Competing on a hot day

May 27
Top tips for rapid cooling:
  • The colder the water…
  • The more of the horse to which you apply water…
  • The greater the total volume of water you apply…
  • And the more water you apply to the horse per minute … the faster the horse will cool down.

Important information
At the end of a ‘heat wave’ that has lasted for at least 2 weeks, most horses will have acclimatised to some extent to exercising in the heat (as long as they have been ridden when it is hot).

However, even if they are acclimatised, horses cannot achieve the same level of performance when it is hot as they can when the weather is cool. They will:
  • Tire earlier
  • Perform less well
  • Be more likely to fall/make a mistake
  • Get hotter
  • Be at risk of heat-related illness and medical conditions such as colic and laminitis.


If the weather gets hot suddenly, no horse will be acclimatised. 
Horses take about 2 weeks to acclimatise to exercising in the heat; a few days of riding in the hottest part of the day will not acclimatise your horse and may in fact make things worse.

The following factors make it more likely that a horse will overheat
Horse-Related Factors
  • Not being acclimatised to exercising in the heat
  • Being unfit, large, of a heavy breed, or very old or young
  • Being overweight
  • Having a dark or heavy coat
  • Having health issues such as asthma, heart disease, or PPID (Cushing’s disease)
  • Exercising, particularly if the exercise is strenuous and/or prolonged
  • Carrying a heavy load (rider + tack).
  • Wearing clothing (rug, travel boots or bandages, etc.)

    If you must put a rug on, make sure it is white and breathable

Weather-Related Factors
  • High temperature in the shade
  • High humidity
  • Strong sunlight
  • Standing or competing on a reflective surface (e.g., arena surface, road)
  • Little to no wind.
On a hot day, what helps horses to stay cool?

The main way that horses stay cool in hot weather, and when exercising, is by sweating. Heat is removed from the body when the sweat evaporates. You can achieve the same effect by wetting your horse – in the same way that sweat does, the water will remove heat from the body as it evaporates. Sweat and water are less likely to evaporate if:

  • The sky is overcast
  • It is humid
  • There is little to no wind

    Horses are therefore at the highest risk of overheating on a hot day if they exercise when it is overcast, the humidity is high, and winds are light.

How to decide whether it is safe to compete your horse

  • Published ‘temperatures’The forecast temperature alone is useful but other measurements are better for estimating the risk of horses overheating when exercising on a hot day.

    • The ‘Heat Index’ (also known as the ‘Comfort Index’) accounts for temperature and humidity (but not the effects of sun and wind); the ‘feels like’ temperature accounts for temperature, humidity, and wind (but not sun).
    • These are both more useful than air temperature alone, but neither is as good as the Wet Bulb Globe Temperature (WBGT).
    • The WBGT is the most useful measurement because it takes into account the effects of air temperature, sun, wind, and humidity.
    • If the event publishes the WBGT, use their guidance to estimate risk.
    • In general, no special precautions are necessary at a WBGT of 28 or less. Above this, you need to be careful.


Listening your horse

You know your horse better than anybody; if you sense that something isn’t quite right, it is always safest to stop riding and assess the horse and the situation.

How to help your horse to stay cool and safe

  • When you arrive at the event, find out where the organisers have arranged for water bowsers or troughs to be sited (this is most often at the cross country finish).

  • Stand your horse in the shade as much as possible.
    • However, if there is a breeze, they will almost certainly be cooler standing outside than inside the vehicle, even if they are standing in the sun.
  • Wet your horse down frequently by pouring cold water all over the body.
    • Do not scrape the water off.
  • If you have fans, use them.

  • Provide free access to plain water at all times, including immediately before, during, and after exercise.

    • Drinking cold water isn’t harmful for horses; however, they prefer water that is 15–25°C; there is therefore no need to cool drinking water.

  • Reduce the total amount of time for which you warm up and split your warmup into several sessions; wet the horse down during the breaks.

  • Reduce the speed and/or distance over which you compete; if possible, move your entry to a less challenging class.

    • Withdraw or retire if you are worried about your horse.

How will I know if my horse is becoming dangerously hot?

  • Flared nostrils
  • Blowing (deep, laboured breathing) – or, alternatively, panting (rapid shallow breathing)
  • Covered in sweat
  • Veins easy to see under the skin
  • Hot to touch
  • Muscle spasms
  • “Thumps” (synchronous diaphragmatic flutter)
  • Unsteady on their feet
  • Distressed, depressed, lethargic, or excited.


What to do with a horse that is very hot

  • Start cooling IMMEDIATELY.
  • You will need a team of people – ask for help if you are on your own.
  • Finding shade and using fans will be helpful – but applying water to the horse’s body is the absolute priority.
  • Pour water all over the horse’s body – the only bit you can leave out is their head if it is obvious that they don’t like that.
  • DO NOT SCRAPE THE WATER OFF: This will only slow you down – and will actually slow the rate of cooling.
  • The colder the water the better – but don’t let a search for cold water stop you – as long as the water is cooler than the horse, it will help to cool them down.
  • Apply water continuously for several minutes; if the horse seems to be recovering (blowing or panting less), or if they are agitated, take them for a short walk; then again apply water continuously for several minutes.
  • Repeat this sequence until the horse starts to recover (breathing returns to normal and the horse seems more comfortable); this may take 10–15 minutes.
  • If you are using a hose that has been lying in the sun as a water source, be sure to run it until the water runs cool.
  • If the horse is unsteady on their feet, try to keep them walking (whilst continuing to cool them).
  • If the horse goes down, keep cooling them as fast as you can and call for a vet.
  • Call for a vet immediately if you are in any doubt about whether it might be necessary or if the horse:
  • Isn’t showing signs of recovery (i.e., if they continue to blow or pant just as hard)
  • Is deteriorating
  • Goes down
  • Keep cooling aggressively while you are waiting for the vet.

Myth Busting

There is a lot of misinformation and scaremongering on social media about how to manage hot horses. This becomes dangerous if it means that people don’t cool their horses down properly. The information below is correct and is fully supported by scientific studies.

  • It’s absolutely fine to put cold water on a hot horse; it will not increase the risk of any health condition; this includes colic, muscle damage, kidney damage, and laminitis. If a horse does develop colic, etc, after they have overheated, it is almost certainly related to the overheating – it is certainly not related to the cooling.
  • A wet horse will always cool faster than a dry horse – water does not insulate horses/make them hotter.
  • Scraping water off a hot horse is a waste of time & will actually slow down their recovery.
  • Horses cool faster if water is applied to their entire body than if it is applied to a few selected areas.
  • Placing ice packs over large veins is not an effective way of cooling horses.
  • Evaporative coolers and cooling blankets/rugs should not be used when a horse needs rapid cooling – this can only be achieved by applying large amounts of cold water to the horse.
  • It is OK (and in fact may be helpful) to give electrolytes to a horse that isn’t drinking. However, don’t suddenly start giving electrolytes, or increase the amount of electrolytes that you give, at a competition on a hot day; this is something to have in place before you compete.