It's a hot, humid day with the sun blistering down and you are riding your horse along the trail, or in the arena. Exercise is moderate, after all, it's hot outside. So, who do you think is likely to overheat....you or your horse? The answer may surprise you to know that your horse gets hotter much faster than you and is more in danger of the negative effects of heat stress.
According to Michael Lindinger, PhD., MSc, an animal and exercise physiologist of Guelph University, "it takes only 17 minutes of moderate intensity exercise in hot, humid weather to raise a horse's temperature to dangerous levels. That's three to 10 times faster than in humans. Horses feel the heat much worse than we do."
And these effects can be very dangerous to your horse! If the body temperature of a horse increases from the normal 37 to 38C temperature to 41C (98.6-105.8F) temperatures within the working muscles can reach as high as 43C or 109.4F, a temperature in which proteins in the muscles literally begin to cook. Horses suffering excessive heat stress can experience issues such as hypotension, colic and even renal failure.
The BBC News has a video on-line showing a thermal illustration of rider and horse during the 2008 Olympic Games in Hong Kong on how the horse is affected by heat. You can graphically see the difference in rider and horse body temperature and can now visualize how exercise affects the horse during hot weather.
Horses are sensitive to heat for many reasons the main one being is that they are BIG and have a higher percentage of active muscle when exercised. When they are working, the muscles produce a lot of heat.
My horse sweats, so I know he's cooling down...
Horses can sweat 15 - 20 litres per hour on a cool, dry day but be aware that this can increase to up to 30 litres per hour on a hot, humid day. Even though they sweat, however, only 25-30% of the sweat produced by your horse is actually effective in cooling him down through evaporation. Unlike us where up to 50% of our sweat is evaporated from our body, your horse is different because more sweat is being produced that can be used for evaporation and the rest just drips off his body and basically is useless in cooling him down!
As explained by Lindinger, the salts in the horses sweat is four times as concentrated as in human sweat. "Those salts must be replaced. Just giving your horse water will not rehydrate a dehydrated horse. When horses drink plain water, it dilutes their body fluids, and their bodies respond by trying to get rid of more water and more electrolytes." So, what can we do to help our horses from the harmful effects of the summer heat? Electrolytes! Get your horse used to drinking an electrolyte solution to replace those lost through sweat. Keeping your horse properly hydrated is the most important step in protecting against the harmful effects of heat.
If you are preparing for competition, acclimatize your horse to riding in the heat. Most riders exercise their horses in the morning or evening when it's cool and then go to a competition that is held during the hottest time of the day. You need to get your horse used to riding in the heat. Lindinger recommends "trying to acclimatize your horse to the heat by spending four hours daily, at least five days a week for three weeks, in hot conditions. Horses that are used to being ridden in the heat will develop the full spectrum of beneficial adaptations that come with heat acclimation."
When your horse is hot, never put a blanket or cooler on your sweating horse. The best way to reduce their temperature is to rinse the body with water repeatedly and scrape off the excess water. Scraping is an important function otherwise the water trapped in the horse's hair will quickly warm up. You can cool the horse by 2 degrees in ten minutes by using this method...water on, water off, water on, water off.
Cool Medics offer many options to keep your horse cool during exercise. The products they manufacture are activated by soaking in water and the cooling process is established by charging the fibers with moisture and creating an environment for evaporation. When moisture in the batting evaporates, heat is removed and cools the surrounding area, transferring the cooling effect to the wearer.
Just as we riders go prepared with a bottle of water, sunscreen, sunglasses and a hat, we should also consider our horse and prepare ourselves with the tools necessary for protecting them from the hot, humid weather. If you have a plan in place to cool him down if he becomes overheated, even on those hot, humid days you can still have fun riding!