Horses are cool, literally. When the daytime temperatures keep creeping up, you see people sweat, you see dogs pant, you might see birds with their beaks gaping as they also pant, breathing rapidly to dissipate heat out of their bodies. To battle the heat, horses have a couple metabolic adaptions to put some relief in their hot summer days.
Throughout a horse’s body exist sweat glands which allow for evaporative cooling as the sweat (a liquid) changes to a gas absorbing energy from its surroundings. In this case, the energy is in the form of heat from the skin leaving the air just above it cooler. But this is a secondary method to keep their cool. The primary cooling mechanism is a dilation of the capillaries at the surface of the skin. As horses exercise, especially in high ambient temperatures, the normal absorption of heat in the internal organs of a horse can no longer keep up with the need to shed heat being developed by the current muscle activity. At this point, the capillaries become dilated allowing more blood to move to the surface putting heat to the environment. When this dilation proves not to be effective enough, the afore mentioned sweating will begin.
At this point you may be reflecting on the idiom of being rode hard and put away wet. While in horseman’s terms this generally refers to someone not taking proper care of their horse by allowing them sufficient time to cool down and brush the sweat out of their hair, there is another necessary care item that must be addressed: drinking plenty of water. If allowed to continue to sweat, the fluids from the bloodstream pass through the sweat glands resulting in an inability to maintain proper blood density leading to a level of concentration making the heart work harder to circulate the blood efficiently throughout the body. Without ingesting proper levels of water, a horse’s body will begin to steal what it needs from the areas between the cells (interstitial spaces) and/or the gastrointestinal tract. While horses are some of nature’s most durable creatures, they are as equally fragile and prone to life-threatening ailments when it involves their gut. Without access to fresh water, horses can easily suffer from several health issues ranging from impaction colic to tying up.
After allowing your horse access to water, some time to bring the heart rate down, and placing them in a cooler shady spot, if something just doesn’t seem right with your equine partner after a hard workout or ride in the hills, consider consulting your veterinary expert before it becomes a dire situation. Pouring water over a horse will be effective also as a treatment because it will lessen the need for the horse to produce sweat in order to cool down. Like humans, horses respond similarly to basic first aid techniques related to possible heat exhaustion. Their disadvantage is the overall coating of their hair which may not allow a faster cooling process, not unlike your hairy Uncle Robert who passed out at the lake last year. His condition may have been exacerbated by the light beers he consumed out on the boat, but I digress.
This summer, take care of yourself and your silent partner by drinking plenty of water and paying attention to signs of overheating. Soon enough we will all be concerned again about keeping warm enough when the seasons change.