Feeding a small dog large dog food can be dangerous. It contains a far higher amount of calories than small dog food, which can cause major health issues like obesity and digestive distress. The extra-large chunks of kibble can also be difficult for the small pooch to chew and digest, leading to further complications. Furthermore, the levels of proteins and fats in large breed food might be too high for a smaller pup leading to an upset stomach or strain on their organs. For these reasons, it’s always best to consult with your veterinarian before switching a small pet’s diet over to large breed food or vice versa.