|
The
Wilson family had puzzled over their mutt Drake’s
distinctive behavior ever since they brought him home
from the Washington Animal Rescue League four years ago.
Workers
at the shelter told them the dog was a mix of spaniel
and Plott hound. But his propensity to leap over
four-foot fences and herd family members as if they were
livestock had them thinking border collie.
The
answer to Drake’s past came in the form of a $65 DNA
test that promised to scour his genes for telltale signs
of the breeds in his family tree. “We were always
curious as to what breeds went together to create him,”
Marcy Wilson said. “We just assumed we could never find
out.”
Not long
ago, genetic testing was a rarefied pursuit used
primarily to settle paternity suits, diagnose medical
conditions and identify rapists and killers.
Now DNA
testing has gone to the dogs. With sequencing technology
becoming less expensive, dog owners are having their
pets tested—and sometimes finding that unraveling the
mysteries of their genetic code can be a mixed blessing.
For less
money than a luxury shampoo and doggy massage, owners of
Canis familiaris can uncover their pooch’s
ancestry or take an inventory of its constituent breeds.
The tests can also reveal debilitating health problems
and other genetic surprises.
“If
you’re an animal lover, you can’t resist this,” said Jan
Lovelady, a nurse administrator in
Gilbert,
Arizona,
who had her mutt’s DNA analyzed to see which breeds were
in his lineage.
Half a
dozen or so dog DNA-analysis companies have sprouted
across the country and peddle their services at dog
shows and over the Internet. The firms guard their sales
figures closely, but each claims to have tested several
hundred to several thousand dogs.
The DNA
of 400,000 purebred dams and sires has been registered
with the American Kennel Club, which has required
breeders to submit genetic samples since 1998.
But the
rush to genetically type man’s best friends has raised
many of the same concerns as the typing of man himself.
“It’s
one more way of codifying the American cultural belief
in genes as the foundation of everything important,”
said Donna Haraway, a historian of science and culture
at UC Santa Cruz. “I find it mildly disgusting.”
Then
again, as the proud owner of two dogs, she added: “I
might actually buy such a test.”
Dog DNA
tests generally fall into three categories: proof of
maternity or paternity, genealogy, and identification of
mutations associated with disease. Genetic tests are
available for other animals — to determine the sex of
birds, for instance, or the coat color that cats may
pass to their kittens.
Far more
can be gleaned about dogs because of their use in
medical research for human diseases, including cancer,
heart disease, blindness, epilepsy and diabetes. The
complete dog genome was published in 2005, making it the
fifth mammalian genome decoded, after humans, mice, rats
and chimpanzees.
The
earliest consumer tests stemmed from the American Kennel
Club’s attempts to ensure the validity of pedigrees for
155 breeds of dogs.
As it
turned out, the DNA evidence cast a shadow on the
scrupulous record-keeping that is the hallmark of elite
purebreds.
When the
policy was implemented nine years ago, random
inspections found that 13 percent of puppies had the
wrong parents listed on their pedigrees, said club
spokeswoman Lisa Peterson.
Some of
those cases involved legitimate mix-ups, because puppies
in the same litter can have different fathers. But there
were also cases that involved unscrupulous breeders
falsifying information on a pedigree to boost the
puppy’s value.
“Whenever there’s a question about the parents, it
raises questions about the integrity of the breeder,”
said Randall Smith, manager for DDC Veterinary, a
Fairfield, Ohio, company that tests tens of thousands of
animal DNA samples each year.
Today,
the pedigree error rate has dropped to about 4 percent,
according to the AKC.
Genetic
tests have proven a powerful tool for breeders to
continue shaping the evolution of dogs, which began more
than 15,000 years ago when a few curious wolves ventured
into ancient human encampments. Selecting for desired
traits like docility and obedience, prehistoric people
domesticated those animals and created a new species.
But
hundreds of years of inbreeding to create modern
purebred dogs has come at a cost. Certain breeds have
persistent genetic problems cemented into their DNA. A
crippling joint ailment known as hip dysplasia, for
instance, is common among German shepherds,
Labrador retrievers, Rottweilers and other large dogs.
