A lot of what you see on a pet food label is marketing. Pictures of handsome dogs or appealing foods and even words like “holistic,” “ancestral,” “instinctual,” or “premium” have no bearing on what’s inside. But there are important differences between foods designed for adult dogs and puppies.
Reputable manufacturers produce foods that follow the guidelines put forth by the Association of American Feed Control Officials (AAFCO). The following table compares the AAFCO minimum requirements for a variety of vital nutrients:
Puppies need to eat more in the way of protein (including higher concentrations of specific amino acids), fat, and certain minerals than do adult dogs. Additionally, many manufacturers provide higher amounts of nutrients that are not regulated by AAFCO in their puppy foods. Good examples are the omega-3 fatty acids that have been shown to promote healthy brain and eye development in young animals.
The caloric density of foods designed for adults and puppies can also be very different. Growth and development take a lot of energy, so puppies need to take in more calories than do adult dogs of a similar size.
Large breed puppies have an extra consideration. They are at higher than average risk for developmental orthopedic diseases (e.g., hip and elbow dysplasia). Overly rapid growth appears to be an important factor in determining which individuals develop these conditions and which do not. Large breed puppy foods are slightly lower in fat, contain a little less calcium and phosphorus, and have a carefully balanced calcium to phosphorus ratio to help these dogs grow at a healthier rate.
When puppies have reached approximately 80% of their expected adult size, they can usually be switched to an adult dog food. This happens at different times for different individuals. Extremely small dogs (e.g., Chihuahuas, Miniature Pinschers, and Toy Poodles) reach this point first, usually at around 9 or 10 months of age. Medium sized dogs should eat puppy food until they are about 12 months old, and large and giant breeds should continue until they are 12-16 months old.
Puppies are at risk for nutritional deficiencies if they eat a diet designed for adults. Some adults (particularly athletic individuals or females who are pregnant or lactating) can thrive on the higher concentrations of protein, fat, and other nutrients found in puppy food, but most should be switched to an adult food when the time is right. Not doing so can increase the chances that your dog will become overweight or obese.
Talk to your veterinarian if you have any questions about which food is right for your dog.
Dr. Jennifer Coates