This is my dog, Tucker.   Tucker is a male dog that I adopted from a shelter near me.   His history is unknown, as he was found as a stray.   When I got him he was estimated to be between six months and a year old, which would make him about two and a half or three today.   The vet was confident he was not signifficantly older than a year old.   However, we had no idea of the breed mix.

Tucker is very small, about ten pounds.   His face looks distinctly terrier like and his habits are also very terrier-like.  He’s prone to jumping, he likes to hide things like bones and come back for them later and he’s very dominant toward other dogs, even larger ones, although he is not generally aggressive.

I figured him to most probably be a combination of a Chihuahua and a Border Terrier.   He looks more like a border terrier than any other kind of terrier, Border Terriers are not very much larger than he is and they seemed to be the closest match.  They have wire hair, like he does and many of their disposition traits match him.   However, his ears look very chihuahua-like and he has big eyes like a Chihuahua.   He is also quite small, a bit smaller than most terriers, but he’s about the right size to be a mix of the two.

Some Chihuahuas are of the “hairless” variety, which have very little fur.  Others have short hair which is of a distribution and length similar to that of Tucker, although the texture is different.   The color is consistent with either breed.

Others generally had a similar opinion.   The veterinarians that have seen him universally agreed he was a terrier mix of some kind.  They also said that he could quite possibly be a Chihuahua-Border Terrier mix.  The general agreement was that he likely had some Chihuahua in him.   Some of the vets and veterinary assistants suggested that he include a different breed of terrier than Border, citing the fact that they’re al that common of a breed.

So there we have it:  He is primarily terrier, possibly Border or another small breed terrier and also shows traits similar to a Chihuahua or possibly a mix of other small dog breeds.  Right?   Wrong.

Out of curiosity and because it’s only about fifty dollars, I sent out his DNA to be tested for breed. It’s a relatively simple affair.  You get two cotton-tipped swab sticks that you rub on the dogs gums and inner cheeks and place in envelopes to send off for testing.   Boy did I get a shock when the results came back!

Okay so he’s… wait… what the…?

A “Level 2″ result is a fairly strong match.  It could indicate that one of the dog’s parents are of the type noted.  It would also be consistent with at least one of the grandparents being a purebred.  One would expect with that level of a match that either one or more of the grandparents were nearly 100% of the breed in question or that multiple grandparents had at significant portion of the breed’s heredity.

The Newfoundland is a very large dog, with normal adult males almost always being over 100 lbs and often 150 lbs.    They’re sometimes called “gentle giants” for their mild temperament and extremely large size.   They have very broad faces and large heads.   The hair of the Newfoundland is usually black and they have a real lot of hair.  The hair is generally very thick and has a substantial undercoat.   They’re one of the strongest and largest breeds of domestic dog.

Could it be that this is a mistake due to some other breed of dog being closely related to the Newfoundland?   Unlikely.   The Newfoundland breed has been around for a long time and was bred from the dogs native to the area of Newfoundland.  Their closest relatives amongst domestic dogs are Laboradore Retrievers, but labs are common and therefore would likely have had their genetics well indexed.

As for the other breeds represented, a level three is still fairly high.  It could indicate that a grandparent was a purebred.  It is likely that at least one of the grandparents had a strong inheritance of the given breed or that more than one had some level of inheritance from the breed.   A level four could indicate a grandparent that is a purebred, but is more likely a great grandparent.

The other dog breeds identified include:

Maltese – That one seems to make some sense.  The Maltese is a small companion dog that is about the right size.  It also does have some features that Tucker has, including large eyes and some facial features.  They only weigh four to ten pounds.   The hair is completely wrong for Tucker, but given that it’s only a level three, it could easily be explained as simply being a trait that was not inherited from that ancestor.

Papillon – The Papillon is a small dog of the Spanial type.   While I would have never guessed this to be one of Tucker’s ancestors, it does make sense.  The Papillon is fairly small in size, and has ears that are similar to the ones that he has.  The eyes and face do show some resemblance and the dog is known for “thinking it’s a big dog” – meaning that it tends to be bold and dominant.  It is also fairly athletic and has good jumping ability.

The Palpion is also a fairly well established breed of dog that is unlikely to be mistaken in a genetic test.  However, if there were another breed, it would likely be a Spaniel.   No other members of that family appear to be a better match.

Mastiff - Mastiff is sometimes used to describe a group of breeds also known as  Molossers.   However, the proper Mastiff is a breed classically represented by the English Mastiff, but also includes the American Mastiff and the Spanish Mastiff.   These are amoungst the largest domestic dogs around.  Although Great Danes are generally taller, adult English and American Mastiffs can be up to 250 pounds.

Mastiffs have been used as sheep dogs, cattle dogs and guard dogs, due to their very large size and robust nature.   They’re not a very popular breed, at least not in recent years, although there are a reasonable number of them.

It’s highly unlikely that a much smaller dog could be mistaken for a Mastiff on a DNA test.  Their closest relative that is of a small size is the Pug, but Biopet labs has the Pug already in their database.

Chinese Shar-Pei – Another real shocker on this one.   There are few dogs I can think of that look LESS like Tucker.   The Shar Pei is a medium to large sized dog that is believed to be related to the Chow-Chow.   The average adult weighs about 50 lbs.  The breed is known for often having a distinctive “wrinkled” look, although not all individuals display this to the extent of the one pictured.

I’ve got no idea about this one either.  I never would have guessed this.

Given, it is only a level four match, but it still seems to have almost nothing in common with Tucker.   It’s possible that the short hair trait came from this breed or that none of the distinctive traits are readily apparent.

So just what the hell is going on here?  Two of the dogs seem to be a reasonable possibility but the other three are about as different as I could imagine.  Could it be contamination?   It certainly was not on my side, as I was both very careful with the sample and would have no way of getting material from the dogs mentioned above onto the sample.   I’d have to assume the lab has procedures to isolate samples and avoid contamination.

If this is real, that brings up another issue.  Just how do dog breeds of such vastly different size… get lucky.   This is actually more than an issue of… mechanics and geometry.   A small dog could father dogs with a larger dog, but if the mother is much smaller, then the offspring will almost certainly be born too premature to be viable.   A small dog is simply not capable of providing enough space in the uterus for the gestation of a large breed dog.

Of course, size is not controlled by a single gene and it can be a little chaotic.  A small and a large dog don’t always produce a medium sized dog, although in most circumstances the offspring is somewhere between the sizes of the two parents.

It’s hard for me to even conceive of a hypothetical situation that could cause this, short of human intervention and artificial insemination.   Could an abnormally small Maltese Shar-Pei mate with an abnormally large Maltes?   Or a large Shar Pei mated with a Mastif, resulting in a dog that was roughly the size of a Shar Pei, which mated with a large Papillon?  The presence of the Newfoundland material in such high levels is the hardest part to reconcile.

If anyone knows anything about dog breeding or genetic testing and thinks they can offer some insight, I’d love to hear it!

Since the test was reasonably cheap, I’m considering doing it again, just to see if it might have been contamination.

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This entry was posted on Friday, October 16th, 2009 at 7:02 pm and is filed under Good Science, Misc. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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