High quality food is important no matter how many legs you may happen to have. Read labels, read read read. No matter what you choose, learn something about your dog's anatomy, physiology, and nutrition. Choosing a good food will go a *long* way with health, *and* so called allergies. There is more than one quality food out there.
We have ours right now on a grain free. It is not surprising that dogs don't do well on grain. They really weren't 'made' to. I won't get into names of foods here, this can be a controversial topic.
We did actually feed raw years ago. It saved a life of one of our dobies. That is something too, to research. It is called B.A.R.F. Raw food is what dog's bodies are 'made' for, although dogs as a species have adapted to how we feed them.
Feeding well does take research, and a 'mindset' or perspective to do so. I have thought holistically for a long time. I am excited to see the general awareness step up and start to notice.