Michael J. Fox and his pal, Gus

Gus, a "Great Dane-ish" mutt, has been by Michael J. Fox's side about half as long as the "Back to the Future" actor has been battling Parkinson's disease, and figures prominently in Fox's new book, "No Time Like the Future." Fox talked with correspondent Lee Cowan about the special bond between human and dog. Subscribe to the "CBS Sunday Morning" Channel HERE: http://bit.ly/20gXwJT Get more of "CBS Sunday Morning" HERE: http://cbsn.ws/1PlMmAz Follow "CBS Sunday Morning" on Instagram HERE: http://bit.ly/23XunIh Like "CBS Sunday Morning" on Facebook HERE:   / cbssundaymorning   Follow "CBS Sunday Morning" on Twitter HERE: http://bit.ly/1RquoQb Get the latest news and best in original reporting from CBS News delivered to your inbox. Subscribe to newsletters HERE: http://cbsn.ws/1RqHw7T Get your news on the go! Download CBS News mobile apps HERE: http://cbsn.ws/1Xb1WC8 Get new episodes of shows you love across devices the next day, stream local news live, and watch full seasons of CBS fan favorites anytime, anywhere with CBS All Access. Try it free! http://bit.ly/1OQA29B --- "CBS Sunday Morning" features stories on the arts, music, nature, entertainment, sports, history, science, Americana and highlights unique human accomplishments and achievements. Check local listings for CBS Sunday Morning broadcast times.