Whilst the UK is in the midst of a heatwave, a discussion is going on about the best ways to cool horses down. Usually we don’t have this problem and almost any method is sufficient.
It makes me wonder how equestrians cope in hot climates. Would any readers from those countries care to enlighten me? I think I was told when I was in Dubai that the polo horses had air conditioned stables and were exercised very early in the morning. Horses from those climates also tend to be fine coated and thin skinned, unlike our hairy natives who are all struggling as the thermometer nudges thirty degrees Celsius.
Some people advocate hosing and scraping, others say to hose and let evaporation do the cooling down.
In fact, the best answer is to do a bit of both. Imagine you are standing next to a very sweaty horse. Quickly run the hose over him. Touch his side; the water is warm isn’t it?
Now comes the pseudo science part. By which I just mean I’m haphazarding a guess at the science but. Heat from the horse’s body transfers immediately to the water, so the water becomes the same temperature as the horse. The water then acts like an insulator (although scientists will say that water isn’t a particularly good insulator, some would say it’s enough of one in this case) so preventing the horse’s body from losing any more heat. At this point the horse can’t cool down until the water has evaporated.
Now, scrape the excess water off the horse and hose him again. Keep removing the warmed water until the water runs off cool. Now the horse’s surface temperature is returning to normal, but he still needs to continue cooling down. This happens when the cooler blood leaves the skin and goes to the hot muscles, so removing some heat from there.
It’s at this point that leaving cool water on the body to evaporate, mimicking the sweating process, is effective.
I found this explanation of why sweating cools you down:
Beads of sweat on your skin are in liquid form. When the water temperature rises, the molecules become more active and gain energy. When a molecule gains enough energy, it can break free from the bonds that hold the liquid together and transform into water vapor. This is evaporation. As the molecule evaporates, its energy — or heat — is removed from the sweat that remains on your body. This loss of energy cools the surface of your skin.
In the same way, water and sweat evaporating from the horse’s skin will cool them down.
A friend told me that endurance riders advocate washing and scraping until the water runs cool off their backs and then leave the rest to evaporate. Which makes me feel better in my hosing the horses until the water feels cool against my hand, then scraping off excess and then turning them out to roll and dry out naturally.
I found the following article about the cooling process followed at the Beijing Olympics – Read it here – which makes the valid point that if you continue to apply water to the horse’s body then warmed water will be displaced so cold water is always next to the skin and heat will displace to the water. So scraping excess water away can be replaced by just continuous hosing. This article also points out that to maximise the cooling effect of washing down it’s important to cover as much of their body as possible to increase the area that is being cooled, so don’t just wash the sweaty shoulders, wash all the neck and hindquarters too.