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Can DNA Decipher the Mix?

DeNise explains it this way: “In a population of any breed, there are dogs that are carriers but don’t exhibit phenotype [observable characteristics]. If you reduce the size of breeding population—creating what we call a bottleneck—you start increasing the frequency of deleterious traits, like dwarfism or white coat. If we looked at the DNA of, for instance, a group of white mini-German Shepherds, they would probably cluster with German Shepherds. After they’ve intermated for five to six generations, we may not come up with that. They would cluster with each other. If breeders were changing allele frequencies quickly, you could do it very fast.

“There are always contradictions that make you say, ‘Huh, that’s really weird.’ One odd thing that happens is due to some sort of random assortment of genes in mixed-breed dogs. The algorithm may identify a breed that is not consistent with the physical appearance of the dog. We sometimes get an indication of this when the certificate is printed with the picture of the dog provided by the owner, and the certificate is reviewed by our customer service department prior to mailing it to the pet owner.”

A 90-pound, wiry-haired mongrel who swims, chases balls and makes goo-goo eyes like a Golden Retriever and whose only pedigreed relative is a very distant Chihuahua confounds the process, but says a whole lot about the complexity of canine genetics and why some scientists devote their careers to studying canine evolution. Extreme variation in anatomy and behavior is unique to the domestic dog. If humans were an equally anomalous species, we’d weigh between 20 and 650 pounds and range in height from three to 10 feet. In dogs, adaptations change with such speed that scientists suspect there may be a clue in the canine genome that could reveal how evolution works.

Sorting It Out
Before they launched the project, MMI tested DNA from a street dog rescued from a Thai village. You’d think there would be no clusters of any kind, but the computer identified Chow and Akita in the mix. This isn’t surprising, because the free-living common village cur who populates most of the developing world may be the closest living relative to the original proto-breed. Findings suggest that Thai pooch stores a sizable chunk of the original genetic blueprint of every single living dog in her DNA. The question is, how much?

MMI can’t as yet define the percentage of “breedness” in mixed-breed dogs. One reason is that some breeds cluster loose and others tight. Why this happens isn’t clearly understood. German Shepherds, Standard Poodles and Collies cluster tight. Miniature Poodles cluster tight, but Toy Poodles cluster loose. Within their breeds, Labrador Retrievers and Beagles often cluster as two different groups. According to DeNise, “Labs from the United Kennel Club that are bred specifically for hunting and AKC Labs do not necessarily cluster as one breed. And AKC Beagles and Beagles bred specifically for research don’t cluster together either.”

She adds, “In my opinion, it’s possible that a population that increases rapidly doesn’t cluster as well as those populations that have remained static. This is because, as you increase a population to accommodate breed popularity, people breed everything, including animals that may not exhibit all the physical characteristics that are desirable.”

And even when dogs look alike, they can display behavioral differences. As DeNise notes, “We understand so little about how behaviors are coded. Many behaviors are learned, but there are probably multiple genes that are responsible for herding, birding, heeling—these kind of hard-wired behaviors.”

Scientists are eager to tease out genetic connections to breed-associated motor patterns. When wolves hunt, they display these behaviors sequentially: orient > eye > stalk > chase > grab-bite > kill-bite > eat. Artificial selection, however, extracts and segregates these patterns in incomplete sequences. In certain breeds, individuals perform the abbreviated motor pattern repeatedly. A Pointer who stops dead in her tracks and stands stock still with her front leg held rigid in mid-stride to indicate the presence and position of game is the lofty goal of bird-dog breeders. To wolves, it’s just a good meal interrupted.

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Submitted by Anonymous | August 4 2011 |

Fascinating. So are DNA tests accurate enough to be useful in identifying the breeds in your mutt?

