Smoky (1946)

Clint Barkley first sees Smoky as a runaway, and drives him back to the ranch where he meets the owner, Julie Richards. He is given a job on her ranch, but the head cowhand is doubtful about Clint and fears that since he refuses to talk about himself, he must have some dreadful secret in his past. Clint and Smoky become close to each other, weathering the hardships of Western life and the suspicions of others together, until one day, Smoky tragically vanishes. Will Clint ever see him again?

Unfortunately the movie Smoky is not yet available on HBO Max.