The science of sweating
Humans primarily rely on eccrine sweat glands, widely distributed across the body, to produce sweat. This sweat is composed of water with relatively low electrolyte content, allowing for efficient evaporative cooling with minimal mineral loss.
Horses, on the other hand, utilise apocrine sweat glands. Their sweat, while also aiding in evaporative cooling, contains significantly higher concentrations of electrolytes, including sodium, chloride, and potassium. This electrolyte-rich composition necessitates careful attention to replenishment to prevent dehydration and electrolyte imbalances.
A unique aspect of equine sweat is the presence of latherin, a protein that acts as a surfactant. Latherin facilitates the even distribution of sweat across the horse’s coat, maximising the surface area for evaporation and enhancing cooling efficiency. This results in the characteristic ‘lathery’ appearance of horse sweat, particularly noticeable in areas of friction like the neck and flanks.
Cooling strategies: beyond sweating
Evaporative cooling, while crucial, is not the sole mechanism for thermoregulation. Both horses and humans employ various cooling strategies to assist in heat dissipation.
- Post-exercise cooling: After intense exercise, horses are routinely hosed down with cool water. This practice rapidly lowers skin temperature, removes excess sweat, and facilitates continued evaporative cooling. Horses should ideally be cooled in a designated shaded area equipped with misting fans, which is why all horse stalls and hose bays are undercover at Flemington. In addition, misting fans, ice boots and cooling devices are located in the stalls to keep horses cool on warm days. Ice-cold water (0-12°C). Cooling collars and vests, similar to those used by human athletes, can provide localised cooling, particularly around major blood vessels in the neck region, aiding in overall body temperature regulation.
Hydration and electrolyte replenishment
Maintaining proper hydration is paramount for both equine and human athletes.
- Human athletes: Typically, athletes replenish fluid and electrolyte losses through the consumption of sports drinks containing electrolytes such as sodium, potassium, and magnesium.
- Equine athletes: Due to the high electrolyte content of their sweat, horses require diligent electrolyte supplementation. Providing access to clean water and electrolyte solutions before, during, and after exercise is essential for maintaining hydration, preventing dehydration-related issues, and ensuring optimal performance.
