Opened cans of Science Diet, Healthy Advantage or Prescription Diet cat or dog food should be stored in the fridge to retain moisture, minimize exposure to air and reduce transfer of odors to other food. The best way to store opened cans of cat or dog food is to use a plastic pet food lid that fits the top of the can to prevent moisture loss and transfer of odors. If a plastic lid is not available, plastic wrap also provides a very good moisture, air and odor barrier. Zip-to-close bags provide good moisture barriers but do not provide good oxygen and odor barriers.