Yogurt treats are pretty popular rodent treats; my own two ratties love them! So here’s two recipes!
For simple frozen yogurt bites, empty a container (or containers) of your favorite flavor yogurt into a ziptop plastic bag. Snip off just a tiny piece from the corner, and pipe dime-to-nickel sized drops onto a wax paper-lined cookie sheet. Place cookie sheet in freezer and allow drops to freeze til solid, then transfer into and store in a large ziptop bag.
The above are Frozen Yogurt Blueberry Bites. The blogger individually skewers blueberries and dips them into greek yogurt, then drops them onto a wax paper-lined cookie sheet, then freezes, then transfers them to a baggie or tupperware. I imagine you could use the same piping-bag method as the non-berry drops to make it go a little quicker. Raspberries would probably be pretty tasty, too!