All Dogs Are Purebred

In Real Life, most dogs, whether stray, feral, or pet, are mixed breed. This is not so in many fictional universes. In TV shows and movies, most dogs and dog characters will be purebred. Even in cases where a purebred dog has a litter with a dog of another breed, the puppies will resemble only one of the parents. This is rather jarring in shelter and pound settings, where the large majority of dogs are mixed-breed. While there are stray purebreds in Real Life, they only make up a small portion of strays.

This happens for a few reasons. In live action works, studios often use multiple animals to play one animal character. This is a lot easier with a purebred dog, since there are many other individual animals that will look almost exactly the same. It's a lot harder to find "doubles" for a mixed-breed dog that has a more unique appearance. In other cases, studios believe that viewers will respond more positively to a dog of a recognizable breed. Said reason also helps fit into the matter of Breed Stereotypes, in which they want the "girly" dog to be a poodle, a "mean" dog to be a rottweiler, or other dog breeds often associated with certain traits.

Use of this trope in media is often criticized for causing a The Red Stapler Effect, with certain dog breeds becoming popular after a popular movie or show featuring the breed is released. When that happens, people sometimes try to make a quick buck by breeding as many of the dogs as they can, and they aren't always responsible about it. The popularity of 101 Dalmatians is often blamed for many of the genetic problems that occur in dalmatians today.

This trope rarely occurs with other animals.

Anime & Manga

 * In the anime Ginga Densetsu Weed, the dog characters are purebred despite living in the wild.

Film -- Live Action

 * Most of the dogs in Hotel For Dogs are purebred, which is a little jarring considering all the dogs in the movie are supposed to be strays.
 * The film Cats and Dogs uses purebred dogs for their main characters along with side and background characters.

Film -- Animated

 * In Oliver and Company, all the main canine characters are purebreds (including a chihuahua and a saluki) with the exception of Dodger.
 * Other than the titular Tramp, many of the side characters in Lady and The Tramp are purebred.
 * The sequel follows this as well. In a case of Gender Equals Breed, most of the Lady's litter are females that resemble purebred cocker spaniels, while the male puppy, Scamp, resembles his mongrel father.
 * The Pixar film Up has several dogs: one is a Golden Retriever, another is a doberman, and the rest are all bulldogs and other "bully breeds".
 * The Disney film Bolt doesn't feature many dogs, but the dogs it does show are all purebred.

Live-Action TV

 * Benji is probably the most famous aversion to this trope, being a mixed-breed shelter dog. In fact, the original producer wanted to use a shelter dog to play Benji in hopes of raising awareness about the plight of abandoned and unwanted dogs.

Video Games

 * In Nintendogs and similar games, the dogs are generally purebred.
 * The dog anthros in Star Fox are all purebred based.

Western Animation

 * One famous inversion is Charlie Dog from Looney Tunes. He uses his mongrel status to claim that he's "all the good breeds rolled into one", then rattles off half a dozen breeds that he is 50 percent of.
 * The dogs in the most recent iteration of Pound Puppies are all purebred as well.

Real Life

 * Most dog shows (at least, the big ones) will only allow purebred dogs to enter. Justified in breed comformity competitions where the dog in question must adhere to a breed standard.