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Excerpted from "What
Do Dogs Know?":
Dogs
can sense more than just oncoming seizures. Richard Simmons, a research
associate working on a project supported in part by the U.S. National
Institutes of Health, told me a story about Marilyn Zuckerman of New
York and her Shetland sheepdog, Tricia.
Tricia had developed the annoying habit of
sniffing or nuzzling Marilyn's lower back whenever she sat down.
Marilyn's husband looked and noticed that there was a dark mole in the
location that Tricia seemed to be interested in. It seemed odd that the
dog cared about this mole, but since it caused no discomfort, Marilyn
just ignored it. One spring day, though, Marilyn was lying face down on
her balcony in a bathing suit, simply enjoying the sunshine when
suddenly she felt teeth on her back. It was Tricia, who apparently was
trying to remove the mole.
Marilyn's husband suggested that there must be
something odd about the mole if it was bothering the dog that much. More
out of curiosity than anything else, Marilyn showed it to her doctor.
Before the day was out, Marilyn was at the Cornell Medical Center; where
the mole was diagnosed as skin cancer -- actually a virulent and
potentially fatal form of melanoma. Tricia's early warning probably
saved Marilyn's life.
As Simmons told me: "it was because of stories
like Marilyn's that we began testing dogs' diagnostic abilities. Our
preliminary data suggests that dogs can detect melanomas and several
other types of cancer well before there is any other indication of a
problem. Some dogs will show agitation the moment a person with cancer
enters the room. It may well be that someday in the future, inspection
by a dog may become a routine part of cancer screening." |
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Why Do Dogs Have
Wet Noses?
Did you know that dogs can outrun an Olympic sprinter and "speak" three
languages? Or that they can tell when storms are coming and even predict
earthquakes before they happen? These are just a few of the doggone
fascinating facts to discover in this ultimate companion book for young
dog owners and admirers. World-renowned dog expert and author Dr.
Stanley Coren knows our four-legged friends better than anyone, and this
book is jam-packed with stories and photographs to engage and delight
children.
The Pawprints of
History: Dogs and the Course of Human Events
The Pawprints of History shines a new light on a favorite subject -- the
relationship between humans and their four-legged best friends. Stanley
Coren, a renowned expert on dog-human interactions, has combed the
annals of history and found captivating stories of how dogs have lent a
helping paw and influenced the actions, decisions, and fates of
well-known figures from every era and throughout the world.
As history's great figures strut across the
stage, Coren guides us from the wings, adoringly picking out the canine
cameos and giving every dog of distinction its day. In this unparalleled
chronicle, we see how Florence Nightingale's chance encounter with a
wounded dog changed her life by leading her to the vocation of nursing.
We learn why Dr. Freud's Chow Chow attended all of his therapy sessions
and how the life of the Fifth Dalai Lama was saved by a dog who shared
his bed. Dogs have even found their way to the battlefield -- great
military leaders such as Robert the Bruce and Omar Bradley have shared
their lives, exploits, and gunfire with dogs. From Wagner, who admitted
that one of the arias in the opera Siegfried was "written" by one of his
dogs, to the dogs that inspired and lived with Presidents Lincoln,
Roosevelt, Johnson, and Clinton, these loving canines do double duty as
loyal pets and creative muses.
From war to art, across the spectrum of human
endeavor and achievement, there often stands, not only at his side but
leading the way, man's beloved "best friend." For those who believe that
behind every great person is a good dog, the uplifting stories in The
Pawprints of History will be a lasting delight.
How Dogs Think :
Understanding the Canine Mind
With information not widely known to lay people, this lively guide also
provides practical advice and wisdom that allows owners to discover the
best ways to teach dogs new things, why punishment doesn't work, how a
dog can actually learn to love or to fear, and how to turn that new
puppy into a "perfect," emotionally sound, inquisitive, happy, and
obedient dog.
Combining solid science with numerous funny,
informative anecdotes and firsthand observations -- all characterized by
Dr. Coren's own searching intelligence and his (and sometimes his dogs')
irrepressible sense of humor -- How Dogs Think shatters many common
myths and misconceptions about our four-legged friends and reveals a
wealth of surprises about their mental abilities and intellectual
potential.
How To Speak Dog
At
long last, dogs will know just how smart their owners can be. By
unlocking the secrets of the hidden language of dogs, psychologist
Stanley Coren allows us into the doggy dialogue and makes two-way
communication a reality. For the first time, instead of receiving an
incomprehensible mash of mixed human signals, man's best friend will be
treated to the proper use of dog language. Finally, effective
communication can take place between canines and these "strange tall
dogs" who have mystified them for so long. (Available at bookstores
everywhere.)
Why We Love the Dogs We Do
"Why
We Love the Dogs We Do" is Coren's newest dog book to reach best-seller
status. It explores how the personality of people determines the
specific dog breeds that they will love and be happiest with. It has a
scientific basis, and is based on testing the personality of over 6000
people and determining the dogs they loved and hated from among the
breeds that they actually lived. Based on this information he created a
personality questionnaire that you can take, and the scores will tell
you which dog breeds you are most likely to be happiest with. You can
compare your choice of a dog to those of many celebrities and historical
people. However, what endeared this book the most to dog lovers, was the
extensive collection of stories of many well known people and their
relationship to their dogs.
What Do Dogs Know?
"What
Do Dogs Know?" which is co-authored by Jan Walker, has been called a
"touchingly hilarious, fact-filled book". It is a small book with a
collection of short true stories about dogs, their behaviors and their
relationship to people. There is history, folklore, humour, and science
all mixed together in a readable collection of dog related matter.
Perhaps the most interesting aspects of the book have to do with the
relationships between people and dogs.
