In February 1963 during the third season of Mr. Ed, Keating was diagnosed with leukemia. Despite his illness, Keating returned to the series when filming began for the fourth season that summer. He filmed three episodes for the 1963-1964 season and worked right up to the week before his death on August 26, 1963. His final movie role was in The Incredible Mr. Limpet. He is entombed in Portland, Oregon's Mount Calvary Cemetery. He was survived by his wife, two sons, a stepson, a brother, and two grandchildren.