Wearable Heat Stress Detectors for Exercising Horses

Point-of-care (POC) devices are becoming commonplace in equine medicine, allowing veterinarians and owners the satisfaction of instant results. One of the newest POC devices developed for horses is a flexible, wearable sensor that measures body temperature as well as potassium level and pH of sweat. These are important indicators of a horse’s health and may identify animals at risk of heat stress.

As described by Chinese researchers, a flexible, lightweight sensor measuring less than 4 cm x 4 cm can be securely placed on the side of the horse’s neck affixed with a light elastic bandage.^* This sensor has real-time signaling that sends data directly to a smartphone via Bluetooth technology.

“This type of device would benefit exercising horses, particularly those in endurance sports where the horse may be sweating extensively and alterations in sweat potassium, particularly decreases in potassium, can indicate impending metabolic issues and the need for an electrolyte supplement,” explained Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research.

Sweat is composed primarily of the electrolytes sodium, chloride, and potassium as well as water. The purpose of sweat is to help cool the horse during exercise when it evaporates from the skin. Excessive sweating, however, results in excessive electrolyte losses.

“Equine sweat is hypertonic, which means it has a higher concentration of electrolytes than blood does. The equine body is not very efficient at storing electrolytes, so with extensive sweating there is an advantage to replacing some of the electrolytes lost in sweat with an electrolyte supplement,” Crandell said.

Further, sweating alone may not sufficiently cool horses. Horses exercising in hot climates may be at risk of heat stress as they become dehydrated from sweat loss. Signs of heat stress include elevated body temperature, elevated heart rate, irritability, or even depression depending on the severity. These horses need to be cooled immediately using cold water, and veterinary care may be indicated.

“This sensor allows for early identification of heat stress, giving owners, trainers, and veterinarians the ability to intervene before detrimental signs of heat stress develop,” Crandell said.

According to the researchers, this device is a promising tool that can provide a noninvasive means of continuously monitoring vital parameters in horse sweat to guide personal fitness and health management.

Crandell added, “Electrolyte supplements, such as Restore SR and Race Recovery, can be fed daily to exercising horses to stave off dehydration. Further, they can be preloaded before a competition to help a horse start fully hydrated; supplemented during any competition that involves endurance exercise to replenish electrolytes lost in sweat as they occur; and given after exercise to re-establish electrolyte balance.”

 ^*Pan, Y., X. Su, Y. Liu, P. Fan, X. Li, Y. Ying, and J. Ping. 2024. A laser-engraved wearable electrochemical sensing patch for heat stress precise individual management of horse. Advanced Science (Weinh):2310069.