Puppies are tiny and it can be hard to distinguish male from female at a young age. Unfortunately, many owners who plan to give their newborn puppies up can find that those wanting to purchase or adopt the puppies are specific about wanting either a male or female. The good news is that a vet is not necessary to distinguish the sex of the puppy. With care, dog owners can determine the gender of their puppies before the dogs get too old.
Wait until the puppies are at least three weeks old. Before this age, there is a risk that the mother will not accept the puppies that have been handled too often by humans. It is best to wait until the puppies are weaned, but the earliest should be three weeks after birth. Though it is possible to tell which puppies are male and which are female beforehand, the mother and the puppies can be distressed at being separated while the puppies are too young.
Hold the puppy gently on a warm towel. It should be on its back for ease of determining its sex, but should only be on its back for the time it takes to determine whether the puppy is male or female. At this age, the puppies can be chilled easily, so a warm towel will keep them warm until they are placed back with their siblings and mother.
Look directly below the umbilical cord. The female puppies will have a bare tummy without anything below the umbilical cord, but the male puppies will have a raised circle slightly below the umbilical cord.
Watch for distress from the mother before taking the puppies. A distressed mother dog can bite or refuse to accept the puppy back.