My dog is part shih tzu, and it's blowing my mind.

First, you have to understand that I have an unnaturally close relationship with my dog. Was she lying on the top of my head in bed this morning? Yes. Does she sleep under the sheets every night? Yes. Do I share ice cream with her? Yes. Do I consider her my romantic partner? No. It's very important that you know that.

So, given my incredibly intense love for Ella, and given that I have never known her breeds, my boyfriend got me the perfect gift. On Ella's approximate birthday (since she's a rescue, her birthday was pretty much made up), Drew presented me with a Wisdom Panel Doggy DNA kit, to which I made all sorts of high-pitched celebration noises only Ella could hear.

Here's how it works: I sat Ella down on one of her four doggie beds, and gently placed a cotton swab in her mouth, rubbing it lightly against the inside of her cheek. Since Ella is perfect, she didn't mind this one bit, and even let me do it once more, with another swab. Then I let both swabs dry, placed them in the box provided, and mailed it back to the lab, where they would analyze her heritage. This is where the real wait began.

For three painful weeks, Ella and I paced and pondered. When, oh when, would we know how she got those perky ears and long, graceful neck? Her Chihuahua genes are clear, but how did she inherit that beautiful coloring? And why is she 10 pounds when the average Chihuahua tops out at about 6 pounds? Where did she get her playful temperament and lapdog energy, when Chihuahuas are known for their cliquishness and propensity to yap? For 21 long nights did we suffer, awaiting the results.

Meanwhile, back at the lab in Lincoln, Neb., the scientists were crunching data, leaning over Ella's DNA and wiping their brows with a towel as they puzzled over how such a perfect specimen came across their desks. Or perhaps they were just running it through a computer algorithm. But either way, they were using genotyping technology to compare hundreds of Ella's genetic markers to those of 10,000 different breeds.

GeneSeek, the testing facility which analyzes the specimens, calls itself "the world's largest animal genomics testing facility, processing approximately 1.5 million samples a year for customers around the world." Its algorithm is proprietary, but you can see the process in this video from its site.

Essentially, every living thing has its own DNA blueprint, and this blueprint is different for every individual (with the exception of identical twins). Our DNA markers developed over millions of years of evolution, so animals from different parts of the world have genes that look similar to one another. A dog (or human) whose heritage is from Norway will have different-looking DNA than someone from Japan. The same is true of dog breeds. Certain breeds have certain genetic markers, and when a dog is a "mix," she will carry some pieces of these various DNA codes, like heirlooms from her genetic past. The test aims to find these heirlooms.

Without being able to double-check GeneSeek's work, it can be difficult to trust that they will deliver accurate information about your companion, but two things build confidence. First, they were trusted by the USDA to analyze the DNA of a cow infected with Mad Cow Disease in 2004, and find the parentage of the disease. Second, their results offer some predictive information, like your dog's approximate weight, which you can check for accuracy. If they said Ella was probably a 75-pound mastiff, for example, it would have given me paws. Heh heh. Heh heh. Heh.

Once three weeks had passed, I logged into my account and sitting there waiting for me was a shiny PDF with the keys to the kingdom: Ella's DNA results. I shrieked in delight, awaking both my dog and my boyfriend, and looked at Drew with the eyes of a person about to jump out of a plane.

"This is it!" I said.

I opened the PDF and was immediately greeted with words I could not process. Words that I could not have expected, for all my thinking and waiting and picturing this moment.

"Ella is a Chihuahua, Shih Tzu mix."

I paused, staring at the screen.

"What does it say?" asked Drew. Slowly, I turned my phone screen toward him, eyes wide with wonder.

"A shih tzu mix!" he said, lighting up. Drew grew up with two shih tzu mixes, and so has a fondness for them, but neither of us had expected this. Compare a shih tzu to Ella and behold the differences.

But the next page spelled it out a little more clearly. While around three of Ella's great-grandparents were purebred Chihuahuas, one was likely a shih tzu, which made her DNA only 1/8th that breed. The rest of her markers were either Chihuahua or "mixed breed," meaning the mixing went back so many generations, the genetic markers were no longer clear. Her proud Chihuahua and mutt traditions were in tact. Just a little shih tzu. Heh heh. Heh heh. Heh.

To be fair, next to the picture of a shih tzu, there was a tiny star, which meant, "Breed detected, however at a lower confidence."

What Wisdom Panel does not point out is that the amount of breed-specific DNA a dog has does not necessarily correlate to an ancestor being purebred. For example, Ella's 1/8th shih tzu DNA could mean that she has one great-grandparent who was a purebred shih tzu, it could also mean that she had two great-grandparents who were half shih tzu, and so on. This is muddled even further by the fact that "purebreds" are a human construction. At some point, all DNA is an evolutionary mix, whether our own or our dog's.

Next were included descriptions of her three dominant breeds. The Chihuahua sheet clearly matched up: small size, alert, playful, intimidated by large dogs. But there were some matches from shih tzu, too: Friendly, moderately active. The "mixed breed" sheet expounded her mixed heritage. While it could not be conclusively detected, her mix was most likely within the terrier breeds, which include Chihuahuas and miniature pinschers, with whom Ella bears a striking resemblance.

Now, I know what you are thinking: "Ella is the cutest dog I've ever seen, and I can't get enough information about her looks, but what about her drug sensitivities?" Good point.

Along with the breed information, Wisdom Panel supplies a screening for a mutation on the MDR1 gene. Such a mutation gives canines an increased risk of side effects from certain drugs. Fortunately, Ella's MDR1 genes are normal.

Finally came the weight prediction. While this is intended for those who have adopted puppies and don't yet know their adult weights, it also serves as a check for those of us with full-grown dogs. The test was accurate enough to guess Ella's weight range correctly, predicting 5 to 13 pounds to Ella's 10.

As for consistency, as Forbes reported in 2015, various "skeptics" have tried to outsmart the test by either sending the same dog's DNA through twice (under different names) or sending the DNA of another species - say, cat or human. But those tests fail for logistical reasons: every dog's DNA is as unique as that dog is (which, in Ella's case, is very unique), so sending the same sample through twice just tells the computer that you're cheating the system; and sending cat or human DNA is a quick way to waste $70, since the computer will simply find the sample unreadable.

Another cross-check is to send the same dog's sample to two different companies, as Forbes writer Colleen Kane did. Her dog's profile came back nearly identical from the two labs, but with some differences in the less-present breeds.

Some shelters have also used DNA testing to speed up the adoption process, reporting marked success. According to the Humane Society of the United States, 25 percent of all purebreds end up in shelters, so even those who are obsessed with a pure bloodline can find the love of their life at a shelter.

Even some haughty landlords have used the testing to spot the worst humans among us: those who do not pick up their dog's poop. (I recently stepped in one enormous dog turd and can tell you, people who don't pick up their dog's poop share at least a quarter of their DNA with Hitler.)

In the end, the dog tests appear to be mostly consistent, if not the be-all, end-all of your dog's identity. If you really want to know who your dog is, sit down with her, look her in the eyes, and lick her face slowly and gently, with the loving kiss of a soul mate.

I swear, I'm fine.

Photo: The Kennel Club | Flickr 

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