When the pups are between seven and eight months old, they are harnessed with the teams for short runs. Positioned next to well-trained adult dogs, they learn much of what it takes to become a sled dog from their furry mentors, though they occasionally chew on lines or harnesses, play with the dogs running next to them, and are distracted by new sights such as other dog teams. The pups develop into working sled dogs very quickly. By the end of their first winter, they will already have several hundred miles of experience running in harness. This first winter of training is so significant to their physical and mental development that by the time their second winter comes around, they will be hooked up into team as full-fledged sled dogs.
The Greenlandic Inuit have a very long history of using sled dogs and they are still widely used today. As of 2010, some 18,000 Greenland dogs were kept in western Greenland north of the Arctic Circle and in eastern Greenland (because of the effort of maintaining the purity of this culturally important breed, they are the only dogs allowed in these regions) and about half of these were in active use as sled dogs by hunters and fishers. As a result of reduced sea ice (limiting their area of use), increasing use of snowmobiles, increasing dog food prices and disease among some local dog populations, the number has been gradually falling in decades and by 2016 there were 15,000 Greenland dogs. A number of projects have been initiated in an attempt of ensuring that Greenland's dog sledding culture, knowledge and use are not lost.
In 2019, a study found that those dogs brought initially into the North American Arctic from northeastern Siberia were later replaced by dogs accompanying the Inuit during their expansion beginning 2,000 years ago. These Inuit dogs were more genetically diverse and more morphologically divergent when compared with the earlier dogs. Today, Arctic sledge dogs are the last descendants in the Americas of this pre-European dog lineage.
Historical references of the dogs and dog harnesses that were used by Native American cultures date back to before European contact. The use of dogs as draft animals was widespread in North America. There were two main kinds of sled dogs; one kind was kept by coastal cultures, and the other kind was kept by interior cultures such as the Athabascan Indians. These interior dogs formed the basis of the Alaskan husky. Russian traders following the Yukon River inland in the mid-1800s acquired sled dogs from the interior villages along the river. The dogs of this area were reputed to be stronger and better at hauling heavy loads than the native Russian sled dogs.
Sled dogs were used to deliver the mail in Alaska during the late 1800s and early 1900s. Alaskan Malamutes were the favored breed, with teams averaging eight to 10 dogs. Dogs were capable of delivering mail in conditions that would stop boats, trains, and horses. Each team hauled between 230 and 320 kg (500 and 700 lb) of mail. The mail was stored in waterproofed bags to protect it from the snow. By 1901, dog trails had been established along the entirety of the Yukon River. Mail delivery by dog sled came to an end in 1963 when the last mail carrier to use a dog sled, Chester Noongwook of Savoonga, retired. He was honored by the US Postal Service in a ceremony on St. Lawrence Island in the Bering Sea.
Airplanes took over Alaskan mail delivery in the 1920s and 1930s. In 1924, Carl Ben Eielson flew the first Alaskan airmail delivery. Dog sleds were used to patrol western Alaska during World War II. Highways and trucking in the 40s and 50s, and the snowmobile in the 50s and 60s, contributed to the decline of the working sled dog.
Recreational mushing came into place to maintain the tradition of dog mushing. The desire for larger, stronger, load-pulling dogs changed to one for faster dogs with high endurance used in racing, which caused the dogs to become lighter than they were historically. Americans and others living in Alaska then began to import sled dogs from the native tribes of Siberia (which would later evolve and become the Siberian Husky breed) to increase the speed of their own dogs, presenting "a direct contrast to the idea that Russian traders sought heavier draft-type sled dogs from the Interior regions of Alaska and the Yukon less than a century earlier to increase the hauling capacity of their lighter sled dogs."
In 1925, a massive diphtheria outbreak crippled Nome, Alaska. There was no serum in Nome to treat the people infected by the disease. There was serum in Nenana, but the town was more than 970 km (600 mi) away, and inaccessible except by dog sled. A dog sled relay was set up by the villages between Nenana and Nome, and 20 teams worked together to relay the serum to Nome. The serum reached Nome in six days.
The Iditarod Trail was established on the path between these two towns. It was known as the Iditarod Trail because, at the time, Iditarod was the largest town on the trail. During the 1940s, the trail fell into disuse. However, in 1967, Dorothy Page, who was conducting Alaska's centennial celebration, ordered 14 km (9 mi) of the trail to be cleared for a dog sled race. In 1972, the US Army performed a survey of the trail, and in 1973 the Iditarod was established by Joe Redington, Sr. The race was won by Dick Wilmarth, who took three weeks to complete the race.
