Proof of Canadian citizenship, the Doctor of Veterinary Medicine degree or its documented equivalent, any provincial or state licence held, and the employer's letter naming the profession and describing the position and its period. Keep board correspondence separate but available, since it explains the timing of the intended duties.
Keep the professional and immigration files apart but aligned
Maintain two folders that tell a consistent story. The professional folder holds the degree, licence, board correspondence, examination results and credential verifications, and it is what the state authority cares about. The immigration folder holds citizenship evidence, the degree, the licence if issued, and the employer's letter, and it is what an officer reads. The point of alignment is the description of duties: the letter should not describe work the licence does not yet permit, and any staged arrangement should be described accurately with the dates on which each stage begins. Keep certified copies, since the same documents will be presented on later entries and at any extension, and keep a scanned set accessible from outside the house.
Hypothetical example: a Tyendinaga urban planner has a master file full of design samples but no employer letter that explains the specific role. The first review creates a document map: citizenship proof, qualification evidence, a signed job description, salary and dates, plus any licence material. The letter should be internally consistent with the résumé and contract. A mismatch between a broad consulting invoice and a full-time employment description invites avoidable questions. Also retain the signed version used for the request, because later amendments are easier to assess when the original account is available.