Homeward Bound: The Incredible Journey (1993)

Three pets (Chance, a young dog unfamiliar with the world; Shadow, an aging, wise dog; and Sassy, a snobby cat) are left behind when their owners go on vacation. Unsure of what happened, they set out on a quest to find their owners. This journey across America is very dangerous and they risk never seeing their owners again. They travel across forested mountains and areas of wide-open countryside, while their owners search for them in the same areas.