The best diet for a pet dog typically includes high-quality dog food that is appropriate for your dog's age, size, and activity level. It is important to choose a dog food that is balanced and provides all the necessary nutrients. Additionally, you can supplement your dog's diet with fresh fruits and vegetables, lean proteins, and occasional treats in moderation. It's also important to provide fresh water at all times. Consulting with your veterinarian can help determine the best diet for your specific dog.