Horses normally cool themselves down by sweating — sweat evaporates from the skin surface, causing a cooling effect. However, sweating might not be enough to bring the body temperature down quickly. If it is a hot day, your horse has exercised intensely or spent a lot of time in a horsebox or stuffy stable, then they might need some extra help to cool down.
Whether sourced from a hose, pond or river, the fastest way to cool down your horse is to continually pour water over them. Continuous application of water removes heat via conduction, which is the direct movement of heat from the horse into the water. This happens because of the difference in temperature between the horse, which has a surface temperature of 40°C or higher, and the water being poured onto them.
Ideally the water should be between 10 and 25°C, but would be effective as long as it is cooler than the temperature of the horse. If the temperature of the water is the same as the horse, it will only cool by evaporation which takes longer than conduction.
To scrape or not to scrape?
Scraping water off your horse will not help to cool him down. This is because evaporation is much slower at removing heat compared to conduction — so when the water is scraped off, there is less capacity for conductive heat transfer to take place. Leaving the water on during hot days will help him stay cooler for longer.
What about cooler weather?
During winter, your horse can still get hot through exercise and need help to cool down. If he is sweaty, feels hot to touch and is blowing hard he needs cooling.
You should apply the same principles as above, and cover the horse with water until he starts to feel cool again, which will happen faster in the winter as ambient temperatures are lower than the summer. Once he’s cooled down, he might need a light rug or fleece to prevent him from getting too cold and help him dry off.
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