Dog cake frosting that has a shelf life

I make dog cakes for the dogs in our family and have used cream cheese to frost. After a day cracks and looks nasty. What is the best frosting to use that has a decent shelf life and looks good?

Chef's Answer ~ You can find a lot of great dog cake and dog treat decorating supplies at K9 Cakery.com. Many of them are sugar free and they will have a better shelf life than a homemade dog treat frosting.