Alright, so 'Shiloh' by Phyllis Reynolds Naylor? I'm thinking of the one that won the Newbery Medal, about the boy and the beagle. The core triangle is Marty Preston, the 11-year-old protagonist; Judd Travers, the grumpy, neglectful hunter who owns the dog; and Shiloh himself, the mistreated dog Marty finds and hides.
Marty's family are key supporting characters—his dad Ray, mom Louise, sisters Dara Lynn and Becky—who represent the ethical dilemma and the family's strained finances. They're all decent people caught in a hard spot. There's also the local doctor, Doc Murphy, who becomes an unwitting accomplice. The story really hinges on Marty's moral struggle, Judd's gradual, rough-edged humanity, and the quiet, desperate loyalty of that dog. It's a simple cast, but each one serves the tension between a boy's conscience and the harsh realities of his world.
I always found Judd's character arc more interesting than most give credit for—he's not a cartoon villain, just a mean, lonely man shaped by his own hardships.