The pair headed to the county animal shelter, where the staff took to calling the new resident Baby Girl.
Buhler and TJ Jordi, then the shelter's animal-control director, had no inkling that 3200km away, Hollywood was looking for a dog to play Bella in a film written by Cathryn Michon and W. Bruce Cameron and based on Cameron's book.
Cameron is a prolific author who specialises in dog books, perhaps most notably A Dog's Purpose, which was on the New York Times bestseller list for nearly five months and was made into a 2017 movie starring Dennis Quaid. (A sequel to that film, A Dog's Journey, opens on May 17.)
Cameron and Michon, who are married, are unabashed dog lovers and say part of their passion is expressed by advocating for homeless dogs whenever possible.
"We started off in the very beginning saying that the dog that is the star of the movie will have to be a rescue, because we were trying to prove something," Cameron said. "We think we're making a difference in the animals' lives when they are adopted, and we're trying to reveal to the world that rescue dogs are wonderful animals."
The film-makers hired trainer Debbie Pearl, whose company Paws for Effect functions as an animal talent agency of sorts, one known for finding adoptable dogs and training them for on-screen roles.
Pearl then assigned the find-a-Bella job to Teresa Ann Miller, a freelance trainer whose credits include White God, an acclaimed 2014 Hungarian film that features more than 200 dogs.
One day, Miller spotted Baby Girl's adoption photo, which Jordi had taken.
"Honestly, it was a really good picture, and she was flat-out smiling," Miller said. "I mean, it was beautiful."
Within two weeks, Cameron and Michon travelled to Tennessee, met Baby Girl and developed the same crush. In an email, Michon said that she was struck by "the extraordinary sweetness of her soul". Baby Girl, she added, "was loving, smart, oh-so-eager to please, and we knew instantly we had found our Bella."
In short order, Miller adopted Baby Girl from the shelter on behalf of Pearl and Paws for Effect, renamed her Shelby ("a really cute Southern name") and took her to California for training.
Miller said her approach reflects the style of her late father, a well-known Hollywood animal trainer, eschewing quick commands in favour of talking in sentences to elicit more relaxed behaviour.
"Instead of saying, 'Come, sit, stay,' — you know, all these sharp commands where the dog's looking at the trainer — we might say: 'Can you come over here? Hey, what are you doing?'" Miller explained. "She'll stop and she'll look around a little bit more, and I'll say, 'Why don't you go ... go lie down, put your feet up.' And she'll start to do it, and I'll say, 'That's good.' ... So it's kind of a different type of training technique."
Miller and Shelby trained for just over three months before filming began. Then they were together each day on the set. Most of the film's reviews, thumbs up or down, have lauded Shelby's performance. Variety wrote that the film "is at its best when relying on Shelby and her trainers: It's amazing how much of the humour, drama and emotion is carried on her canine shoulders."
Has its heroine gone Hollywood? Not Shelby. After additional training, she's now working as a therapy dog on location at places that include veterans' facilities, hospitals and schools attended by students with special needs.