Joan
Bendure, who breeds Portuguese water dogs in Fairview,
Pennsylvania, became interested in canine genetics when
two of her dogs were diagnosed with progressive retinal
atrophy, a disease that attacks peripheral and nighttime
vision before leading to blindness.
The
disease “destroyed a lot of kennels,” she said. “For me,
it took four dogs out of the breeding pool and left me
with one.” Bendure and other Portuguese water-dog owners
recruited a pair of ophthalmologists to study the
disease and sent them DNA samples from their blind dogs.
The
researchers zeroed in on the gene responsible and
discovered that it took two faulty copies to make a dog
go blind. Dogs carrying a single defective copy from one
parent were not affected.
With a
genetic test in hand, it became possible to breed dogs
with one mutated gene as long as their mates were
“clean.” That helped keep the gene pool bigger and the
overall population healthier, Bendure said. “If you
don’t have healthy dogs, it doesn’t matter how beautiful
they are,” she said.
For many
dog owners, the allure of peering into DNA stems from a
simpler desire. No matter how well they think they know
their dog, there is always a sense of mystery about
them.
Rob and
Carole Sims of
Morrisville,
North Carolina,
turned to DNA to answer a question that had stumped them
for years: How could their two golden retrievers—born of
the same mother and father—be so maddeningly different?
Liberty
was gentle, mild-mannered and easy to train; Justice was
the complete opposite. It drove the Simses crazy. Had
there been a mix-up at the kennel? Did they take home
the wrong dog?
Rob Sims
mailed swabs from the dogs’ cheeks to a lab in Ohio that
charged $35 for each test. The results arrived 10 days
later.
“As
soon as you open the report, it’s crystal clear—they’re
sisters,” he said.
The DNA
results did little to explain why the sisters were so
different. But it helped him to accept Justice for the
dog that she is.
As the
dogs have grown, he has even come to embrace their
differences. He compares them to his daughters, Audra
and Nicole, one a forest service investigator and the
other a high-school computer science teacher.
“I have
to say in retrospect, I’m absolutely delighted that we
have Liberty and Justice,” he said.
A more
elaborate test was necessary to parse out the various
breeds that made up Marcy and Rip Wilsons’ dog, Drake.
Tests to
determine various breeds examine specific points in a
dog’s DNA and look for signature patterns that are known
to be correlated with specific breeds.
“It’s
just like when people say, ‘Where’d your ancestors come
from?’” said Elaine Ostrander, who helped develop one
such test while searching for genes to study cancer in
dogs at the Fred Hutchinson Cancer Research Center in
Seattle.
The
result is a blood test that can detect DNA contributions
from 134 recognized breeds. Mars Veterinary will begin
selling it through vet offices next month under the name
Wisdom Panel.
The
Wilsons used a $65 Canine Heritage Breed Test from MMI
Genomics Inc. of Davis, Calif. The test looks at 96
points and can identify 38 breeds that encompass 75% of
all dogs.
“We
always thought he was a border collie,” Marcy Wilson
said. “If we go anywhere near the foyer of the house, he
will come from whatever room he’s in and try to herd us
out the door.”
While
they waited for Drake’s test results, the four family
members placed $1 bets on his true heritage. “We were
all guessing border collie, chow and lower levels of lab
and spaniel,” Marcy Wilson said.
They
were right about the
Labrador and spaniel genes, but none of them expected that the test would
conclude he was more Siberian husky than anything else.
After the results came in, Rip Wilson spent hours
reading up on huskies to better understand his dog’s
true nature.
In
retrospect, said the biotech executive, the family
shouldn’t have been so surprised. Drake’s proclivity for
digging holes near the backyard azalea bush turned out
to be a characteristic husky trait.
And
that’s not all.
“He
adores the snow —he’ll just hang outside in the snow for
hours,” Rip Wilson said. “I never clued in on it.” |
