Surprise Litter of Puppies

Tuffnut: This is the worst thing I've ever seen. It's terrible. The horror! [reveals Chicken cuddling up with a rooster] Oh look! There they are, doing all the things we used to do together. [the rooster starts preening Chicken]
Astrid: Um... you preened Chicken's feathers?
Tuffnut: What does he give you that I can't, huh? Huh? [a clutch of baby chicks walks onscreen]
Astrid: Aw, Chicken has a family!
Tuffnut: Okay. Yeah, other than that. I can't lay eggs.

— Dragons: Riders of Berk, "Searching for Oswald... and Chicken"

Tropey's gone missing!!! Oh dear Lord, what am I gonna do? I mean, he's been acting so strangely. He's been wanting to get out of the house more, he won't eat, he won't sleep, he doesn't want me to pet him, I'm at a complete loss!

What? Wait a minute... is that... Tropey with a girl dog? And (gasp!) PUPPIES! And look, they're so cute!

This is somewhat Truth in Television; compared to humans, other mammals aren't always as visible with the signs of pregnancy, and the next generation really can appear by surprise, the animal's owner having been none the wiser. And that's only counting the female's owner — the male pet, obviously, would show no signs that he knocked up another animal.

See Your Tomcat Is Pregnant if they incorrectly thought the pet was a boy and Monster Is a Mommy for another "unexpected baby animals" trope. Despite the trope name, this can apply to pets other than dogs—in fact, it's just as common for it to involve kittens.

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Examples:

Anime & Manga

• In Golden Kamuy, Noble Wolf Retar is friendly towards Asirpa, and used to live with her until he left her to live in the wild. He's later revealed to have left because he found a mate, and had several cubs with her.

Comic Books

• Allergic: Maggie's hidden pet mouse Pipsqueak gives birth to a surprise litter of mice. She and Claire try to hide the mice and plan to split them between each other—until her younger twin brothers blurt out the secret to their grandmother.
• In one very rare long-term arc in The Beano during the early 1980s, Dennis the Menace's dog Gnasher went missing for several weeks, with readers being encouraged to join in the search in real life. It finally turned out that he'd fallen in love with a poodle and had a litter of puppies with her. The only one who looked like him, Gnipper, subsequently joined the cast.

Films — Animation

• In Gift of the Night Fury, all of the dragons on Berk get up and leave Berk without warning (with the exception of Toothless, who can't fly on his own), leaving the Hooligan Tribe at a loss of what's happened. When Meatlug, who Fishlegs had restrained before she had the chance to leave, flies off with Hiccup, he and the other riders discover what they were all leaving for. Hiccup finds the island where they all left, along with eggs and hatchling baby dragons, while the others find a bunch of unhatched gronckle eggs in the barn.

Films — Live-Action

• Averted in Air Bud World Pup, where the puppies don't come as a surprise; people witness Buddy falling hard for Molly, and notice him nipping off to see her before she has their puppies. Also, their respective owners, Josh and Emma, and their families are on friendly terms, so Josh never loses track of Buddy for very long.
• In the second Beethoven movie, the kids are surprised to learn that Beethoven has a St. Bernard girlfriend and several purebred puppies.

Literature

• Annie and the Wild Animals starts off with Annie's pet cat, Taffy, acting unlike a usual pet cat and then disappearing into the woods, causing Annie attempting to attract and tame a pet from the woods. The story literally illustrated in the frames of each page reveal that while this is going on, Taffy gives birth to a litter of 3 kittens and eventually comes back to Annie with them.
• By the end of Madeline's Rescue, Genevieve, the dog that rescued Madeline, what the girls keep fighting over ownership of, and was taken away by Landlord Cucuface, is found again by Miss Clavel and taken in. After the girls' second fight over her, Genevieve gives birth to 11 puppies, giving each girl a dog of their own.

Live-Action TV

• There's an episode of Full House where the Tanners are taking care of a golden retriever named Minnie. When it's almost time for her to go home, they find her on Jessie's bed, where she turns out to have had puppies. Jessie bemoans his rotten luck, but the rest of the household is delighted.
• Frasier is horrified to learn that Martin's dog Eddie hasn't been neutered when a woman shows up with a box full of puppies that are the result of Eddie mating with her dog Phoebe. Daphne immediately falls in love with the puppies and wants to keep them but Frasier insists they have to go.

Western Animation

• Arthur has the episode "Arthur's Pet Business", based on the book of the same name where he takes care of many pets to prove he can care for a dog. One of them was a grouchy dog, who was later revealed to be pregnant as she gave birth to puppies. Arthur was allowed to keep one of them, naming him Pal.
• In the Dennis the Menace epsiode, "Ruff to the Rescue", Mrs. Vandersnoot demands that the Mitchell family keep Ruff, Dennis' dog away from Muffy, her cat, even though Ruff has absolutely no malice towards her. One rainy night, both Ruff and Muffy go missing and Mrs. Vandersnoot accuses Ruff of chasing her. Dennis eventually finds Ruff inside a hollow tree in the park, looking after Muffy and her new litter of kittens.
• An episode of Doug has Roger's Right-Hand Cat acting sick (much to the dismay of his owner) until is discovered that it was just expecting kittens.
• In the Dragons: Riders of Berk episode "Searching For Oswald... and Chicken", the B-plot involves Tuffnut's pet chicken has going missing and has recruited everyone (except for Hiccup and Fishlegs, who is helping Dagur in the main plot of the episode) to help him. By the end of the episode, it is revealed that she was actually with a fetching young rooster and their clutch of newborn chicks.
• In the Gotham Girls episode "Gotham Noir", Catwoman has hired Harley to find her cat Velma who has disappeared. It turns out Velma has found a mate and has had a kitten. The kitten is returned to Catwoman and Velma chooses to stay on the streets.
• The sixth episode of Filmation's cartoon series Lassie's Rescue Rangers is "The Imposters," wherein the Turners are apprehended for larcenies committed by look-alikes. After Lassie succeeds in exposing the imposters, the Turners are vindicated and freed. Upon returning home, however, they are greeted by a snarling Lassie. "Don't tell me you believe we're the culprits?" Fortunately, no: Lassie was being protective of her newborn collie pups. Which means Lassie did her heroics while a Pregnant Badass.
• In Milly, Molly's cartoon adaptation, Milly's cat Marmalade and Molly's cat Tom Cat both go missing in the first episode "Monday", and when they find them, Marmalade has had kittens and it's heavily implied that Tom Cat is the dad.
• Rugrats: In "Bow Wow Wedding Vows", Tommy gets jealous when Spike seems to spend more time Fifi than with him, but soon finds out that Fifi was having their puppies.
• In The Simpsons episode "Two Dozen and One Greyhounds," the family adopts female racing greyhound She's the Fastest after she and family dog Santa's Little Helper mate at the dog track (during a race). Despite the fact that they embarrass Marge by constantly engaging in "you-know-what" in front of the house, she's as surprised as anyone else when She's the Fastest suddenly gives birth to 25 puppies.
  Marge: Oh my God, she's having babies! I'm sorry, girl, I thought you were just getting fat!
• The SpongeBob SquarePants episode "Spot Returns" has Plankton's pet amoeba getting fatter until he and Karen discover that Spot is pregnant. Afterwards, it gives birth to millions of amoeba puppies.

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