Every year, roughly 3.3 million dogs end up in animal shelters. Although this figure includes a sizable population of pups surrendered by their owners or seized during animal cruelty investigations, the majority are strays of unknown origins. Since shelters rely on basic demographic information—including breed, age and temperament—to market dogs for adoption, workers are left to assess strays based largely on their appearance.
As Jessica Boddy reports for Gizmodo, these assessments often prove incorrect: According to a new study published in Plos One, shelter staff correctly identify a dog’s primary or secondary breed just 67 percent of the time. When asked to guess a mixed breed pup’s primary and secondary breed, this figure drops to 10 percent.
To measure the accuracy of shelter breed assignments, researchers from Arizona State University collected DNA from more than 900 dogs housed at shelters in Phoenix and San Diego. Wisdom Panel, a canine genetic testing company that co-sponsored the study, compared this extracted DNA to 321 genetic markers associated with specific breeds.
“The level of genetic diversity in the shelter dogs exceeded our expectations,” said the study’s lead author Lisa Gunter in a statement. “We found 125 distinct breeds.”
Genetic testing identified American Staffordshire Terriers, chihuahuas and poodles as the most common breeds amongst the animals tested. These breeds accounted for fewer than half of shelter pups, however, suggesting that strays’ backgrounds constitute a wider array of breeds than indicated by shelter labels.
In fact, the researchers report that the percentage of purebred dogs in shelters is around 5 percent, significantly lower than the 25 percent commonly reported. Most of the animals tested could trace their heritage to three different breeds; those with the most unique genetic signatures boasted a background of up to five breeds.
Breed identifications have a significant impact on an animal’s chances of getting adopted, Sara Chodosh writes for Popular Science. Dogs labeled as pit bull mixes, for example, remain in shelters nearly twice as long as non-pit bulls. This trend is worrying in and of itself, as pit bulls are often wrongly condemned as inherently aggressive, but becomes even more concerning in conjunction with the widespread misidentification of pit bull mixes.
A 2015 study published in the Veterinary Journal found that shelter staffers overlooked one in five dogs carrying genetic markers associated with pit bulls. At the opposite end of the spectrum, one in three dogs labeled as pit bull-type dogs lacked DNA associated with pit bull breeds.
This isn’t the first time studies have pointed toward the failings of visual breed identification. The National Canine Research Council notes that such analysis is “very often inaccurate,” as even first generation mixed breeds look dramatically different than their parents. What’s perhaps more damning is that those performing visual breed identifications rarely arrive at a consensus, with half of participants in a 2013 study agreeing on a pup’s dominant breed just 35 percent of the time.
Given the low accuracy of visual assessments, the researchers advocate a shift from breed labeling to individual behavioral assessment. Although adoptees often look to a dog’s breed in order to predict its temperament, these genetic projections carry little weight amongst the mixed breed canines found at shelters.
Environmental factors also influence animal behavior, Carol Beuchat, a vertebrate biologist and science director at the Institute of Canine Biology, writes for their blog:
A dog exhibiting high levels of aggression may carry the genes for low aggression, but poor socialization and negative experiences early in life outweigh such genetic predispositions.
“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, a spokesperson for the Arizona shelter included in the study, 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.”