Prancer (movie, 1989)

Jessica, the daughter of an impoverished apple farmer, still believes in Santa Claus. So when she comes across a reindeer with an injured leg, it makes perfect sense to her to assume that it is Prancer, who had fallen from a Christmas display in town. She hides the reindeer in her barn and feeds it cookies, until she can return it to Santa. Her father finds the reindeer an decides to sell it to the butcher, not for venison chops, but as an advertising display.