Black and white American Pit Bull Terrier. Credit: Shutterstock

Using DNA analysis, researchers have shown that shelter workers frequently mislabel dogs as “pit bulls.” They say this is a serious problem given the social stigma surrounding the breed—which, technically speaking, doesn’t actually exist.




The new study, published in The Veterinary Journal, shows that animal shelter staff—and even some veterinarians—consistently misidentify dogs, particularly those classed as pit bull-type dogs. Much of this has to do with the fact that animal shelter staff are expected to guess the breed of dogs strictly based on physical appearance alone. And even when dogs are assessed at the same time, staff members often disagree on what breed it actually is.



“Unlike many other things people can’t quite define but ‘know when they see it,’ identification of dogs as pit bulls can trigger an array of negative consequences, from the loss of housing, to being seized by animal control, to the taking of the dog’s life,” said study lead author Julie Levy in a press statement. “In the high-stakes world of animal shelters, a dog’s life might depend on a potential adopter’s momentary glimpse and assumptions about its suitability as a pet. If the shelter staff has labeled the dog as a pit bull, its chances for adoption automatically go down in many shelters.”


There’s really no such thing as a purebred “pit bull,” which makes the findings of this study all the more problematic. The catch-all term “pit bull-type breeds” describes any dog derived from the heritage breeds American Staffordshire terrier or Staffordshire bull terrier. The purebred American pit bull terrier is also descended from these breeds, and is often included in the loose definition of “pit bull.”

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For the study, University of Florida researchers observed four staff members (including some veterinarians) at each of four different animal shelters, recording how they identified incoming dogs. In total, there were 120 dogs involved in the study, comprising 16 different breeds (admittedly, not the greatest sample size, both in terms of staff members and dogs analyzed). After this, the researchers took blood samples from the dogs for DNA analysis; their genetic profiles were then compared to the staff’s assessments.

The researchers learned that one in three dogs lacking DNA for pit bull heritage were labeled by at least one staff member as being a pit bull-type dog, while one in five dogs who actually had some kind of pit bull DNA were missed by all shelter staff. Dogs with pit bull heritage were correctly labeled only 33 to 75 percent of the time, depending on which staff member did the judging. And dogs with no relevant DNA were mislabeled as pit bulls anywhere from zero to 48 percent of the time.


According to the ASPCA, nearly four million dogs enter animal shelters in the United States each year, of which 1.2 million are euthanized. About 1.4 million dogs are adopted each year. How many of these dogs are not being adopted because they’ve been mislabeled?



A muzzled pit bull-type dog. Tatiana via Flickr/CC BY 2.0


Many jurisdictions are enacting legislation restricting certain breeds, including pit bulls and dogs that resemble them. “The restrictions are based on the assumptions that certain breeds are inherently dangerous, that those breeds can be reliably identified, and that restricting these breeds would improve public safety,” the authors wrote in their study.

But many dogs are identified based on their physical appearance alone, and these assessments are often wrong—even when made by experts. It’s quite difficult, if not impossible, to predict a dog’s behavior even when its genetic profile is known.


“A dog’s physical appearance cannot tell observers anything about its behavior,” said Levy. “Even dogs of similar appearance and the same breed often have diverse behavioral traits in the same way that human siblings often have very different personalities.”

Previous studies have shown that injuries from dogs have not decreased in jurisdictions where certain breeds have been banned. Public safety would be better served, argue the researchers, by focusing on other variables, including the supervision of children, recognizing a dog’s body language, not approaching an unfamiliar dog in its territory, neutering dogs, identifying “dangerous dogs and reckless dog owners,” and raising puppies to be social companions.


As for animal shelter staff, they should simply enter “mixed breed” or “unknown” in their records when a dog’s actual pedigree is unavailable.

[The Veterinary Journal]

Email the author at george@gizmodo.com and follow him @dvorsky .