Feeding your dog quality food is one of the most important things you need to do if you want it to live a long and healthy life. While the quality of your dog’s food is important, you also need to pay close attention to what you feed. Just as humans need to eat a variety of foods to stay healthy, so do dogs.  That said, there are some foods that you should never mix with your dog's food since they can negatively affect your dog. For example, some dogs can react negatively to nuts, raisins, avocados, and onions. However, there...