Smiley(1979)

A heartwarming story about a boy named Jesse who discovers a friendly dog without a collar and names her Smiley. As Jesse and his family take care of Smiley, they hope to find her owner, but she becomes a beloved part of their lives. After a week of bonding, Smiley runs away, leaving Jesse heartbroken. However, she is eventually found and returned to her original owner, bringing a bittersweet conclusion to Jesse's experience with the dog he grew to love.