I went looking back through the archives; there are bursts of human-only strips, animal-only strips and interactions between Sandra and Woo (and her family). The animals seem to be on an equal footing. Plus, there was a spate of ponies.
You may be right - it takes only a small but dedicated fan-base to get a work onto the ballot, but once it is seen by a larger group of fans they tend to choose works dedicated to the theme. Even if you don't win, though, it could mean more readers.
