Updates on DNA Canine Testing

http://news.vin.com/vinnews.aspx?articleId=23206

It’s a long article………here is an excerpt……………talking about Canine Heritage testing kit. (It appears that the Wisdom Panel had better results.) Article talks about testing mutts, purebreds and more.

The final dog we tested was Laika. Her owner, Dr. Maureen Roberts, is a veterinarian in California who tested Laika in 2007 when Canine Heritage first became available. We repeated that test to see if the results would be consistent, and to compare the results with Wisdom Panel’s. Here’s what we got:

2007: Canine Heritage reported Chinese shar-pei, Akita, Siberian husky and border collie as secondary breeds.

2012: Canine Heritage reported Siberian husky as a secondary breed, with border collie and Bernese mountain dog “in the mix.”

2012: Wisdom Panel determined Laika to be half Siberian husky and a melange of other breeds, possibly bull terrier, shiba inu, basenji, dachshund and greyhound.

Roberts found the results no more informative than her own guess about Laika’s lineage.

“Based on looking at Laika, I know she is a husky mix, but I don’t know what she is mixed with,” Roberts said. Of the possible breeds named in the three tests, the only one she finds believable is border collie.

From her experience, Roberts would not recommend DNA testing to determine breed. “I don’t think the test really tells us anything more than we can tell just by looking at the dog and making a guess,” she said. “Since I got different results even with the same company, it makes me pretty skeptical.”

Is this dog part beagle? By chance, Sidney’s DNA was run through the Mars Wisdom Panel Professional test twice last year. Both showed toy fox terrier and flat-coated retriever, but one detected 25 percent beagle, while the other showed no beagle at all. The inconsistent results led his owners to doubt the test’s validity.

Unplanned repeat test yields fickle result

In the midst of our project, we became aware of another dog that by chance was tested twice. The dog, Sidney, belongs to Dr. Luis Tarrido and his wife, Dr. Kelly Czech, veterinarians in New York state.

Using the Wisdom Panel Professional kit, they mailed a blood sample from Sidney that got lost in transit. Wisdom Panel provided a second kit at no charge, and the veterinarians sent in a second sample. A few weeks later, the lost sample made it to the laboratory. This time, the people at Wisdom Panel apparently did not notice they had run the same dog before. Sidney ended up getting back-to-back analyses.

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Is this dog part beagle? By chance, Sidney’s DNA was run through the Mars Wisdom Panel Professional test twice last year. Both showed toy fox terrier and flat-coated retriever, but one detected 25 percent beagle, while the other showed no beagle at all. The inconsistent results led his owners to doubt the test’s validity.

The results didn’t quite match.

One identified Sidney as a mix of flat-coated retriever, toy fox terrier, beagle and an assortment of other breeds.

The other showed Sidney as toy fox terrier, flat-coated retriever and assorted others.

The list of possible other breeds named were fairly consistent: The first test results identified Chihuahua, Australian shepherd, Finnish spitz, miniature dachshund and weimaraner. The second had the same breeds with the exception of the spitz. That analysis detected rat terrier instead.

But the beagle’s disappearing act Tarrido found hard to swallow.

Reporting his experience on a message board  of VIN, Tarrido wrote: “I know that the mixed-breed make-up percentage might be a little off and might vary a little but (for) the beagle to not be there … come on!?”

Tarrido called Wisdom Panel and spoke with geneticist Hughes. She reviewed the results, and discovered that the statistical confidence in the beagle finding was marginal. “When you delve into the data, it was at a low confidence; as low as you can get and still make it onto the chart,” Hughes told the VIN News Service.

She dubbed the beagle report a mistake. “It falls into our 10 percent (possibility of) false-positive or false-negative,” Hughes said.

Interestingly, Tarrido noted that Sidney “does have a beagle bark, unfortunately … that I get to hear every night.”

To the general consumer, a DNA test for breed may project an aura of scientific precision. But as our six test dogs plus Sidney demonstrate, the analyses are not exact. Bell, the veterinary geneticist at Tufts, said the commercial tests should not be confused with highly accurate medical diagnostic genetic tests.

“A mixed-breed ancestry test is a non-diagnostic novelty test that is consumer-driven,” he said.

“The science of these tests can be compared to trying to deconstruct the ingredients of a complicated recipe – maybe there’s some of this, or maybe some of that. While we would like it to be as accurate as possible, no medical decisions are going to be based on it. For the consumer, it is probably more important that they are happy with the results than their exactness.”

As Hughes sees it, DNA testing is much more accurate than someone looking at a dog and surmising its heritage. “Our brains are able to handle one, maybe two breeds and put them together, but when you talk about 9 percent giant schnauzer and 14 percent German shepherd, we can’t figure it out,” she said. “Genetic testing is a significant improvement over visual identification.”

