For owners of rescue dogs of mixed breed heritage, it can be tempting to buy a DNA kit to get intel on your pup's ancestry. Catherine Falls Commercial | Getty Images

When Los Angeles resident Marie Kordus takes her rescue dog Anya out walking, some people say she looks like a wolf or a fox. Once a little boy even said, " 'Mommy, look at that lady, she's walking a coyote!' " Kordus recalls.

But when she adopted her slender, cream-colored rescue pup, she was told she was a German shepherd mix.

Still, Kordus decided to try to find out more about Anya's ancestry. She went online, ordered a DNA kit, swabbed Anya's mouth for saliva, put it in a tube, and mailed it off. One week later she had results.

"What came back was that 88 percent of her is German shepherd," she says. "So that tells you that one parent was probably a purebred and the other parent was a mix; and they identified it as the hound family, like a greyhound, bloodhound, or whippet."

So now when people say "coyote," Kordus says a firm "no, not a coyote."

If you're one of the millions of Americans who owns a rescue dog, you may be curious about what breed your best friend is. Increasingly, pet owners are buying DNA testing kits to try to figure out their dog's ancestry. But the promise of these kits may be getting ahead of the science, according to some geneticists and animal researchers.

For dog owners, the appeal of such tests is that knowing more about the breed could give them insights into how to handle their dog's quirks. Angela Hughes, a veterinary geneticist with Mars Petcare which makes one of the dozen or so DNA testing kits on the market, says it's about understanding your dog's behavior: "What makes them tick? Why do they look the way they do? Why do they act the way they do?"

It helped Hughes with her own dog who turned out to be part Jack Russell terrier and part Australian cattle dog. She says it gave her an understanding that her pup needs a lot of exercise, and that "she needs certain things that terriers need like a quiet dark place to den so she can get away and not feel like she has to be on patrol all the time." This, plus recognizing that "she's going to go ballistic at the sight of any squirrel."

These kinds of insights can help us humans understand that "our dogs aren't trying to irritate us, it's just how they work," Hughs says.

The Wisdom Panel, the DNA test made by Mars Petcare, tests for over 350 breeds going back to the "great-grandparent level," explains Hughes. It examines the DNA from the dog's cells for thousands of genetic markers and compares it to the company's large breed database to calculate the "best match" in terms of breed.

The test can analyze over 20 genetic traits, and Hughes cites as evidence of its accuracy that it can often precisely predict coat color patterns and body traits like ear erectness, leg length and weight. In the case of Anya, the shepherd mix, Kordus says the test results were "right on" in guessing Anya's coloring and her weight accurately, based on genetic trait analysis. "They didn't even see a picture of Anya," she says.

Though it certainly makes a fun conversation-starter in the dog park, some experts warn these tests should be taken with a grain of salt. "It's hard to know how accurate they are," says Lisa Moses, a veterinarian and a researcher with Harvard Medical School Center for Bioethics. "Different test companies use different methodologies as far as we know."

And without peer-reviewed publications describing the methods and assessing their accuracy, it's basically a "black box/trust-what-the-company says situation," says Elinor K. Karlsson, a genetics researcher with the University of Massachusetts Medical School and the Broad Institute of MIT and Harvard.

From a practical point of view, Moses worries about inaccurate breed determination especially if the breed comes back as a potentially problematic dog, like a pit bull.

"Once you have given away your dog's DNA and some company has the results, you may not have control over what happens to that information," she says. There could be issues with prejudices and actual discrimination against certain breeds of dogs that might impact things like people's housing and their ability to get insurance, says Moses. "So you may want to think twice about doing a test for that reason."

The Embark DNA test is one among a dozen or so tests on the market that promise to tell you your dog's ancestry. John Tlumacki | The Boston Globe | Getty Images

Many of the DNA tests also offer to provide information about genetic risks for potential health problems. This could be helpful for dog owners because some breeds are more susceptible to certain conditions, says Hughes. They might have an increased risk of a bleeding disorder or of a heart condition or cancer, she says. And knowing that can impact how the veterinarian cares for your pet.

But Moses says DNA testing for potential health conditions can be highly problematic, as she argued in a recent article in the journal Nature. She says the tests just aren't that accurate and the FDA doesn't regulate them. "I want pet owners and veterinarians to understand that they should not be using direct-to-consumer dog DNA testing to make medical decisions about individual animals," she says.

There are no industry wide standards for testing either breed or health status she notes. "Manufacturers are not obligated to tell us what methodologies they use — what quality control they use," she says.

And inaccurate information on health risks could create more problems than they solve, she says. If a DNA test suggests a vulnerability to a disease, Moses says that doesn't mean the dog will actually get it. In fact, most dogs don't, she says.

"It's quite possible that you would end up doing a lot of unnecessary testing to look for signs of disease if you have a dog who seemed perfectly healthy and not only could that be costly but it could also be invasive and potentially even harmful to your dog," she says.

Making treatment decisions based on misleading DNA results can be even more harmful, she says: "What could possibly happen that would be really bad is if people choose to do treatments based on a wrong diagnosis."

If you're concerned about a health problem, John Howe, a veterinarian and president of the American Veterinary Medical Association says your best bet is to talk with your vet. "Because veterinarians are really adept at using all of our education, experiences, senses and knowledge to diagnose and treat the patients that we have as well as incorporating any external information from our clients or from literature or from other veterinarians," he says.

Howe says if you just want to find out more about your dog's ancestry a DNA test could be a fun thing to do. Just understand, he says, that it may not be accurate. DNA testing runs between $80 and $150.

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