Just Dogs

Just Dogs is a 1932 Silly Symphonies animated film, directed by Burt Gillett. It marked the first solo appearance of Pluto.

Summary
Pluto's cage-mate at the dog pound breaks out and lets all the other dogs out as well. In the park, the dog who helped Pluto earlier keeps following him too closely for Pluto's tastes, until he digs up a huge bone and gives it to Pluto (who doesn't particularly want to share). But soon all the other escaped dogs are chasing after the bone.