The investigation began when one cow from the herd tested positive at a packing plant in the United States.
The Canadian Food Inspection Agency has put 34 premises under quarantine, two of them in Saskatchewan, while it continues to test.
A total of about 18,000 animals are now under quarantine.
Both the number of premises and cattle might increase as a result of ongoing CFIA investigations which include tracking the movement of cattle from infected herds and/or sites.
So far the situation has not triggered trading bans.