Understanding the important role electrolytes play in healthy performance horses

Electrolytes are minerals that break up into electrically charged ions in water. They play crucial roles in the functions of all cells and are particularly important for muscle and nerve function and fluid balance within the horse’s body. When horses sweat, they lose a significant amount of electrolytes from their body. These must be replaced for the horse to maintain optimal fluid balance, nerve function, and muscle function.

Manufacturers market a plethora of electrolyte products in a variety of forms to horse owners. Understanding when, how much, and which products to supplement is critical for optimizing equine health and performance.

Another Kind of Sweat Equity

When your horse sweats, you might see a white residue that remains on his hair coat after the sweat evaporates. Those are the residual electrolytes lost through sweat. Therefore, even by simply looking at a working horse it becomes obvious that the more he sweats, the more electrolytes he has lost. The primary electrolytes a horse loses in sweat are sodium, chloride, and potassium. He also loses calcium, magnesium, phosphorus, and sulfur, but in smaller quantities.

Don Kapper, a professional animal scientist based in Beach City, Ohio, with more than 37 years of experience formulating products, researching, and teaching in the industry, says, “Electrolytes are anions and cations (negatively and positively charged ions, respectively), so the positives and negatives must work together. When the horse runs out of cation or anion molecules the muscle will stop functioning properly. Therefore, when electrolytes are supplemented, the anions and cations must be balanced and match what the horse has lost in their sweat.”

Why Do Horses Need Supplemental Electrolytes?

Electrolytes tend to be front of horse owners’ minds in the summer months but, regardless of season, if a horse sweats, he should consume supplemental electrolytes. Sweating is the primary method of thermoregulation for working horses. Therefore, when temperatures increase, electrolyte losses are more substantial. Michael Lindinger, PhD, a former professor at the University of Guelph, in Ontario, Canada, and current president of the Nutraceutical Alliance, also in Ontario, notes, “When horses sweat, they are losing a lot of electrolytes through their skin, nearly three times more than humans. Therefore, if the horse is sweating even for just one hour, they can lose a significant amount and may become dehydrated.”

The electrolyte levels your horse needs are directly proportional to what he loses in sweat. In order to decipher how much you should be supplementing, rely on the National Weather Service’s heat index chart (weather.gov/ffc/hichart). This chart takes into consideration the day’s temperature, humidity, and work intensity level. Due to horse sweat being more concentrated with electrolytes than human sweat, it is imperative we provide electrolytes to dehydrated horses and don’t just give them water.

When a dehydrated horse receives plain water but cannot replenish electrolytes, it can negatively affect his ability to recover. “A key role of electrolytes is that they retain fluid in the body, both within cells (intracellularly) and outside of cells (extracellularly). Therefore, the only way to rehydrate a dehydrated horse is to restore hydration with a solution of water and electrolytes,” says Lindinger.

The Benefits of Supplementing Electrolytes

Lindinger, in a study published in the Journal of Experimental Physiology, demonstrated that providing a properly formulated oral performance electrolyte administered in solution at the recommended rate can delay the onset of fatigue by over 22%, reduce muscle cramping, and improve the horse’s ability to recover and perform the following day.

Kapper notes, “During this research, the electrolyte was detected in the bloodstream within 10 minutes of administration, and within 10 minutes of starting to exercise was present in the sweat.” To do this, the optimal osmolarity (concentration) of the performance electrolyte solution must be attained. The amount of electrolyte powder Lindinger and his team used was 4 ounces/gallon of water.

Indeed, to capture the benefits of electrolyte supplementation described, it is not always enough to simply provide salt and water to your horse.

Our sources don’t consider many commercially available electrolyte products properly formulated as performance products. A performance electrolyte replenishes what the horse has lost in his sweat. So if the product does not match the losses, it might not be effective for hydrating the horse, delaying fatigue, or improving his ability to recover from work.

Performance Electrolytes

The chemical makeup of equine sweat expressed as an equation is Na + K + Ca + Mg = Cl + P + S. Again, “performance electrolytes are those that emulate what has been lost in sweat,” says Kapper. “The addition of dextrose also improves the rate of absorption in the small intestine. When you are choosing a performance electrolyte for your horse, the sodium and potassium should be close to equaling the amount of chloride in the product.” You can find this information in the guaranteed analysis of the product.

Understanding ideal formulation of performance electrolytes is critical to choosing the right product for your hard-working horse. For instance, Himalayan salt and sea salt are very popular among horse owners. “However, they are very different from the electrolyte composition of sweat and, therefore, poor choices when aiming to rehydrate a horse after working,” says Lindinger.

