Keith Urban [ tickets ], whom doctors have ordered to rest his voice for about six weeks, has canceled all of his concert appearances until April.

According to a statement posted on his official website, Urban is suffering from a "persistent and serious vocal chord ailment," and has been ordered to rest his voice for about 6 weeks.

"Although Keith is improving, he is still very much at risk," Dr. C. Gaelyn Garrett of the Vanderbilt Voice Clinic said in a statement. "Should he return prematurely to normal voice use, including singing and speaking, he could risk damage of a potentially permanent nature."

Urban had been scheduled to co-headline a February tour of Canada with Carolyn Dawn Johnson, and to appear at RodeoHouston at Reliant Stadium on March 1.

"I'm devastated by these developments and the number of people who will be affected by this situation and for that I am sorry," Urban said in a statement. "There are no words to express my disappointment, but I know that I need to abide by my doctors' instructions so that I am completely healthy in time to kick-off the tour with Kenny Chesney [ tickets ] in April."