04/17/2009 at 02:19 PM EDT
Singer Emmylou Harris has performed before millions and picked up a dozen Grammys, but at home in Tennessee, one audience member isn't listening. "We've kind of hit a wall," she says of Gunnar, a 4-year-old Shepherd mix who was brought to her rescue facility on her estate outside Nashville.
's Sherry Woodard. On tonight's new episode, the animal behavior expert will try to help the country star tame the unpredictable canine, who's bitten several of Harris's staff. Gunnar had been picked up off the streets of Nashville. "She was asked by people in her neighborhood to take a dog that was running around the neighborhood," Woodard tells PEOPLEPets. "And he actually had to be live trapped to get him." Will Woodard help get Gunnar under control? Watch the video above for a sneak peek of tonight's episode, airing at 10pm ET on National Geographic.Plus: See our full interview with Sherry Woodard, and catch up on the Michael Vick dogs