Age range: for cats of all ages, type of advent: reusable advent your fill with treats What are the best advent calendars for cats? Alternatively, you could invest in a reusable calendar – Not On The High Street and Etsy are good places to look for these. Where do I buy advent calendars for cats? You can also personalise the calendar with your cat’s name to create a family heirloom that will have pride of place over the hearth at Christmas or by the tree. The treats are also grain-free so no worries over sensitive tummies and they contain prebiotics, which contribute to good gut health. The best advent calendars for cats are very much like those for people, in that they contain a gift or small treat for each day in December leading up to Christmas. Some also contain a treat for the big day itself.