The Intelligence
of Dogs
Perhaps
Coren's most popular book is "The Intelligence of Dogs." (This book went
into 16 printings in hard cover, and is still briskly selling in
paperback. It has also been translated into 18 languages.) This book
contains a facinating description of how dogs think, their mental
abilities, and the various types of dog intelligence. Perhaps one of its
most controversial, but intriguing, findings, was that there are
systematic and regular differences among the dog breeds in their working
and obedience intelligence. These findings, and the list ranking the
relative intelligence of dog breeds, became front page news in many
newspapers around the world.
Sleep Thieves
"Sleep
Thieves" was a startling book which pointed out the fact that as a
society we are all chronically sleep deprived. For example, what do the
nuclear accident at Chernobyl, the near melt down at Three Mile Island,
the environmentally disastrous oil spill by the Exxon Valdez, and the
loss of the NASA space shuttle Challenger all have in common? They were
all caused by people who were making mistakes because they had had too
little sleep. Coren not only reviews the scientific information about
sleep in a lively and interesting way, but also presents some first hand
interviews with people whose jobs or life style forces them to lose
sleep.
The Left-hander Syndrome
Coren's first best seller was "The left-hander
syndrome: the causes and consequences of left-handedness" now in
paperback
(Bantam Books). This best selling book was widely discussed in the media
because it not only talked about the nature and origin of
left-handedness, but also explored the startling research findings which
suggested that left-handers may have shortened lifespans.
Much of the book, contains interesting insights about handedness and
left-handers. For instance, he points out the kind of discrimination and
abuse that left-handers have had over the years, and how the very words
associated with the left have become negatively tinged. |
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Excerpted from "The
Intelligence of Dogs": For
example, over 200 professional dog obedience judges, ranked 110
dog breeds on the basis of their intelligence. According to them,
the top dozen dogs in terms of intelligence are:
| |
Rank Breed
1. Border Collies
2. Poodle
3. German Shepherd
4. Golden Retriever
5. Doberman Pincher
6. Shetland Sheepdog
7. Labrador Retriever
8. Papillon
9. Rottwieler
10. Australian Cattle Dog
11. Pembrook Welsh Corgi
12. Miniature Schnauzer
At the low end of the intelligence rankings are:
106. Borzoi
107. Chow Chow
108. Bull dog
109. Basenji
110. Afghan Hound |
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One of the more surprising things that
this book points out is that, depending upon your life style, it
may be more difficult to live with a more intelligent, rather than
a less intelligent dog. To quote from the book:
An example of how an intelligent dog can use bad behavior to
manipulate its owner comes from a single woman who owned a
Miniature Poodle named "Arnold". She inadvertently trained it to
urinate on her bed whenever she had a male guest stay over at her
house. She interpreted this behavior as "jealousy" on Arnold's
part. The real problem was that the dog was simply too smart. When
the owner was by herself she paid a good deal of attention to the
dog. However, she fell into the trap that many of us do, and paid
more attention to the dogs misbehaviors than to its desirable
activities. One particularly undesirable behavior, which brought a
lot of attention, was urinating on the bed. However, the woman
managed to break the dog of the habit, and was confident that it
was now under control. Whenever her boyfriend came to visit,
however, she paid considerably more attention to her guest and
consequently less attention to the dog. Arnold remembered the
amount of social contact which was engendered by urinating on the
bed, and was smart enough to understand that this behavior would
work in the present conditions. The end result was obvious.
Whenever she hosted a male guest, the dog would head for the
bedroom with malice aforethought. It was a guaranteed method of
gaining attention.
Intelligent dogs are inadvertently taught many unwanted behaviors.
Increasing the activity level in a household, and increasing the
number of people that are present in it, increases the likelihood
that chance associations will be learned. For the intelligent dog
this means that there is a greater opportunity to learn things
that will be useful in adapting to everyday life, but also
provides a greater opportunity for the dog to learn "odd" or
annoying associations. Consider the case of "Prince", a Border
Collie whose great joy in life was to race around outdoors.
Whenever someone was about to leave the house Prince would race
after them, trying to get outside. Once, after Prince had started
his mad dash for the exit, the screen door swung closed and the
dog ended up crashing through the wire mesh. Rewarded by the
chance to romp outside, the dog learned from this one instance
that it could create its own "doggie door" by simply running full
tilt at the screen. After several repairs had been attempted,
Prince's owners added a protective layer of heavy farm wire that
the dog could not break through. Frustrated by this new
development Prince began casting around the house and noticed that
many of the windows were open and only covered by the same
material that used to cover the screen door. For this intelligent
dog it was easy to reach the conclusion that these windows could
also be used as exits.
Instantaneously, every open ground floor
window then became a target Prince's headlong rush for the joys of
the outdoors, much to the dismay and annoyance of the dog's
owners. A less intelligent dog would have been considerably less
likely to form the association that crashing through the screen
results in outdoor time, based upon a single instance.
Furthermore, when confronted with the obstacle of the heavy wire
over the door screen, the less intelligent dog would have been
considerably less likely to generalize its knowledge and apply its
newly learned information to windows or other screened apertures.
Simply put, the less intelligent dog will miss many of these
chance contingencies and hence will move through the noise and
chaos of a busy household without learning bad habits from only
one or two associations.
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1b
I had great hope of finally finding a way to solve my mold smell problem so I
wrote to www.Mold-Dog.com
----- Original Message -----
Sent: Tuesday, July 31, 2007
1:20 PM
Subject: Mold Dog Information
Request
Hi, I am looking to find a mold
dog in Houston Texas. We have a mold smell but can not find the source of it.
