Taking place two years before Clifford arrived on Birdwell Island, Clifford's Puppy Days tells the story of Clifford's life as a young puppy. He lives with Emily Elizabeth, her parents, and their pet rabbit Daffodil. Clifford has a range of friends, dog and otherwise, in his apartment complex that he likes to play with.
Clifford's Puppy Days provides examples of:
- Artistic License Animal Care: The kittens like to eat jelly from sufganiyahs. Cats are obligate carnivores.
- Attention Deficit... Ooh, Shiny!: It is typically possible for one of the puppies to end a conversation they don't want to have by simply asking "Are we going to talk about X all day, or are we going to play?", which prompts an excited response of "Play, play, play!" At least for a little while.
- Catchphrase: Daisy has "Sure I'm sure".
- Cuteness Proximity: Clifford is extremely small, extremely cute, and tends to evoke this reaction, particularly in anyone seeming him for the first time.
- Dub Name Change: "Jorge" was renamed "George" (the English translation of the name) in Britain.
- Early Installment Character-Design Difference: Daffodil's pink fur later became a more natural white.
- Family Theme Naming: Lucy, Lewis, Sophie, Sid are mice siblings.
- I Can't Hear You: In "Clifford's Field Trip" from Clifford's Puppy Days, the group encounters a group of noisy birds during a trip to a rainforest exhibit.Emily Elizabeth: These birds sure are loud.Shun: (holding his hand to his ear) Sorry. Can't hear ya'. These birds are too loud. (Clifford barks from inside Emily Elizabeth's backpack.)Emily Elizabeth: Did you hear that? It sounded like a dog!Shun: A frog?!
- Interspecies Adoption: Daffodil, a rabbit, acts like Clifford's older sister.
- Know-Nothing Know-It-All: The bird Norville is full of suggestions and advice for Clifford, whom he refers to dotingly as "Little Red." Few of them are actually helpful.
- And Knowing Is Half the Battle: The "Clifford's Idea to Grow On" segments teach aesops.
- Meaningful Name: Tricksie is a now-elderly dog who used to do tricks for a circus.
- Remember the New Guy?: Emily Elizabeth had a rabbit named Daffodil before adopting Clifford. Daffodil was never mentioned in the books or in the episode "Little Clifford" from the main cartoon. It's never clarified what happened to Daffodil between the two years between Clifford's Puppy Days and Clifford the Big Red Dog.
- Seldom-Seen Species: Daffodil is a Holland Lop rabbit.
- Shout-Out: In the Clifford's Puppy Days book The Little Red Sled, Clifford's sled is named "Rosebud."
- Somewhere, a Mammalogist Is Crying: The kittens like to eat jelly from sufganiyahs. Not only will that make cats sick, but cats can't even taste sweet things.
- Talking in Your Sleep: In "Paw Print Picasso," after Clifford gets paint paw prints all over Emily Elizabeth's painting and his friends suggest he tell her the next day, Daffodil discovers him alone the next morning on Emily Elizabeth's bed, tossing and turning in his sleep and muttering "It's my fault, it's my fault..."
- Theme Twin Naming: Brother and sister kittens Flo and Zo.