Next airing Sat Feb 13, 4 p.m. ET

The Secret Life of Dogs

Today, there are about 500 million dogs alive and more than 400 recognized dog breeds. Dogs are found in more shapes, sizes and varieties than any other mammal on the planet. They're so familiar to us that we often forget how extraordinary they are. This is man's best friend. Now, Nat Geo WILD takes an intimate look at our faithful friends with fresh eyes and renewed appreciation -- from their super senses to their unquestioning loyalty.