(Airs Sunday, May 23) Are you cat-crazy or a dog die-hard? Watch as NATURE shares the stories of pet owners and their beloved animals.

The behavior of dogs is shaped in part by instinct that is selectively bred. View photos of popular dog breeds and learn about their hard-wired behaviors.

For 6,000 years, the Bedouin have bred Saluki from only the quickest dogs with the best eyesight.

Scientists continue to debate when, where, and why dogs evolved from wolves, but they are clear on one issue: the physical alterations that mark the transformation.

The two-part special "Dogs That Changed the World" tells the epic story of the wolf's evolution, how "man's best friend" changed human society and how we in turn have radically transformed dogs.

See a slideshow about working dog breeds.

Can Holly the bloodhound zero in on the exact seat where her target sat, long after the ball game is over?

Strong-willed Herbie takes a lesson in obedience.

The poignant story of two misfit dogs whose lives were turned around by people who saw their potential for greatness.

Medical dogs are trained to sense disease and seizures, to assist the physically and emotionally disabled, and to provide comfort, affection, and therapy to their human companions.