Electrolytes & Hydration

Professor Jo-Anne Murray
PhD, MSc, PgDip, BSc (Hons), BHSII, RNutr, PFHEA University of Glasgow Veterinary School

While most people have their fingers firmly crossed for plenty of hot and sunny weather during the summer months, horse owners are hoping for something slightly different. We are hoping for just enough rain (ideally at night!) so that the grass keeps growing and there is a little bit of cut in the ground, and some sunshine during the daytime. Sadly, none of us can control the weather and we are likely to see some spells of very hot weather before autumn arrives. If the mercury does rise when you’re scheduled to be out competing, it’s important to take steps to prevent dehydration.

Why dehydration is an issue
Dehydration inhibits athletic performance, can be scary for a horse owner to deal with, and serious cases can be fatal if not treated quickly and efficiently. Just like humans, horses sweat to keep cool when they are hot. That means that they can lose a lot of fluid if they are exercised or transported during hot summer weather. The amount of fluid a horse loses when it sweats varies from animal to animal and will depend on the intensity of exercise it is undertaking, but it can be as much as 2.5 litres every 30 minutes. That sweat also contains electrolytes, the minerals and compounds which are essential for a wide range of bodily functions. When a horse becomes dehydrated and their blood electrolyte levels drop, their athletic performance and their health will be impacted. Dehydration can also trigger colic and other veterinary conditions such as azoturia, and the thumps. Signs of dehydration include dry gums, lethargy and in more severe cases, a fast, weak pulse. The skin pinch test can be useful provided you know what your horse’s skin is normally like.

How to keep your horse hydrated
A good rule of thumb if you do exercise or compete with your horse during hot or humid weather is to replace water and electrolytes at every opportunity. That way, you are not waiting for clinical signs before acting. Offer them fresh water after exercise or travelling in the heat and use an electrolyte that can be given to them with feed or in an oral syringe. Adding electrolytes to their water can cause a horse to reject the water, leading to further dehydration.

You can also take other steps to minimise their chances of overheating in hot weather. Some horses can lose litres of sweat during travelling, so it’s worth transporting them early in the day before the heat builds. When you arrive, make sure they are tied up in the shade, move them to take advantage of any breeze if there is one and don’t shut a horse or pony in a lorry if it’s hot and in the sun. If they are normally turned out on grass during the day and you take dry hay for them at a show, don’t forget that they will lose the water intake from the grass. Consider giving them a very wet and slopping chaff mix to top water levels up (well before exercise).

How to use electrolytes
It’s important to note that you can’t ‘preload’ electrolytes prior to an event if the forecast looks hot. All that will happen is that the extra electrolytes in the horse’s bloodstream will be excreted in their urine, and you will have wasted your money. You need to feed them electrolytes after travelling or exercise and offer water at the same time. Giving them water alone risks diluting their diminished reserves of blood salts yet further, so ensure you have an electrolyte supplement in the lorry with you ready for days out.

The Equine Products UK Ltd Restore-Lyte syringes are perfect for sticking in your lorry or trailer. These helpful one-dose syringes can be quickly administered after travelling, exercise or competing to help keep electrolyte levels high and contain an energy source to aid recovery too.

Take a closer look at the full electrolyte range here and don’t forget you can use our APP to ask our nutritionist if you have further questions about keeping your horse hydrated in summer.

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