George Jones was admitted to a Nashville hospital Thursday (April 18) for observation. His publicist released a statement reporting that during a routine checkup, the country legend was "running a slight fever with irregular blood pressure."

Currently on the final tour of his illustrious career, the 81-year-old singer has been forced to postpone this weekend's shows in Atlanta, Ga. and Salem, Va. The rescheduled dates will be announced soon.

George has battled ongoing respiratory problems over the past few years, among other health issues. Last spring, doctors ordered him to postpone several shows to recover from an upper respiratory infection. Most recently, he canceled a concert in Minnesota in November, after falling ill from a virus.

The icon's last show on his farewell tour is set for Nov. 22 in Nashville. Special guests at the already sold-out concert will include Garth Brooks, Kid Rock, Shelby Lynne, the Oak Ridge Boys, Sam Moore, Dierks Bentley, Charlie Daniels, Jamey Johnson, Montgomery Gentry, Lorrie Morgan, Kenny Rogers, Randy Travis, Tanya Tucker, Josh Turner and Gene Watson.