1952 Warner Bros. animated cartoon, directed by Chuck Jones with story by Michael Maltese. The basic plot: large bulldog Marc Anthony adopts a tiny, almost constantly purring black-and-white kitten, trying to hide it from his female owner (who has the only speaking part in the cartoon).
This cartoon takes the viewer on an emotional rollercoaster -- almost literally, since there isn't much downtime in a 6-minute cartoon. There are some funny moments at the beginning, such as the kitten being completely unfazed by Marc Anthony barking in its face. Then the emotional tone gradually changes as the kitten worms its way into the dog's heart, to the point where he lets it knead him with its claws as it lies down on his back.
Eventually, desperate to hide the kitten, Marc Anthony stuffs it in the kitchen flour canister, and is then shooed out of the kitchen, then out of the house entirely, while his owner bakes cookies. Marc Anthony doesn't see everything that happens, so he assumes the worst, and then, adding insult to injury, his owner lets him back in the house and hands him a cookie fresh from the oven: it's been cut into the shape of a cat.
And then, in one of the most heartwrenching scenes ever captured on film, animated or live action, he sadly puts the cookie on his back and walks around crying and sniffling.
Since this isn't "What's Opera, Doc?" there's an eventual happy ending, which means a different kind of tears. The Saturday morning TV showings of this cartoon have no doubt introduced many young children to the concept of "pathos," and taught them that even Merrie Melodies don't have to be funny all the time.