My neighbour has a miniature Schnauzer that the vet diagnosed as being allergic to meat protein too. She was on SD ZD for 5 or 6 years. From what I understand, the chicken is broken down to the molecular level where the body doesn't recognise it as chicken. I believe that food is meant to be a temporary, not a long term solution.
I persuaded her to try fish. We started with one of the California Natural Fish formula's and the dog handled the food just fine. From there she has been on Orijen 6 Fish, EVO and another couple of fish formula's.
And, what a difference, body odour is way down, her paws and face are not orange anymore (constant licking), her eyes cleared up, her skin cleared up and stopped itching, wasn't red and inflamed, her whole demeanour changed into a fun loving energetic dog. She still gets ear infections, not as chronic as they use to be, but I think that is something that will stay with her for life.
Maybe fish could help with your dog too.