Unique problems with puppies
Your puppy's diet and care will need to take into account two specific problems which affect young dogs far more than adult dogs: their delicate digestive system and their reduced immunity.
A puppy has a weaker digestive system than an adult dog, particularly immediately after they've been weaned, and it's easily upset by changes in environment or new foods. They need to be given food that is the right size, shape, and texture to make it easy to eat, and highly digestible so they can get all the nutrients they need from it without it causing stomach upsets.
Between the ages of four to 12 weeks, puppies enter a phase called the "immunity gap." This is where their mother's immune support, passed through her milk, is lessening but your puppy's own natural defenses aren't fully developed. During this time, their diet is a key way to support this process and boost their immunity through nutrients like vitamin E.
Changing from a puppy to an adult dog diet
Once your puppy reaches maturity, you can transition their diet and care so you're making sure they get exactly what they need now they're fully grown.
Adult dogs need two meals a day, and a food which is nutritionally balanced to give them the energy they need without too much fat. You can transition to a new food gently by introducing it slowly over a week: mix it with their puppy food, gradually increasing the percentage of new food, so your dog gets used to it.