Standing 21 to 27 inches (53 to 69 cm) in height at the withers and weighing 45 to 90 pounds (20 to 41 kg), the Chinook is balanced and muscular.

Health issues include normal hereditary problems such as epilepsy, hip dysplasia, and atopy.

The breed derives principally from one male ancestor born in 1917, named "Chinook", who was Walden's lead dog and stud.

Walden, in his effort to create his own Chinook, bred a Greenland Dog directly descended from the lead of the Peary North Pole expedition named Ningo with a large, tawny male Mastiff/St.

As Rikki grew, he showed the traits which Walden had searched for and was renamed Chinook after his native american companion's dog.

The 12-year-old "Chinook" went missing on the Byrd expedition while hauling supplies miles overland from ship to shore, and was presumed to have died.

Control of the core breeding stock passed from Walden to Julia Lombard and from her to Perry Greene in the late 1940s.

Rare and closely held by Greene, who was for many years the only breeder of Chinooks, the population dwindled rapidly after his death.

[2] Breeders in Maine, Ohio and California divided the remaining stock and managed to save the type from extinction.