I was at the Feed Supply store today and made a new treat discovery. They're called KONG Stuff'n TOT's (Treat of Trainers), and so far the dogs have gone nuts over them! They're 1 calorie per treat and about the size of half a cheerio, but they must have a lot of flavor. Another plus is that they're wheat and gluten free (the only ingredients are organic beef liver and milo grain) so they don't upset Izzy's tummy.
Hope that helps