Polka-Dot Puss is a 1949 one-reel animated cartoon and is the 39th Tom and Jerry short produced in 1948 and released on February 26, 1949. The short was directed by Tom and Jerry's creators, William Hanna and Joseph Barbera, produced by Fred Quimby, animated by Kenneth Muse, Ed Barge, Ray Patterson and Irven Spence, and scored by Scott Bradley, who here did an early version of the duo's recognizable iconic theme tune that would continue to be used in their cartoons throughout the 50's and 60's.
Tom is using Jerry as a yo-yo. Tom then hears Mammy Two Shoes telling him that it is time to put the cat out for the night. Noticing that the weather outside is rather unpleasant, Tom craftily fakes a cold, pretending to sneeze violently.
Mammy enquires if Tom has got a cold. Tom nods and sneezes again. Mammy has a change of heart and allows Tom to sleep inside for the night, but gives the cat a stern warning that she'd wash his mouth with soap if he was lying.
Tom grabs an onlooking Jerry, who appropriately shoves a bar of soap in Tom's mouth. Tom spits out a multitude of soap bubbles and chases Jerry into his mousehole, but ends up with a mousetrap on his nose.
Tom prepares to sleep on the living room floor, nose bandaged up. While Tom is asleep, Jerry enters the room with a small pot of red paint, painting several polka dots on his face after removing the bandage on Tom's nose. When Tom wakes up, Jerry convinces him that he has measles, showing evidence of a measles epidemic in the newspaper, and producing a mirror, showing Tom his own spotty reflection.
Jerry consults Dr. Quack's medicine book and does a number of unorthodox treatments to the now hypochondriacal cat, such as placing a stethoscope next to a ticking alarm clock to intensify Tom's apparent heartbeat, then setting off the alarm. Later, Jerry tests Tom's reflexes, almost bludgeoning the cat with a hammer. As Tom screams in pain, Jerry places a thermometer in Tom's mouth. Out of Tom's view, Jerry holds a cigarette lighter underneath the thermometer, causing the temperature to rise, expanding the thermometer, such that it explodes.
The next chapter of the medical book urges Jerry to apply chills to Tom's high fever. Soon Tom is in the freezer, teeth chattering. Jerry unloads a spoonful of ice-cubes into Tom's mouth and then closes the freezer door for a few seconds. As he opens the door, a frozen-solid Tom slides out of the freezer. Jerry panics and following the book's advice on extreme chills, shoves Tom into the oven, turning it onto a low temperature. Opening the oven door, Tom is now conscious, but still very cold, and baking in his own juices. Jerry pours some juice over Tom and then closes the door, adjusting the oven's temperature. When he opens the door again, Tom is bright red and burning. Jerry quickly touches the hot cat and burns himself. Thinking quickly, he places Tom onto a baking tray and heads for the bathroom, giving the cat a cold shower.
Tom later emerges from the shower, covered in towels and using hot-water bottles as sandals as Jerry continues reading from the medical book. He observes himself in the mirror, and notices that most of his spots have gone. As he wipes his forehead, the final two spots are removed and transferred to his paw. Jerry, who sees this and realizes he's about to get caught, drops the book and quietly tip-toes away from Tom. Just then, Tom sees a small jar of red paint hidden in the corner, and realization dawns on him; his mirror image changes to a jackass. Tom becomes furious and grabs a sword, ready to get back at Jerry. He finds the mouse sitting hunched-up with head in hands, looking very sorry for himself, and Jerry only blinks at Tom apathetically when prodded with the sword's keen point. Only when Tom snatches him up does Jerry break out in genuine measles spots, which proliferate before Tom's horrified gaze. Tom quickly dashes in terror to the bathroom medicine cabinet and doses himself frantically with everything he can find (throat sprays, pills, mouthwash, nasal drops, etc., but little does he know that there is no cure for measles), while a sped-up version of George Friedel Handel's Dead March plays over. By the cartoon's end, both the cat and mouse are covered in spots from head to foot and are being quarantined by Mammy-Two-Shoes herself. Jerry holds up a mirror, looks into it and sticks out his tongue, which, too, is covered in spots, which may also imply that Jerry caught a more severe case of the measles than Tom did.
- Lillian Randolph as Mammy Two Shoes (original) (uncredited)
- Thea Vidale as Mammy Two Shoes (dubbed version) (uncredited)
- In Romania, United Kingdom, Polish, Hungarian, the beginning was reissued to hear the beginning from Life with Tom.
- When Tom runs after Jerry realizing that Jerry made him sick all along, Tom disappears for a frame.