You say your husband's prospective employer has applied for an LMO, which means that he will be applying for a temporary work permit (not a permanent resident visa).
In many cases, temporary foreign workers do not need medical exams; however, if you decide to eventually apply for permanent residence, it is required of all applicants - since you have posted in this forum for permanent residence applicants, I believe Dr. Hasib may have been confused.
You say you are "in America" but don't say if either of you are US Citizens. If so, you will not need a medical exam for a temporary work permit (unless for some reason you are instructed to get one by the visa officer).
Read p. 5 of the application guide:
http://www.cic.gc.ca/english/pdf/kits/guides/5487E.PDF