London - Wales hooker Lloyd Burns has been forced to retire because of a neck injury, his club Newport Gwent Dragons said on Wednesday.
The 27-year-old, who won seven Wales caps, has not played since January and medical tests show he has damaged his aorta meaning he may need heart surgery.
Dragons' Director of Rugby Robert Beale said on the club's website (www.newportgwentdragons.com) that Burns's enforced retirement came "as a massive shock to Lloyd and his family".
Burns played 33 times for the club, signing for them after having previously worked as a bricklayer.
He made three appearances for Wales in last year's World Cup in New Zealand, playing against Samoa, Namibia and Fiji.
Beale continued: "I am personally relieved that this serious condition has been identified off the field of play and would therefore like to thank our medical team at the Dragons, staff at the Royal Gwent Hospital and University of Wales Cardiff for all their efforts in ensuring Lloyd has and will continue to receive the highest standards of care."
Last month, the sporting world was shocked when English Premier League soccer player Fabrice Muamba, of Bolton Wanderers, collapsed on the field after a cardiac arrest during an FA Cup tie against Tottenham Hotspur.
Doctors said Muamba was "in effect dead" for 78 minutes but he is continuing to make a good recovery and is expected to be discharged from hospital within the next week.
No decision has been made about whether Muamba will be able to resume playing.