Can Dogs Smell Cancer in Human Blood Samples?
May 15, 2019
The human sense of smell plays a major role in how people perceive and interact every day, how they decide what to eat, and even which life partner they choose. Smell strongly influences behavior as well as shapes human perception. The human smelling function is performed by two (2) odor-detecting sensory zones located high in the nasal passages.
Collectively, humans have approximately six million olfactory receptors in these areas. Most importantly, smell is the only sense that bypasses the thalamus in humans and communicates directly to the forebrain. Nonetheless, people simply do not use their sense of smell the same way as other mammals, which mean there is a lack of a standard metric for measuring the difference in scent sensitivity.
Since ancient times, humans have recognized the fact that the dogs that they took on hunts had an excellent sense of smell. Rightfully so, our canine companions possess up to 300 million olfactory receptors located in their noses and the portion of our dog's brain that is devoted to smell analysis is about 40 times larger than the zone in humans. Moreover, there are physiological differences in how a dog's nose functions when air is inhaled. When a human breathes, the air we inhale passes through the same airways within our nose. However, when your furry friend inhales, a flap inside the nostrils helps to direct the airflow through different paths. Conversely, when a dog exhales, the air exits through the slits on the side of the nostrils and helps new odors to enter.
A recent research study presented by the American Society for Biochemistry and Molecular Biology suggests that due a dog's highly evolved sense of smell they can identify cancer in blood samples with about 97% accuracy. Four beagles were trained to accurately distinguish lung cancer cells in laboratory blood samples. Though there is currently no cure for cancer, early detection still provides the best chance for human survival. Previous research studies had identified other dogs that could detect the presence of colon cancer through stool samples and lung cancer in a patient's exhaled breath. Human and veterinary researchers are excited by the fact that cancer is probably not the only disease that dogs may be able to assist humans in detecting.