Proper hydration is key to your horse’s health and wellness.
Everyone looks forward to the warm weather as the ideal time to ride their horse. Most understand the dangers of working the horse under conditions of high heat and humidity. However, your horse can be easily compromised under less than sweltering conditions if you do not know how to correctly protect them.
Dehydration through sweat loss is the major danger. As little as a 3% of body weight sweat loss can cause an almost 10% reduction in the horse’s exercise tolerance. For a 500 kg (1100 lb) horse, that’s only 15 liters (3.96 gal) of sweat. Research has shown that a horse sweating heavily can lose as much as 16 liters (4.23 gal) of sweat in just one hour.
Even at light levels of sweating – horses working in milder weather conditions or horses on turnout in hot weather that are obviously sweating – sweat losses are around 4 liters (1.06 gal) per hour. An adequate supply of palatable water is obviously a huge factor in avoiding dehydration. However, water is only part of the answer. For the horse’s body to hold onto the required amount of water, electrolyte levels must be correct.
Sodium, potassium and chloride are the major electrolytes. Bicarbonate is also important but the horse’s body can produce that from carbon dioxide and water as needed and bicarbonate is not lost in sweat.
Sodium is the electrolyte that the horse’s body “reads” in the brain to determine whether to send out the impulse to drink more water. If sodium concentration in the blood increases in relation to water, the brain will send out the message to drink. However, if sodium content in the body is not what it should be to begin with, blood concentration will not increase enough to trigger drinking even if there is a significant reduction in body water (dehydration).
A 500 kg (1100 lb) horse loses 20 grams of sodium per day in bodily fluids, not including sweat. This equates to about 1 oz of plain table salt (sodium chloride). A horse standing around and not exercising but under conditions of high heat could need two to three times more than that just to meet basic losses without even being exercised.
Make sure you provide baseline requirements first, then use an electrolyte supplement as needed to replace sweat loss. This will maximize performance and protect against problems caused by dehydration and electrolyte imbalances. Choose an electrolyte sweat replacement supplement close to a ratio of potassium:sodium:chloride of 1:2:4. Horses getting generous forage can go with lower potassium.
Eleanor Kellon, VMD, currently serves as the staff veterinary specialist for Uckele Health & Nutrition. An established authority in the field of equine nutrition for over 30 years, Dr. Kellon is a valuable resource in the field of applications and nutraceuticals in horses. She formerly served as Veterinary Editor for ‘Horse Journal’ and John Lyons ‘Perfect Horse’ and is owner Of Equine Nutritional Solutions, a thriving private practice. Founded in 1962, Uckele Health & Nutrition has been a trusted leader in the formulation, development and manufacture of quality nutritional supplements for fifty years.