A Dog Named Duke (2012)

US marines Afghanistan veteran Terry Polesky can't handle his honorable discharge due to a crippling wound, disabling him as breadwinner, and ends up leaving his teacher wife Bethany and their doting kid daughter Alice. Homeless, Terry lives in a camper on the property of fellow veteran Javier, otherwise deserted except for shepherd dog Duke, whom he adopted while still convalescing at home, and becomes a handyman. After ten years his world collapses again when Duke needs vet care he can't afford, so he leaves his buddy with a plea note at the animal clinic, presumably to be put down. However the vet team lovingly cures the lovable canine and even mounts a search for its owner, which also allows Alice, now happily married after her mother died from cancer, to track down her father, willing to bond again.