Spend enough time
around dogs and one of the foremost things you’re going to notice about them is
their keen sense of smell.
I have two terriers; and as such I pity any unfortunate field mouse silly enough to attempt to cross into their territory.
I have two terriers; and as such I pity any unfortunate field mouse silly enough to attempt to cross into their territory.
Were I not to intervene, my one terrier-mix would pass countless hours to her own detriment, standing on guard: staring, waiting, biding her time for the unfortunate little rascal to emerge from behind its sliver of a safe haven.
The scent that drives
the hunt.
She does not discriminate;
she’ll hunt spiders and birds too … as well as the shadows of all the aforementioned.
And when I have a cold,
they get right up in my face and sniff; and then, as though understanding
something’s not right, they’ll snuggle up beside me and not pester me to go out
for a walk.
It is this ability to detect illness, in particular, that can cause someone like me, someone with slightly hypochondriac tendencies, to become rapidly and unreasonably concerned when my dogs, especially my Schnauzer sniff at my stomach, my throat or my whatever. In a paranoid moment of absolute certainty, I jump to the most reasonable conclusion and become convinced that I must surely have a tumor.
Dog's hear what we cannot hear; they see what we cannot see; but it is their sense of smell that I have always found most fascinating. Just imagine living in a world compelled to act without discretion, driven purely by power of scent.
Imagine living as Jean-Baptiste
Grenouille—the euphoria part, not the murder part.
Some fanatical lawn
manicurist neighbor of mine once said to me,
"Why do you think it’s okay to walk your dogs and let them sniff around on other people’s lawns?"
"Why do you think it’s okay to walk your dogs and let them sniff around on other people’s lawns?"
In my silence, he continued:
"If I had a dog I’d just keep it in my own backyard."
I silently hoped he never did get a dog, because anyone who has ever witnessed the unbridled bliss of a dog running through an open field would never question the absurdity of depriving them of the freedom of searching out and reveling in new scents.
ANTHROPOLOGISTS believe
the most significant benefit our ancestors derived from dogs was the use of
their keen sense of smell to assist with the hunt.[4][12]
- A 2004 study of hunter groups with and without a dog gives quantitative support to the hypothesis that the benefits of cooperative hunting was an important factor in wolf domestication.[4][13]
ANATOMY OF A DOG’S NOSE
- While the human brain is dominated by a large visual cortex, the dog brain is dominated by an olfactory cortex. [6]
- The olfactory cortex of a dog’s brain is (relative to total brain size) 40 times larger than that of humans. Dogs, depending on breed, may have as many as 300 million odor receptors in their nose, where as humans typically have about 5 million. [4][5]
- It has been estimated that dogs can identify smells somewhere between 1,000 to 10,000 times better than humans can. [7]
Scent Receptors in People and Dog Breeds
Subject
|
Number
of Scent Receptors
|
Humans
|
5
million
|
Fox
Terrier
|
147
million
|
Beagle
|
225
million
|
German
Shepherd
|
225
million
|
Bloodhound
|
300
million
|
Source data for table
came from www.dummies.com
[7]
INTERESTING SIDE NOTE: The pattern of each dog’s
nose makes up a ‘nose print’ as unique as a human's fingerprints. [7]
- The moisture on a dog’s nose provides a good surface for dissolving chemicals from the air and absorbing them into the skin. [9]
- Inside the nostrils of dogs, there is a fold of tissue that helps to separate smelling and breathing. [5]
Brent Craven, (a
bioengineer at Pennsylvania State University who modeled airflow and odor
transport using high-resolution MRI scans of a lab cadaver's nose) and his team found that in dogs, [5]
"... about 12 percent of the inspired air detours into a recessed area in the back of the nose that is dedicated to olfaction, while the rest of the incoming air sweeps past that nook and disappears down through the pharynx to the lungs. Within the recessed area, the odor-laden air filters through a labyrinth of scroll-like bony structures called turbinates. Olfactory receptors within the tissue that lines the turbinates, in turn, 'recognize' these odor molecules by their shape and dispatch electrical signals to the brain for analysis."
Craven and his team are working to, "reverse-engineer the canine nose, in part to aid in the design of artificial 'noses' that can sniff out odors as well as man's best friend can."
