Toby Keith has cancelled a Nov. 4 concert in Casper, Wyo., after his doctors ordered a brief vocal rest, his publicist confirmed Friday (Oct. 29). Keith and tourmate Terri Clark were scheduled to perform at the Casper Events Center during his Big Throwdown tour. "No other shows have been cancelled, but Toby is taking time off resting his voice until Nov. 5," publicist Elaine Schock told CMT.com. Keith is scheduled to perform Nov. 5 in Denver and Nov. 6 in Salt Lake City before heading to Nashville for the CMA Awards show on Nov. 9. Keith is scheduled to join Clint Black, Kenny Chesney, Alan Jackson and George Strait when they perform "Hey Good Lookin'" with Jimmy Buffett on the CBS telecast.