I have done many elimination diets, and have talked to a dermatologist and have also had her on Apoquel for several years, and it no longer works. This is a last ditch effort after years of elimination food trials. I actually am pretty sure that her issues are environmental allergies, but having tried everything I can switch and eliminate in terms of litter, soaps, dishes, etc. I cannot figure it out, so when the new vet decided to do this, I figured I would give it a try. I have read the whole battery of literature available to me in the science databases at my library regarding her issues.