Dear AKC: For more than 10 years, I've worked for a cleaning service and many of my clients are dog owners. In the winter many of these pet owners set their thermostats between 68-74 degrees, regardless of whether they're home or not. It's extremely stagnant and dry. I can't breathe in these homes because of this. The animals are clearly uncomfortable and the dogs are panting. Please give advice about a comfortable and healthy temperature setting for animals, especially since the animals now have their winter “coats.” — Burning Up
Dear Burning Up: Dogs, like humans, do not tolerate significant variation of body temperature. On average, a dog's normal body temperature is 101.5 degrees F. Small dogs may have a slightly lower temperatures and large dogs slightly higher. Because of this inability to handle wide swings in their body temperatures, dogs have wonderful internal mechanisms that keep their body at the correct temperature at all times, regardless of the air temperature.
Dogs don't use their skin to perspire, like humans, because of their insulating coat. Their coat keeps them both cool in hot weather and warm in cool weather. Dogs do have sweat glands, located in the pads of their feet and in their ear canals, but sweating plays a minor role in regulating body temperature. The dog uses the panting mechanism to rid his body of excess heat. And like your observation of your clients' dogs, when they are panting they are getting hot.
To put panting in simple terms, a dog breathes in air through his nose, where it picks up moisture from tissue (i.e. a wet nose). The moisture then captures the heat generated from the body and it is exhaled through the mouth. This rids the body of the excess heat, thereby, keeping the body at a normal temperature. The faster and more shallow the panting, the more heat the dog is trying to release from his body. In the reverse, if the dog wishes not to lose body heat, like in cold weather, he breathes in air through his nose and also exhales through his nose to hold the body heat in.
You did not mention the types of dogs and their coats. I would say that “winter” coats play a small role in the comfort level of the dog indoors. Less coat means less insulation, so smooth-coated breeds can loose more body heat but I would be more concerned about brachiocephalic breeds, (i.e. Pugs, Bulldogs and Boston Terriers) that don't have as efficient breathing to keep cool through panting, their primary cooling mechanism.
An ideal temperature doesn't exist for all dogs, since their normal body temperature will vary according to size. Most dogs begin to show signs of overheating when the air temperature is between 81 and 85 degrees F. Perhaps that is why the airlines won't ship dogs above that temperature. But even if a dog is panting, it doesn't mean his is uncomfortable, it just means his internal mechanism has kicked in to keep him cool. You may want to play with the thermostat and when you see that the dog is no longer panting, that may be the correct temperature for his optimum comfort.