Like many dog lovers, I love the idea of knowing my dog's genetic ancestry. If I know what her DNA says, I reason, I can answer many questions about her in a smart, informed way. "Of course she exhibits that trait, she's part [INSERT BREED HERE]."
Is it worth the expense to DNA test your dog?
I decided to test my dog, Pistachio, using the Wisdom Panel 4.0 test. I'd tested her using the Wisdom Panel 2.0 test a couple years ago, but had been confused by the results — they pegged her as a Chihuahua and Yorkshire terrier mix, which to me didn't explain her size (she's 16 pounds, larger than most Chihuahuas or Yorkies, or so I thought).
Determining a dog's genetics is a complex process. Here's how Wisdom Panel works, according to their site: "We examine your dog's DNA at 1800+ points (markers) and send the data to a computer that evaluates them using an advanced algorithm and more than 18MM calculations. The algorithm uses information from our ... sample database to analyze your dog's potential pedigree trees going back three generations." After it gives each of the millions of possible combination a score based on how well each matches your dog's data, the computer then selects the "tree" with the overall best score. That's what you see in your dog's results.
Re-testing Pistachio with the Wisdom Panel 4.0 yielded the same results, but this time around, I had the benefit of more information.
Juli Warner, Senior Brand and Corporate Affairs Manager for Mars Veterinary (the company that owns Wisdom Panel), helped me out by explaining more about the roots of my mysterious Chihuahua mix.
According to the test results, Pistachio is 75 percent Chihuahua and 25 percent Yorkie. But here's where it gets interesting. Pistachio is on the large side for both those breeds — she weighs 16 pounds, which is why her results initially confused me. Ms. Warner explained an interesting distinction: Wisdom Panel has both the U.S. Chihuahua and the larger Mexican Chihuahua breed signatures in their database, but they don't yet call these different breed signatures out on the report. That's why the results only show "75 percent Chihuahua." However, the geneticist that processed my test revealed that Pistachio is 50 percent Mexican Chihuahua, and 25 percent U.S. Chihuahua. This larger percentage of Mexican Chihuahua might account for her larger size.
I found this information very fun and cool to learn. Also, I feel smart knowing the difference between the U.S. and Mexican Chihuahua. But is this knowledge actually useful, or do I just like having the answer to the question "what mix is your dog?"
I asked Dr. Jessica Hekman, a scientist who studies dogs' brains as well as canine genetics, whether dog DNA tests are actually useful. Dr. Hekman told me that "these tests are the most accurate on dogs who have a small number of breeds in their mix." The tests, she says, are pretty good at identifying purebreds or dogs with 2-3 breeds in them. More than that, she says, "and the results start being more iffy." If you get a result saying your dog is "12 percent something or other," Dr. Hekman suggests taking it with a grain of salt. However, she says, if it says a larger percentage, like 30-50 percent, "you can put some stock in that."
I asked Dr. Hekman if the tests are useful for determining possible health problems, which many dog lovers tout as a benefit of DNA testing. Dr. Hekman says it's possible, but she's never heard of them actually being used this way.
"Many of the breed-specific health problems (cancer, heart disease) become much less predictable when you have a mixed breed," she says. "Will your vet use the results of your genetic test to aid in diagnosis of a confusing set of symptoms? ... I imagine most will take the information as something interesting and then really depend on the results of their testing." Additionally, she questions whether people really will change the way they manage their dogs' health based on the results. "Hopefully you are already managing your dog well, feeding healthy food and keeping them slim and fit," she says.
However, Dr. Hekman says, she thinks the test is a fun thing to do. "I did it on my mixed-breed dog, Jenny," she says. "It confirmed some things I already knew (she's more than 25 percent Labrador retriever), gave me some other information I'd suspected (she's got some northern breed in her, but I didn't know what — the test said Samoyed), and failed to help out with other questions (she's got some herding breed in her, and the test agreed with that but couldn't tell me what specifically)."
The takeaway is probably something like this: Dog DNA tests are useful to a degree, and they're a relatively new science that's still evolving (so to speak). Every new iteration of DNA tests gets more detailed. The question is, what do you plan to do with the information your tests provides? Personally, I plan to brag about how smart I am for knowing the difference between a Mexican Chihuahua and a U.S. Chihuahua.