Dog the Bounty Hunter Cancels Hazzard Fest Appearance to Focus on Laundrie

Dog the Bounty Hunter is skipping a scheduled gig with fans to keep grinding on his search for Brian Laundrie -- speaking to how seriously the guy's taking this manhunt.

A rep for Duane Chapman tells TMZ ... Dog will NOT be appearing this weekend at Hazzard Fest in Tennessee, where he was booked for a celeb meet-and-greet alongside the likes of folks like 'Duck Dynasty' stars, 'Swamp People' stars and other A&E famous faces.

Dog's presence at Hazzard was announced in mid-September ... and he was probably booked well ahead of that. However, in light of his recent involvement in the Laundrie search ... we're told he's forgoing Hazzard to keep working -- which is his top priority right now.

In his place ... Dog's son, Leland Chapman, will show up and shake hands on behalf of his pops.

Long story short, it's clear Dog is taking this assignment to heart ... and, as it turns out, he plans to see it through 'til the end -- no matter how long it takes, we're told. His rep says Dog will stay on Laundrie's trail so long as viable tips come in, and there's still belief he may be out there and alive.

For the time being, that certainly seems to be the case ... at least according to Dog himself, who told us Monday that he does think Brian is still breathing, and surviving in the wilderness ... but perhaps struggling along the way.

TMZ broke the story, Dog has gotten offers for a potential TV series to be made out of his search for Laundrie -- but that's secondary to the task at hand, which is tracking the guy down and bringing him to justice.