No, as long as they are not a major source of energy when compared to protein and fat, carbohydrates can provide the aforementioned benefits to your dog. Sources of Carbs. There is a variety of common sources of carbohydrates in commercially available dog food. Look for higher quality carbohydrate sources like these listed below: 1  rice. 2  oats. 3  barley. 4  millet. 5  potatoes. 6  sweet potatoes. 7  peas.