The Fox and the Hound is based on a 1967 novel written by Daniel P. Mannix.
In the book, the fox is raised by the dog owner’s/hunter’s family, but eventually returns to the wild.
He occasionally returns to taunt the dogs, and flash his cunning fox skills.
One of the dogs breaks his chain, and chases him.
That dog ends up getting hit by a train.
The hunter is devastated, and vows revenge on the fox.
He becomes obsessed, but can never catch him (although he does kill the fox’s first mate, second mate, and children).
Eventually, Tod the fox DOES die, but of exhaustion from being chased so much.
Copper (the dog from “The Fox and the Hound”) is so old that he needs to be shot, and that is the end of the book.