Submitted by Dave Strack | February 5 2013 |

I am still a skeptic as to the accuracy of these tests. There have been results that have been documented in which the same dog's sample was submitted to the same lab twice with entirely different results, dogs with color patterns and coat types that have been studied to identify the specific genes needed to produce them but the DNA test did not identify any breeds in the test result that could have produced the dog being tested, and an unscientific report of a test on ans 8 pound dog that listed only large breeds in its ancestry (a little white Rottweiler?).
The DNA testing is not one where a sample is put into a machine that spits out the answers. A human still has to interpret the raw result to come up with the answers - can you say human error. If you are just curious go ahead and have your dog tested. I would not like to think of a situation where my dog's life depended on these test results.

Submitted by Jane Brackman | March 28 2014 |

Read a more recent article I wrote about DNA tests, published in Bark in December 2012. http://thebark.com/content/do-dna-tests-reveal-genetic-secrets
You still may be a skeptic, but you'll have more knowledge about why the tests are accurate but appear contrary to what we see in our mixes.

Submitted by Lorri | October 20 2011 |

Thank you Jane Brackman for this article. It was very informative and interesting. I'd love to know what has transpired, since it's been three years since the article was published in The Bark.

Submitted by Jane | March 1 2012 |

That's the same thing I've been asking myself Lorri. And yes, I'm working on an updated piece. I've been sending my mixed breed pooches DNA into two companies to see if the results are the same.

Submitted by Kathi | July 30 2012 |

Jane,

I have been doing my own research on the various DNA tests plus DNA breed identification. This is because my city has a breed ban on certain breeds of dogs. I am not a scientist:( which makes this difficult. Mars Wisdom Panel is the only test that is available now to my knowledge. The shelter at our city has been testing questionable mixed breeds since 2009 with the Wisdom Panel Professional. We've done 20+ dogs so far. We have even done both test(Insight & Professional)on the same dog to see if we received the same results (we did). Our city does not acknowledge DNA testing but the city council is open on us gathering information (with the city) to determine if DNA testing can determine the banned breeds. Our city will accept the banned breeds if they are less than 50% of the banned breeds. This is currently determined by animal control officers visual identification. When will your updated piece be out? I'll be looking forward to it.

Submitted by Mia | November 17 2012 |

It is completely cruel and just plain wrong to ban an entire breed of dog. The dog is what you bring it up to be. PEOPLE are the ones that should be punished for TEACHING the dog to fight or be cruel or purposely inbreeding....Jail time and permanently keeping animal cruelty on their records should be put into law!

I have recently gotten a pitt bull mix (weimeraner we think) but he has fit right in! And is the most loving dog....I have six dogs and the lab/labradoodles that we have are more aggressive than he is - Especially with strangers walking in front of the house or people coming in....

Banned breeds should be banned people - people are the ones that are cruel.

Submitted by Anonymous | February 4 2013 |

I agreed to watch a friend's pitbull for one night and he moved out of state. So I had this huge brendle 11 year old pit bull, and I was scared of him. I had him for 3 years, and he was one of the most sweetest dogs I ever owned. At first I thought he was mute, he never barked for 3 months until I had him tied up outside and I walked out of his line of sight, that was the first time I ever heard him bark. A drunk friend of mine climbed through my window in the middle of the night and the dog just tackled him and licked him to death. I thought "what a lousy guard dog." But I would take him with me on runs, and a creepy guy approached me and he sensed my unease and went after the guy. He would let babies ride him like a horse. He was a great dog. But I couldn't get renter's insurance because of him.

Submitted by Anonymous | October 27 2011 |

So the "groups" are: Two hounds, MULTIPLE Spitz dogs, and a few small breeds... I think these groupings are messed up. At the very least, Asian Spitz dogs should have been one group (with the exception of the Chow Chow the visual and behavioral similarities are striking.)

Submitted by Erin | April 18 2012 |

Thanks for the interesting article! I had my dog's DNA tested recently and it was an interesting experience to say the least! She came back with about nine different breeds detected! The Humane Society believed her to be an Australian Cattle Dog/mix, however none was detected. They came up with boxer/miniature schnauzer mixed with a keeshond/chow chow. We really just did it for fun and it was affordable (around $60), but it might be interesting to see if the other companies that offer this service would come up with similar results. I am looking forward to reading your follow-up article regarding this. Of course, we love her no matter what the results are!

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