Astro - Grey Great Dane dog on the animated cartoon THE JETSONS/ABC/1962-63. Astro (voice of Don Messick) lived with the Jetson family in the twenty-first century Sky Pad Apartments. When it was time for Astro to take a walk, his master George Jetson placed him on a treadmill just outside their home. Originally, Astro was found wandering the streets by George Jetson's son, Elroy (episode "The Coming of Astro"). The family fell in love with Astro, but George decided it would be better to have an electronic guard dog named Lectronimo. It, at least, didn't eat. But when a cat burglar entered their home, Astro not the electronic mutt saved the day. The electronic dog was programmed to attack anything in a mask. So the burglar put his mask on George Jetson and it  was "run for your life time" for old George.   

Astro on his treadmill