The seven-year-old red cloud kelpie became Australia's best-known and beloved dog when he starred in the film about a dog who united a Pilbara mining community in the 1970s.
Red Dog producer and Koko owner, Nelson Woss, said he was devastated to have lost his "best mate".
"Through the making of Red Dog, Koko became Australia's favourite dog," he said.
"He certainly changed my life forever.
"I will miss his companionship, his remarkable outgoing, friendly nature and the many long walks that we enjoyed together in Perth and around the country."
Red Dog, which co-starred Josh Lucas and Rachael Taylor, was based on a Louis de Bernieres novel about a real-life dog in Western Australia. "
Red Dog star dies from heart disease
Red Dog and the Sacred Kingfisher / Tree/ Owl Synchronicity
|The last page of the book Red Dog.|