When the temperature climbs, there is one thing worth checking before the sweat starts running: is your horse getting enough electrolytes?
There are plenty of supplements that horses can be overfed. Electrolytes aren't usually one of them. In fact, under supplementation of electrolytes is surprisingly common, particularly in horses in regular work.
Think of electrolytes as a game of cat and mouse. Every day, your horse loses electrolytes through urine and faeces. Add exercise, sweating, and hot weather, and the mouse starts running faster. The aim isn't to suddenly chase it down with a huge dose the night before competition. The aim is to keep pace with it.
So, what exactly are electrolytes?
Electrolytes are minerals including sodium, chloride, potassium, calcium, and magnesium. They are essential for almost everything the body does, including nerve function, muscle contraction, heart function, digestion, and maintaining fluid balance.
Your horse loses electrolytes every day, even when it doesn't appear to be sweating. Once sweating starts, losses increase considerably. In hot weather, the mouse starts running even faster.
That sweat isn't just water…
Take a look at a sweaty horse after exercise. Sometimes the sweat is clear and watery. Sometimes it is white and foamy, particularly around the neck, chest, and between the hind legs.
That white foam isn't simply "salt coming out." Horse sweat contains a protein called latherin, which helps sweat spread across the coat and improves evaporation, helping the horse lose heat more efficiently.
Sweat also contains electrolytes, particularly chloride and sodium, followed by potassium, with smaller amounts of calcium and magnesium. So when a horse sweats heavily, it isn't just losing water, it is losing electrolytes, too.
What happens when it's hot?
Horses regulate their body temperature primarily through sweating. When temperatures rise, they need to lose more heat, and exercise can increase sweating significantly. That means electrolyte losses increase, too.
This is where riders can get caught out. It is common to see electrolytes added to the feed only when the weather gets hot, or in the few days before a competition. But if electrolytes have been lost day after day during training without being adequately replaced, a big dose just before competition isn't going to magically undo months of inadequate intake.
There is also a practical problem with suddenly increasing the amount. Your horse may dislike the taste, refuse its feed, or develop a digestive disturbance. Chasing the mouse at the last minute isn't the best strategy. A consistent daily supply provides a much better foundation, with provision adjusted according to workload, sweating, diet, and weather conditions.
But what about the salt lick?
Salt matters because most horse diets are relatively high in potassium but low in sodium. Table salt is sodium chloride, providing both sodium and chloride.
A salt lick can be useful to have available in the stable, but it shouldn't be relied upon as proof that a horse is getting enough sodium. Research has shown that horses don't reliably regulate their salt intake from free-choice blocks or licks.
A plain Himalayan, sea, or rock salt lick can be a useful addition, giving the horse the opportunity to consume additional salt. Just don't assume that because the lick is there, or looks well used, your horse has necessarily met its sodium requirement.
There is also something to consider when choosing a lick: keep it simple and natural where possible. Flavoured licks may smell and taste appealing to us as owners and riders, but making salt highly palatable can encourage some horses to have a real licking frenzy rather than simply taking salt as and when they need it. This can make intake much harder to predict and may result in considerably more salt being consumed than intended.
A plain salt lick without added flavours is therefore a sensible option for horses that enjoy using one, alongside a measured daily salt or electrolyte intake where required. For horses in more than light work, a balanced electrolyte supplement providing the major electrolytes should be considered and fed consistently according to the manufacturer's recommendations.
Salt is salt… mostly
Table salt, sea salt, rock salt, and Himalayan salt are all predominantly sodium chloride. Natural salts can contain small amounts of other minerals and naturally occurring trace elements. With Himalayan salt in particular, it makes sense to buy from a reputable supplier.
Processed table salt may contain tiny amounts of anti-caking or free flowing agents. At the levels normally present in salt, these are not generally considered a concern for horses.
So there is no need to assume that Himalayan salt is automatically "better" than ordinary table salt. For providing sodium and chloride, salt is salt.
You don't need to drown it in sugar
Another misconception is that electrolytes need high levels of sugar to be absorbed. While a tiny amount of glucose or dextrose is sometimes included for palatability or to speed up the initial uptake of water and electrolytes from the gut during acute dehydration, an everyday electrolyte supplement does not need to be packed with sugar.
For routine supplementation, look at what you're actually getting for your money. If glucose, dextrose, or another sugar is right at the top of the ingredients list, a considerable amount of what you're feeding may be a filler rather than active electrolytes. Sugar can serve a subtle taste purpose, but it shouldn't simply be there to bulk out the tub.
Salt needs water
This one is non-negotiable. Whenever salt or electrolytes are increased, fresh, clean water must be available at all times.
This is particularly important in hot weather and after exercise, when a horse may already have lost significant amounts of fluid through sweating. Salt stimulates thirst, encouraging the horse to drink and replace lost fluid, but that only works if water is right there.
No water, no electrolytes.
This is also why concentrated salt syringes are not generally recommended as a routine way of replacing electrolytes. A large, concentrated dose of salt entering the gut can create a high osmotic load, drawing water into the intestinal contents rather than providing a gentle, balanced replacement of what has been lost. It can also be unpalatable and cause digestive upset.
If electrolytes are required after significant sweating, a properly formulated electrolyte supplement, given with free access to water and according to the manufacturer's recommendations is a much more sensible approach. Never restrict water because a horse has been given electrolytes. If you're feeding salt, make sure the water bucket is full.
Can you give too much?
Yes, but in practice, underfeeding is far more common.
One of the simplest things to watch is what happens at the water bucket. If electrolyte intake has been significantly increased and there is suddenly a noticeable increase in drinking, or the bedding becomes considerably wetter, that may be a sign that more is being fed than the horse needs. Feed refusal or loose droppings can also indicate that the amount is too high or has been increased too quickly.
The answer isn't to avoid electrolytes; it's to use them sensibly, consistently, and according to the horse's individual needs.
What about electrolyte loading before exercise?
This is where the science gets interesting.
Research published in 2021 by Waller and Lindinger found that pre-exercise electrolyte loading can be beneficial. In the study, horses were given a large volume of a balanced, hypotonic electrolyte solution before prolonged exercise. The approach helped maintain fluid and electrolyte balance and increased exercise duration compared with water alone.
So the message isn't that electrolyte loading doesn't work. However, there is an important distinction: the study involved large volumes of a specifically formulated, balanced hypotonic solution given alongside fluid. It should not be interpreted as a reason to suddenly give a horse a large dose of concentrated electrolyte powder or paste immediately before competition.
Pre-exercise hydration and electrolyte loading may have a place where significant sweating and prolonged exercise are expected, but it is part of a wider strategy, not a substitute for sensible day to day electrolyte management.
Keep up with the mouse
The amount of electrolyte your horse needs depends on the whole picture: diet, workload, duration and intensity of exercise, weather, fitness, how much the horse sweats, and individual variation.
So don't wait until the mouse has disappeared into the skirting board. Build a sensible electrolyte routine into everyday management, adjust it when the weather gets hotter, the workload increases, or sweating becomes greater, and make sure plenty of fresh, clean water is always available.
Plan ahead for hard work and competition, because when the thermometer hits 35°C, the mouse isn't slowing down. Keep up with it.