The transition period (from neonate to PUPPY!) is from 13 to 20 days and is marked by a number of physical changes. At the beginning, the puppies eyes will start to open - on average around day 13. While their eyes react to light, the retina is still undeveloped and the puppy is unable to see objects or movement until around 21 days. The puppies are now crawling backward and forward and have begun to stand on wobbly legs. Their first teeth will erupt later this week, around day 20. Tail wagging will begin during this period indicating that tail wagging is not reliant upon seeing or hearing since the pups cannot see or hear yet. Pups begin to react to sound on average at day 19 when they startle to sounds but cannot usually locate the source. Another big week in store for the C litter.