From fertilisation to foetus Weeks 1-3
Once the egg is fertilised, this future puppy nestles inside its mother’s womb and starts a nine-week journey from only four cells to fully grown puppy. This four-celled being quickly multiplies to 64 cells, ready to form a head and spine. Week 4
The foetus continues to multiply and develop, and at week 4 it grows a head, eyes and its first vertebrae. At this point, the dog foetus has nearly tripled in size and has already grown to 15 mm, or as big as a hazelnut. The foetus also develops its organs and can be seen in an ultrasound at the vet’s surgery. Weeks 5-6
During weeks 5 and 6, the foetus starts to look more like a puppy, with toes, nails and whiskers. The foetus’s organs have completely developed, along with its skin colour. At the six-week mark, the foetus has sex organs and begins to develop into either a male or a female. Weeks 7-8
Starting at week 7, the soon-to-be-pup’s skeleton has developed completely, and may be seen clearly by ultrasound. In preparation for the birth, the mother will start to develop a bald spot on her stomach so that her pup can easily find where to feed from her nipples. Week 9
From day 57, the beginning of Week 9, the puppy can safely be born, although it will usually wait until 60 to 63 days. Not all puppies are born with the coat color of adulthood. For example, Australian Cattle Dogs (red heeler, blue heelers) are all born white.