The NDP leader was finishing up his customary early morning walk today when he slipped on a patch of ice, hidden under a dusting of fresh snow.
Mulcair says he "went flying," landing with "all four horseshoes in the air," his right shoulder taking the brunt of the impact.
The resultant pain was sufficiently severe that Mulcair missed his party's weekly caucus meeting in order to get checked out by a doctor.
Aides say an MRI was done but it's still not clear if Mulcair broke any bones.
Mulcair returned to Parliament in time for question period in the afternoon, in good spirits but holding his immobile right arm gingerly across his midriff.
"I'll be okay," he said outside the House of Commons.
In the Commons, Prime Minister Stephen Harper prefaced his response to Mulcair's first question of the day with a reference to the NDP leader's fall.
"First of all, let me say it is good to see the leader of the NDP here today and on his feet and none the worse for wear."
Mulcair is not the first politician to lose his footing in Ottawa.
Interim Liberal leader Bob Rae took a bad spill in 2010 as he made his way to the annual Liberal caucus Christmas party. He dislocated his left shoulder and fractured his upper humerus.
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