Accepted Answer
Every "warm-blooded" living thing needs a way to make heat and keep it when its body is too cold inside, and a way to get rid of extra heat when its body is too hot inside.Moving around (using muscles) makes heat inside, and the animal needsa way to get rid of the heat. Fast.Evaporation is a very effective way to get rid of heat.Human animals do it by perspiring. We excrete moisture through our skin,and when the moisture evaporates, that takes heat away very efficiently.That's why we like to fan ourselves when we're hot ... moving more airpast our skin makes moisture evaporate faster.Dogs don't perspire, so they badly need another way to get rid of heatin a hurry.They do it through their mouth. They put water in their mouth if it's available,or else just collect a lot of saliva in there if there's no other water, and thenthey blow air over it to evaporate it and get rid of heat. Panting moves moreair over the moisture, which causes more evaporation and more heat loss.
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