Donald McKay, identified by printed name on the mount face and by the promotional text on the reverse, is the subject of this cabinet card portrait, one of a series produced to advertise Ka-ton-Ka, a patent medicine marketed as a Native American remedy and sold from Corner State and Adams Streets, Chicago, Illinois. McKay was a half-Warm Springs Chinook government scout and interpreter who served the United States Army for over twenty-two years and gained national celebrity for his role in leading Warm Springs scouts against the Modoc during the war of 1872 to 1873. His portrait and endorsement were used as promotional material for the Ka-ton-Ka product, which was marketed as "Nature's Gift to Nature's Children."

McKay is shown in close profile facing left, his long dark hair falling loose to his shoulders, wearing a buckskin or fringed leather garment and a shell or bone ornament at his chest. His prominent mustache and strong profile are rendered with exceptional tonal quality in the albumen print. No photographer's imprint is visible on the plain mount.

Born in about 1836 in Oregon Territory to fur trader Thomas McKay and a Cayuse woman, McKay worked as a translator for the Bureau of Indian Affairs and the U.S. Army beginning in 1852. During the Modoc War he met at considerable personal risk with Captain Jack Kintpuash in an attempt to negotiate an end to hostilities, and when those efforts failed he led fourteen Warm Springs scouts in the campaign that resulted in the Modoc's defeat and Captain Jack's capture and execution. Following the war McKay toured the country with Warm Springs scouts, performed in Wild West shows, and later toured Europe before settling on the Umatilla Indian Reservation, where he died in 1899.

The reverse carries a full red-printed advertising text for Ka-ton-Ka, describing McKay as the oldest government scout and most noted Indian warrior, crediting him with introducing the remedy to white people, and directing orders to Corner State and Adams Streets, Chicago, Ills. Pencil notations read "12634" at left and "650" and "4ys" at upper right, likely dealer inventory numbers.