How dogs stay warm in cold weather

I'm having trouble finding facts about how dogs manage in cold weather. The web is rife with the following type of stuff: "General rule of thumb is that whatever length of time it takes for YOU to get uncomfortably cold, then that would be the same for your dog. A shorthaired dog would be minutes, akin to you going out in a t shirt and underwear only. A full coated oes is more like going out with a good coat on, but still, you WILL get cold." [ source ]
Totally ignorant. The worst kind of anthropormorphizing. It is -25 C today with about 15 cm of fresh powder snow and the dogs, short hair, long hair, big, little are having a ball. I can't stand it for more than about 20 minutes wearing long johns and a down parka.

It's not just the northern dogs either. If you look north, you don't find big long-hair huskies and malamutes so much anymore as smaller, short haired bred-for-racing huskies that stay outside most of the time, and they seem to do fine, as do German Shepherds:
"My adult dogs stay out in temprature like -10 to -15 degree C and no problem at all. In the night, they are inside the kennels. I use windbreakers on the entrance and put lot of straws on the floors. They are fine and active and never saw them snuggling. However, when temprature falls below -25C I bring them in. I havnt seen any problem so far with these tempratures." [ source ]

Wikipedia deals with heat and dogs, not cold, but does offer some insight into how different the anatomy and thermal processes of dogs are:

"A common misconception is that dogs do not sweat. Primarily, dogs regulate their body temperature in a completely different way, through their tongue. That is why after a dog has been running or on a hot day, its mouth will be seen wide open with the tongue hanging out. This form of cooling maximizes heat loss while conserving moisture, because it carries heat from the hottest part of the body, the interior core of the thorax, unlike sweating, which cools the already coolest part of the body, the skin—or in less intuitive, more scientific terms, this higher efficiency of thermal loss relative to moisture conservation arises because heat flow is proportional to temperature gradient. In addition, dogs effectively sweat through the pads of their feet, since they are not furred. On a warm day and after exercise, a dog's naturally wet footprints might be visible on a smooth floor.

"Dogs possess a rete mirabile in the carotid sinus at the base of their neck, a complex of intermingled small arteries and veins which acts as a heat exchanger to thermally isolate the head, containing the brain, the most temperature-sensitive organ, from the body, containing the muscles, where most of the heat is generated. The result is that dogs can sustain intense physical exertion over a prolonged time in a hot environment, compared to animals which lack this apparatus; thus, a dog chasing a jackrabbit through the desert may not be able to outrun the rabbit, but it can continue the chase until the rabbit literally drops dead from overheating."

But the answer, I think, I finally found here in an article written by Ted Greenlee in 1971, worth quoting at length:

"I would now like to discuss two mechanisms of heat control, one which is utilized specifically in the case of Northern animals, and one which is utilized by dogs in general. I would first like to discuss the problems of severe cold and how the animal protects his body temperature in addition to his insulation. It is not possible to totally insulate the dog and in general, the areas not adequately insulated are the areas that are in contact with his snowy world. Those areas are, of course, his feet and legs. Problems of the feet and legs, or in the case of man, the hands and feet, are frequently noted in cold exposure. Man, who is not well insulated, to protect his body temperature and vital organs, will literally shut off blood supply to the feet and hands. When one goes out in the cold and is not properly dressed, one's feet and hands become extremely cold and frostbite or freezing of the fingers and toes is a common occurrence. If this process was followed in the case of a dog in his 60 to 70 degree below zero weather, he would of course be in very bad straits. Therefore, instead of stopping the blood supply to the extremeties so the blood does not become chilled, what occurs is that the warm, oxygen carrying arterial blood going into the limb runs right next to the cold, unoxygenated blood leaving the limb. Since they are right next to each other, the warm blood gives up its heat to the cold blood, preventing the loss of this heat as it gets down to the exposed part of the dog's foot. The oxygenated blood can get to the vital parts of the foot to maintain their nutrition, but at the same time does not allow a loss of body heat to the cold air.

"The ability of the animal's foot and lower leg to live at very low temperatures requires addition adaptation of the tissue, some of which is not well understood. There is one example though that is well understood and noted, and that is the difference in the melting (or freezing, Ed.) temperature of the fat associated with the foot and leg as compared to the melting temperature of body fat. The best example of this noted in the case of neatsfoot oil which is the fat from the foot of a cow as compared to the tallow which is the fat from the body of the cow. As you remember, neatsfoot oil is a liquid at normal room temperature, whereas tallow is solid. Therefore, the fat is adapted in the foot of the animal to keep it from becoming solid at these low temperatures and becoming brittle and breaking. I am sure there are other changes in the cells in the tissues of these parts which allow them to tolerate this lower temperature and still function for the animal, but the heat exchange mechanism between the arterial and venous blood in the limbs of cold adapted animals is absolutely essential to their survival."


cool or what?