How anticlimactic would it have been if Chance, Sassy, and Shadow had trudged all the way back home only for their owners to turn them over to an animal shelter, where Shadow would probably be euthanized because he's old? Pretty anticlimactic is the answer you're groping for, although that sort of ending would teach children a good PG-13 lesson about the true responsibilities of pet ownership.
A Bronx woman named Ruth Torres lost her Irish wolfhound Dusty after her brother took Dusty for a romp in the park and unceremoniously left him there. Three nail-biting weeks passed and Torres nearly gave Dusty up as yet one more hopelessly lost creature doomed to forever wander the subway bowels of New York, but thanks to the miracle of television, she spotted Dusty on a Friday pet adoption segment of Today. Torres and her mother rushed over to claim poor, overwrought Dusty, whom shelter workers told Torres they found at an abandoned dog run in the Bronx. Thus reunited through morning television, Torres and Dusty were poised to live happily ever after.
Of course, they didn't live happily ever after because while Dusty was gone Torres moved back in with her mother, who has a gaggle of grouchy, misbehaved dogs of her own that don't understand anything about what makes a news story compelling. The dogs didn't like Dusty, and so Torres was forced to return him to the shelter. Though she feels "awful" that she had to give Dusty up, she explained that he was too wild with her mom's dogs, which is really just a decorous way of saying that Dusty had gotten a sweet taste of transient street life and wanted to go on adventures rather than stay home with the Torres ladies and watch Today over and over again. I bet the next time we see him he's playing jazz clarinet in New Orleans or shipping out from a port in San Francisco on a boat bound for Tahiti.