Hauhau
The Hauhau are strange creatures from Tsimshian myth. They resemble bear cubs or puppies, and dogs can be transformed into Hauhau on command. They are monstrous and powerful with a loud roar and the ability to kill many mountain sheep at once. Txamsem, the Raven, created a pair of these creatures for when he retired into the mountains, and they bring him meat every day.
Citations:
Barbeau, Marius, and Beynon, William. Tsimshian Narratives: Tricksters, shamans, and heroes. Canada, Directorate, Canadian Museum of Civilization, 1987.
Boas, Franz, and Tate, Henry W.. Tsimshian Mythology. United States, U.S. Bureau of American ethnology, 1916.
Gill, Sam D., and Sullivan, Irene F.. Dictionary of Native American Mythology. United Kingdom, Oxford University Press, 1994.