- In a study conducted by the University of Oslo in Norway, it was determined that, "a hunting dog, holding its head high into the wind while in search of game, sniffed in a continuous stream of air for up to 40 seconds, spanning at least 30 respiratory cycles." [8]
Located at the bottom
of a dog’s nasal passage, an organ called the Jacobson’s organ gives dogs an additional
olfactory advantage over humans. The Jacobson's organ enables dogs to sense and
differentiate between,
“pheromones, the chemicals unique to each animal species that advertise mating readiness and other sex-related details. The pheromone molecules that the organ detects—and their analysis by the brain—do not get mixed up with odor molecules or their analysis, because the organ has its own nerves leading to a part of the brain devoted entirely to interpreting its signals. It's as if Jacobson's organ had its own dedicated computer server.” [5]
From 7 Amazing
Facts About Your Dog's Senses of Smell Dogster.com Maria Goodavage Jul
16th 2012: [21]
#4. You can't fool your
dog
“Research indicates that it’s quite likely that dogs can smell fear, anxiety, even sadness. The flight-or-fight hormone, adrenaline, is undetectable by our noses, but dogs can apparently smell it. In addition, fear or anxiety is often accompanied by increased heart rate and blood flow, which sends telltale body chemicals more quickly to the skin surface.”
ANOTHER INTERESTING SIDE NOTE:
From Sick
People Smell Bad: Why Dogs Sniff Dogs, Humans Sniff Humans, and Dogs Sometimes
Sniff Humans Scientific American January 15, 2012: [22]
Apocrine glands are responsible for producing the dog’s unique scent; though these glands are located all over the dogs body, by far the largest and most concentrated are at the derriere — the anal glands.
Primates also have Apocrine glands, though their location has made an anatomical shift to the North in the course of our evolution; Natural Selection favoring, “individuals with genes for producing glands in places where the sniffing would be, well, easy.”
A DOG'S keen sniffer can be used to detect narcotics, currency, explosive devices, cell phones, DVD’s
as well as miscellaneous products (foodstuffs and plants, for instance) brought
illegally from one country to another.
They can be trained to detect termites, carpenter ants, bedbugs, mold, endangered and invasive animal species, landmines, crime evidence (like fire accelerants), and to aide emergency workers in search-and-rescue efforts.
Dogs can not only detect cancer, but are actually able to differentiate between different types of cancer. They have also been documented as having the ability to alert people with epilepsy in advance of the onset of a seizure. And can be trained to detect and alert diabetics (licking, pawing, jumping and even fetching a blood sugar monitor) when their blood sugar is low.
They can be trained to detect termites, carpenter ants, bedbugs, mold, endangered and invasive animal species, landmines, crime evidence (like fire accelerants), and to aide emergency workers in search-and-rescue efforts.
Dogs can not only detect cancer, but are actually able to differentiate between different types of cancer. They have also been documented as having the ability to alert people with epilepsy in advance of the onset of a seizure. And can be trained to detect and alert diabetics (licking, pawing, jumping and even fetching a blood sugar monitor) when their blood sugar is low.
KEEPING US SAFE
Trainers at Lackland
Air Force Base in San Antonio, Texas conduct 12-week programs for bomb-sniffing and
drug-sniffing dogs and their handlers. [19]
"According to Walt Burghardt, a veterinary behaviorist who serves as a consultant to the program, certified bomb-detecting dogs, for instance, can distinguish the scent of nine basic explosives even when the explosives are mixed with any of tens of thousands of other compounds." [19]
SEARCH & RESCUE
"Search-and-rescue dog trainers have learned that people shed about 40,000 dead skin cells, called rafts, per minute. The rafts contain bacteria and vapors unique to each individual. Wind currents carry the rafts away from people and spread them in a roughly cone-shaped volume of air. Dogs learn to detect this cone of scent and follow it. That is why dogs on a scent typically move back and forth across an area—they are staying within the boundaries of the cone as they follow it to its source."
BED BUGS [23][24]
“... sniffer dogs had a 97.5% correct positive indication rate on detecting bed bugs and their eggs – with zero false positives – all while accurately distinguishing them from carpenter ants, cockroaches and termites. They could detect as few as a single adult specimen or 5 viable eggs.”
