What Do a Breath Sample, a Dog and a Mammogram Have in Common?

A dog’s sense of smell is somewhere between 1000 to 10,000 times better than that of a human.  In a human, the area devoted to scent detecting cells and nerves is approximately the size of a postage stamp.  If you could unfold the same area within a dog’s nose, it would be approximately the size of a piece of typing paper.   Additionally, a dog’s brain is specialized for identifying smells.  The amount of a dog’s brain that is used to analyze scents is approximately 40 times larger than the amount in a human brain!

This amazing sense of smell has led to dogs being used to detect explosives and drugs, search for survivors of disasters, and locate people missing in the mountains.  They are also being used to warn of seizures and heart attacks and are serving as companions to people who suffer from numerous other ailments.  And although they are not yet performing CPR, some do know how to contact 911.

It doesn’t seem to be much of a “leap of faith”  to begin using those amazing powers of smell to assist in diagnosing health problems in humans.  Even olfactory challenged humans, have used their sense of smell to help diagnose patients.  Diabetes, at one time was detected by the smell of a patient’s urine, gum disease is often detected by bad breath and certain infections in burn victims can be detected by an odor present in the patient’s skin.  If a human, with their relatively poor sense of smell can do it, why not make use of a dog’s remarkable abilities?

There have been incidents where an owner was alerted to a cancerous area by a dog that had received no formal training in cancer detection at all.  Scientific studies have proven the ability of dogs to detect melanoma in patients by sniffing skin lesions.

There are studies currently being done that provide compelling evidence that dogs can detect cancers simply by smelling a person’s breath.  With only a few weeks of basic training, ordinary dogs learned to accurately tell the difference between breath samples of lung and breast cancer patients from those samples of healthy individuals.    It is believed that the presence of cancer leads to biochemical markers that are exhaled by the patient.  Cancer cells produce metabolic waste that is different from that of normal cells.  These differences can be detected by a dog’s keen sense of smell, even in the early stages of the disease.

Using a food reward-based method, researchers have successfully trained dogs to sit or lie down in front of test tubes that contain breath samples of patients known to have cancer.  Using scent alone, the dogs could successfully detect lung cancer samples between 88 and 97 percent of the time.  This remarkably high degree of accuracy didn’t seem to be influenced by whether or not the person was a smoker or by the stage of the cancer.

Currently, a dog’s ability is to state: cancer—yes or no.  The next stage of research is to see if they can differentiate kinds of cancer.  Assuming that further research corroborates the current findings, dogs could eventually become integrated into direct patient care or become a screening test used by labs.  Potentially, a breath sample could be more accurate and an earlier way to detect cancer than the commonly used methods.  Who knows?  Perhaps one day, a yearly medical exam will include giving a breath sample instead of submitting to a mammogram or a prostate exam!


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