Can
“Spot” spot cancer, diabetes, Parkinson’s disease and more? We’ve
rounded up some of what the initial research shows so far — and it’s not just
fluff.
“The
full potential of dogs to detect human disease is just beginning to be
understood,” says Claire Guest, chief
executive of a U.K.-based organization called Medical
Detection Dogs, which trains “biodetection dogs”
(involved in some of the research cited below). “If all diseases have an
odor, which we have reason to believe they do, we can use dogs to identify
them.”
Sniffing
out the latest studies
Several
media outlets reported this fall that scientists are currently training dogs to sniff out the scent of malaria, which
is on the rise and especially deadly in children. In October, researchers
announced at the American Society of Tropical Medicine and Hygiene conference
that two dogs correctly detected malaria in children (who appeared healthy,
without symptoms) 70 percent of the time.
Following
this small “proof of concept” study funded by the Bill & Melinda
Gates Foundation, researchers will continue to work on training biodetection
dogs and also try to develop a device that could one day mimic what the dog’s
nose does — pick up scents or compounds associated with diseases.
What
other diseases or conditions might dogs be able to detect? While many of these
studies are small and call for additional research, here’s what scientists have
found so far:
- Prostate cancer – In
a small 2015 study, Italian researchers
found that two German Shepherd explosive detection dogs correctly identified
prostate cancer compounds in urine samples 95% of the time (which STAT notes is “more
accurate than the prostate-specific antigen test used to screen for prostate
cancer”).
- Colorectal cancer – A 2011 study published in BMJ found
that a Labrador retriever specifically trained to detect cancer could identify
the breath and stool samples of people with colorectal cancer with high
accuracy. The dog would sniff the sample, then sit down if cancer compounds
were present. “The accuracy of canine scent detection was high even for
early cancer,” the researchers say.
- Breast and lung cancer – The
researchers behind this
2006 study said, “In a matter of weeks, ordinary household dogs
with only basic behavioral ‘puppy training’ were trained to accurately
distinguish breath samples of lung and breast cancer patients from those of
controls.” (How were the dogs trained/rewarded? FOOD!)
- Melanoma (skin cancer) – A 2004 study (in an animal
behavior journal) found that “two dogs demonstrated reliable localization
of melanoma tissue samples hidden on the skin of healthy volunteers.”
As this article summarizes, a 1989
report in the journal Lancet says a woman’s border collie mix kept sniffing a
mole on her thigh (and even tried to bite it off) while ignoring other moles —
and said mole turned out to be malignant melanoma.
- Bladder cancer – In
this 2004 “proof of principal” study in the BMJ, six
trained dogs had a mean success rate of 41% in correctly selecting urine from
patients with bladder cancer (on 22 out of 54 occasions). More research is
needed.
- Parkinson’s disease – Parkinson’s UK and
the Michael J. Fox Foundation have
teamed up to fund research into biodetection dogs for PD. “Two Labradors
and a cocker spaniel will next week start work on swabs from 700 people to spot
a smell that appears years before people start experiencing mobility
problems,” Parkinson’s UK reported when the research kicked off in summer
2017. Stay tuned.
- Diabetes and other conditions – Several
other studies have shown that dogs may be useful in other types of
“biodetection” beyond diagnosis. For example, they could give alerts
about oncoming low blood sugar (hypoglycemia) in
people with diabetes, or other types of
imminent episodes, such as narcolepsy, migraine and seizures.
Seems
like dogs are onto something! STAT cautions that “much more work is
needed, as dogs haven’t done as well on more rigorous tests in
some cases [of cancer detection].”
Why are
dogs such super-sniffers?
Dogs
are known for their noses, but exactly what is so special about them?
- Wired reports that dogs’
sense of smell is “powerful enough to detect substances at concentrations
of one part per trillion—a single drop of liquid in 20 Olympic-size swimming
pools.”
- “Dogs
have something called neophilia, which means they are attracted to new and
interesting odors,” according to Guest, of Medical Detection Dogs.
- Scientists estimate that a dog’s sense of smell is 10,000 to
100,000 times more acute than a human’s, NOVA/PBS reports.
“If you make the analogy to vision, what you and I can see at a third of a
mile, a dog could see more than 3,000 miles away and still see as well,”
says researcher James Walker, the former director of Florida State University’s
Sensory Research Institute.
- Dogs
even have an additional organ called the vomeronasal organ (also known as
Jacobson’s organ) to help them pick up scents.
Pretty
neat! We’ll certainly be nuzzling our pups’ muzzles a little closer now.
What do
you think about the potential for dogs to be “biodetectors”? Join
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