It's really quite simple. The OWP is issued as soon as CIC verifies that an Inland application has been received (even before they even look at it, in terms of sponsor approval, for example). So...that also means that the OWP will be issued (with the same restrictions regarding working in the sex trade, health care, etc.) even without the PR required medical having been submitted. That, in and of itself, tells you/us/all that the medical is not a requirement for this OWP...right?
Further to your questions:
http://www.cic.gc.ca/english/resources/tools/temp/work/admissibility/open.asp
If a medical examination was not completed, one of the conditions below must be imposed. The specific occupational sector restriction will depend on whether the person has resided in a designated or non-designated country.
For persons from non-designated countries, the following condition should appear on the work permit:
“Not authorized to work in 1) child care, 2) primary or secondary school teaching, 3) health services field occupations.”
For persons from designated countries, the following condition should appear on the work permit:
“Not authorized to work in 1) child care, 2) primary or secondary school teaching, 3) health services field occupations, 4) agricultural occupations.”
Who can be issued an open work permit?
qualifying foreign nationals who have submitted an application for permanent residence under the spouse or common-law partner in Canada (SCLPC) class.
As of December 22, 2014, open work permits may be issued to eligible applicants under the SCLPC class at an earlier stage in processing. This pilot project will end on December 21, 2016.
Officers will issue open work permits to SCLPC class applicants if they meet the following requirements:
a permanent residence application has been submitted under the SCLPC class;
a Canadian citizen or permanent resident spouse has submitted a sponsorship application on their behalf;
the SCLPC class applicant resides at the same address as the sponsor; and
the SCLPC class applicant has valid temporary resident status (as a visitor, student, or worker).
Applicants whose application for permanent residence is being processed under the spousal public policy (subcategory “PP” in GCMS) on the basis that they do not have a valid temporary resident status are not eligible to be issued an open work permit under the pilot project. They must wait until they receive approval in principle to be eligible to apply for an open work permit.
Case processing centres will ensure that the requirements are met and conduct a systems check to identify any adverse information on either the sponsor or the applicant that would render the applicant ineligible to receive an open work permit. If there is information that an applicant is inadmissible, their application for an open work permit will be refused.
Validity: These work permits are valid for two years or until the date the SCLPC class applicant’s passport expires, whichever is the earliest.
Additional GCMS coding: Use special program code “SPO” (sponsored spouse or partner) and standard note “Pending FC APR” (to be entered in User Remarks so it appears on the physical document).
In combination with LMIA exemption code A70 and NOC code 9999, this additional coding will allow Citizenship and Immigration Canada (CIC) to capture and report on data specific to the issuance of open work permits to SCLPC class applicants.
If a medical examination has not been completed, work permits should be open employer/occupation-restricted.
The OP's wife will still be eligible for an OWP, albeit with the aforementioned restrictions outlined in previous posts here, without having the need to provide a medical exam upfront.