They're not likely to care for us to not be there unless you change their meal time, reduce attention they want or go back to sending them outside all day. Our new feline took a particular liking to one of my boys when he was home from Uni and seemed put out when he left - she took to meowing in his room for the first week.

Dogs however love having the pack always there, and will be really put out as people go back to full-time office work.