General
- Canon Immigrant: We only see these characters in the Puppy Days, not the original books or, for that matter, in the 2000-2003 series.
People
Nina Flores
- Voiced by: Masiela Lusha
- Nice Girl: In contrast to Jetta from the original series
- Mythology Gag: She was subtly alluded to in the 2019 reboot with a character named Pablo Flores.
Shun
- Voiced by: Lauren Tom
- Ambiguously Absent Parent: We only see his unnamed mother but not his dad, so it's not clear if his parents never married, got divorced, his dad died, or if his dad is just away working.
- Only One Name: Of all the kids, his surname was never revealed.
Mr. Solomon
- Voiced by: Alan Oppenheimer
- Christmas Episode: Chanukah in his case.
Ms. Z
- Voiced by: Russi Taylor
- No Name Given: It's not said what her full name is.
Pets
Daffodil
- Voiced by: Kath Soucie
- Hair Color Dissonance: Initially, when she was first shown, she had something of a pinkish or lilac hue, but this was changed to something more like a gray later on.
- What Happened to the Mouse?: A meta-version. If it's presumed that Puppy Days is canon to the original series, then that would have y'all wonder what happened to Daffodil between Puppy Days and Big Red Dog. Was she given away, or is she just offscreen?
Flo and Zo
- Voiced by: La Tonya Holmes (Flo) and Ogie Banks (Zo)
- Foolish Sibling, Responsible Sibling: As demonstrated in the Chanukah episode, Flo tends to be more sensible than Zo, the latter is more impulsive and impatient.
Tricksie
Mrs. Z's dog and performing partner
- Exhausted Eye Bags: With the way the show is drawn/animated, her wrinkles look like this.