, an endurance race is a test of how much physical challenge an athlete can endure. When it comes to equine athletes, though, there’s the complicating factor of ensuring we’re not asking too much of an animal—especially one who didn’t choose to participate.

That’s why scientists in Qatar have honed-in on biomarkers that might signal which horses are ready to race—and which are not. If confirmed through additional studies, their new findings could protect horses from reaching breaking limits, the researchers say.

In a sport in which up to 70 percent of competitors get eliminated before the finish line, it makes sense to know which athletes have the stamina to run the race. Thanks to six biomarkers that have just been identified as linked to fitness in endurance horses, we might finally be able to know which horses have the breeding and especially conditioning necessary to the task, before asking the animals to go through with it, according to Qatar researchers.

In their new pilot study, scientists have discovered a set of metabolic proteins that accurately predicted horses’ performance in endurance races. Armed with such knowledge, people could potentially prevent catastrophic events that might occur from pushing horses too far, said Tatiana Vinardell, DVM, IPSAV, MSc, PhD, of the Equine Veterinary Medical Center and of the College of Health and Life Sciences at Hamad Bin Khalifa University, both affiliated with the Qatar Foundation, in Doha, Qatar.

The biomarkers identified in this research won’t tell you if your horse is going to win, but at least they might say if he’s going to finish the race—meaning he has all the right conditions and that all the right parameters are set up for him to achieve good results in these conditions, say the researchers. Image Dreamstime.

“The biomarkers won’t tell you if your horse is going to win, but at least they might say if he’s going to finish the race—meaning he has all the right conditions and that all the right parameters are set up for him to achieve good results in these conditions,” Vinardell said. “As a result, you could avoid welfare issues, or horses dying or being dehydrated, or sustaining a fracture.”

Vinardell and her fellow researchers took blood plasma samples from 47 endurance horses before and after competing in races of 80, 100, or 120 kilometers. Because some of these horses ran in more than one race, the researchers collected a total of 62 before-and-after pairs of samples, which included plasma from 22 horses with strong finishes as well as the 40 which were eliminated for various health reasons (or in three cases, a rider fall).

They noted that none of the standard health test parameters at the start of the race—chemical profiles, heart rates, and dehydration rates—differed between the horses that ultimately finished and those that didn’t, Vinardell said.

However, using mass spectrometry, they also assessed the small molecule (metabolite) profiles of each horse in detail. And here, they found some distinct differences pre-race between finishers and non-finishers. Of the 792 metabolites they measured, they identified six that were reliably different at the start of the race in successful versus eliminated horses.

Specifically, those metabolites were imidazole propionate, pipecolate, ethylmalonate, 2R-3R-dihydroxybutyrate, β-hydroxy-isovalerate, and X-25455. These biomarkers could red-flag horses that are truly ready to race and those that aren’t, thereby potentially helping prevent pushing endurance horses to their limits.

“We were really surprised to find these six metabolites so consistently; we thought the results would be more varied, especially because the horses were eliminated at so many different parts of the race,” Vinardell said. “So we were honestly really happy to see this set [as potential biomarkers].”

Even so, the findings can’t yet be considered conclusive, she warned. “This research is still really in the early stages, but if we can validate this through additional studies, that could lead to a test that looks specifically for those six markers,” said Vinardell. Although validation studies were planned, they had to be postponed due to Covid-19 restrictions. “We’re really looking forward to repeating the study to see if we find the same trends,” she said.

Interestingly, they also identified more than 400 metabolites that significantly changed in the horses before and after the race (regardless of whether they completed the race or not), Vinardell added. These molecules—all involved in the metabolism of lipids and amino acids—suggest particular pathways horses’ bodies use during endurance racing.

As for the six predictive metabolites, they probably have little to do with breeding and are more likely a reflection of conditioning, explained Vinardell. “Arabian horses are already bred for endurance and have the genes for this kind of race,” she said. “But [a successful race] isn’t all about genetics or ‘the right parents’ or whatever. It takes a lot of training.

“Even if it’s supposed to be a good horse, if you train it the wrong way, you will have terrible results,” she continued. “So we have to find a way of assessing that before putting the horse through an entire competition when he’s not ready for it.”

Further studies will confirm whether Vinardell’s team has successfully achieved that objective, she said.

 The journal article by Halama, Anna; Oliveira, Joao M.; Filho, Silvio A.; Qasim, Muhammad; Achkar, Iman W.; Johnson, Sarah; Suhre, Karsten; Vinardell, Tatiana. Titled: “Metabolic Predictors of Equine Performance in Endurance Racing” is open access and can be found here.