Jack London’s “The Call of the Wild” ranks as one of the most famous books about a canine ever written. So director Chris Sanders knew that the composer of his film adaptation simply had to be a dog lover.

Luckily, Sanders’ “How to Train Your Dragon” composer, John Powell, has two standard poodles. And when Powell watched a full-length animatic version of the film, long before there was even a rough cut, he wasn’t the only one who appreciated the work. “My older dog Chase sat and watched the whole thing with me on the couch,” the composer reports.

Powell (who earned an Oscar nomination for his 2010 “Dragon” score) was also the right choice, Sanders says, for “his ability to transport us so fully to a time and place” — in this case the Yukon Territory during the Gold Rush days of the 1890s. The music needed to be “something a little bit folksy,” the director explains.

Powell calls it “immigrant music, a kind of music that seemed to be part of that world.” Thus, banjos, accordions, mandolins, guitars, fiddles and harmonium become the heart of the score, although they’re augmented by a 90-piece orchestra and 60-voice choir to deliver, as Sanders says, “moments when you need scale and majesty.”

To hear Powell explain it, “People didn’t take grand pianos up to those kinds of places; they would take accordions and banjos, maybe because they were from France or Ireland, but also because they were mobile.” Irish flutes, Native American flutes and penny whistles round out the many ethnic sounds that color the score.

The “immigrant” sound also hints at Irish, English and Scottish flavors and rhythmic, dance-like movement throughout. “I do write in dance form,” Powell concedes. “[The music] can be very slow because people are just talking, or very fast because people are in peril, but dance is, to me, very much the sound of music.”

He cites a sequence from another outdoors movie as an inspirational model: the barn dance from the 1954 classic “Seven Brides for Seven Brothers.” “They take a little phrase from [the song] ‘Bless Your Beautiful Hide’ and whip it into this amazing construct that keeps heading in different directions. So this idea that all sorts of life are a dance is always there.”

Although in “Call of the Wild,” Harrison Ford is top-billed as Thornton, the film’s central character is the dog Buck, kidnapped from his comfortable California home and transported to an uncertain future north of the Canadian border. As Sanders notes, the film is filled with scenes where no one speaks. “Music is the voice for these critical moments where we’re alone with Buck,” he explains. “In a very real sense, music is the voice of Buck.”

As usual in Powell scores, multiple themes serve various aspects of the story. But Buck’s “work tune” is the most fun, involving an ensemble of 12 banjos. “It’s about the toughness of work and the nobility of running,” Powell says.

He used the same dozen players — session guitarists who have played on everything from Steely Dan to Britney Spears, he says — to perform passages on acoustic guitar and mandolin, depending on the scene.

While the score follows Buck’s adventures, there’s also music of “regret and loss” for Thornton, Powell says. “He’s the facilitator of Buck’s launch into a world that he can be authentic in. It’s way more than a coming-of-age story; it’s a transition story. It’s finding your way in the world.”

There is also, Sanders notes, an initially disquieting sound for the mysterious giant black wolf that only Buck can see. And the choir, Powell reports, sings phrases in the Inuit language of the indigenous peoples of northern Alaska and the northern Canadian provinces.

As for the dogs, Sanders introduced Powell’s pups Chase and Moose to Buckley, the Kansas rescue dog that Sanders and his wife adopted and became the digitally scanned model for Buck in the movie. Buckley came to the recording sessions, and, reports Powell, “he was wonderfully calm and encouraging to the orchestra.”

Says Sanders: “Music is the closest you can get to real magic. When we work on these films, I always feel that we get about 50% there and the score takes you the other 50% of the way. John brought Buck’s voice to the story. He did the heavy lifting, story-wise. He speaks for the wilderness — he brought the environment to life — and he speaks for Buck.”