Hickox, the music director of Opera Australia, is currently in Australia and suffering from an inner ear infection, which will prevent him making the 24-hour journey to Pittsburgh.
The program, which is unchanged, includes Elgar's Violin Concerto with violinist Gil Shaham and Holst's The Planets with the Women of the Mendelssohn Choir of Pittsburgh.
Robert Moir, the orchestra's vice president of artistic planning, said, "There seems to have been an epidemic of cancellations in the symphonic world this year, and with little advance notice, replacements are very difficult to find. There are many considerations, including previous commitments, usually scheduled years in advance and, in the case of non-Americans, international visa dilemmas. In this instance, Leonard Slatkin happens to be on a scheduled vacation this week, is at home in Virginia, and willing to help us out."
Leonard Slatkin is in his tenth season as music director of the Washington, D.C.-based National Symphony Orchestra. He last conducted the Pittsburgh Symphony Orchestra in December 2001.
The conductor casualty list this season so far includes Robert Spano, James Levine, Christoph von Dohnšnyi, and Kurt Masur.