No, Greenies dog dental treats have recipes both with and without grains. They include easy to digest grains in most of there blends for good reasons. Grains can be a good source of nutrients such as protein, fats, and vitamins/minerals. They provide a variety of carbohydrates, some of which serve as energy sources, and they help with digestion by providing fiber that helps with firm poops and a clean GI tract.
But, they also know that some pups have sensitives to grains, so they also have grain-free options.