For several decades, researchers have been studying canine smell as a diagnostic tool. Dogs have up to 300 million receptors, compared with five million in humans. They can detect volatile organic compounds released by the body during various physiological and pathological processes.
Scientific interest in the diagnostic potential of dogs’ sense of smell arose in 1989, after The Lancet published a case in which a dog persistently reacted to its owner’s mole, which later turned out to be melanoma. Today, scientific experiments show that trained dogs can detect several types of cancer by smell, including lung, breast and prostate cancer. In studies, animals are given samples of breath, blood or urine, and they identify those in which chemical markers of disease are present. Similar projects were also carried out during the COVID-19 pandemic: in some countries, dogs were tested for rapid screening of passengers’ sweat samples at airports.
Dogs also help people with chronic conditions. For example, specially trained animals can warn owners with diabetes about a sharp drop in blood sugar by reacting to changes in the smell of breath or skin.
The point of such experiments is not for every clinic to keep a staff of diagnostic dogs. Rather, dogs act as a kind of biological detector that helps scientists understand which chemical signals are linked to disease. After that, electronic sensors can be created — devices that work on the same principle, but in a laboratory form.
