The documentary series continues, highlighting how newborn pups' simple desire for sustenance from their mother evolves into a more complex set of emotions, covering everything from relationships with litter-mates to their bond with humans. Dexter the dalmatian cultivates a strong early attachment to his owner via massage sessions, while Loki the weimaraner discovers that - even though he may have been removed from his litter - a playful child can make for the perfect companion.

The development of puppies' senses. The dalmatian litter has reached six weeks old. As a breed they are susceptible to deafness, so they are taken for to the vet for a crucial hearing test. A new litter of golden doodles reveal how puppy eyesight develops week by week, cameras track the progress of a springer spaniel as he begins training to become a mountain search-and-rescue dog, and the labrador puppies reach six weeks old - time to find out if they have the senses and skills to pass their guide dog test.