Hollywood stars have been discovered in all sorts of places — but never before in a dog shelter in Arizona.

Monte, a two-year-old mongrel, was languishing in its pen when Disney casting agents came calling. The dog’s star power seemed to shine through and it was selected for one of the titular roles in a live-action remake of the 1955 animated classic ‘Lady and the Tramp’.

Monte will play the Tramp and has been whisked away to California to film alongside Rosie, a cocker spaniel which stars as Lady.

Heather Allen, president of the Helping Animals Live On (Halo) animal rescue shelter in Phoenix, said: “We knew the people meeting him were considering him to be a Hollywood star. But we didn’t know for what because it was top secret.

“This isn’t just some obscure movie. This is Lady and the Tramp. Everybody knows Lady and the Tramp. This is a staple in a child’s life.”

She added: “We knew he had the potential to become a Hollywood dog. When he arrived at the shelter he was super friendly.” The film tells the story of Lady, a dog that lives with a wealthy family, and its romance with the Tramp, a stray. Monte and Rosie will recreate the classic spaghetti eating scene from the animated film.

Justin Theroux, the actor, who has his own rescue dog, will provide Monte’s voice, and Rosie will be voiced by the actress Tessa Thompson.

Monte’s rags-to-riches story began at the Animal Services Centre of the Mesilla Valley, a municipal “high-kill” shelter in Las Cruces, New Mexico. A high-kill shelter usually sets time limits for animals to be adopted or they are euthanised. A year ago, Monte and some other dogs were rescued from there by Halo. Notes taken when it arrived in Arizona said the dog “gives kisses, loves attention, knows how to sit, and walks well on a leash.”

Ms Allen said other dogs from the shelter had been in advertisements, but never anything as high profile as a Disney film. She said Monte’s exact breed was unknown. “He’s a terrier mix of some sort. He’s a shelter mutt. That’s what makes this extra cool. He really represents how great shelter dogs are. They are super friendly and can be outgoing. He’s unique. If he needs a stunt double it’s not going to be easy to find a dog that looks like him.”

Monte was adopted by Mark Forbes, an animal trainer working on the Disney film. He sends the shelter pictures of Monte in California where, between filming and publicity appearances, it lives an ordinary life, going for walks.

Allen said: “It’s special when these things happen. It helps show the world that shelter animals are wonderful and people can find their next best friend there. They can be highly trained to be in movies. It shows they’re not a bunch of broken and discarded animals. They make great family pets as well.”

The film will go out on the Disney+ streaming service on Nov 12.

Disney said all other rescue dogs appearing in the film alongside Monte had also been secured “forever homes” where they will live after filming finishes, rather than being returned to shelters.

A spokesman for Halo said: “His adopters say Monte is a good boy and loving life. We are all so happy for him and can’t wait to check out the movie.”