Please advise of the contact
information of someone in this city. Brian Nelson 31 Gessner Rd. Houston, TX
77024 713-467-3025. Fax 713-467-3192 Thanks
1c
. Sad news in the letter I received
below. They don't have any trained dogs in Houston. This would be a
great opportunity to get into a business area with very little
competition. If you do then call me and I will help you market
your mold dog business. In the mean time if you know of any business in
Houston that uses a dog to detect mold please have call me or email me.
Click: E-mail me
713-467-3025. Fax
713-467-3192
See my website about Dogs Detecting Cancer.
http://www.newmedicaldirectories.com/Dogs-Detecting-Cancer/Fact-Or-Fiction.html
-1d
---- Original
Message -----
Sent: Wednesday, August 01, 2007
10:42 AM
Subject: Re: Mold Dog Information
Request
I'm sorry we don't have any
certified mold dogs in texas from our academy
Master Canine Trainer, Bill Whitstine
Florida Canine Academy, Inc.
19 Marshall St.
Safety Harbor, FL 34695
direct phone 813-267-5925, toll free 1-800-665-3364
www.mold-dog.com
fax: 727-791-4343
|
Blue Box 1
Scan Below
|
Published: January 17, 2006
In the small world of people who train dogs to sniff
cancer, a little-known Northern California clinic has made a big claim:
that it has trained five dogs -- three Labradors and two Portuguese water
dogs -- to detect lung cancer in the breath of cancer sufferers with 99
percent accuracy.
The study was based on well-established concepts.
It has been known since the 80's that tumors exude tiny amounts of alkanes
and benzene derivatives not found in healthy tissue.
Other researchers have shown that dogs, whose
noses can pick up odors in the low parts-per-billion range, can be trained
to detect skin cancers or react differently to dried urine from healthy
people and those with bladder cancer, but never with such remarkable
consistency.
The near-perfection in the clinic's study, as Dr.
Donald Berry, the chairman of biostatistics at M. D. Anderson Cancer
Center in Houston, put it, ''is off the charts: there are no laboratory
tests as good as this, not Pap tests, not diabetes tests, nothing.''
As a result, he and other cancer experts say they
are skeptical, but intrigued. Michael McCulloch, research director for the
Pine Street Foundation in Marin County, Calif., and the lead researcher on
the study, acknowledged that the results seemed too good to be true. (For
breast cancer, with a smaller number of samples, the dogs were right about
88 percent of the time with almost no false positives, which compares
favorably to mammograms.)
''Yes, we were astounded, as well,'' Mr.
McCulloch said. ''And that's why it needs to be replicated with other
dogs, plus chemical analysis of what's in the breath.''
He is applying for National Science Foundation
grants to try just that, he said. The fact that the study was carried out
by a clinic supported by the Pine Street Foundation that combines
traditional chemotherapy with acupuncture and herbal medicine raised
suspicions, as did the fact that it is to be published by a little-known
journal, Integrative Cancer Therapies. (The journal published it online
last year.)
But experts who read the study could not find any
obvious fatal flaw in its methodology, and the idea that dogs can detect
cancer is ''not crazy at all,'' said Dr. Ted Gansler, director of medical
content in health information for the American Cancer Society. ''It's
biologically plausible,'' he said, ''but there has to be a lot more study
and confirmation of effectiveness.''
Dr. Berry, too, was interested but suspicious.
''If true, it's huge,'' he said. ''Which is one reason to be skeptical.''
Dr. Berry noted, half-jokingly, that Gregor
Mendel, the 19th-century discoverer of the laws of genetics, also reported
data on his crossbreeding of green and yellow peas that was too good to be
true: he repeatedly came up with the perfect 3-1 ratios he predicted.
''But we've forgiven Mendel and his gardener,'' Dr. Berry added, ''because
his theory turned out to be right.''
In Mr. McCulloch's study, the five dogs, borrowed
from owners and Guide Dogs for the Blind, were trained as if detecting
bombs. They repeatedly heard a clicker and got a treat when they found a
desired odor in many identical smelling spots.
The clinic collected breath samples in plastic
tubes filled with polypropylene wool from 55 people just after biopsies
found lung cancer and from 31 patients with breast cancer, as well as from
83 healthy volunteers.
The tubes were numbered, and then placed in
plastic boxes and presented to the dogs, five at a time. If the dog
smelled cancer, it was supposed to sit.
For breath from lung cancer patients, Mr.
McCulloch reported, the dogs correctly sat 564 times and incorrectly 10
times. (By adjusting for other factors, the researchers determined the
accuracy rate at 99 percent.)
For the breath from healthy patients, they sat 4
times and did not sit 708 times.
Experts who read the study raised various
objections: The smells of chemotherapy or smoking would be clues, they
said. Or the healthy breath samples could have been collected in a
different room on different days. Or the dogs could pick up subtle cues --
like the tiny, unintentional movements of observers picked up by Clever
Hans, the 19th-century ''counting horse,'' as he neared a correct answer.
But Mr. McCulloch said cancer patients who had begun chemotherapy were
excluded, smokers were included in both groups and the breath samples were
collected in the same rooms on the same days. The tubes were numbered
elsewhere, he said, and the only assistant who knew which samples were
cancerous was out of the room while the dogs were working.
|
Diagnostic Accuracy of Canine Scent Detection in Early- and Late-Stage Lung
and Breast Cancers
Michael McCulloch Pine
Street Foundation, San Anselmo, California,
mcculloch@pinestreetfoundation.org
Tadeusz Jezierski Polish
Academy of Sciences, Institute of Genetics and Animal Breeding, Jastrzebiec,
Poland
Michael Broffman Pine
Street Foundation, San Anselmo, California
Alan Hubbard University
of California at Berkeley
Kirk Turner EZ Train, El
Sobrante, California
Teresa Janecki
Centerville, Utah
Background:
Lung and breast cancers are leading causes of cancer
death worldwide. Prior exploratory work has shown that patterns
of biochemical markers have been found in the exhaled breath
of patients with lung and breast cancers that are distinguishable
from those of controls. However, chemical analysis of exhaled
breath has not shown suitability for individual clinical diagnosis.
