Zen, a five-year-old border collie, circles friskily around a mound of snow as he picks up a scent, his quick movements ...

Zen, a 5-year-old border collie, circled friskily around a mound of snow as he picked up a scent, his quick movements ...

Ranking the best movie dogs ever, from Lassie, Toto, and Rin Tin Tin to Hooch, Snoop, and the newcomer Great Dane from 'The Friend.' ...