Workaround for feed reader ignoring custom field?

I’ve added a custom field to my feeds (to rss2 and to atom), and visiting the feed directly in Chrome verifies that the values have printed correctly to the feed. However, it seems that Google Reader, Feedburner, and whatever Firefox has in-browser seem to ignore the custom field altogether. Is there a workaround for this? I’d hate to have to re-haul how the entire site is built, so any suggestions would be marvelous. Thanks in advance.