Methods:
The authors used a food reward-based method of training 5
ordinary household dogs to distinguish, by scent alone, exhaled
breath samples of 55 lung and 31 breast cancer patients from
those of 83 healthy controls. A correct indication of cancer
samples by the dogs was sitting/lying in front of the sample. A
correct response to control samples was to ignore the sample. The
authors first trained the dogs in a 3-phase sequential process
with gradually increasing levels of challenge. Once trained, the
dogs’ ability to distinguish cancer patients from controls was
then tested using breath samples from subjects not previously
encountered by the dogs. The researchers blinded both dog
handlers and experimental observers to the identity of breath
samples. The diagnostic accuracy data reported were obtained
solely from the dogs’ sniffing, in double-blinded conditions, of
these breath samples obtained from subjects not previously
encountered by the dogs during the training period.
Results:
Among lung cancer patients and controls, overall sensitivity of
canine scent detection compared to biopsy-confirmed conventional
diagnosis was 0.99 (95% confidence interval [CI], 0.99, 1.00) and
overall specificity 0.99 (95% CI, 0.96, 1.00). Among breast
cancer patients and controls, sensitivity was 0.88 (95% CI, 0.75,
1.00) and specificity 0.98 (95% CI, 0.90, 0.99). Sensitivity and
specificity were remarkably similar across all 4 stages of both
diseases.
Conclusion:
Training was efficient and cancer identification
was accurate; 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. This pilot work using canine scent
detection demonstrates the validity of using a biological system
to examine exhaled breath in the diagnostic identification of
lung and breast cancers.
Future work should closely examine the chemistry
of exhaled
breath to identify which chemical compounds can most
accurately identify the presence of cancer.
Key Words: dogs • canine scent
detection • breast cancer • diagnosis • lung cancer, diagnosis |
Public release date: 5-Jan-2006
Valerie Johns
Can dogs smell cancer?
Study shows dogs ability to
distinguish breast and lung cancer in people compared to healthy controls
In a society where lung and breast cancers are leading
causes of cancer death worldwide, early detection of the disease is highly
desirable. In a new scientific study, researchers present astonishing new
evidence that man's best friend, the dog, may have the capacity to
contribute to the process of early cancer detection.
In this study which will be published in the March
2006 issue of the journal Integrative Cancer Therapies published by SAGE
Publications, researchers reveal scientific evidence that a dog's
extraordinary scenting ability can distinguish people with both early and
late stage lung and breast cancers from healthy controls. The research,
which was performed in California, was recently documented by the BBC in the
United Kingdom, and is soon to be aired in the United States.
Other scientific studies have documented the
abilities of dogs to identify chemicals that are diluted as low as parts per
trillion. The clinical implications of canine olfaction first came to light
in the case report of a dog alerting its owner to the presence of a melanoma
by constantly sniffing the skin lesion. Subsequent studies published in
major medical journals confirmed the ability of trained dogs to detect both
melanomas and bladder cancers. The new study, led by Michael McCulloch of
the Pine Street Foundation in San Anselmo, California, and Tadeusz Jezierski
of the Polish Academy of Sciences, Institute of Genetics and Animal
Breeding, is the first to test whether dogs can detect cancers only by
sniffing the exhaled breath of cancer patients.
In this study, five household dogs were trained
within a short 3-week period to detect lung or breast cancer by sniffing the
breath of cancer participants. The trial itself was comprised of 86 cancer
patients (55 with lung cancer and 31 with breast cancer) and a control
sample of 83 healthy patients. All cancer patients had recently been
diagnosed with cancer through biopsy-confirmed conventional methods such as
a mammogram, or CAT scan and had not yet undergone any chemotherapy
treatment. During the study, the dogs were presented with breath samples
from the cancer patients and the controls, captured in a special tube. Dogs
were trained to give a positive identification of a cancer patient by
sitting or lying down directly in front of a test station containing a
cancer patient sample, while ignoring control samples. Standard, humane
methods of dog training employing food rewards and a clicker, as well as
assessment of the dog's behavior by observers blinded to the identity of the
cancer patient and control samples, were used in the experiment.
The results of the study showed that dogs can
detect breast and lung cancer with sensitivity and specificity between 88%
and 97%. The high accuracy persisted even after results were adjusted to
take into account whether the lung cancer patients were currently smokers.
Moreover, the study also confirmed that the trained dogs could even detect
the early stages of lung cancer, as well as early breast cancer. The
researchers concluded that breath analysis has the potential to provide a
substantial reduction in the uncertainty currently seen in cancer diagnosis,
once further work has been carried out to standardize and expand this
methodology. |
| Posted 9/24/2004 7:12 AM
Updated 9/24/2004 10:37 AM |
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Study shows dogs able to smell
cancer
LONDON (AP) — It has long been suspected that man's
best friend has a special ability to sense when something is wrong
with us. Now the first experiment to verify that scientifically has
demonstrated that dogs are able to smell cancer.
Experts say it's unlikely that
pooches will become practical partners in cancer detection any time
soon, but the results of the study, outlined this week in the British
Medical Journal, are promising.
They show that when urine from
bladder cancer patients was set out among samples from healthy people or
those with other diseases, the dogs — all ordinary pets — were able to
identify the cancer patients' urine almost three times more often than
would be expected by chance alone.
