Creator/CharlieChaplin is The Little Tramp, a homeless man very down on his luck but trying to make the best of it. We first see him sleeping in a junkyard, plugging a draft in the fence with his handkerchief, and trying to steal himself breakfast, and escaping the cop who catches him doing it.
Scrappy is a purebred mongrel. In the beginning, it just lies around and looks cute.
The Little Tramp tries to get a job at an employment office and, because of horrible timing for line-switching, fails completely. On his way back, he sees Scrappy in the center of a huge dogfight with many dogs. He takes it upon himself to rescue Scrappy, getting a hole in his pants in the process. He then gives it the last trace of milk in a milk bottle, eventually using its tail for this. (Without Scrappy, he'd have tried to drink it himself.)
Cut to a sausage stand. Scrappy steals two sausages; the Tramp sneaks the entire contents of a plate during periods when the cook isn't looking, except for one when a ''cop'' is looking.
Cut to the Green Lantern--dancing free, beer 5 cents. The Little Tramp enters; since no dogs are allowed, he hides Scrappy in his pants. (It had already been established that they were extremely loose pants.) Scrappy's tail sticks out of the hole and is wagging, which gets noticed, and gets unavoidable when the tail wags into a large drum. Then, Scrappy is let out; now that the dog is already there, no one wants to boot it.
An attractive singer with a lovely voice sings. She moves everyone who hears her to tears. When she is done singing, the owner of the Green Lantern suggests she set herself to flirting to attract customers. She focuses her attention on the Tramp--who really doesn't get that sort of thing...
It turns out that you aren't supposed to hang out at the Green Lantern without buying anything, so the Tramp is given the boot. He heads back to the junkyard. Just about then, a very rich and very drunk fella has his wallet full of cash stolen from him; the thieves bury the wallet in the junkyard before the Tramp and Scrappy get there.
If you thought hilarity was ensuing ''before''...
Do not confuse with [[Theatre/ADogsLife the one act play]] of the same name.
The film can be seen [[https://www.youtube.com/watch?v=6tSjP90frsw here]].
* BabiesEverAfter: A funny variant. In the last scene we see Charlie and Edna working a little farm. They go inside and look over a little cradle--which contains Scrappy nursing a litter of puppies.
* CrossCastRole: Henry Bergman, who was one of Chaplin's collaborators and stock players for 25 years, here appears as a large woman at the Green Lantern who weeps copiously when the singer sings a sad song.
* CanineCompanion: Charlie takes his dog everywhere. Even to a nightclub. Justified, in that Charlie is homeless.
* TheChanteuse: Edna Purviance, Chaplin's leading lady in almost all of his films from 1915 to 1923, here plays a singer at the Green Lantern that Charlie falls for.
* PetTheDog: Literally.
* Shoutout: More specific a CharlieChaplinShoutOut: In the Belgian comic strip series ComicStrip/DeKiekeboes, in the album ''"Kies Kiekeboe"'' a clip from ''A Dog's Life'' is shown on TV. Konstantinopel seats himself next to his dog and says: ''"I like a Chaplin movie more. [than watching a political advertisement]''.
* TheTramp: He's doing particularly badly in this one, sleeping in a junkyard.