After 45 years of fronting U.K. rock stalwarts Nazareth, singer Dan McCafferty has been forced to retire.

Fans won't be surprised by McCafferty's announcement. They've watched as health woes affected his ability to perform at a pair of recent Nazareth shows. On July 9, McCafferty collapsed onstage just moments into the band's first song of the night, and on Aug. 24, after reportedly complaining of shortness of breath, he had to bow out partway through their allotted time at the Summerdays Festival in Switzerland.

"We sadly have to tell you all that Dan has been forced to retire due to ill health," reads an announcement at Nazareth's website, which explains that McCafferty suffers from chronic obstructive pulmonary disease, a chronic condition that severely restricts the afflicted's ability to breathe. "It has gotten worse lately, and after trying to play a festival in Switzerland last weekend, Dan found it impossible to continue after performing only three songs. In the dressing room afterwards, he told the band that he couldn’t go on any longer."

It's the end of an era for Nazareth, who have been led by McCafferty and bassist Pete Agnew since December 1968. While the band's announcement promises to keep fans "updated on further developments," it seems safe to assume that McCafferty's departure signals the breakup of the band, although there's at least a glimmer of hope that they'll be able to finish the new studio album they've been recording.

More From Ultimate Classic Rock