At approximately 3 weeks of age the puppy first begins to notice other individuals at a distance and shows evidence of conditioning and habit formation. This is the beginning of the period of socialization, in which its primary social relationships are formed. At almost the same time the mother begins to leave the puppies unattended, so that there is a tendency for the strongest relationships to be developed with the litter mates rather than the mother. During the next few weeks it is easy for the human observer to form a positive social relationship with the puppy. This period of primary socialization comes to an end somewhere around 7 to 10 weeks of age, which is the normal period of weaning.
Basically the puppy before 3 weeks of age is highly insulated from its environment by the immature state of development of the sense organs, by the lack of ability for conditioning, and by maternal care."
Now when puppies are 3 weeks old we will start exposing them to various stimuli. We will continue with touch conditioning, and they will get toys made of rubber, fabric, metal, glass and leather. They will be put on various surfaces.
In this upcoming week puppies teeth will start to erupt. The first teeth to come will be the canines followed shortly by the incisors. In wirehaired dachshunds there is a correlation between the texture of the coat and the timing of the teeth eruption. Puppies with shortest hair will have the teeth early, while pups whose coats will grow longer and and soft will have their teeth quite late. Even now we can see the difference. Olive's teeth are already coming out and her coat will be the shortest. You can see the difference in the coat between Olana (left) and Olive (right). Olana's teeth have not erupted yet.