Puppies grow faster than any other life stage and have nutritional needs that are fundamentally different from adult dogs. Puppy food is formulated with higher protein and fat for energy and growth, DHA (an omega-3 fatty acid) for healthy brain and eye development, appropriate calcium and phosphorus ratios for bone and teeth formation, and higher calorie density to support rapid development. Critically, large and small breed puppies have different nutritional requirements. Large breed puppy food has controlled calcium levels to prevent overly rapid bone growth — a risk factor for joint problems in breeds like Labradors, German Shepherds, and Rottweilers. Small breed puppy food is higher calorie with smaller kibble sizes. Switch from puppy to adult food at 12 months for small and medium breeds, and 18–24 months for large and giant breeds.