by Dr. Philip S. Chua.
March 16, 2012
Highly skilled explosive- or drug-sniffing dogs are fairly common and in great demand these days, thanks to Osama bin Laden. But what’s equally, or perhaps, more interesting is the dog’s ability to learn how to detect diseases, like cancer of the lungs or breasts, simply by using its nose. Even more amazing is the degree of accuracy of “their diagnosis,” which ranges up to 99 for lung cancer, 88 for breast cancer.
Trained dogs can also detect skin cancer called melanoma, prostate cancer, termites, fertile cows and dead bodies buried really deep. In 1999, a UK scientific study was published reporting the ability of dogs to detect seizures among their owners 15 to 45 minutes before the convulsion occurred.
Physicians undergo at least 18 years of schooling and often use diagnostic tools to make a definitive medical diagnosis, but all the dog need is its nose and, perhaps, a commendation pat on the head. No stethoscope. No X-ray. No CT scan. Just a super-sensor nose. (Incidentally, in Africa, trained rats are used to detect tuberculosis.)
The olfactory lobe (sense of smell center in the brain) in dogs is about 4 times greater than in humans, where it is rudimentary. They also have 20 to 40 times more receptors (“detectors”) in their nasal (nose) cavity than humans, so a dog’s sense of smell is that much more powerful and acute. Dogs can detect differences in the concentration of individual odors, with their highly attuned sense of smell. They are like the ultra sensitive “breath analyzer” gadgets commonly used by police to detect the level of alcohol in the body of drivers suspected of DUI (driving under the influence).
Actually, medical students and residents are trained to use all their senses, including the sense of smell in working up patients and making diagnosis. The older physicians of the past centuries were more astute in the art. In the 1988 Academy Award Best Picture, The Last Emperor, for instance, the “nurse” caretaker smelled every bowel movement of the 3-year-old Emperor Aisin-Gioro “Henry” Pu Yi to detect any abnormality or illness. More commonly recognized smell or odor indicating an ailment is that of “ammoniacal breath” (uremic fetor) among those with severe kidney disease, in end-stage liver disease, and even in helicobacter pylori gastric ulcer, or, there is the typical strong smell of decaying flesh of a gangrenous leg among diabetics or those with blocked leg arteries, which anyone can smell several meters away. But these are the strong and obvious ones our nose can identify.
What the trained dogs can detect effortlessly and almost instantly with a sniff is the “specific scent” of individual illnesses, explosives, drugs we humans cannot even smell at all, much less differentiate them. Dogs are also excruciatingly sensitive at detecting air, particles and vapor.
All these observations suggest the possible presence of a distinctive biological marker or a subtle chemical scent or vapor in each disease condition. And if that were so, perhaps science can find out how dogs senses or detect the “odor”. And from there, we can certainly utilize our modern technology to invent a super-sensitive artificial bio-sensor (“sniffer-machine”) for these various scents and biological markers for a more expedient detection and diagnosis of diseases.
For more than 12,000 years, dogs have been known to sniff out prey for the hunter. Today, seeing-eye dogs are helping millions “see” and cross the streets. As pets, they also soothe the emotion of menopausal women, sick children and old people in hospitals and at home. Besides being bomb-detectors, drug-sensors, escaped prisoner-finders in the K-9 Patrol team, dogs are also fast becoming celebrities as medical diagnosticians of late. (Watch out, Doc!)
With these great findings on our best friend’s probable additional fabulous acumen, will the doctor’s offices, clinics, and hospitals soon be “equipped” with a four-legged “medical assistant”? No, not yet. The studies are very limited and the reports are preliminary at best. As you read this, hundreds of scientific studies are already ongoing on this particular fascinating subject. This doggy inspiration could lead to great advances in medical science and technology in the future, which will be a great boon to better patient care.
In the meantime, our most loyal canine pet will continue to remain as our best friend, house guard, and protector. And, of course, still the happiest and most eager greeter who celebrates our homecoming each day.
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