LEARNING CENTER
Helping Your Horse Cope with Heat by Kathleen Landwehr
Horses are large, muscular animals that produce excessive amounts of heat when exercising: it’s been calculated that an endurance horse competing in a 50-mile race at ambient temperature will generate enough heat to melt a 150-pound block of ice and bring it to a boil. Whatever the breed or discipline, it’s critical that horses get rid of that heat, and exercising in hot conditions presents an even greater challenge for both horse and rider. Horses have a high body weight and low surface area, and this unfortunate ratio makes it hard for them to dissipate the large amount of heat generated by their muscular activity. That makes it all the more important to know how to cool your horse properly. There are three main ways horses can get rid of heat: Evaporative cooling. Exercising horses produce sweat and that heated fluid evaporates from the skin surface dissipating heat. Horses can produce from 1 to 4 gallons of sweat during strenuous work in hot weather. Conduction. Heat is moved from one surface (the horse’s skin) to another surface (water applied to the skin). If done correctly, this can be an invaluable method of heat loss in the horse. Respiration. This is a significant source of heat loss in humans and dogs, but it accounts for only a small amount of heat reduction in horses. While sweating is one of the primary methods for horses to cool themselves, it can also be problematic because of the barrier 34 SUMMER ISSUE 2018
it can create on the skin. “In humid weather, where evaporation is greatly slowed, sweat accumulates on the skin surface,” Marcella explained. “This fluid layer is quickly heated to body temperature, and if it is not removed and it cannot evaporate, then it effectively coats the horse, making it very difficult for the horse to cool down.” Cooling in Humid or Dry Heat Since horses can struggle with heat loss, it’s imperative that equestrians know how to cool a horse properly in hot conditions. “Spray/wipe, scrape, repeat,” urges Marcella. You need a bucket of cold water, a sponge (or cold water from a hose), and a sweat scraper. Repeatedly spray or sponge the cold water on—the best areas to target are the neck, chest, inner legs, belly, and groin—and scrape it off almost immediately. Marcella said it’s even better if you can do that in front of a fan to incorporate evaporative heat loss, too. Pouring buckets of water or spraying a horse without scraping that water off will not result in effective cooling, Marcella said. Scraping the water off is crucial. Putting a cold wet towel on the horse’s neck or back is frequently done, but it reduces any chance of evaporative cooling, because it blocks airflow to the skin. Across the country, hot conditions can vary by being dry or humid, and both conditions affect horses differently. Marcella
PHOTO: BECKY PEARMAN PHOTOGRAPHY
Dr. Ken Marcella at the FEI World Equestrian Games™ Tryon 2018 Endurance Test Event in April.
It’s summer show season! How can you maximize your horse’s performance in the heat? We asked Dr. Ken Marcella—a member of the USEF Endurance Veterinary Advisory Group, a Fédération Équestre Internationale 4*-rated official endurance veterinarian, and owner of KLM Equine in Canton, Ga.—for his tips. Check out the US Equestrian Learning Center online at USequestrian.org/learn for more tips on post-competition care, the endurance discipline, and much more.
