Nursing pups require special nutrition that is best found in their mother's milk, although specially formulated milk replacers will do the trick. After three weeks, the puppies can start the weaning process with a homemade gruel mixture and then move onto puppy food shortly after.
While some people may tell you to feed a nursing pup cow's or goat's milk, don't. Not only are these not nutritionally complete for puppies, they can also cause severe diarrhea. Canine milk replacement formulas are available at most big-box style stores, pet-supply stores and at your veterinarian's office. They come in either liquid or powder form. Liquid is pre-mixed, but you have to use it rather quickly. The powder form is ideal because you can mix small amounts at a time and store the powder in either the fridge or freezer.
First Three Weeks of Life
During the first three weeks of life, the puppies would naturally nurse strictly from their mother's teats. All of the nutrition they need is in their mother's milk. During the first week of life, the puppy will eat approximately every two hours. During the second and third weeks, gradually decrease this to four feedings per day, or every six to eight hours. To feed the pups, use sterilized nursing bottles you can find at pet-supply stores, online retailers and sometimes at your veterinarian's office. Hold the formula-filled bottle under hot water to get it warm.
Let the messy, rambunctious spectacle of weaning begin. At around 3 1/2 to 4 weeks old, your pup is ready to get his face dirty in some gruel. To make the gruel, mix a high-quality puppy food, either wet or dry, with some milk replacement and warm water. If you're using dry puppy food, let the mixture sit until the pieces are soggy and soft. Put the tip of your finger in the mixture and then up to your pup's nose. Upon smelling it, the pup should eagerly try to eat what's on your finger. Slowly move your finger to the saucer of gruel and watch as your pup proceeds to get a little of it in his mouth and the rest of it all over his paws, belly, face and of course, the floor.
Dry Kibble or Puppy Food
Between 4 and 7 weeks old, gradually decrease the amount of milk replacement you're putting in the gruel mixture. By 7 or 8 weeks, your pup should be eating plain puppy food, either wet or dry. Using a high-quality food is best, and always use a puppy formula. The smaller pieces of puppy formula are easier to manage, plus these foods are nutritionally complete for growing puppies.