The newly reformulated Wysong Epigen 90 is a disaster. It nearly killed one of my cats with life-threatening diarrhea and emesis.It required two vet visits, subq fluids, cerenia and immodium before I tracked it to the changed food. I'd been using the old formulation without issues and it was wonderful for my sugar-kitty's blood sugars. The newly reformulated one has been known to kill ferrets, and I report the problems with the "new and improved" wysong at the amazon site under my moniker "gas doc".
Since that review there have been multiple confirming reviews and read the comments section on that link.
I have filed a complaint with both wysong (they don't care) and the FDA, which hasn't done anything I can see about the problem.
Since wysong epigen 90 became unusable, I've bounced from brand to brand and was suffering through high blood glucoses on orijen because of what looked like a superior ingredient list.
I'm now giving young again zero carb another try. My cats don't seem to like it as much as orijen, but that's just tough.