Dierks Bentley is dealing with the loss of one of his oldest -- and most loyal -- friends: On Sunday (July 10), the singer revealed that his dog Jake has passed away.

Bentley shared the sad news on Instagram, posting a black-and-white photo of 15-year-old Jake standing in a truck bed, captioned simply, "Rest in peace, pal."

Jake was fighting cancer and had been going through chemotherapy. Throughout Bentley's career, the pup was by his side during so many big events -- including at the Grand Ole Opry and at the opening of Bentley's Country Music Hall of Fame exhibit -- and many, many smaller ones.

“Jake’s been with me through every phase of my career, since before I had a publishing deal … before I even had a gig, really,” Bentley told those gathered at the opening of his Hall of Fame exhibit. “When I got my first gigs downtown, he’d be waiting there in the windowsill; he actually wore out a little spot in the couch where he’d wait for me. I’d come home real late, and he’d be there sitting in the window, putting in his time. Those were his years of grinding, sitting in the window waiting for me.”

Even fans not particularly familiar with the ins and outs of Bentley's career know Jake: Bentley's furry friend appears in the music video for the country star's very first single, "What Was I Thinkin'," and "Can't Be Replaced," from Bentley's newest album, Black, has a full verse about Jake.

“For 15 years, right by my side / From a single man to three kids and a wife," Bentley sings in "Can't Be Replaced." "Friends come and go, but when it comes to Jake / There’s just some things that can’t be replaced.”

Bentley says it's tough for him to get through those lines without crying.

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