As with all dogs, we would recommend a diet that meets the AAFCO standards and is feed-tested to meet nutritional adequacy.  With the issue with grain-free foods, we would suggest that if there are grain sensitivities, you choose a diet that uses more traditional protein sources like poultry, lamb, and beef, as well as avoid some of the unusual proteins like kangaroo, rabbit, bison, etc. It is also important to choose a diet where legumes (peas, chickpeas, lentils or beans) are not within the first five ingredients.  Another consideration would be to use more than one diet from different established food companies that do feed-testing for your feeding regimen.