Chill Out: Researchers Compare Cooling Methods For Equine Athletes

Elite athletes like racehorses and three-day event horses sometimes exercise on hot, humid days, often resulting in high body temperatures that must be lowered quickly before heat-related stressors set in. While much research has been performed on effective cooling strategies, a new study compared several different cooling methods.^*

Thoroughbreds were exercised on an inclined treadmill until the pulmonary artery temperature reached 107.6 degrees Fahrenheit. One of five cooling methods was then implemented. The methods included:

• Walking on a treadmill with one commercial fan placed 6.5 feet in front of the horse set at low velocity to simulate the breeze that would occur if walked outside (control);
• Walking on a treadmill with two fans placed 13 feet in front of the horse set at almost twice the airflow of the fans used in the control;
• Cooling with intermittent application of cold water (4.2 gallons at  50 degrees Fahrenheit) every three minutes on its body behind the neck, scraping as much water as possible after dousing; two cycles of dousing performed with return to treadmill walking and two low-speed fans in the interim;
• Cooling with intermittent application of cold water (16 liters; 50° F or 10° C) every three minutes on its body behind the neck with no scraping; two cycles performed with return to the treadmill and two low-speed fans in the interim; and
• Showering continuously with tap water (78.8 degrees Fahrenheit) for 30 minutes with no return to the treadmill.

To determine the most effective cooling method, researchers measured the time necessary for the pulmonary artery temperature to return to 102.2 degrees Fahrenheit or lower, and recorded the rectal temperature at 30 minutes after onset of cooling.

The researchers concluded that showering the horse continuously with a large volume of tap water resulted in the most rapid decrease of both pulmonary artery and rectal temperatures, signifying its effectiveness as a way to achieve cooling in hot, humid conditions.

Sweat production goes hand-in-hand with exercise. Multiple factors determine how much sweat is lost doing any exercise bout (heat, humidity, and work intensity, for example). Light exercise with minimal sweating may induce a sweat loss of 1 quart to 1 gallon, while high-performance horses at the peak of exertion may have losses of 12.25 to 3 gallons.

Because large quantities of electrolytes are lost in sweat, electrolyte supplementation becomes a key factor in managing the diets of performance horses. Choose research-proven electrolytes formulated by specialists in equine nutrition and exercise physiology.

Electrolyte supplementation is not season-specific. Well-formulated electrolytes should be used whenever horses sweat on a daily or near daily basis, no matter the season.

^*Takahashi, Y., H. Ohmura, K. Mukai, T. Shiose, and T. Takahashi. 2020. A comparison of five cooling methods in hot and humid environments in Thoroughbred horses. Journal of Equine Veterinary Science 91:103130.