The modern Iditarod is a 1,800 km (1,100 mi) endurance sled dog race. It usually lasts for ten to eleven days, weather permitting. It begins with a ceremonial start in Anchorage, Alaska on the morning of the first Saturday in March, with mushers running 32 km (20 mi) to Eagle River along the Alaskan Highway, giving spectators a chance to see the dogs and the mushers. The teams are then loaded onto trucks and driven 48 km (30 mi) to Wasilla for the official race start in the afternoon. The race ends when the last musher either drops out of the race or crosses the finish line in Nome. The winner of the race receives a prize of US$50,000. It has been billed as the "World Series of mushing events" and "The Last Great Race on Earth".
The first Arctic explorers were men with sled dogs. Due to the success of using sled dogs in the Arctic, it was thought they would be helpful in the Antarctic exploration as well, and many explorers made attempts to use them. Sled dogs were used until 1992, when they were banned from Antarctica by the Protocol on Environmental Protection to the Antarctic Treaty over concerns that the dogs might transfer diseases such as canine distemper to the seal population.
Robert Falcon Scott brought twenty Samoyeds with him. The dogs struggled under the conditions Scott placed them in, with four dogs pulling heavily loaded sleds through 45 cm (18 in) snow with bleeding feet. Scott blamed their failure on rotten dried fish.
Douglas Mawson and Xavier Mertz were part of the Far Eastern Party, a three-man sledging team with Lieutenant B.E.S. Ninnis, to survey King George V Land, Antarctica. On 14 December 1912 Ninnis fell through a snow-covered crevasse along with most of the party's rations, and was never seen again. Their meagre provisions forced them to eat their remaining dogs on their 507 km (315 mi) return journey. Their meat was tough, stringy and without a vestige of fat. Each animal yielded very little, and the major part was fed to the surviving dogs, which ate the meat, skin and bones until nothing remained.
The men also ate the dog's brains and livers. Unfortunately eating the liver of sled dogs produces the condition hypervitaminosis A because canines have a much higher tolerance for vitamin A than humans do. Mertz suffered a quick deterioration. He developed stomach pains and became incapacitated and incoherent. On 7 January 1913, Mertz died. Mawson continued alone, eventually making it back to camp alive.
The original sled dogs were chosen for size, strength and stamina, but modern dogs are bred for speed and endurance Most sled dogs weigh around 25 kg (55 lb), but they can weigh as little as 16 kg (35 lb), and can exceed 32 kg (71 lb). Sled dogs have a very efficient gait, and "mushers strive for a well balanced dog team that matches all dogs for both size (approximately the same) and gait (the walking, trotting or running speeds of the dogs as well as the 'transition speed' where a dog will switch from one gait to another) so that the entire dog team moves in a similar fashion which increases overall team efficiency." They can run up to 45 km/h (28 mph). Because of this, sled dogs have very tough, webbed feet with closely spaced toes. Their webbed feet act as snow shoes.
A dog's fur depends on its use. Freight dogs should have dense, warm coats to hold heat in, and sprint dogs have short coats that let heat out. Most sled dogs have a double coat, with the outer coat keeping snow away from the body, and a waterproof inner coat for insulation. In warm weather, dogs may have problems regulating their body temperature and may overheat. Their tails serve to protect their nose and feet from freezing when the dog is curled up to sleep. They also have a unique arrangement of blood vessels in their legs to help protect against frostbite.
Appetite is a big part of choosing sled dogs; picky dogs off trail may be pickier on the trail. They are fed high-fat diets, and on the trail may eat oily salmon or blubbery sea mammals. Sled dogs also must not be overly aggressive with other dogs. They also need a lot of exercise.
In 2015, a study using a number of genetic markers indicated that the Alaskan husky, the Siberian Husky and the Alaskan Malamute share a close genetic relationship between each other and were related to Chukotka sled dogs from Siberia. They were separate from the two Inuit dogs, the Canadian Eskimo Dog and the Greenland dog. In North America, the Siberian Husky and the Alaskan Malamute both had maintained their Siberian lineage and had contributed significantly to the Alaskan husky, which showed evidence of crossing with European dog breeds that was consistent with this breed being created in post-colonial North America. The modern Alaskan husky reflects 100 years or more of crossbreeding with English Pointers, German Shepherd Dogs and Salukis to improve its performance. Occasionally, Alaskan huskies are referred to as Indian Dogs, because the best ones supposedly come from Native American villages in the Alaskan and Canadian interiors. They typically weigh between 18 and 34 kg (40 and 75 lb) and may have dense or sleek fur. Alaskan huskies bear little resemblance to the typical husky breeds they originated from, or to each other. 041b061a72