The only thing I could find with regards to nonreving with pets is that Allegiant employees can travel with their pets on pass travel in the cabin at no charge. I could not find any info specific to ZED fares. I imagine it is still possible to bring your pet while traveling on a ZED fare but unfortunately they may make you pay the $100 per segment fee. Hopefully with a smile and a crew badge they will do the right thing and not charge you.