During the Summer months, we typically get out and about to enjoy the weather with our horses, but if things hot up it’s important we know how to effectively cool them after they’ve worked up a sweat.
Why do horses get hot, and what is happening?
All living creatures create heat as a normal part of cell function and they are adapted to deal with that at maintenance. The harder the cells, i.e. the body, is working, the more heat is produced. The body needs to maintain a balance between heat production and heat dissipation, but even on a cool day a hard working horse may create more heat than they can easily lose quickly. If we add in the radiating warmth of the sun the issue can easily become a problem. If not controlled heat stress may impact, where the horse’s body is actively working to control that temperature rise to the detriment of another process – i.e. performance or recovery may suffer.
How do they cool?
Like all animals, horses can use four different pathways to deal with excess heat – radiation, convection, conduction and evaporation - and all of these work at the interfaces between the body and its environment.
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Radiation – heat travels through air
Warmth of the sun.
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Convection – heat transfer via moving gas or fluid
A cooling breeze
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Conduction – heat transfer between objects via direct touch
Your hand warms when placed on a hot horse
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Evaporation – loss of heat through vaporisation of water or sweat
Sweat losses
As natural athletes, horses are prolific sweaters, and losses of up to fifteen litres an hour are not unheard of, dependent on temperature, humidity and exercise intensity1. Typically levels of around 5-7L in mild conditions or 10-12L in hot conditions are more usual – still very significant2.
How can we help?
When our horses or ponies are hot and sweaty it is important to cool them quickly and efficiently. We sometimes hear the outdated belief that suddenly cooling a horse is dangerous, but that isn’t true. There is no evidence to suggest that you can cool any athlete too quickly, but you can cool them too far, so ensure you only take them back to their normal temperature. The most effective way to cool a horse is by continued application of water, either hosing or simply sponging down from a bucket if necessary. There’s no need to stop and scrape as you go, as this offers no further benefit. Simply keep applying that water until the horse has cooled.
For most horses in mild conditions, or not working to elite levels, simply cooling with plenty of water immediately after exercise will cool effectively. Add a couple of capfuls of NAF Cooling Wash. This no-rinse formula is designed to cool, relax and refresh tired horses.
For heavily sweating horses, and when it is really hot, latest research suggests that major muscle groups remain at a higher temperature for longer, compared to respiration and heart rates which both drop rapidly on hosing. Further research is needed to fully understand the timelines, but for hot horses it is advised to hose immediately, cool further by walking, allow recovery in the stable with an electrolyte feed and water, and then hose again a few hours later to help those large muscles masses return to normal temperatures.
Replacing Sweat Losses
Remember for any sweating horse they don’t just lose water in sweat but electrolytes too. These are essential body ions, vital to many pathways in the body including hydration and muscle function. The most important electrolytes lost are sodium, potassium and chloride together with smaller amounts of magnesium and calcium, so ensure that you replace with a broad spectrum electrolyte product, such as NAF ElectroSalts, that covers all bases. Add to a sloppy wet feed, or train your horse to take his electrolytes in water – as it is essential the water is replaced alongside the electrolytes. It is advised not to replace electrolytes with a super-concentrated hypertonic solution, i.e. electrolyte syringe, on an empty stomach as this has been associated with gastric ulcer risk3. Using the wet feed or in-water method are the safest ways to rehydrate.
Whilst sweat losses are significant they don’t have to be replaced all in one go. Following competition, travel or hard work, add ElectroSalts to their daily feed for a few days to fully replenish.
When to rehydrate
Alongside the outdated belief in cooling too quickly, is the idea that you shouldn’t give a hot horse cold water because of a risk of colic. There is no evidence to support this risk, and horses should be offered a cooling drink as soon as possible after exercise when they’ve sweated.
Keep Cool and Carry On
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Exercise your horse appropriate to their fitness levels, and take it easy if the weather is warm
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Ride early in the morning to avoid the heat
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Cool by applying water continually – add a splash of NAF Cooling Wash to refresh your horse
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Offer forage, not concentrates, after sweating to encourage water intake
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Replace sweat losses with NAF ElectroSalts
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Ensure clean, fresh water is always available
References
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Davis M. Heat Stress: A comparative approach between species and disciplines. 27th KER Equine Health and Nutrition Conference. (2024). Ocala, Florida.
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Pagan J. New methods for studying heat stress in horses. 27th KER Equine Health and Nutrition Conference (2024). Ocala, Florida.
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Holbrook TC, Simmons RD, Payton ME, MacAllister CG. Effect of repeated oral administration of hypertonic electrolyte solution on equine gastric mucosa. Equine Vet J. (2005) Nov;37(6)
Written by: By Kate Hore RNutr(Animal). Head Nutritionist at N (Guest Author)
