Humans vs. Dogs
Go out on a hot summer day and there is a good chance you will start to sweat. That is how your body cools itself and maintains a constant temperature. Like people, dogs have two types of sweat glands. Yet, dogs do not sweat to regulate their body temperature, they pant.
Eccrine glands are located over the majority of the human body. However, they are in highest density in the palms, soles of the feet, and scalp. In those areas there are as many as 3,000 glands per square inch. Their main function is to help control body temperature. Eccrine sweat is usually odorless but contains lots of sodium and other electrolytes.
Dogs also have several eccrine sweat glands located on the pads of their foot. Similar to human feet, they secrete a watery sweat. You have likely seen the outline of a damp paw print on the sidewalk during summer. This is an example of the sweat that your dog can emit during a hot day. These glands do not cool the body as a whole but serve to counter rapid rises of temperature on the paw that could lead to burns.
Apocrine sweat glands are primarily located in a person’s armpits and groin. You know they can perspire profusely when you get hot. Apocrine glands produce a thicker sweat that contains proteins, fats, and other substances that are broken down by bacteria on the skin causing the unpleasant odor associated with heavy perspiration.
Dogs have similar apocrine sweat glands associated with the hair follicles over most of the body. These secrete a protein-containing sweat when a dog gets hot, but there is too little fluid to get a dog moist and aid in controlling body temperature. The function of canine apocrine glands is unclear although some believe they may act as scent glands that attract the opposite sex.
Why Dogs Pant
The long and the short of it is that dogs have the same types of sweat glands as humans, but do not realize the temperature controlling function that sweat glands afford humans. Like people, dogs still have to control their body temperature on hot days. Unlike humans, dogs pant to control their body temperature.
When your dog becomes overheated, his or her brain sends the body signals that tell the body to cool down. The heart rate increases and the lungs work harder to bring in more oxygen. Panting is an important method of oxygenating the dog’s blood. The tongue drapes out of the mouth and the dog begins to pant. They rapidly breathes in through the nose and out through the mouth. As air passes over the tongue, saliva and moisture evaporate, cooling the tongue. Blood vessels in the tongue, airways, and lungs circulate the cooled blood throughout the body to maintain temperature.
The normal breathing rate of a dog is 30 to 40 breaths per minute. A panting dog can take 300 to 400 breaths per minute. Under a moderate heat load a dog alternates between brief periods of panting at high frequencies and periods of normal slow respiration. It looks like a panting dog is working very hard, but panting does not use much energy due to the natural elasticity of the lungs and airways. It also does not generate additional heat. Nature worked this out very well.
Dogs and humans need to maintain a constant body temperature on hot summer days. While both have sweat glands, their cooling processes work quite differently. People sweat to cool while canine sweat glands are inconsequential in the cooling process. Instead, dogs pant to cool.
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C. Sue Furman, Ph.D. spent 40 years at several major universities including the University of Maryland, School of Medicine and Colorado State University, College of Veterinary Medicine and Biological Sciences teaching future physicians and veterinarians and conducting research involving nerve and muscle. Learn more about Dr. C. Sue Furman here.