Dogs are from the Carvivora family, an early mark of their domestication however is the fact that they were breed to also thrive on sources of starch. http://www.nature.com/nature/journal/v495/n7441/full/nature11837.html
Unlike cats that are obligate carnivores, meaning they need a diet of meat for their survival, dogs can do well on diets that include good sources of carbohydrates as well as meats and fats. Corn, wheat and soy are compounds that have been used in dog foods for years to make the kibble shelf stable and consistent. Various reports list these ingredients to cause allergic reactions in dogs from 3 to 13 percent of the population. The problem with these ingredients in the past hasn't been with the ingredient so much but what may be included with it. http://www.dogfoodadvisor.com/dog-food-industry-exposed/dog-food-corn/#fn-3102-3. In any event nutritionally the use of these grains may not present a problem, but it is an easily avoidable one.
When choosing a dog food look at three things. The quality of the ingredients used, the recipe, and the manufacturer. Quality of ingredients means no by-products or unspecified proteins or fats. The words "animal protein" in an ingredient panel could mean any kind or meat they don't want to list specifically, from a mouse to an elephant and any part thereof.
There should be no added dyes or colorants to make us think of fresh greens or "real meat". Those things do nothing but help stain the carpet if it comes back up. You should see meats as the first ingredient (quality, no by products), starches other than corn, wheat or soy, and a fat in the first five ingredients. The saying goes that if it isn't in the first five ingredients, there's not that much of it in the food. It's good to know that the company selling the food also purchased their ingredients and manufactured it themselves. If their name is on the product from purchasing the raw material to putting it on our shelves they take more pride in its results.
The last thing to remember is that there are as many variations in dogs as there are people, maybe more so. One food is not the magic recipe for all dogs, that's why we carry so many high quality foods.