The VAC forms that are required to be completed by a medical practitioner ( be it a MD/Physio Therapist/etc) that I have seen are multi page and extensive. Don't know if there are different form sets for different classifications of ailments/injury or just a generic set of forms. My civilian MD refuses to fill them out. He does not have the time or the inclination. VAC pays, I believe $250 to the MD to fill out their forms.
I would suggest that you get from Ottawa his med records or if you have them take to the MD. You should go through the med docs and highlight with highlighter and page markers everything to do with his injury from start, follow up through his service to his release med. That way it will be easy for the Doctor to follow the progression and fill out the forms. Back up the report with recent medical tests/X-rays/etc. Verify and inform the Doctor he can bill VAC for his report.
If you do not have your Dad's med docs and cant't wait, write out all the details about the injury, follows ups by military medical pers, subsequent/consequential medical problems i.e. constant pain/lack of mobility/etc.
If his MD refuses to fill out the VAC paperwork, does you Mother/Sister/Brother/etc have a MD you can approach? Or try a Walk In.
P.S. Once his claim is approved, VAC will pay for medications (saves the 20% deductible from Sun Life), Physo/Massage treatments, aids to daily living ( e.g. a grab bar in a shower, wheelchair) that is related to the condition.
Also the VIP program could be of assistance: "The Veterans Independence Program (VIP) helps you remain independent and self-sufficient in your home and your community. Depending on your circumstances and health needs you may qualify for financial assistance to obtain services such as grounds maintenance; housekeeping; personal care; access to nutrition; health and support services provided by a health professional".
A successful claim is important to a survivor (your Mother??) as she would get a Survivors Award and get VIP after you Dad is gone.
Benefits and Services - Programs of Choice (POC) - http://www.veterans.gc.ca/eng/services/health/treatment-benefits/poc
Veterans Independence Program - http://www.veterans.gc.ca/eng/services/health/veterans-independence-program