Myhorse.com - Full Article
Story by Eleanor Kellon, VMD
When you understand conduction, convection, and evaporation, cooling your horse makes sense.
Summer's heat and humidity can be much more than just uncomfortable. They can be deadly. Horses lose their lives every year to heat stroke. Countless others struggle through anything from weakness to colic as a result of inadequate care in hot weather. Don't let this happen to your horse!
How Your Horse's Body Cools Itself
The business of simply being alive, breathing, digesting, producing manure, processing foods, etc., keeps your horse's body temperature in a range between 98.5 and 101 degrees Fahrenheit. When your horse begins to work, an inevitable consequence of increased energy generation and movement is for the body temperature to increase. To avoid reaching temperatures that can damage the brain and organs by interfering with enzymes, your horse must have a way to get rid of that heat.
Some of the heat is transferred to air exiting the lungs, but this is not enough for efficient cooling in an animal this size. The remainder of the extra heat is carried from the interior of the horse to the skin surface by the blood stream. Blood vessels very close to the surface of the skin dilate and heat is lost from the skin's surface by several mechanisms:
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