Love truly knows no bounds as this abandoned puppy is taken in by a mother cat.

We may think of our pets like another member of the family - but they exist in a secret world that we would hardly recognise. In this series new filming techniques reveal our pets' wild behaviour and natural abilities. Using the latest filming techniques, from spycams to thermal imaging and moving x-rays, this series reveals why just a small select group of animals have the perfect characteristics to become human companions. The first episode shows how our pets use play to get in touch with their wild side, while the second episode shows how our pets maintain links with their wild nature.