You pay for a clan of wild hyenas to prowl the gardens at night at your swanky crib to disembowl any intruder that tries getting in, only to see on the security cameras that they let the burglars in after a quick round of fetch and a belly-rub. Just can't find good help anymore, can you?
Often times the animal in question comes in one of two flavors. The first is that the animal tried being a vicious guard animal, but is physically incapable of accomplishing this, like a chihuahua or a pomeranian or a pet rock. The second kind (the more popular kind because it is more hilarious) is often an animal that should be intimidating - like a rabid wolf-hybrid doberman, a Bengal tiger or a megaladon in the castle moat - but it doesn't have a vicious bone in its body. It'll purr, rub against the intruding person, lick their face, maybe even roll-over wanting a belly-rub. It is just the cutest thing ever and it has no right to be. Go Fetch or Monster's Favorite Petting Spot may be used to demonstrate this.
- Invoked in The Prisoner of Limnos when Penric twice uses his sorcerer's version of a shaman's geas to convince guard dogs that he's actually their best friend. The first time is with the huge mastiffs guarding the Xarre estate, and the second time is with fluffy little dogs of the Lady's order on Limnos who are trained to sniff out males.
- The ferocious three-headed dog Fluffy in Harry Potter and the Philosopher's Stone is normally pretty effective at guarding the titular stone, but he has a Weaksauce Weakness (music makes him instantly fall asleep) and a caretaker with Loose Lips, so both the heroes and the villain are able to get past him easily.
- In the first Percy Jackson book, Annabeth plays fetch with Kerberos/Cerberus, the three-headed guardian dog of the underworld, and he lets them pass. It's suggested that this only works because Hades doesn't play with him at all.
- Pinkerton: Pinkerton fails every single lesson when his owners take him to obedience school, including the one about attacking a burglar dummy. (He licks it instead.) Meeting a real burglar doesn't make him learn, but luckily the girl manages to use some of his other behavior to scare the guy off.
- On one episode of It Takes a Thief (2005), a homeowner trained his own guard dog. The dog was vicious, but the design of the house, combined with incomplete training, meant Jon was able to trick the dog outside and lock the dog on the back patio while he robbed the house. This was subverted on the return visit, where the patio had been redesigned to not allow the dog to be trapped outside, and the dog himself had received professional training.
- In the "Family Dog" episode of Amazing Stories, the dog fails to stop burglars twice; the first time because he had eaten too much, the second because he overslept. His owner takes him to be trained to be a more vicious guard dog, and the third time he succeeds in chasing away the burglars. In fact, it works too well, as the dog has followed them to their hideout, and when it attacks a cop who came to arrest them, they decide to use him as an accomplice in their crimes. Eventually, the dog turns on the burglars and he returns home... where it attacks his master after he gets locked out of the house and has to sneak in through a window.
- Invoked in Hogan's Heroes with the dogs of Stalag 13, which were secretly trained by the Heroes' French member Le Beau to disregard their comings and goings (one of their secret tunnel entrances is even beneath the dogs' kennel) and bark on their command whenever it was necessary to the Heroes' scams to pretend to be captured "trying to escape".
- The infamous "Kennel From Hell" match between Al Snow and Big Bossman from the 1999 Unforgiven pay-per-view had "angry guard dogs" in the space which separated the Hell in a Cell and the Steel Cage. The problem was that the dogs (two rottweilers) generally acted like overgrown puppies, defecating, urinating, and even mating.
- Detroit: Become Human: When Connor breaks into Hank's house (to help Hank, who was passed out on the floor) a huge Saint Bernard named Sumo confronts him, growling—but a few calm words from Connor are enough to befriend him. Slightly later, as Connor drags Hank into the bathroom to sober him up, and Hank protests:
Hank: Sumo, attack! [Sumo is lying on the floor. He barks lazily and doesn't get up.] Good dog.
- Fang, Jagged Stone's pet crocodile from Miraculous Ladybug, behaves less like the swamp predator that he is and more like a pet dog, wagging his tail, panting with his tongue hanging out, having his belly scratched and so on. In "Pixelator", he consistently act like a lovable pet, so when the titular villain Pixelator breaks into Jagged's hotel room with the intent of kidnapping him, Jagged tries to have Fang attack him, only for the crocodile to roll over, wanting a belly-rub.
- One of the dogs that would eventually fused into Wiggy-Jiggy Jed (full-named Sir William Wexell Wingding Whizzlebang the Third) in The Grim Adventures of Billy & Mandy episode "Dream Mutt" is Trigger, who wound up being put up for adoption because she did nothing to stop burglars from breaking into her owner's home and then escaping.
- House of Mouse: In the short "Pluto vs. the Watchdog", Mickey tries to test Pluto's watchdog abilities by pretending to be a burglar, but he's only interested in playing with him, prompting him to buy another dog. Little does he know that the new dog is actually working with Pete to help rob the house, but Pluto ends up foiling both of them.
- In the Goofy cartoon "Man's Best Friend", Goofy goes out for the evening and leaves his dog to guard the house. That night, a burglar breaks in, has a shoot out with police, and gets arrested, all without the dog waking up. But when Goofy returns, his own dog growls at him and chases him up a tree.
- Throughout most of the Foghorn Leghorn shorts, Barnyard Dog is shown to be an almost counter productive guard dog. Almost always sleeping on the job, he tends to only pay attention to farmyard predators like Henery Hawk and "Bill" the Weasel when directing them towards his Arch-Enemy Foghorn, who trolls Barnyard ceaselessly for his idleness.
- The Simpsons:
Burns: I remember when he bagged his first hippie. That young man didn't think it was too "groovy".
- In the episode "Homer the Vigilante", a cat burglar very easily keeps Santa's Little Helper at bay by offering it a sausage. Amusingly straight afterwards he uses the same trick to distract a sleepwalking Homer.
- Usually subverted with Mr Burns' terrifying hounds, though the episode "Dog of Death" shows The Runt at the End, Crippler. As Burns laments, Crippler was once as vicious a beast as all his other dogs, but having been around since Woodstock, time hasn't been kind to him.
- Used as a Brick Joke in The Loud House: The episode Lock 'n Loud has Lana training Charles to chomp burglar butts, but his laziness interferes. Subverted at the end where Charles does chomp on a burglar's butt (who's actually Mr. Loud) only because Charles saw some strips of bacon on the backside of his pants.
- In The Batman episode "The Laughing Cats", the Joker, having recently acquired his hyenas, sets them on Catwoman. Selina instantly befriends them while lecturing the Joker that Hyaenidae are more closely related to felines than canines.
- There is Truth in Television in this. Many people will buy a dog as a guard dog, only to find out guarding isn't a born trait and is something that needs to be trained into the dog. Staffordshire Bull Terriers and American Pit Bull Terriers are two breeds commonly used as guard dogs thanks to media portraying them as such, however, they're both bred to be people-friendly dogs.
- People have brought large-breed dogs because they look intimidating, subverting this trope.
- Subverted in the case of Dubai the Great Dane, who greeted the intruder and accepted his petting at first. Once his owner turned the corner and screamed, his protective instincts finally kicked in and he chased the intruder out the door, barking and snapping at him the whole way.