Challenge of the Yukon was a radio series based on Detroit's station WXYZ that explored the adventures of Sergeant William Preston of the Northwest Mounted Police and his lead sled dog, Yukon King, as they fought wrongdoers in the Northern wilderness during the Gold Rush of the 1890s. The program adopted an adventure format, focusing on the heroics of a working dog and the characters' efforts to help injured trappers, smuggle trackers and protect cabin dwellers from wolverines. Yukon King was a critical character in the show, helping to drive the premise and action of the storyline.

The radio show began as a 15-minute serial, airing locally from 1938 until May 28, 1947. After acquiring Quaker Oats as a sponsor, the series expanded to a half-hour format and moved to network programming. Challenge of the Yukon aired on ABC from June 12, 1947 to December 30, 1949 and later on The Mutual Broadcasting System from January 2, 1950 until its last episode on June 9, 1955. The title changed from Challenge of the Yukon to Sergeant Preston of the Yukon in November 1951, and that name remained until the end of the series and transitioned into television.

Sources: archive.org, wikipedia.org, otrcat.com