Sled dog each year, but after the 1995 events, it was decided to hold them every two years, which facilitated the bidding process and enabled the host organization more time for preparation. Togo was the lead sled dog of Leonhard Seppala and his dog sled team in the 1925 serum run to Nome across central and northern Alaska. Balto was the lead dog of the sled dog team that carried the diphtheria serum on the last leg of the relay to Nome during the 1925 diphtheria epidemic. He was driven by musher Gunnar Kaasen, who worked for Leonhard Seppala. Seppala had also
Sled dog Greenland, Siberia, Chukotka, Norway, Finland, and Alaska. In 2017, a study showed that 9,000 years ago the domestic dog was present at what is now Zhokhov Island, arctic north-eastern Siberia, however this area was connected to the mainland then. The dogs were selectively bred as either sled dogs or as hunting dogs, which implies that a sled dog standard and a hunting dog standard existed at that time. The optimal maximum size for a sled dog is 20–25 kg based on themo-regulation, and the ancient sled dogs were between 16–25 kg. The same standard has been found in the remains