OpenStreetMap to the rescue! Its cycling map shows contour lines and shaded relief (even in Canada):

[![][1]][1]  
<sub>(source: [opencyclemap.org](http://c.tile.opencyclemap.org/cycle/10/306/368.png))</sub>  

Like most open data projects (probably Natural Earth, too), they use NASA's [SRTM (OSM Wiki)](http://wiki.openstreetmap.org/wiki/SRTM) dataset that has global coverage, as far as I know. As you seem to need contour shapefiles, refer to the article [Contours (OSM Wiki)](http://wiki.openstreetmap.org/wiki/Contours) for a workflow on how to convert raw SRTM data to shapefiles using GDAL.

**Jackpot:** Apparently, [OpenDEM](http://www.opendem.info/opendem_client.html) went through the effort of preparing contour shapefiles worldwide from SRTM with 25m precision. They offer a pretty convenient download for an arbitrary region. (Download manager or wget recommended.)

**How I found the data:** For all my spatial data needs, usually before googling, I have a look at the [OpenStreetMap Wiki](http://wiki.openstreetmap.org/wiki/Main_Page) and search for relevant keywords, in this case: contour, height, SRTM.
 [1]: https://i.sstatic.net/4lUZA.png