As we enter into the warmer months here in Ontario, many horse owners will begin to use electrolyte supplementation products for their horse. This blog post is going to provide a brief overview of electrolyte supplementation and what recent research is telling us!

Electrolytes

Electrolytes are involved in many physiological processes. They play a role in the maintenance of fluid balance, transmission of nerve impulses as well as muscle contraction to list a few examples.

Just like humans, sweating is crucial to thermoregulation. With horses, when they are under more intense work, especially in a hotter climate, their electrolyte losses can be substantial. It is estimated that horses can sweat up to 10-15L per hour! When there are substantial electrolyte losses that are not replenished health consequences can arise. These include dehydration, muscle weakness, fatigue, lower exercise tolerance etc.

Equine sweat is hypertonic to plasma, and rich in a few key electrolytes. Sodium (Na+), chloride (Cl-) and potassium (K+) are lost in the greatest quantities. Magnesium (Mg2+) and calcium (Ca2+) are lost in smaller quantities. Knowing the key electrolytes lost can help you determine an ideal supplement.  

Supplementation Methods

If you have shopped around for electrolyte supplements you know that there are many on the market! From pastes to powders, to flavoured and non-flavoured. So, how do you choose the right one?

The critical ingredients are the actual electrolytes! Looking at the ingredient list for sources of sodium, chloride as well as potassium, calcium and magnesium is ideal. Some products will also include sugar for palatability, but this is not required, and sources cite that it should not be the first ingredient.

Powdered Products

When reviewing the research, it is recommended that electrolytes are fed in combination with water. This should be done by mixing the electrolyte powder with clean fresh water and offering two buckets, one with the electrolyte and one without. When using this method, many experts suggest getting your horse used to the supplement prior to using it after competition or trailering off property. The powdered products can also be added as a top dress to feed. Just remember – access to clean water is crucial!

Paste

When using a paste product, it is highly cautioned to ensure that the horse is drinking as when a dehydrated horse is given a large dose of electrolytes not mixed with water the dehydration can worsen. Therefore, although the pastes are concentrated doses of electrolytes, if the horse is not consuming adequate water this may not be the best option.

Loose Salt

After I posted the Salt Block blog post, an interesting point was brought to my attention by a very well-respected equine professional. Providing horses with a source of loose salt can be an effective supplementation method, however, something I had not thought about was if the horse does not have adequate roughage access or is restricted from chewing opportunities, they will not have saliva production which can negatively impact their free choice salt intake. When I was reviewing the research on electrolytes, loose salt was recommended for leisure horses and those in light work. When I balance a diet, I almost always include loose salt – so before jumping to the commercial electrolyte supplements I encourage you to have your horse’s diet evaluated to ensure their baseline Na, Cl, K, Mg, and Ca requirements are being met.

Overall, when choosing a supplement, evaluate your horse’s drinking behaviour to help you decide which may be ideal and get your horse used to consuming the product so that it is not novel when given after heavy exercise. Always follow the manufacturer’s instructions as well. It is possible to over-supplement beyond what is necessary. The excess electrolytes will then need to be excreted in the urine.

Recent Research

There are many interesting studies on electrolyte supplementation. For this blog post I am going to focus on two studies completed at the University of Guelph.

Let’s start with the 2013 study! This study (Lindinger & Ecker, 2013) used a powdered electrolyte supplement (Perform’N Win Buckeye Nutrition). It was dissolved in water to create an electrolyte solution. They investigated a variety of parameters related to electrolytes and hydration including gastric emptying, intestinal absorption of Na+ and K+, and time to fatigue.

The authors concluded that this oral electrolyte supplement designed to replace sweat ion losses was absorbed and rapidly distributed within the body. They were also able to show that supplementation prior to exercise resulted in an increased duration of submaximal exercise.

I would also like to include the ingredient list of the product used that was provided in the paper: NaCl, MgSO4, dextrose, calcium formate, silicon dioxide, sucrose, sodium acetate, potassium citrate, calcium lactate, natural and artificial flavours (<1%). The authors noted that the flavouring was to increase palatability.

The 2021 study (Waller & Lindinger 2021) investigated pre-loading a large volume of oral electrolytes. The nutritional aspect of the study was the same as the 2013 study. These authors were able to show that when 8L of electrolyte supplementation was given prior to exercise (1 hour before) there was increased exercise performance and an improved maintenance of extracellular fluid volume. To summarize, there is scientific evidence that shows that proper electrolyte supplementation can have a positive impact on horses that are under moderate-intense exercise and experiencing large electrolyte losses.

Does your horse need additional electrolytes?

As always, starting with a balanced diet is crucial. If the horses baseline requirements for sodium, chloride, potassium, magnesium, and calcium are not met, this should be evaluated as step #1.

For leisure horses or horses in light work, adequate salt intake is important and likely will be adequate support for electrolyte replenishment if their diet is balanced.

The classes of horses that typically do require an additional electrolyte source above and beyond a balanced diet with free choice salt access are those in hot/humid conditions, horses under a moderate-heavy workload, those exercising for a number of hours, and potentially any horse with illness that results in an excess loss of electrolytes. If illness is part of the equation, a veterinarian will recommend an electrolyte if they feel it would be beneficial to the animal.

This is just scratching the surface of electrolyte research and I encourage you to read some of the studies referenced below if you are interested in knowing more! Every situation is unique, and what is best for one horse may not work for another. The main takeaway message is that electrolytes are crucial to proper physiological functioning, but when supplemented must be given with adequate water intake. Additionally, not all horses need electrolytes supplemented, but it is important to ensure their diet is balanced and salt intake is adequate.

If you have any questions please contact me at balancedbaynutrition@gmail.com

Written by: Madeline Boast, MSc. Equine Nutrition

About the author: Madeline Boast completed her master’s in Equine Nutrition at the University of Guelph and started an independent nutrition company known as Balanced Bay. She has worked with a variety of equids – from miniature ponies to competing thoroughbreds. Through Balanced Bay she designs customized balanced nutrition plans that prioritize equine well-being. This includes diets for optimal performance as well as solving complex nutritional issues and everything in between. For additional information see www.balancedbay.ca