I have no idea if that could be caused by a food allergy but I would think your vet would know more than me, or anyone here for that matter. That said, my vet does say high protein diets can elevate liver enzyme count so who knows. Different vets seem to have different answers for everything.
If I needed a simple duck based food I would personally go with Farmina. Protein is also more moderate if that is what you are looking for. It couldn’t hurt to lower the protein a bit. Dogs do not need 35%+ protein. Not that higher protein is necessarily bad, but if you suspect it may be causing problems with your dog you can certainly cut it down https://www.farmina.com/us/dog-food/n&d-quinoa-functional-canine/443-skin-&-coat-duck.html
They also have a duck based canned food
I would not feed Zignature right now as they have had quite a few links to DCM in dogs. Seems like a risky food until more is found out. I do not like Instinct either as most of their formulas are quite high in ash, calcium and phosphorus. I am not familiar with the other brands listed.
