Newborn puppies rely heavily on their mother for nutrition. The milk that a mother provides doesn't just fill her pups' bellies -- it provides their immune systems with vital support as they adjust to life in the outside world. Mama typically begins producing milk days before the puppies are born so, by the time she finishes giving birth to the litter, they can start feeding almost right away.
Puppies are born hungry and with the instinct to feed at their mother's teats. Within minutes of being born, the pups will latch themselves onto their mother and begin suckling. This give them the nutrition and antibodies they need to survive outside the womb. They'll continue suckling once every several hours for the next five weeks or so, enjoying the nutrient-rich milk that helps them grow until they can be weaned and fed solid foods.
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