The story as it is told
In 1931 Mickey Mouse went hunting for a moose, and he brought along a dog. The cartoon was The Moose Hunt, and the dog, the story goes, made his debut there, with a name nobody had given a cartoon dog before: Pluto.
Where did Walt get it? One answer is the sky. A new planet had been discovered the year before, and the whole world was talking about it. The other answer is closer to home: Walt's own dog. People tell both.
What we can confirm
The Moose Hunt (1931) is where the name Pluto first appears, but it is not where the dog first appeared. The planet link is plausible and unproven, and Lowell Observatory's own archive calls it a theory. Wikipedia gives two further accounts. The Disney animator Ben Sharpsteen said the team thought Rover was too common and that he could not remember why they chose Pluto, and the animation historian John Canemaker says Disney named him after a dog he once owned himself. So the family-dog version does have a published source, though not an archive one.
The dog came before the name. The Walt Disney Archives, writing on D23 for the character's 90th anniversary, trace him to The Chain Gang (1930), where he appears as a pair of unnamed bloodhounds. Later in 1930, in The Picnic, he is Minnie Mouse's dog, called Rover. In The Moose Hunt (1931) he becomes Mickey's dog, named Pluto. The Catalog of Copyright Entries lists The Moose Hunt as "Mickey Mouse, no. 13," a one-reel cartoon by Walt Disney Productions, registered April 30, 1931.
Meanwhile, astronomers had a new world to name. NASA's Pluto facts page says that in 1930 Venetia Burney of Oxford, then 11, suggested the name over breakfast to her grandfather, Falconer Madan, who passed it to the Lowell Observatory. In a 2006 interview with NASA, she dated that breakfast to March 14, 1930. Lowell chose the name, and the observatory announced it that spring.
Were the two Plutos linked? The Lowell Observatory Archives' own exhibit says Disney animators "are unsure why Walt Disney changed the dog's name, but many have theorized that he did so to capitalize on the popularity of the recently discovered planet." That is the honest state of the evidence. The planet came first, by about a year, and the name was suddenly famous. No document we found records Walt Disney or a story artist saying why they picked it.
Pluto went on to a long career. The Walt Disney Archives count 48 cartoons with Pluto as the star, beginning with Pluto's Quin-Puplets (1937). Lend a Paw (1941) won the Academy Award for best cartoon. In 1940 the Tailwaggers Foundation of America gave him its "Academy Award" for Most Promising Dog Actor. Pinto Colvig, the original voice of Goofy, also supplied some of Pluto's barks.
For the public domain, the key fact is the date. Disney renewed The Moose Hunt on November 20, 1958 (R225433), so the cartoon gets the full 95 years and enters the US public domain on January 1, 2027. The Chain Gang and The Picnic are 1930 works, so their maximum US term ended on December 31, 2025, whether or not they were renewed. What becomes free is the specific 1931 cartoon and the character as drawn in it, the same principle that applied when Steamboat Willie entered the public domain in 2024. Disney's trademarks in the names and character images, and every later version of Pluto, remain protected.
The facts
- First appearance as bloodhounds in The Chain Gang (1930); as Minnie's dog Rover in The Picnic (1930); named Pluto as Mickey's dog in The Moose Hunt (1931); 48 starring shorts from Pluto's Quin-Puplets (1937); Lend a Paw (1941) Oscar; 1940 Tailwaggers award; Colvig and Bill Farmer as voices. Walt Disney Archives (Nicole Carroll), D23, Sep 5, 2020, d23.com ; D23 A to Z, d23.com
- THE MOOSE HUNT, a motion picture in one reel by Walt Disney Productions, Ltd. (Mickey Mouse, no. 13). © 30Apr31; M2524. Walt Disney Productions (PWH); 20Nov58; R225433. CCE 1958 renewals (motion pictures), line 46952
- Venetia Burney, 11, of Oxford suggested the name; grandfather Falconer Madan forwarded it to Lowell; March 14, 1930 breakfast (her 2006 NASA interview). NASA, science.nasa.gov
- Disney animators unsure why the name changed; planet theory is a theory. Lowell Observatory Archives exhibit, collectionslowellobservatory.omeka.net
Sources
- First appearance as bloodhounds in The Chain Gang (1930); as Minnie's dog Rover in The Picnic (1930); named Pluto as Mickey's dog in The Moose Hunt (1931); 48 starring shorts from Pluto's Quin-Puplets (1937); Lend a Paw (1941) Oscar; 1940 Tailwaggers award; Colvig and Bill Farmer as voices. Walt Disney Archives (Nicole Carroll), D23, Sep 5, 2020, d23.com ; D23 A to Z, d23.com
- Venetia Burney, 11, of Oxford suggested the name; grandfather Falconer Madan forwarded it to Lowell; March 14, 1930 breakfast (her 2006 NASA interview). NASA, science.nasa.gov
- Disney animators unsure why the name changed; planet theory is a theory. Lowell Observatory Archives exhibit, collectionslowellobservatory.omeka.net