“Supplements containing greater than 70% salt (NaCl₄) are not performance electrolytes. They are simply expensive salt,” adds Kapper.

Therefore, when shopping for an optimal performance electrolyte product for your horse, read the guaranteed analysis and compare it to the equation of electrolytes in equine sweat. Nutritionists typically recommend using salt to meet your horse’s daily sodium and chloride requirement and then adding a performance electrolyte when he starts sweating.

Consequences of Dehydration and Electrolyte Imbalance

Dehydration has a variety of negative consequences ranging from fatigue and weakness to serious health issues such as colic and tying-up. Kapper says, “Most horse owners are familiar with the skin-tent test and looking at the color of the gums when assessing for dehydration. However 14 other parameters exist that horse owners can check. The Horse Health Check (tool), developed by Art King, DVM, and Gayle Ecker at the University of Guelph, details 16 checkpoints to evaluate dehydration.”

As mentioned earlier, when a horse has lost electrolytes in his sweat and becomes dehydrated, the body will stop working properly. “Nerves and muscles will stop functioning,” says Lindinger.

Kapper adds, “The positive and negative (electrolytes) must work together so, when there is an imbalance, the horse owner will notice muscle soreness starting, more stumbling, and a shortened stride.” When considering elite performance horses that compete multiple days in a row, delaying fatigue and muscle soreness can make a significant difference in their abilities to successfully perform.

Administering Electrolytes to Horses

When selecting from the myriad equine electrolyte products and administration methods available, horse owners must understand how the horse’s body absorbs electrolytes and how they contribute to rehydration.

“All electrolytes are hydroscopic and will dehydrate your horse if they do not drink enough water after administering,” explains Kapper. For this reason, adding the electrolytes into an appropriate volume of water for dehydrated horses is extremely critical.

Additionally, he does not recommend paste electrolytes for this reason. “All paste electrolytes will lie in the digestive tract of the horse until they draw enough water from the body to break them down,” he adds.

When mixing the solution, follow the manufacturer’s instructions. “Use concentrations that are more dilute if palatability is an issue,” says Lindinger.

One of the biggest challenges owners face when supplementing electrolytes in their horses is determining how much they should offer, and if top-dressing over feed is adequate or if they need it in solution. “Feeding electrolytes as a top dressing is common, however, this should not be done for a dehydrated horse,” says Lindinger.

Providing the electrolyte in solution is the gold standard, but for horses traveling, idle, or at lower levels, top dressing the performance electrolyte on feed at the recommended amount per day is often adequate. For horses at the upper levels and exercising intensely, the electrolyte solution should be provided during and after transport to events to ensure optimal hydration prior to training and competition sessions. In addition, electrolytes are best provided within 45 minutes after training or competing.

“Relying on the average heart rate of the training session can assist horse owners in determining how much electrolyte to give,” notes Kapper. “For example, a horse that is sweating for 15 minutes during a work session will not require the same electrolyte supplementation as an endurance horse doing 100 miles per day.”

Kapper’s charts summarize electrolyte supplementation recommendations in various situations.

Supplementation Recommendations for ‘MILD’ Heat Stress Index (Below go)

Supplementation Recommendations for ‘MODERATE’ Heat Stress Index (90-105)

Supplementation Recommendations for ‘SEVERE’ Heat Stress Index (Over 105)

Tips for Supplementing Finicky Horses

When introducing a performance electrolyte to your horse’s diet, start it at home—not at an event or during travel. “Buy a small amount of the performance electrolyte and try it, especially with finicky horses,” says Kapper. If you sometimes add it as a top dressing and other times mix the product into water, Kapper recommends using the same product both places to ensure taste consistency.

“When introducing a performance electrolyte mixed with the horse’s water, start with a dilute solution and, over the course of multiple days, slowly increase the concentration to full strength,” says Lindinger. If your horse does not like one product, do not hesitate to try a different one.

Including dextrose in performance electrolytes should improve palatability. Nutritionists know that when sugar content exceeds what the body needs, muscles will weaken but, as noted earlier, adding dextrose to performance electrolytes improves absorption. Some practitioners don’t recommend adding electrolytes to feed or water because of the risk of decreasing feed consumption and causing dehydration; instead, they recommend a free-choice electrolyte. What you offer depends on the horse.

Take-Home Message

When horses sweat, they lose a significant amount of electrolytes that must be replaced to help them maintain adequate fluid balance as well as muscle and nerve function. Dehydration can be detrimental to equine health and performance. Therefore, adopt effective electrolyte supplementation strategies to promote hydration. Remember to critically review the  guaranteed analysis prior to purchasing a performance electrolyte and introduce it to your horse to consume at home prior to traveling or competing in warmer weather.