Shelby, the star pooch in "A Dog's Way Home," has soulful eyes, acting chops and a warm nose for her human co-stars.

She also boasts a powerful rags-to-riches Hollywood story: Filmmakers discovered her in a dog shelter after she was saved from a filthy, parasite-ridden existence in a Tennessee garbage dump.

"Shelby is absolutely extraordinary in our movie," says Bryce Dallas Howard, who voices Shelby's character, Bella, in the story of a dog trying to find her way home through the rugged Colorado mountains (in theaters). "But her true story is also absolutely extraordinary, just as riveting as Bella's tale in 'A Dog’s Way Home.' ”

The filmmakers were intent on choosing a rescue dog to star in the survival tale adaptation of the novel by W. Bruce Cameron, the same author who wrote the book adapted for 2017's "A Dog's Purpose." The pooch also had to be a pit bull mix, as in the book. The Internet search ended at a Tennessee no-kill shelter, which had rescued Shelby from a squalid life in a nearby landfill.

Megan Buhler, the animal control officer in Cheatham County who found the dog, said Shelby was "a little skinny and a little scared" at first. But she quickly warmed up and showed real personality.

"It was her whole demeanor. She wanted lovings from everybody," says Buhler. "She tried very hard to get attention. She was very happy and happy to just be inside. Period."

But Buhler never thought the darling dog would go onto movie stardom.

"I didn’t think that would happen to any person, or dog, coming out of Cheatham County," she says.

Former animal control officer Thomas “T.J.” Jordi says Shelby did have star quality.

"She had a really unique personality. If you stood next to her you'd get a black and blue mark from her tail wagging," he says. "She was that kind of dog that made you smile."

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Cameron made the trip with his wife, co-screenwriter Cathryn Michon, and dog trainer Teresa Ann Miller to check Shelby out in person. It was casting love at first nuzzle.

"I knew the second I knelt down and looked into those eyes," Cameron says. "I just could see her willingness to join the life she would have being with people."

The dog aced a number of tests with Miller that proved a dogged willingness to learn moviemaking basics. She showed both a fierce intelligence and an eagerness to follow basic prompts. "It was obvious after just an hour of working with her, this was going to be the dog," Cameron says.

Shelby flew to Hollywood to live with Miller and start training for her unlikely acting debut.

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On the Vancouver set, the cast and crew went to lengths to make sure Shelby and her double, Amber, were treated well. All crew members were given three numbers to call if they saw anything amiss, and could phone anonymously to report any instance of dog mistreatment – such as those that arose in a horrifying video shot on the set of "A Dog's Purpose."

"Everybody was hypervigilant because of 'A Dog’s Purpose.' It was very clear that the welfare of the animal superseded all other considerations," Cameron says. "Every time you see Shelby doing something complicated onscreen, it's because she's looking forward to praise, affection, treats and squeaky toys."

After filming wrapped, Shelby moved on to humanitarian work. Adopted by trainer Debbie Pearl, the dog is a therapy animal for children with autism or in the hospital, much like Bella, who soothes veterans in the movie.

Buhler and Jordi visited the star dog for the Hollywood red carpet premiere of "A Dog's Way Home."

"It was emotional. She's a big movie star now, but she gave me kisses," says Buhler. "It made me value my job a lot more. My everyday. I helped an animal out in the best way to have a better life."

Cameron agrees the transformation is profound.

"Shelby was once on track to have a really miserable, short life. All of that has changed," says Cameron, who has published the book "Shelby's Story: A Dog's Way Home Tale" about her life. "She's more than a movie star – she's just an amazing dog."