“What kind of dog is that?”
If you’re the owner of an offbeat canine who’s obviously a classic Heinz 57 mix of multiple breeds, you’re familiar with this question. And while it’s fun to imagine which branches might be included in your particular dog’s family tree, it can be frustrating not to know.
But there’s no need to guess — or get creative — when people ask about your dog’s ancestry. The answers lie in his genes.
A dog DNA test can shed some light on your mutt’s heritage. And while it may seem like fun to know what kinds of dog your fur friend is descended from, there’s more to DNA testing than just identifying a dog’s lineage. “Knowing your dog’s breed makeup can help you tailor his training and help you be on the lookout for breed-specific diseases,” says Dr. Marty Becker. “We’ve had all six of our mixed-breed dogs at Almost Heaven Ranch tested for that reason.”
If you’re thinking of DNA testing for your dog, here’s what to consider.
How Canine DNA Tests Work
A basic dog DNA kit includes everything you’ll need to prepare a sample for testing. The process is pretty simple: In most cases, you will swab the inside of your dog’s cheek with the provided brush for up to a minute to collect cheek cells in saliva containing DNA. Some kits ask for blood samples, which will need to be drawn at your veterinarian’s office. While blood samples yield larger amounts of DNA, both blood and saliva provide accurate results. For genotyping — the process of determining an individual’s unique genetic makeup — DNA from saliva is sufficient. “Assuming a sample has enough DNA, there’s no difference to us analyzing genotyping data from a saliva and blood sample,” says Adam Boyko, Ph.D., an assistant professor in biomedical sciences at Cornell University College of Veterinary Medicine and founder and chief science officer of Embark Veterinary, a canine genetic-testing company.
Once you have collected your samples, you’ll mail them back (in the provided packaging) for analysis at a laboratory.
When the sample arrives at the lab, the DNA is extracted and examined for genetic markers — areas where a dog’s DNA varies — from breed databases. Your dog’s DNA is compared with that of other dogs in the database. “All dog DNA tests on the market today have reference panels of breed dogs that encompass the vast majority of dog registrations in the U.S. and Europe,” Dr. Boyko says. The latest version of the Mars Wisdom Panel, for instance, covers more than 250 breeds, types and varieties of dogs. The test was developed with samples from more than 13,000 purebred dogs and has 1,800 genetic markers.
Embark’s test includes more than 150 breeds of dogs, as well as wolves, coyotes and “village dogs,” which are indigenous semi-feral dogs found around the world. The “chip” on which the test is run has more than 200,000 markers.
A test’s accuracy depends on numerous factors, including the number of markers used, the number of breeds included in the breed panel and the sophistication of the algorithms. For example, some tests may have breed panels with only 50 or 60 breeds. Their results will not be as detailed or accurate as those with 100 or more breeds.
“Mixed-breed DNA tests are as accurate as the diversity of samples they are based on and the computerized algorithms used to generate the results,” says Jerold S. Bell, DVM, a canine geneticist at the Cummings School of Veterinary Medicine at Tufts University. “Dogs that are first-generation offspring of two pure breeds will have the most accurate results.”
Depending on the test, results generally take two to eight weeks to arrive.
Beyond Breed ID
Canine DNA tests can tell you a variety of things about your dog, starting with what breeds make him who he is. Pam Becker of Lake Forest, California, discovered from the Mars Wisdom Panel that her dog Roxy was 50 percent Cocker Spaniel and 25 percent each Lhasa Apso and Shih Tzu. Becker had Roxy tested primarily out of curiosity. Roxy’s groomer had suggested that the dog was a Cockapoo (a Cocker Spaniel/Miniature Poodle cross). Becker said the Cocker part made sense to her based on Roxy’s size but that her dog’s other physical characteristics seemed more like those of a Lhasa than a Poodle. The results bore that out.
“I think it was pretty accurate, and I’m happy I did it,” she says.
But DNA tests may be able to tell you more than just what your dog is. Besides an individualized report on the breeds that make up your dog’s ancestry, some tests now provide genetic health information as well. That’s the future, says Urs Giger, DVM, a canine geneticist at the University of Pennsylvania School of Veterinary Medicine and co-author of a study on the potential of genetic panel screening as a diagnostic and research tool in veterinary care, research and breeding published last August in the journal PLoS One.
According to Dr. Giger, genetic disease screening that was originally done for specific diseases in certain breeds is now expanding to these panel tests. As panel screening tests become more common, researchers may discover, for instance, that known disease alleles (alternative forms of genes caused by mutations) are more widespread across different breeds than previously known.
Embark screens for 160 genetic diseases. They range from common conditions such as MDR1 sensitivity, von Willebrand disease and progressive retinal atrophy to some you might never have heard of, such as complement 3 deficiency (which can make dogs highly susceptible to infections and kidney disease) and polyneuropathy — a neurologic disease that can cause generalized limb weakness, difficulty walking and other signs that get progressively worse.
Roxy’s Wisdom Panel test found that she had two normal copies of the MDR1 gene, meaning she wasn’t at risk for side effects from certain drugs. She’s also free of the gene mutation that causes exercise-induced collapse. That makes sense because her ancestry doesn’t include any of the breeds that tend to be prone to those problems.
The results aren’t the same as a true diagnostic test, Dr. Boyko says, but the information these tests provide can help owners and veterinarians predict or rule out certain conditions. “Our goal is to give you and your veterinarian comprehensive genetic information in an accessible way,” he says, “so that you can avoid needless laboratory tests and get to the right diagnosis more quickly or even avoid certain diseases before they start by knowing your dog is at risk and taking appropriate measures.”
By Kim Campbell Thornton | Vetstreet.com
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