Dunkley almost lost his leg three years ago

The hooker, who returned to the sport after battling back from a serious leg injury, will be out for a month.

"The players are sad that one of their most popular members is not able to play," said Canada coach David Clark.

Aaron Abrams has been called up as Dunkley's replacement in the front row.

Dunkley contracted a flesh-eating disease three years ago and came close to losing his leg.

But after a series of operations the 31-year-old returned to full fitness and was rewarded with a call-up to Canada's World Cup squad.

"The work Pat has done to get to the World Cup is now to no avail," said Clark.

"This is tragic, but the team will deal with it."

Canada are in Pool D with Italy, New Zealand, Tonga and Wales.