First - I'm inclined to agree with Darin.
I've been marketing to MDs for over 17 years and have had some incredible successes and some major disappointments regarding my approach.
To help you with your marketing plans might I suggest:
1. You get more specific about your "avatar" (i.e. prototypical ideal client). How old are they? What type of medical practice? Why are they retiring? etc.
2. You get clear on what your product / service does for them. Since you didn't give any details I'm not sure what your offer is... If you would be willing to share that perhaps I (and others) might be of more assistance.
Give me a call to discuss - I'm happy to share what's worked for me over the years and what I currently recommend.
And best of luck to you!
Why not try Linkedin Ads? So just targeting Doctors in Canada in Linkedin and targeting the age they usually retire at.
I am not for sure if Facebook allows you to target by profession as its been a while since I've used Facebook Ads maybe look into it as well.
I actually think you need to take a more old school approach with this. Retiring doctors aren't going to actively be checking their LinkedIn accounts. They are worried about their golf handicap :)
Before thinking how to approach them you should really get clearer about the problem you're solving for them or the solution you're offering.
Since I don't know this you should think about all the pains and the desires these doctors will have.
Are they going to search for a solution online? If so, then Google Adwords might be a good idea. You can also try to set up a website/blog, publish content regularly and optimize it for the search engines.
You may try to make YouTube videos as well: giving tips on something that matters to them and is related to your products/services. Keep in mind that optimizing in YouTube is much easier than on Google and also ads are much cheaper than on Adwords.
You can also reach them with LinkedIn - connect with them directly or try LinkedIn ads. It might be harder to do so on Facebook but you can also try that.
You also might try cold calls in hospitals and sending them letters over there with free gifts.
Probably I can give you more ideas but unfortunatly I don't know much about what you're offering. I'll be glad to give you more tips on how to structure and execute a lead generation campaign. So feel free to schedule a call with me if you need more help.
Consider looking at medical school alumni associations. You can look for docs who graduated in the 1950's who are likely headed into retirement. You may be able to sponsor a reunion event or provide a contribution for mailing which could include your brand. Also, working with a professional society such which may have demographic information on its members it may be willing to sell is an option. For instance, in the US the American College of Radiologists is an organization 90% of radiologists belong to. Similar organizations exist for other professionals internationally.
First, Canadians reside in the most upper north, northwest, northeast, mid-west, and then Texas, Arizona, etc. and a retiring Doctor is concerned with wealth and family. I currently, live in Seattle and live it everyday to know what they are thinking.
Second, Construction is their top priority for handling properties to suffice a long-term and long-term portfolio for finances, lunch, dinner, and breakfast.
Third, finally hobbies and travel is a trigger and probably a heart felt key to every sale.