"The issue is not whether or
not they can detect cancer, because clearly they can. The issue is
whether you can set up a system whereby they can communicate with you.
That requires further ingenuity," said Tim Cole, a professor of medical
statistics at Imperial College in London, who was unconnected with the
study and is the owner of a chocolate Labrador retriever.
David Neal, a bladder and
prostate cancer surgeon at Cambridge University in England, said it's
plausible dogs might be able to pick up the scent of cancer because
people with the disease shed abnormal proteins in their urine.
"I'm skeptical about whether
it will be implementable, but scientifically it should be followed up,"
said Neal, a spokesman for Cancer Research UK, Britain's cancer society,
who was not involved in the research. "It might be that the dogs are
better than our current machines at picking up abnormal proteins in the
urine. What are the dogs picking up? Can we get a machine that does the
same?"
It is thought that a dog's
sense of smell is generally 10,000 to 100,000 times better than a
human's.
The idea that dogs may be able
to smell cancer was first put forward in 1989 by two London
dermatologists, who described the case of a woman asking for a mole to
be cut out of her leg because her dog would constantly sniff at it, even
through her trousers, but ignore all her other moles.
One day, the dog, a female
border collie-Doberman mix, had tried to bite the mole off when the
woman was wearing shorts.
It turned out she had
malignant melanoma — a deadly form of skin cancer. It was caught early
enough to save her life.
Then in 2001, two English
doctors reported a similar case of a man with a patch of eczema on his
leg for 18 years. One day his pet Labrador started to persistently sniff
the patch, even through his trousers. It turned out he had developed
skin cancer and, once the tumor was removed, the dog showed no further
interest in the eczema patch.
A handful of similar anecdotes
have since been reported, but the latest study is the first rigorous
test of the theory to be published.
The experiment, conducted by
researchers at Amersham Hospital in Buckinghamshire, England, and the
organization Hearing Dogs for Deaf People, set out to prove whether dogs
could be trained to detect cancer.
Six dogs — all pets of the
trainers — were used in the study. They included three working strain
cocker spaniels, one papillon, a Labrador and a mongrel.
The trainers used urine from
bladder cancer patients, from people sick with unrelated diseases and
from healthy people to train the dogs over seven months to select the
cancer-unique elements by process of elimination. They learned to ignore
differences in the urine samples that were due to age, sex, infection,
diet and other factors.
Urine from 36 bladder cancer
patients and 108 comparison volunteers was used. Each dog had to sniff
seven urine samples and lie down next to the one from a bladder cancer
patient. The test was repeated eight times for each dog, with new urine
samples every time.
Taken as a group, they
correctly selected the right urine on 22 out of 54 occasions, giving an
average success rate of 41%. By chance alone, you'd expect them to be
accurate one-seventh, or 14%, of the time.
The two best dogs, Tangle and
Biddy — both cocker spaniels — were right 56% of the time, according to
trainer Andrew Cook. The papillon Eliza, tied with Bea, the third cocker
spaniel, followed by the Labrador, Jade. Bringing up the rear was Toddy
the mongrel.
"Toddy, bless him, was working
at a rate no better than chance, really, but we still love him," Cook
said.
One of the cancer patients was
identified correctly by all six dogs, whereas two other cancer patients
were consistently missed, indicating that perhaps the strength of the
urine signal varies from person to person, or according to severity of
the disease.
Perhaps the most intriguing
finding, though, was in a comparison patient whose urine was used during
the training phase. All the dogs unequivocally identified that urine as
a cancer case, even though screening tests before the experiment had
shown no cancer.
Doctors conducted more
detailed tests on the patient and found a life-threatening tumor in the
right kidney. |
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Olfactory detection of human bladder cancer by dogs: proof of principle
study
Carolyn M Willis, senior
research scientist1, Susannah M Church,
honorary research fellow1, Claire M Guest,
operations director2, W Andrew Cook,
deputy chief executive2, Noel McCarthy,
medical statistician3, Anthea J Bransbury,
associate specialist1, Martin R T Church,
honorary research fellow1, John C T Church,
honorary consultant1
1 Department of Dermatology, Amersham Hospital, Amersham HP7 0JD,
2 Hearing Dogs for Deaf People, Saunderton, Princes Risborough
HP27 9NS, 3 Centre for Statistics in Medicine, Institute of
Health Sciences, Oxford OX3 7LF
Abstract
Objective
To determine whether dogs can be trained to identify
people with bladder cancer on the basis of urine odour more
successfully than would be expected by chance alone.
Design Experimental, "proof of principle" study
in which six dogs were trained to discriminate between urine from
patients with bladder cancer and urine from diseased and healthy
controls and then evaluated in tests requiring the selection of
one bladder cancer urine sample from six controls.
Participants 36 male
and female patients (age range 48-90 years) presenting with new
or recurrent transitional cell carcinoma of the bladder (27
samples used for training; 9 used for formal testing); 108 male
and female controls (diseased and healthy, age range 18-85
years—54 samples used in training; 54 used for testing).
Main outcome measure Mean proportion of successes
per dog achieved during evaluation, compared with an expected
value of 1 in 7 (14%).
Results
Taken as a group, the dogs correctly selected urine from
patients with bladder cancer on 22 out of 54 occasions. This gave
a mean success rate of 41% (95% confidence intervals 23% to 58%
under assumptions of normality, 26% to 52% using bootstrap
methods), compared with 14% expected by chance alone.
Multivariate analysis suggested that the dogs' capacity to recognise
a characteristic bladder cancer odour was independent of other
chemical aspects of the urine detectable by urinalysis.