That hasn’t been definitively proven, although one team of researchers did compare the results of visual breed identification with genetic identification in a study of 20 dogs with unknown parentage. Looking at what breeds the dogs were said to be by their respective adoption agencies and what the DNA results showed, the researchers found a sizable discrepancy: the two methods agreed less than one-third of the time.

The study, “Comparison of Adoption Agency Breed Identification and DNA Breed Identification of Dogs,” appeared in the Journal of Applied Animal Welfare Science in 2009. The lead author, Dr. Victoria Voith, a professor of animal behavior at Western University, presented the findings at a conference of the American Veterinary Medical Association that year, saying the results raise questions about the validity and enforcement of breed-specific policies.

Do a mutt’s breeds matter?

What breeds comprise a mutt is clearly interesting to most, if not all, dog owners, but beyond simple curiosity, is there any value to knowing?

Giger, head of the clinical program in medical genetics and pediatrics at UPenn’s veterinary school, thinks so — especially if the information is available when the dog is a puppy or before it is adopted. “It’s important when considering a puppy, and it’s tiny and cute and you would like to know how big it’s going to get,” he said.

Similarly, it would be helpful to know its likely behavior, (such as) if a dog has a herding background, in order to place it in the proper home, Giger added. “One wouldn’t want to place it into an apartment where it might go berserk because of boredom.”

The test makers maintain that knowing breed background enables owners and their veterinarians to better target a dog’s health care, alerting them to watch for diseases to which the dog’s breeds are prone.

Hughes often tells a story of her own dog, Rimsky, whom she adopted as an older puppy from a shelter in Sacramento, Calif. The shelter called him a border collie because he was white with black spots, but when his weight topped out around 20 pounds and he developed a feathered coat, Hughes described him as “an overgrown papillon.” At age 5, Rimsky had an episode of frantic scratching at his face and seemed to be choking. Hughes rushed him to an emergency hospital but even before they arrived, he appeared to fully recover, and no cause for his distress could be found.

Six months later, Rimsky had a grand mal seizure. Eventually, he was diagnosed with epilepsy. Hughes believes now that during the face-scratching episode, Rimsky was having a smaller seizure. Years later, when the breed test became available, she tested him. The result said he was part cocker spaniel, part Maltese and other blends. “It made so much more sense,” Hughes said, because cocker spaniels are prone to epilepsy. Had she known his breeds earlier, she may have made the connection to his condition sooner, she said, resulting in less anxiety for her and earlier treatment for him.

Hughes’ personal experience notwithstanding, the notion of tailoring medical care to the results of a DNA mixed-breed lineage test is not widely held. Casal, the veterinary geneticist from UPenn, suggested it is driven more by marketing than science. She said that a dog made up in large measure of one breed might be predisposed to health conditions particular to that breed, but such dogs are likely to be identifiable without needing a DNA test.

“If your dog comes back, for example, 80 percent poodle, then you might actually worry about Addison’s,” she said, speaking of an adrenal-gland disease common to poodles. But in that case, the dog would be apt to look like a poodle, she said. Its veterinarian, therefore, probably already would be on the lookout for health conditions associated with poodles.

Test makers also maintain that knowing a dog’s breed background can make training it easier. Veterinary behaviorists consulted by the VIN News Service said that may be true up to a point.

Dr. Laurie Bergman, a specialist in veterinary behavior, said: “I guess it can help somewhat in terms of helping owners have a better understanding of their dogs but even with purebreds you do get variations in behaviors, even the behaviors that those breeds were selected for ….

“More important than a breed test in successfully training any dog is understanding positive reinforcement training,” Bergman said. “… Find what motivates your dog (which may or may not be shaped by breed) and use that to reward the dog.”

Another behavior specialist and consultant, Dr. Ellen Lindell, had a somewhat different take. “It could indeed be helpful to know the breed background of your dog,” she said.

“We have bred certain types of dogs, to be called purebred, and to exhibit useful behaviors in a somewhat predictable manner,” she elaborated. “Some terriers may herd sheep, but if you have plans to participate in herding trials or need a dog to manage livestock on your farm, you would probably seek a dog from the herding group, rather than rely on the hope that your digger/rodent-killer might want a side job herding sheep.”

She continued: “Purebred dogs were separated into groups based on their functions, not on appearance.” For instance, she said, “Since terriers and hounds work independently, they might not be as sensitive to owner cues. Herding dogs are ultra vigilant — bred to follow subtle movements and notice all sounds. Inexperienced owners might not give these dogs enough information. Most dogs in the working group were bred to guard, so if a person with a working dog wants an open-door policy, then that person will need to work extra hard to teach the dog that everyone is welcome. So yes, it can help people to know what to expect so (as to) make better matches and help establish reasonable goals.”

But she cautioned that breed isn’t a sole determinant. “Of course there can be variation within a breed,” Lindell said. “Each individual dog should always be evaluated based on his own behavior.”

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