Who may perform an immigration medical examination

Only physicians authorized by IRCC may carry out immigration medical examinations.

Technical instructions that define the actions and management of the authorized physicians who perform the immigration medical examinations are located on the Panel Physician Program webpage.
Using an alternate medical practitioner
In exceptional circumstances, an applicant may not be in a position to access a panel physician. In Canada, due to IRCC’s obligations under the Official Languages Act, the Migration Health Branch may temporarily authorize a non-panel physician to perform an immigration medical examination (known as “dispensation”) for in-Canada applicants.
Read more
https://www.canada.ca/en/immigration-refugees-citizenship/corporate/publications-manuals/operational-bulletins-manuals/standard-requirements/medical-requirements/exam/who-may-perform-immigration-medical-examination.html