Puppies are born with many complex needs that need to be met almost immediately. They are born with underdeveloped immune systems and are almost completely helpless for the first couple of weeks, until their eyes open. At this time they're completely dependent on their mothers for protection and nutrition. For people who are caring for a litter of puppies, this means the responsibility of supervising the litter's well-being. One of the most important aspects of this is making sure that each puppy is getting the nutrition it needs.
Direct brand new puppies to their mother's nipples as soon as you've cleaned them up. The first round of nursing is where the puppies receive the colostrum, which contains the majority of the mother's antibodies for the puppies. This is the most important first step in making sure the puppies are getting the nutrition they need.
When the puppies start nursing, listen carefully. You should hear sucking noises coming from each of the puppies.
Observe the puppies carefully. If they're sucking and drinking milk, you will be able to see excess milk on their lips and chin.
After the puppies have been nursing for 10 to 15 minutes, gently feel their stomachs. They should feel round and slightly distended, with the skin firmly stretched. This means that they're getting their fill of milk.
Continue observing the puppies closely for the first 2 weeks of their lives, while they're almost continuously nursing. Their stomachs should continue to grow and look slightly round. If you notice one particular pup not nursing or looking underweight, it's probably not getting enough milk. Consult your vet on your next step.
Puppies will eat until they're full. Don't attempt to remove them when you think they've had enough--they'll stop eating on their own.
Watch your litter carefully, in case one of the puppies is being neglected or pushed out of the litter. If that happens, the pup probably isn't getting enough milk.