Loki is on Canidae. Before I switched him I called them up and then sent out 4 or 5 sample bags. I just explained that he is SUPER sensitive so I needed enough to get him switched before I bought a whole big bag. Well it worked out and cleared up his diarrhea for good (he must have been allergic to something in the old food) and we've been loyal customers ever since.
www.canidae.com
You can email them too. They are pretty prompt.