Dogs pant more than cats because their chosen method of temperature regulation and cooling is panting whereas for cats it is depositing saliva on their fur together with panting in extreme circumstances.
The difference between cats and dogs with respect to losing heat and temperature regulation is that cats lick themselves, deposit their saliva on their fur which evaporates. Through the cooling process of the latent heat of evaporation, cats can cool down using their saliva. Dogs don’t do this. They pant instead. Cats pant too when really hot and/or anxious but but much less so than dogs.
Sweat glands – dogs and cats
Both cats and dogs do not have sweat glands in the skin of their bodies. Dogs have sweat glands on their feet and the domestic cat has sweat glands between the toes and on their paw pads. Therefore there is little difference here.
Cat and dog tongues
For an initially inexplicable reason, the domestic dog does not have a tongue with keratin spines attached to it (FYI hyenas have spines on their tongue but they are not dogs). This means that dogs do not use their tongue to clean themselves whereas the domestic cat’s tongue is famous for the rather strange characteristic that it is covered with spines pointing backwards.
Why is there this difference between cats and dogs? One blogger states that the reason is that domestic cats evolved from the solitary Near Eastern wildcat which is a solitary animal and which needs to keep their scent muffled to avoid predators and therefore they need to groom themselves often to achieve this. Conversely, the domestic dog has evolved from the grey wolf which is a pack animal and which is more able to defend themselves as a group.
If this is true then the reason why dogs pant more than cats is because they are pack animals and the cat is a solitary creature. Ironically, that state of affairs is no longer true. The domestic dog lives in homes where they are often the only dog in the pack leader is their owner, which represents a pack of two sentient creatures. And the domestic cat often lives in multi-cat households and has become quite a social creature living with several humans and other cats and dogs, not uncommonly.
Dr Desmond Morris – Illustrated Dogwatching
Dr Desmond Morris provides some added information. He states that in the evolution of the dog the species “choice of panting…undoubtedly has to do with the very heavy coats worn by their ancient ancestors. It was apparently more important to keep warm in cold weather then cool in hot weather, at the time when the primaeval dog was evolving”.
The primaeval dog had a very thick coat. Under these circumstances there was little benefit to having sweat glands in the skin to help with temperature regulation and therefore they ceased to become important. This begs the question why all wild cats lost their sweat glands from their skin when many species have thin coats. Perhaps the ancient precursor of all wild cat species had a longer and thicker coat?
Nowadays, with many dog breeds having thinner coats, sweat glands on the skin would have been useful but they have not evolved during domestication. The naked-skin breeds of dog such as the Mexican Hairless Dog have dry skins. They do not have sweat glands in the skin either. It is claimed that the Mexican Hairless Dog was bred to act as a hot water bottle on cold nights. As dogs have a higher temperature than humans and as this dog is hairless, they were ideal in this role.
In the dog’s dermal skin layer there are two types of gland which produce fluids but these are not fluids like perspiration designed to cool down the dog. They help to seal the outer layer of the epidermis and they secrete pheromones which gives dogs their distinctive body odour.
In the human’s skin there are sweat glands as we are fully aware. The horse also sweats copiously.