Brad Pitt shared on Wednesday that working alongside a dog in his latest film, the survival thriller "Heart of the Beast," was "a really moving experience." Directed by David Ayer, the film tells the story of a military officer and his combat dog, Odin, who survive an air crash and are stranded in the Alaskan wilderness.

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Four dogs from the same family portrayed Odin, with a German shepherd named Uber delivering most of the performance. At a news conference during Spain's San Sebastian Film Festival, where the film is showing out of competition, Pitt expressed his bond with Uber, who was discovered by a dog whisperer in New Zealand.

"There were times he would do things that were just amazing, that were not in the script that you see in the film, and his expressions, they really moved me with him in the close-up," said Pitt, 62, a former Oscar winner.

The San Sebastian Film Festival is the most prominent in the Spanish-speaking world and will conclude on Saturday. Seventeen films are competing for top awards, judged by a jury led by US director Ira Sachs.