A comment thread about snow dogs led me to an interesting interview with Dr. Susan Whiton, an Alaskan veterinarian who is married to a champion musher who runs a sled dog kennel. She talked about how Siberian Huskies, Alaskan Huskies, Malamutes, and other dogs bred specifically for cold weather are different from other dogs. Their ability to tolerate cold is amazing, as long as they are healthy, well-fed, and are in their prime.
Q. What diet should they eat if they are outside for long periods during the day?
A. The calories in most commercial dog foods come from carbohydrates. In very cold weather, the dogs do better with a higher amount of fat calories. A study indicated a sled dog racing the Iditarod required 10,000 calories a day to meet their metabolic needs. The only way to meet that high caloric need is with a diet high in fat calories. Most pet dogs do not need that many calories and may get very sick from a high fat diet.
When I ran the Yukon Quest in 1987 we encountered -55° F temperatures at night and -20° F during the day. The sled dogs did fine at those temperatures. They were being fed a very high fat, high calorie diet up to four times a day during the rest periods and often got fatty meat snacks during the runs.
Q. How are dogs with a thick undercoat able to keep warm when sleeping?
A. When they sleep they curl up with their tail over their nose, which traps the heat against their bodies. There are lots of photos of resting sled dogs covered with snow. They are holding their heat well since the snow is not melted. The dogs that are not doing well will have ice on their fur. It indicates that they are losing enough body heat to melt the snow. Because their coat is not insulating well more ice will build up making the hair less lofty and less insulating. The thick undercoat of the Northern Breeds provides loft, like a fuzzy mohair sweater, and keeps the warmth next to the animal rather than allowing it to escape. The Iditarod sled dog race only allows Northern Breeds in the race because other breeds can’t retain heat well. So when the ice hits their coat it melts and then freezes.