Many association logos were designed before social media, so there wasn't consideration as to what would happen to it when squeezed into a size smaller than a postage stamp. Look at your own association logo and how it appears on social media sites. Can you do better?
Here are 3 things to think about:
1. Are you unique? The logo my association has used for decades is a trademarked symbol that is also used by many thousands of others. So it would have been difficult to quickly distinguish us from other associations also using that logo if that showed up on News Feeds on Twitter, Facebook, or others.
2. Does it fit? Some logos are so large that posting it results in either getting a portion of the actual logo image, or the image is so tiny that it's impossible to see what the text or images are. It it doesn't fit, consider a change to your logo for your online presence.
3. Do you like it? In a sea of text on social media sites, how color and images are used in logos makes certain organizations stand out. As people quickly scan through hundreds or thousands of options of what to read, finding an apparent and recognizable logo might encourage them to stop and read - which is a big point of even doing social media.
If your logo is social media friendly it gives the impression that you might do the rest of social media right too. If you haven't thought about your logo's online image, check it out. Modify or change if you really do need to.