Summer Heat Too Hot to Handle? (Book Excerpt)

With the exception of the 2000 Olympics in Sydney, which began in September to allow for the southern hemisphere's "reversed" order of seasons--winter in Australia is summer in North America--the summer Olympic Games generally are held in just that: the good old summertime. Add to the usual July-August time frame the fact that most cities that host summer Games are in warm locales to begin with, and you have a potential recipe for heat-related health problems if you're not lucky enough to be involved with a sport that's held in the water or in an air-conditioned arena.

Because of the demands of cross-country day, eventing tends to be the most scrutinized of the three Olympic equestrian disciplines in terms of the horses' health and welfare. When a horse falls on cross-country or finishes the course in an apparent state of exhaustion, the incident makes the news. In Barcelona in 1992, the eventing competition made the news a lot, to the consternation of Leo Jeffcott MA, BVetMed, PhD, FRCVS, DVSc, VetMedDr, and many others in the horse world.

"We had some very bad press as a result of the fact that the weather was pretty hot and a couple of horses did get overtired," Jeffcott, recalled. "It was a great shame, really, because it wasn't the media's fault; the information from the veterinary [contingent] was just not presented. After the speed and endurance, a colleague and I sat for an hour at the press office waiting to be interviewed, to tell them in fact what a great day we'd had: Despite the heat, the horses had all got 'round; we'd had two tired horses but they'd been treated; we'd covered everything and it was all pretty good." Unfortunately, it seemed to Jeffcott as if "the press didn't wish to know that. They reported in the Scandinavian press that two horses were dead; they showed in the [London] Daily Telegraph the Russian horse upside down, being anesthetized, looking as if it was dead...Everyone was saying that [the event in] Barcelona was a disaster."

Jeffcott and other veterinary experts resolved not to allow the 1996 Games--to be held in notoriously hot, sticky Atlanta, Georgia--to become a repeat of the events in Barcelona. So, even before naming of the veterinary officials and committees for Atlanta, Jeffcott, Allen, DVM, and Catherine W. Kohn VMD, Dipl. ACVIM, formed an ad hoc task force to study the effects of heat and humidity on the exercising horse--and, they hoped, to come up with practical recommendations for keeping Atlanta's equine athletes safe and healthy.

According to Kohn, the researchers wanted to learn the answers to three questions:

1. What is the effect of environment on performance?

2. In what ways can the exercise regimen or the competition rules be altered to compensate for hot-weather conditions?

3. What other measures can be taken to enable a horse to cope with heat and humidity?

As Allen recalled, the research project "began to take on a life of its own" as additional veterinary experts and horse-industry groups began to get involved. One of the researchers' concerns was funding, as "there are fairly meager resources in equine research. As it turned out, [the late USET veterinarian] Marty Simensen and [former American Horse Shows Association president, now president and CEO of the USET Foundation] Jane Clark were able to get significant money out of the AHSA. The FEI put money in; the U.S. Combined Training Association [now the US Eventing Association] put money in; everybody who was involved in the horse industry--particularly those who had an interest in three-day eventing--really got involved.

"As it turns out, the research went great: We were able to get it done at an affordable price," Allen said. "When we got done, we probably knew more about the effects of heat and humidity on the exercising horse than the body of knowledge preceding us for the last hundred years."

"When we got done, we probably knew more about the effects of heat and humidity on the exercising horse than the body of knowledge preceding us for the last hundred years." --Dr. Kent Allen

So what did the researchers learn? "We were able to take some old myths and debunk them, such as the notion that you can't put cold water on a hot horse's buttocks," said Allen. The study showed that a hot horse will not tie up or suffer other detrimental effects previously thought to be related to cold-water application. "We were able to look at how hot the actual muscles get--up to 107, 108 degrees Fahrenheit--which is one of the reasons you really need to work hard at cooling them down." The research team discovered that heat has a greater effect on horses than it does on humans because of horses' increased surface-to-mass ratio, he added.

