Tod and Copper – The Fox and the Hound (1981)

Tod, the fox, and Copper, the hound, meet when they're just a couple of newly adopted pups on neighboring farms. Thanks to a mutual appetite for non-stop play time, the two become fast friends, and form one of the cutest inter-species friendships known to Disney. However, as time passes, Copper's hunting duties eventually pull them apart. But despite facing dangerous adversity and being natural enemies, their devotion continues to shine through when it counts. And even though they ultimately can't stay together, the memory of their friendship remains, proving Tod and Copper truly will be "friends forever."