Does a special food for puppies and young dogs make sense?
Why do puppies and young dogs need special food?
When should puppies and young dogs be switched to adult food?
After completing height growth you can switch to food for adult dogs. In the Dachshund, for example, the height growth is completed with about 6 months, with a Great Dane with about 2 years. Grown dogs no longer grow, so they logically have an other nutritional needs than puppies/young dogs and adult food is therefore composed differently than a puppy or young dog food.