Michael J. Fox is saying farewell to his beloved dog.

On Monday, the Canadian actor shared a pic of Gus with the caption, “Great dog and loyal friend, we’ll miss you.”

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Fox also highlighted Gus’ life in his Instagram stories, including the dog’s reaction to Fox wearing a shirt with Gus’ face on it and another of the two of them lounging in the sun.

Michael J. Fox and Gus. Photo: @realmikejfox/Instagram
Michael J. Fox and Gus. Photo: @realmikejfox/Instagram
Michael J. Fox and Gus. Photo: @realmikejfox/Instagram
Michael J. Fox and Gus. Photo: @realmikejfox/Instagram

Gus would frequently make appearances on the “Back to the Future” star’s Instagram, with the actor calling him his “5th child.”

Speaking to CBS News in 2020, Fox spoke about his bond with Gus.

“You know that no matter your situation, no matter what you feel, this animal is with you and is connected to you, and you feel, it’s a force multiplier,” Fox said.

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Gus is even a bit of a celebrity himself, earning a plaque in Central Park that reads, “For Mike Fox and Gus. True New Yorkers.” A gift from Fox’s wife, Tracey.

From Fox’s Parkinson’s Disease and through everything, Gus has been there. “He knows there’s something different about me,” Fox said. “And your instinct when you have a chronic illness is, sometimes, to isolate and make your world as small as possible so you don’t have as much to deal with. But a dog will open you up.”

Rest in peace Gus, all dogs go to heaven.