Dogs Smell Signs of Cancer
Small study found they accurately detected presence of
disease in human breath samples.
Dogs have long been used to sniff out explosives,
narcotics, and even counterfeit currency. Now, a new study
shows that man's best friend can also detect lung and
breast cancer in breath samples.
"When we heard anecdotally that there was a device out
there that might be able to detect cancer at its earliest
stages, before it even shows up on an MRI [magnetic
resonance imaging], it was something we wanted to
pursue," said Nicholas Broffman, executive director of the
Pine Street Foundation, a nonprofit group in California that
conducted the study. The group helps cancer patients who
are facing tough treatment decisions.
That device, of course, is a dog, and researchers believe it
picks up on chemical differences that linger in the breath
of a person with cancer. While canines won't ever replace
standard medical testing, experts think they may become
an important early screening tool in the future.
In this study, three Labrador retrievers and two
Portuguese water dogs were trained for a few weeks to
either sit or lay down in front of breath samples from lung
and breast cancer patients, while ignoring those of healthy
The trial comprised of breath samples from 55 patients
with lung cancer, 31 with breast cancer, and 83 healthy
people. The samples were captured in special tubes. All
cancer patients had recently been diagnosed through
conventional methods, such as mammograms or CT
scans, but had not yet begun chemotherapy. And the trial
samples were different from the ones used to train the
The results show the dogs were 88 percent to 97 percent
accurate in identifying both early- and late-stage breast
and lung cancers.
The ability of dogs to detect cancer was first discovered in
1989, and reported in the medical journal, The Lancet. A
woman's pet had alerted her to the presence of melanoma
by constantly sniffing the skin lesion on her leg.
Subsequent studies have shown, dogs can smell
melanoma and bladder cancer.
A dog's nose is so powerful, it can detect odours 10,000 to
100,000 times better than a human nose can. Later this
year, the research team plans to launch a study on canine
detection of bladder cancer.
In the past, dogs are trained to find everything from drugs
to off-flavoured catfish, but it usually takes him five to six
weeks. The U.S. Military spends about three months,
training explosive detection dogs.
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