Conclusions Dogs can be trained to distinguish
patients with bladder cancer on the basis of urine odour more
successfully than would be expected by chance alone. This
suggests that tumour related volatile compounds are present in
urine, imparting a characteristic odour signature distinct from
those associated with secondary effects of the tumour, such as
bleeding, inflammation, and infection.
Introduction
The hypothesis that dogs may be able to detect
malignant tumours on the basis of odour was first put forward by
Williams and Pembroke in a letter to the Lancet in 1989.1
Their thinking arose from a consultation with a woman who claimed
to have sought medical help as a direct result of her dog's
inordinate interest in a skin lesion, which subsequently proved
to be a malignant melanoma. Since then similar anecdotal claims
of detection of skin cancer, and of malignancies of internal
organs such as breast and lung, have appeared in the press and in
a further letter to the Lancet.2-4
Although these anecdotal events remain unsupported
by experimental evidence, the concept that dogs can "smell"
cancer is not unreasonable. Tumours produce volatile organic
compounds, which are released into the atmosphere through, for
example, breath and sweat.5-9
Some of these volatile organic compounds are likely to have
distinctive odours; even when present in minute quantities, they
could be detectable by dogs, with their exceptional olfactory
acuity.10-13
Interest in the exploitation of volatile organic
compounds for diagnostic purposes is growing,5
6 suggesting that dogs have the
potential to make a contribution in the field of oncology,
providing that a scientific basis to the anecdotal reports can be
established. With this in mind, we designed a study to determine
whether dogs can detect cancer by olfactory means. We chose human
bladder cancer as the experimental model,14
on the basis that tumour related volatile organic compounds are
released into urine,8 which can be
readily collected and presented to dogs for training and testing
purposes. Our aim was to train dogs to recognise an odour, or
combination of odours (an "odour signature"), characteristic of
bladder cancer but distinct from those associated with the
secondary effects of the tumour, such as bleeding, inflammation,
infection, and necrosis. These factors are present in a multitude
of non-malignant conditions of the urinary tract and elsewhere in
the body and must be ignored by the dogs if discrimination is to
be attained. We assessed the dogs' abilities to detect bladder
cancer, once trained, by comparison of their success rate with
that expected by chance alone, in choosing one cancer urine
placed randomly among six controls in blinded experiments.
We should emphasise that our objective at this
stage was to conduct a simple, yet stringent, "proof of
principle" study to answer the question, "Can dogs be trained to
detect bladder cancer more successfully than would be expected by
chance alone?" This was not an attempt to assess or predict the
clinical usefulness of this hypothesised capability of dogs.
Methods
Training
of the dogs
Six dogs of varying breeds and ages completed a seven month
period of training. All were familiar with obedience commands,
but none had been previously trained for search or scent discrimination
tasks. We made no attempt to include dogs with a particular
suitability for scent discrimination.
The training objective was to enable the dogs to
discriminate between urine from patients with bladder cancer and
urine from diseased and healthy people, using samples entirely
new to them, so as to preclude simple memory recognition of
participants' unique odour signatures. Dogs were trained to
detect ("alert to" or "indicate") one urine sample from a patient
with bladder cancer placed among six control specimens. We
selected this task format (of being able to select one urine from
seven) with reference to data on dogs' behaviour.15
Training was by operant conditioning, using the clicker training
method15; the dogs were taught to
indicate the appropriate sample by lying beside it. Early
recognition of the tumour scent was achieved by using search and
find games, which were gradually replaced by discrimination
phases of increasing complexity. Urine from patients with bladder
cancer was presented sequentially against water, diluted urine
from healthy people, undiluted urine from healthy controls, urine
(containing blood) from menstruating women, and urine from
patients with non-malignant active or recent urological disease
or other disease. Samples were not pooled at any stage. Two of
the dogs were located 150 miles from the study centre and were
trained and tested with dried urine samples. The remaining four
Buckinghamshire based dogs were provided with freshly defrosted,
liquid specimens throughout.
Participant selection
We recruited patients from hospitals within the Buckinghamshire
Hospitals NHS Trust and additional healthy controls from among
staff and their families. All participants gave written, informed
consent. Thirty six patients (23 men, age range 48-90, mean age
69; 13 women, age range 49-90, mean age 74) presenting with new
or recurrent transitional cell carcinoma of the bladder gave
urine before surgical intervention. We used 27 of these samples
in training and the remaining nine for evaluation (table 1).
A total of 108 diseased and healthy control
participants supplied urine (54 men, age range 18-85, mean age
45; 54 women, age range 18-85, mean age 40); we used 54 samples
in training and 54 during evaluation (table 1).
We required people aged over 30 to have had recent cystoscopy to
exclude visible bladder malignancy. We included male controls
aged over 50 only if recent prostate histology had been negative
for cancer. We excluded patients with premalignant urological
disease or a history of urological carcinoma. A history of other
malignancy was acceptable providing the patient was now
considered disease-free. All other past or current medical
conditions were permissible. We made no exclusions on the basis
of drugs, menstrual cycle, ethnicity, diet, alcohol consumption,
smoking habits, exposure to chemicals, or findings on urinalysis.
However, we recorded details of all of these factors for each
participant, in case we needed to consider their influence on the
composition and odour of the urine at any stage.
Analysis and processing of urine
samples
After urinalysis (Multistix 10 SG, Bayer Corporation, NY, USA),
we refrigerated fresh urine specimens within 45 minutes and froze
them 2-32 hours later as 0.5 ml aliquots in glass vials. We then
stored them at -40°C for up to five months. For presentation to
the dogs, samples were defrosted and pipetted on to filter paper
in Petri dishes (58 x 15 mm) and used either immediately in a wet
state or within four weeks after overnight air drying and storage
at room temperature.