CANCER DETECTION
Canine cancer detection is an approach to cancer screening that relies upon the olfactory ability of dogs to detect very low concentrations of the alkanes and aromatic compounds generated by tumors. [1]
In
a 1989, letter to the editor of the journal, The Lancet, two dermatologists wrote about
a case in which a woman’s Border collie mix persisted in sniffing at a mole on
her leg. The dog persisted, even when her physician said having the mole removed would be a purely cosmetic option. Her dog, in its persistence, even went so far as to
nip at the mole, attempting to bite it off. The dog had neither nipped at her, nor
paid any attention to any of her other moles before. Another visit to the
doctor followed; this time to a specialist. The tests came back positive as a
malignant melanoma. [2]
This 2006 National Geographic article [16] talks about a study led by Dr. Michael McCulloch in which ordinary dogs with only basic training,
“learned to accurately distinguish between breath samples of lung- and breast-cancer patients and healthy subjects."The results of the study showed that by scent alone, the dogs could detect breast cancer and lung cancer between 88% and 97% of the time.
According to Nicholas Broffman, executive director of the Pine Street Foundation which conducted the study,
"Cancer cells emit different metabolic waste products than normal cells. The differences between these metabolic products are so great that they can be detected by a dog's keen sense of smell, even in the early stages of disease."
- In 2007, the BBC reported on a breathalyzer which changes color according to the, “unique chemical changes in the breath of people with lung cancer. … The hues of a series of 36 dots detect lung cancer accurately in just under three out of four people with the disease.”[14]
- A 2010 Swedish study, [18] using pet Giant Schnauzers to detect ovarian cancer, demonstrated that human ovarian carcinoma tissues can be characterized by a specific odor, detectable by a trained dog. The results were confirmed using an electronic nose. The tissue tests showed sensitivity of 100% and specificity of 95%, while the blood tests showed sensitivity of 100% and specificity of 98%.
- More recently, as reported in The Times of India in 2013, researchers [17] trained dogs to sniff out the signature chemical compound that indicates the presence of ovarian cancer with 100% accuracy.
- The dogs (part of an interdisciplinary research project at the University of Pennsylvania to help scientists discover a chemical footprint that might lead to earlier diagnostic tests) were already introduced to the cancer tissue smell and were taught to sit when they found it.
- In a 2011 study, lung cancer (LC) was identified from the exhalation samples of 220 volunteers (healthy individuals/confirmed LC/or COPD) with a sensitivity of 71% and a specificity of 93% by sniffer dogs.”[3]
- This 2014 study developed an, [15]
"electronic nose instrument based on an array of 13 electro-chemical and optical sensors, designed to maximise the characterisation of gases and volatiles released from biological media.… The urine samples of 92 volunteers (patients of colorectal cancer, irritable bowel syndrome, and healthy controls) were tested. When simulating a clinical diagnosis situation, distinction of colorectal cancer against irritable bowel syndrome was found to have a sensitivity of 78% and a specificity of 79%.”
- Daisy the Labrador has detected 551 cancer patients with an accuracy of 93 percent and in 2014 received the Blue Cross (for pets) Medal for her life-saving skills.[10][11]
EPILEPSY
- Dogs have demonstrated the ability to detect and alert (eg: by whining) their owners of an epileptic seizure before it occurs. The warning gives the person with epilepsy time to sit or lie down in a safe place. [19][20]
- Back in 1993 British veterinarian Andrew Edney published his findings after conducting a study of 37 dog owners suffering from epilepsy. His study suggested that the dogs may be detecting an odor or picking up on a subtle behavioral cue. [20]
DIABETES
- Diabetes Detection Dogs are dogs trained to detect (and alert their diabetic owners) of low blood sugar levels.[25][26]
- According to a study discussed on the website http://companiontraining.com/, the perceived health benefits that owners of diabetes detection dogs experience include:[27]
- Fewer paramedic calls
- Fewer unconscious episodes
- Greater independence
***
FIN
 |
| Photo Courtesy of wildeyed.ca |
REFERENCES
[6] Coren, Stanley
(2004). How Dogs Think. First Free Press, Simon & Schuster. ISBN 0-7432-2232-6.
