Why do cats pant? There are a billion answers to this question and I’m sure that everyone of them is correct. However, I thought I’d better throw my hat into the ring. I will answer the question without reference to books because the answer is more or less common sense. We know that dogs pant to cool themselves.
Latent Heat of Evaporation
Domestic cats pant less often but they do so when they are very hot. When a cat pants he cools himself by the physical process called the latent heat of evaporation. When the saliva on his tongue evaporates it lowers the temperature in the area where this physical transformation (from liquid to vapor) is happening. And therefore the cat feels cooler.
I’m not entirely sure of the physics of the process called the “latent heat of evaporation”. The same process is employed when we sweat. When a breeze passes over our sweat we feel cooler. This is because the heat from our body coming through our skin evaporates the sweat (a liquid) into water vapour which then takes the heat away from our body.
When a cat pants she opens her mouth and her tongue hangs out of her mouth. The saliva on her tongue evaporates just like the sweat evaporates on a person’s body which makes the cat feel cooler. She feels cooler because her tongue is cooler. It’s a small area to feel cooler therefore it probably does not have a huge effect on the cat’s body temperature but it is a contribution to reducing the cat’s temperature. Cats only sweat through their paw pads so they can get hot.
Apparently it is called adiabatic cooling because the physical process is closed. The heat from the body released in the vapour does not change the temperature of the air. When the vapour hits a cold surface it will condense on that surface back into a liquid.
This is why sometimes you see damp in the corner of a room at the point where the walls meet the ceiling. Water vapour from a person’s mouth and nose when sleeping at night rises to a cold spot in the room and condenses on the walls causing mould.