"We came up with a new formula for calculating a heat index for horses" using factors such as the heat, the humidity, the wind speed, and the solar radiation, Allen explained. The veterinary researchers used as a jumping-off point the US Marine Corps' heat index for humans. "We had to adjust it, but we learned that we could take a set of environmental circumstances and directly calculate the time of day that the effects would be less on the horse. That's why we started the cross-country [in Atlanta] at seven o'clock in the morning and had it all finished by eleven-thirty."

Still, cooling a horse that's just run a cross-country course in summer heat and humidity is no small feat. To help prevent horses from overheating in the first place, the researchers recommended shortening the endurance test, reducing the number of jumps, and adding two rest periods. The strategy worked successfully in Atlanta, but, as outlined in Chapter 1, Olympic eventing competition has since dropped the speed-and-endurance phases, adopting instead a shortened format of a warm-up roads-and-tracks phase followed by the traditional cross-country jumping course.

Another first-time strategy that benefited horses and humans alike in Atlanta was the use of misting fans. "They're not like an ordinary fan that you hook up with some water nozzles," Allen explained. "You have to pressurize the water up to at least 150 pounds per square inch and blow it out through a very fine nozzle." The fans consume very little water--only a gallon and a half per hour--and the mist they produce is so fine that it flash-evaporates, with the evaporation cooling even the humid Atlanta air. "If you stood ten feet away from those fans, you never got wet!" said Allen. "But they can be very effective in cooling large areas out in the open."

The misting fans in Atlanta proved so effective that they're now used to cool horses in a multitude of hot-weather activities, from endurance-riding competitions in Saudi Arabia to Quarter Horse shows in Oklahoma City, Oklahoma, said Allen. The Olympic veterinary researchers didn't invent the misting-fan technology--the fans were already in use in feedlots, on poultry farms, and at sporting events in the desert Southwest--but their application had not been widespread because it had been believed that they would be ineffective in humid climates.

Proud of their accomplishments and confident about the welfare of the horses at the 1996 Games, the lead researchers were eager to share their work with the press. The American Association of Equine Practitioners sent Allen and Kohn to a course in media relations. Allen recalled a particularly large press conference held before the Games. "There were, like, sixty cameras in there and people from all over the world reporting. All the speakers except me were MDs. They're talking about their plans for the Games, and they've given me this one little fifteen-minute time slot. I stepped up there and showed them all the research we'd done, and they were absolutely blown away. They had no clue the veterinarians had done all of this work.

"I had all the MDs coming up to me afterward and saying, 'That's amazing that you guys did all that! The fan idea is a really good one; have you tried it?' I said, 'Yeah, we've been doing that for two years.' And I got to use my little line, which got used multiple times during the Games: that the best-cared-for athletes at these Olympic Games are going to be four-legged instead of two-legged."

Allen's prediction came true: As Kohn put it, "We just didn't have horse problems; we really didn't. I know that the chief physicians were treating people for heat problems, but we weren't treating horses for heat problems. I have some cute photos of the three-day dressage judges standing in front of the misting fans to get cooled off."

Additionally gratifying to Kohn is the fact that the heat-beating strategies developed for the Atlanta Olympics have continued to be employed at hot-weather equestrian competitions. "At the 1999 Blenheim three-star event in the west of England in September, it was unseasonably hot and they elected to use the additional phase-C-halt principle. I don't think it had ever been done in Europe before. It worked extremely well.

"I think none of us would suggest that we use hot-weather venues for big competitions," Kohn concluded, "but we do feel that we have some good strategies now for assuring horse safety as well as meaningful sport."

About the Author

Jennifer O. Bryant

Jennifer O. Bryant is editor-at-large of the U.S. Dressage Federation's magazine, USDF Connection. An independent writer and editor, Bryant contributes to many equestrian publications, has edited numerous books, and authored Olympic Equestrian, published by Eclipse Press and available at or by calling 800/582-5604. More information about Jennifer can be found on her site,

Stay on top of the most recent Horse Health news with FREE weekly newsletters from Learn More

Free Newsletters

Sign up for the latest in:

From our partners