When adopting a new canine family member at a shelter, many people choose a dog based on the breed or breeds labelled on its cage. But new research using genetic testing shows that shelters don’t always correctly label dogs, meaning the pointer you just adopted could actually be more of a labrador.
This has implications for how long dogs sit in shelters before adoption, if they get adopted at all. Studies have shown that pit bull-type dogs like bull terriers and American Staffordshire terriers wait three times longer than other breeds for adoption, even when no controlled study has demonstrated that they are significantly more dangerous.
A team of researchers used a little brush to get cells from the cheeks and gums of over 900 dogs in two shelters: the Arizona Animal Welfare League and the San Diego Humane Society. They submitted those samples for genetic testing to Wisdom Panel, a commercially available dog genetic testing company. Wisdom Panel also funded the study.
When the team compared the results to the breeds that shelter staff had assigned the dogs, they found that the staff was correct just 67 percent of the time when guessing the primary or secondary breed of a dog. When trying to guess more than one breed, they only correctly guessed those combinations 10 percent of the time.
The results also revealed some interesting shelter demographics. As noted in the study, published Wednesday in PLOS ONE, there were a total of 125 breeds represented, the three most common being the American Staffordshire terrier, the chihuahua, and the poodle.
“The level of genetic diversity in the shelter dogs exceeded our expectations,” Lisa Gunter, a study author and psychologist at Arizona State University, said in a release. “We also found that just 5% of the shelter dogs were purebred, even though it is commonly assumed that up to a quarter of dogs in shelters are purebred.”
It’s important to note that consumer DNA tests—for both dogs and people—shouldn’t be considered fully accurate. Hekman told Gizmodo that she will generally trust results from a test that describe dog heritage at a fraction of a quarter or higher—like if a test tells you your pup is 25 percent basset hound, for instance. Anything less than that is more likely to be incorrect, she said, and she pretty much discounts any results less than about 12 percent.
The researchers behind this study didn’t include any results that said a dog was less than 12.5 percent of one breed in their study. But the test they used only considered 321 sections of DNA when genotyping dogs and assigning them breeds. This limitation weakens the results, said Jessica Hekman, a veterinarian and canine geneticist at the Broad Institute who was not involved with the study.
“Wow, that is old technology,” Hekman told Gizmodo. “321 is a tiny number.” She added that another dog DNA-testing company called Embark uses 17,000, and she still finds that data hard to use for research—though it can be useful for assigning dog breeds. “I’d still trust the larger percentages, but I’d be even more hesitant about the smaller percentages.”
In mislabeling dogs, shelters may be causing dogs that have a pit bull-like appearance to go unadopted because people are prejudiced toward pit bull-type dogs. But that label shouldn’t matter, Hekman said.
“People see a dog with this fur and this body shape and think they can make assumptions about its behavior,” she told Gizmodo. “That’s totally not true. If you mix two dogs together, you have no idea how it will act. Even in purebred dogs you don’t know how it will act. Genetics are complicated. There aren’t these little programs forcing you to act one way. The world is not that black and white.”
The best thing to do is to see how an individual dog would fit into your household.
“Everything about the life experience of a dog—where he was before coming to the shelter or any medical issues he might have—is what makes him who he is, not who his grandparents might have been,” Michael Morefield, an employee at the Arizona Animal Welfare League, said in a statement. “When you adopt a dog, you are not adopting a bully, a German Shepherd or St. Bernard, you are adopting Jerry or Mo. When you love a dog, you don’t love a German Shepherd. You love Jerry.”