Evaluation of trained dogs
Test samples
We assessed the dogs for their ability to select correctly one
urine sample from a bladder cancer patient placed among six
control samples (the same task as used in their training); all
samples were new to the dogs. For statistical reasons, we used
nine test panels, each with one positive sample and six controls,
to test each dog (table 1). In selecting the samples for
each panel, we first sex matched the controls to the cancer
sample to circumvent hormonal influences. We also age matched (±8
years) at least one control with the cancer sample. Most panels
also had a second age matched control (±12 years). All age
matched controls had some form of urological disease. Most panels
included a further two control samples from people with
urological problems.
The choice of which control we assigned to each
bladder cancer sample was then further determined by the results
of urinalysis. Where possible, we tried to match the quantity of
blood present in at least one of the controls to that of the
cancer urine. We were not able to provide matches for all other
abnormalities present in the cancer urine specimens.
Conduct of tests
One investigator, working in a building separate from the dog
testing area, prepared the test samples, labelling Petri dishes
for each run with the letters A to G, from a randomly ordered
list. Different investigators then placed the Petri dishes under
single use, ventilated plastic pots, in positions (a minimum of
50 cm apart) along a floor grid numbered 1 to 7, by using a
second random number list. Random lists were produced by NMcC,
who was not present during testing, using Stata software. The
trainer allowed the dog to smell the samples until he or she was
satisfied by its indication and then noted the position of the
selected urine. Fresh samples and new random orders were used for
each test run and for each dog. Disposable vinyl gloves were used
throughout and changed each time a new urine sample was handled
in order to prevent cross-contamination. We recorded all test
runs on videotape.
Statistical analysis
The primary outcome measure was the mean proportion of successes
for each dog, compared with an expected value of 1 in 7 (approximately
0.143). Given the small dataset and the uncertainty of the form
of the data, we estimated 95% confidence intervals by using
both normal assumptions and bootstrap techniques. The bootstrap
intervals reported were bias corrected and accelerated bootstrap
confidence intervals,16 as implemented in
Stata, and based on 19 999 replications.
The study had power in excess of 95% to show a
statistically significant result (P < 0.05) for a mean success
rate of at least 55%, irrespective of the method of analysis
used. We assessed power by 1000 stochastic simulations of the
experiment with each dog having an expected success rate of
between 45% and 60% (mean 55%). We analysed results by t
test and bootstrap techniques, to ensure that the power was
adequate under both forms of analysis.
We applied a conditional logistic regression model
to assess whether factors measured on urinalysis (presence of
blood, leucocytes, protein, ketones, bilirubin, nitrites, or
urobilinogen) might confound the association between
participants' cancer status and selection of their urine by the
dogs. Being selected by the dogs was the outcome of this
analysis, with cancer status and urinalysis findings as
explanatory variables. We simplified the full model by backward
stepwise removal of variables not significant at P < 0.1 and then
compared the association between cancer and selection in the
final multivariate model with the univariate model, including
only cancer status. We used a t test and rank sum test to
assess the effect of the method of training (two dogs trained on
dried urine samples compared with four dogs trained on wet
urine).
Results
Table 2 gives the results for
the formal test runs. Taken as a single group, the dogs correctly
selected the positive bladder cancer urine on 22 of 54 occasions.
This gave a mean success rate of 41% (95% confidence intervals
23% to 58% under assumptions of normality and 26% to 52% using
bootstrap methods), compared with 14% expected by chance.
The association between presence of cancer and selection by the
dogs was slightly stronger in the multivariate model, which also
included presence of blood and ketones, than in the univariate
model. This indicated that the association was not due to confounding
with factors measured on urinalysis.
The four dogs trained on wet urine specimens (50%
correct) seemed to perform better than the two dogs trained on
dried samples (22% correct; P=0.03 by t test, P=0.06 by
rank sum test). However, the small numbers involved limit
confidence in the certainty of this observation.
Discussion
Summary
of findings
Given the extraordinary claims made about dogs detecting cancer
on the basis of odour,1-4
our aim was to design and conduct a simple, yet stringent,
experiment to establish whether dogs have this capability. We
achieved the successful detection of urine samples from patients
with bladder cancer 41% of the time (rather than the 14% expected
by chance alone), providing convincing evidence that dogs do,
indeed, have this ability. Multivariate analysis suggests that
the dogs' capacity to recognise an odour signature characteristic
of bladder cancer is independent of other chemical aspects of the
urine detectable by urinalysis, such as the presence of blood.
Although this multivariate model does not fully allow for the
lack of independence in the data, because each dog did the same
set of tests, it is, nevertheless, able to assess possible
confounding of a specific cancer signature with other features of
bladder cancer urine. Exactly what the chemical composition of
the cancer odour signature is we can only speculate at present.
Evidence from gas chromatography and mass spectroscopy studies
indicates that elevated levels of formaldehyde, alkanes, and
benzene derivatives occur with some cancers,5-8
but other volatile molecules are probably produced as well.
Rationale for training approach
When we embarked on this project we had no relevant peer reviewed
publications to refer to. The trainers on the team were experienced
at teaching dogs to scent-match, but this was not the task being
demanded of the dogs here. We needed them to learn to recognise
an odour signature for cancer from among the hundreds present
in urine, without recourse to the "pure" source of the odour.
This makes it very different from training dogs to detect, for
example, drugs or explosives. At the beginning of the study
we considered using surplus tumour material obtained during
surgery. We dismissed this, however, largely because the tissue
could not be chemically fixed without irrevocably altering the
smell, and the use of unfixed tissue had serious health and
safety implications for the dog trainers.
