I found this recipe in the October 2012 issue of Everyday with Rachael Ray, which says: Don't let your cat be haunted by hairballs. The fiber-rich pumpkin in these treats works magic for digestion; the catnip makes them as tasty as candy! Well, who knew?
I don't have a cat to try them out on so I won't be making them, but the uses for pumpkin are never ending. The photo is from the magazine's website.