The key to the appeal of the 2016 animated hit “The Secret Life of Pets” was that the filmmakers understood the lovable quirks and characteristics that make our furry friends who they are. “The Secret Life of Pets 2” offers more of the same, but with babies and toddlers thrown into the mix.

Aside from plumbing the personalities of cats and dogs and bunnies for humor, the first film imagined a whole wild world of adventure for the apartment-bound pets of New York City. Every morning, when their owners left, the animals would reveal their true nature, incongruous or not (headbanging poodle, gangster bunny, etc.) and gather with their pals, hopping from fire escape to fire escape. It all coalesced into a great big adventure.

The sequel, written by Brian Lynch and directed by Chris Renaud (both back from the original) with a co-director credit for Jonathan del Val (who served as director of animation on the first movie), sticks to the formula, but it’s a bit looser, exploring several subplots before tying the vignettes together with, of course, a harrowing vehicular chase. (Side note: Why do all talking animal movies culminate with animals dangerously operating cars in urban areas?)

Patton Oswalt now lends his voice to Max (replacing the controversial Louis C.K.), Katie’s sweet pup. It was bad enough when new dog Duke (Eric Stonestreet) came along, but now Katie’s married with a kid, Liam. It takes some persuading, but soon, Max is hopelessly devoted to Liam and developing a nervous, overprotective itch about it.

The family takes a vacation to a relative’s farm, where the neurotic city dog Max learns some lessons about tough love and bravery from a gruff cattle dog, Rooster (Harrison Ford).

Meanwhile, Max’s pals in the city tangle with some gnarly cats. Gidget (Jenny Slate) has to learn the Way of the Cat to infiltrate a cat lady’s apartment and retrieve Max’s favorite toy, while Snowball (Kevin Hart) and newcomer Daisy (Tiffany Haddish) go on a mission to rescue a tiger cub from an abusive circus.

“The Secret Life of Pets” scooted by on premise alone, and the sequel probably will do likewise, relying on animal lovers adoring the cutesy depictions of pet peccadillos. A preview audience howled — sorry; couldn’t resist — while kitty Chloe (Lake Bell) taught Gidget the precise technique for butt-rubbing a coffee cup and stamping a laptop in a typically feline manner. Cats, right?

That being said, you don’t want to dig too far into the litter box of “The Secret Life of Pets 2.” The pets are essentially animal extensions of their owners, so it feels a bit icky when Rooster scoffs at Max’s anxiety cone and essentially teaches him to shake it off. Some of us humans could use an anxiety cone, and there’s nothing wrong with that. The outlandish circus subplot with its pointy-nosed Russian villain also feels a bit outdated in a film that’s otherwise so urban and contemporary.

“The Secret Life of Pets 2” knows what kids and animal lovers crave, and the heartwarming and funny viral pet videos that play over the end credits demonstrate this perfectly. We want to watch pets behave exactly as we expect them to, and sometimes in a completely incongruous manner.