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Bulldog or Boxer: Ever Wonder What Your Mutt is Made of?

Pet Column for the week of January 11, 2010

Related information:

Related site - "Beagle or Bichon: Can Dog Drool Provide Insight?” Wall Street Journal, September 18, 2009

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Ashley Mitek
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Source - William Laegreid, DVM, MA, PhD
Maybe you just want to settle that bet with your friend who keeps telling you he sees some Maltese in your mastiff. Or maybe you yourself have stared into the eyes of your four-legged companion too many times wondering its true heritage.

Thanks to recent advances in technology, genetic testing your dog's DNA for likely breeds is not only feasible these days, it's affordable. Dr. William Laegreid is a veterinarian at the University of Illinois College of Veterinary Medicine in Urbana who will soon be teaching medical genetics to students. He has a strong interest in the field, as well as decades of genetics research under his belt. "The commercial breed testing kits on the market seem to be reasonably accurate as long as your dog's background is not too complicated," he says.

Meaning, if your mutt is just a combination of a Labrador and a beagle then simple genetics like that are more easily sorted out than, let's say, a pet who has several generations of mixed breed heritage.

If determining your pet's parentage is too tempting, all you have to do is collect a DNA sample. Depending on the test kit and company you choose, sometimes you need a blood sample (which can be collected by your veterinarian), other times you'll need a simple cheek swab. As for accuracy, Dr. Laegreid says, "assuming the sample is taken properly, it shouldn't make any difference whether you use oral epithelial cells [a cheek sample] or blood."

From this point, the sample is shipped to a laboratory and some of the animal's DNA is sequenced. What makes a Chihuahua look different than a coonhound, or a boxer much taller than a bichon frise, is surprisingly, not that big of a difference when you actually look at the animals' genetic make-up.

DNA, as most of us know, is the basic blueprint for life. It is found in all of our cells, and is a way of "storing" information should we need to build another cell, or synthesize an enzyme. Within DNA are genes. All dogs have the same genes, but "what makes dogs look different is the sequence of the genes between individuals," explains Dr. Laegreid.

For example, all dogs (and humans) have a gene that makes insulin-like growth factor, a hormone that controls growth of almost every cell in the body. All dogs have the gene but a Jack Russell terrier is going to have a different sequence in its insulin-like growth factor "size" gene than a Great Dane. It is this sequence difference in a single gene that is a major determinant of body size in dogs.

It is these special sequences that allow an expert to sort out what type of breeds may be in your dog. But a word of warning, "this all really comes down to probability," notes Dr. Laegreid. If you send your dog's DNA sample off to several companies, as the Wall Street Journal did in a recent article, you may be surprised that you may not get back exactly the same breeds from all the companies.

In the end, DNA breed tests in dogs can be accurate, but they are not a 100 percent guarantee.

For more information, contact your local veterinarian.