You can collect DNA from puppies at any age! If the puppies are not weaned they will need to be separated from mum and from each other for at least 30 minutes beforehand. This will prevent cross-contamination of DNA from the mum and litter mates. Do not give them food in this period, but do provide plenty of fresh water.
If the puppies are not easily identifiable by coat markings then we recommend waiting until they are microchipped before taking samples. Clearly label the envelope with the microchip number before posting the cotton tip back to us. This way we can easily assign the test results to the correct puppy and avoid any confusion of identity.