Having decided that we would concentrate on urine
as the source of tumour derived volatile organic compounds, we
then had to consider whether to use each participant's urine
sample separately or whether to pool those of the cancer patients
and, separately, those of the controls. Although pooling might
have led to a greater concentration of the desired odour
signature, we foresaw some important disadvantages and pitfalls.
Firstly, we had no idea whether certain foods, drinks, or drugs,
for example, may obscure, interfere with, or even mimic, the
odour of tumour related compounds. Only by taking detailed
histories from each participant, and introducing each sample
separately, could we gradually eliminate these possibilities.
Secondly, pooling specimens would lead to many fewer samples
being available for the dogs to smell. The very real possibility
then existed that dogs would merely scent-match with known
samples, rather than learn to pick out the distinctive odour
signature common to the cancer urines. Lastly, and perhaps most
importantly, we were concerned that "rogue" control specimens
from people with undiagnosed cancer elsewhere in the body may be
inadvertently added to pooled samples. We did, in fact, have an
occasion during training in which all dogs unequivocally
indicated as positive a sample from a participant recruited as a
control on the basis of negative cystoscopy and ultrasonography.
The consultant responsible for the patient was sufficiently
concerned to bring forward further tests, and a transitional cell
carcinoma of the right kidney was discovered.
We next had to consider the physical state of the
urine when presented to the dog. We felt that air dried samples
would have greater applicability in a clinical setting, by virtue
of easy handling, transport, and storage. However, the overnight
drying process may result in the loss of volatile organic
compounds important to the overall odour signature. We therefore
opted to train one cohort of dogs on wet samples and another on
dried samples. When tested, the dogs trained on liquid urine
performed significantly better, suggesting that the more volatile
molecules are of importance in the cancer odour signature.
However, the small sample sizes, together with other potentially
confounding variables between the two groups of dogs, such as
breed, age, and environmental conditions during testing, limit
confidence in this observation. Further work to determine the
optimum physical state for the urine will therefore be needed.
|
What is already known on this topic
Canine olfactory detection of
cancer has been anecdotally reported but has not, until now,
been the subject of scientific scrutiny
What this study adds
Dogs can be trained to distinguish patients with bladder
cancer on the basis of urine odour more successfully than
would be expected by chance alone
This study provides a benchmark against which future
studies can be compared |
|
Lastly, we gave
careful consideration to the selection of patients and controls.
During training, we exposed the dogs to urine from patients
presenting with a broad range of transitional cell carcinomas, in
terms of grade and stage, as we felt this would increase their
likelihood of recognising the common factor or factors. We took
particular care to train the dogs with control samples containing
elements likely to be present in urine from patients with bladder
cancer but also commonly occurring in other non-malignant
pathologies. In this way, we could teach the dogs to ignore
non-cancer specific odours. This led to the inclusion of urine
samples, during both training and evaluation, from a variety of
patients, such as people with diabetes to control for glucose,
those with chronic cystitis to deal with the influence of
leucocytes and protein, and healthy menstruating women to control
for blood. Given the prevalence of benign prostatic hyperplasia
in the age group of men most likely to have bladder cancer, we
also included this condition in both training and testing.
Conclusion
Our approach to training was vindicated by the results achieved
when the dogs were formally evaluated. Despite the fact that we
had not used dogs with proved scenting abilities, and despite the
inclusion of age matched diseased controls, we achieved a
statistically significant success rate. We learnt a great deal
during the study, and we are confident that improvements in the
success rate can be achieved by modifications to the training
regimen. In particular, we need to work on suitable reward
mechanisms when the trainers are blinded to the samples, so as
not to confuse the dogs. Also, for this approach to cancer
detection to have more clinical relevance, we would need to teach
the dogs to respond to more than one positive sample at a time,
and to have a signal for "no positive sample present."
In summary, our study provides the first piece of
experimental evidence to show that dogs can detect cancer by
olfactory means more successfully than would be expected by
chance alone. The results we achieved should provide a benchmark
against which future studies can be compared, and we hope that
our approach to training may assist others engaged in similar
work.
We thank all the participants who helped us with the study,
Sandra Stevenson and Jan Smith for their expert training of
four of the dogs, and Lezlie Britton for expert laboratory assistance.
We also thank the following people for their advice and support:
the consultants who contributed patients to the study, particularly
Amar Bdesha; senior nurses Glenys Newton and Hilary Baker; consultant
pathologist David Bailey; and Mike Scott, Pete Smith, and Alistair
Stevenson. We also acknowledge the enthusiastic support of the
Trustees of the Erasmus Wilson Dermatological Research Fund.
Contributors: All authors participated in conception and
design of the study, interpretation of data, and critical
revision of the manuscript. SMC, JCTC, MRTC, and CMW did the
patient recruitment and sample collection, and CMW was also
responsible for the storage and management of the urine samples.
WAC and CMG had overall responsibility for the training of the
dogs. With the exception of NMcC and AJB, all authors contributed
to the acquisition of data. NMcC did the statistical analysis.
CMW drafted the manuscript, with assistance from SMC and NMcC.
CMW is the guarantor and accepts full responsibility for the
conduct of the study, had access to the data, and controlled
the decision to publish.
Funding: The Department of Dermatology, Amersham Hospital,
received financial support from the Erasmus Wilson Dermatological
Research Fund (registered charity No 313305), which had no active
role in the design or conduct of the study. The dog trainers, all
employees of Hearing Dogs for Deaf People (registered charity
No 293358), trained the dogs in their own time; their expenses
were met through a private donation given by Derek Wilton, who
did not participate in the study in any way. SMC, MRTC, and
JCTC were funded by their small family company COBiRD Ltd (company
No 03426189), which also contributed to the project expenses. |
|
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reserach, resaerch, reesarch, rseearch, ersearch, esearch |
Blue Box
2
Brian Nelson