Have you eliminated all grains, corn and starches from her diet? I would think they would be a more likely candidate for allergies. Starches would be in the form of potatoes. Possibly rice but unlikely. Dogs seem to be able to process rice better than potatoes if there is an issue. Possibly eliminate grains and corn first. I don't understand why corn was put in pet foods to begin with. We can't digest corn. Why would they think cats and dogs can?
Assumptions do nothing but make an ass out of u and me.
We can stick our heads in the sand for only so long before it starts choking us. Face it folks. The pet population is bad ALL OVER THE WORLD!