The Fox and the Hound (1981)

After his mother is killed, Tod the fox (Mickey Rooney) is taken in by the kindly Widow Tweed (Jeanette Nolan). He soon befriends the neighbor's new hound dog, Copper (Kurt Russell). The two are inseparable, but their friendship is hampered by their masters and by the fact that they are, by nature, enemies. They grow apart as they grow older; Copper has become a strong hunting dog and Tod a wild fox. The pair must overcome their inherent differences in order to salvage their friendship.