[8] Steen
JB, Mohus
I, Kvesetberg
T, Walløe
L. (May 1996) Olfaction in bird dogs during hunting Acta Physiol Scand. 157(1):115-9.
[10] Terry
Gasking. "How
my dog sniffed out breast cancer and saved my lifeYYY".
[11] "Medal
for the heroic dog who sniffed out her owner's cancer: Daisy the Labrador has
helped find disease in 551 patients". November 21, 2014.
[12] Tacon, Paul;
Pardoe, Colin (2002). "Dogs make us human". Nature Australia 27 (4):
52–61.
[13] Ruusila, Vesa;
Pesonen, Mauri (2004). "Interspecific
cooperation in human (Homo sapiens) hunting: the benefits of a barking dog (Canis
familiaris)". Annales Zoologici Fennici 41 (4): 545–9.
[14] "BBC NEWS - Health -
Lung cancer 'colour breath test'".bbc.co.uk.
Development and
application of a new electronic nose instrument for the detection of colorectal
cancer.
Westenbrink
E1, Arasaradnam
RP2, O'Connell
N3, Bailey
C3, Nwokolo
C3, Bardhan
KD4, Covington
JA5.
[16] http://news.nationalgeographic.com/news/2006/01/0112_060112_dog_cancer.html
[18] Horvath G,
Andersson H, Paulsson G. Characteristic odour in the blood reveals ovarian
carcinoma. (2010) BMC Cancer. 2010;10:643. doi:10.1186/1471-2407-10-643.
[19] http://animals.howstuffworks.com/animal-facts/dogs-at-work-info3.htm
"Dogs at Work" 21 October 2008. HowStuffWorks.com.
<http://animals.howstuffworks.com/animal-facts/dogs-at-work-info.htm>
07 March 2015.
7 Amazing Facts About
Your Dog's Sense of Smell
Maria Goodavage | Jul
16th 2012 |
Sick People Smell Bad:
Why Dogs Sniff Dogs, Humans Sniff Humans, and Dogs Sometimes Sniff Humans
By Rob Dunn | January 15, 2012 |
[24] Lewis,
Vernard R; Moore, Sara; Tabuchi, Robin L; Sutherland, Andrew M; Choe,
Dong-Hwan; Tsutsui, Neil D (July–September 2013). "Researchers combat
resurgence of bed bug in behavioral studies and monitor trials". California
Agriculture.
IMAGE CREDITS
"US Navy 101108-N-8546L-040
Chief Master-at-Arms Nick Estrada, left, a U.S. Navy military working dog
handler from Orange, Calif" by U.S. Navy photo by Mass Communication
Specialist 1st Class Peter D. Lawlor - This Image was released by the United
States Navy with the ID 101108-N-8546L-040 (next).This tag does not indicate
the copyright status of the attached work. A normal copyright tag is still
required. See Commons:Licensing for more information.বাংলা |
Deutsch | English | español | euskara | فارسی |
français | italiano | 日本語 | 한국어 | македонски | മലയാളം |
Plattdüütsch | Nederlands | polski | português |
Türkçe | 中文 |
中文（简体） |
+/−. Licensed under Public Domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:US_Navy_101108-N-8546L-040_Chief_Master-at-Arms_Nick_Estrada,_left,_a_U.S._Navy_military_working_dog_handler_from_Orange,_Calif.jpg#mediaviewer/File:US_Navy_101108-N-8546L-040_Chief_Master-at-Arms_Nick_Estrada,_left,_a_U.S._Navy_military_working_dog_handler_from_Orange,_Calif.jpg
"Washington DC
Security Search". Licensed under Public Domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Washington_DC_Security_Search.JPG#mediaviewer/File:Washington_DC_Security_Search.JPG
"The British Army
in Normandy 1944 B6499" by Christie (Sgt), No 5 Army Film &
Photographic Unit -
http://media.iwm.org.uk/iwm/mediaLib//48/media-48942/large.jpgThis is
photograph B 6499 from the collections of the Imperial War Museums.. Licensed
under Public Domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:The_British_Army_in_Normandy_1944_B6499.jpg#mediaviewer/File:The_British_Army_in_Normandy_1944_B6499.jpg
No comments:
Post a Comment