Wales hooker Lloyd Burns will miss the Six Nations due to a neck injury.
The 27-year-old made his international debut against the Barbarians in June 2011.
"Lloyd has been advised to withdraw from rugby for at least three months in order to fully rehab his neck," said Newport Gwent Dragons director Robert Beale.
"We are obviously disappointed for Lloyd, particularly with the Six Nations coming up, but Lloyd's safety and welfare has to be paramount."
Wales travel to Ireland in their opening match of the championship on Sunday, February 5.
