Yes. Trained dogs are able to signal certain cancers, drops in blood sugar levels in diabetics or the imminence of an epileptic seizure, by recognizing by the smell of compounds that the body releases when it is ill. This is not a diagnosis, but a real detection, documented by tests.
A sense of smell with 200 to 300 million receptors
Dogs have around 200 to 300 million olfactory receptors, compared to 5 to 6 million in humans, and the part of their brain devoted to analyzing odors is proportionally much more developed. However, an illness modifies the metabolism, and this modified metabolism releases volatile organic compounds in the breath, sweat or urine. It is this chemical signature that the dog learns to recognize, after training over several months.
Specialized organizations such as Medical Detection Dogs in the United Kingdom train medical alert dogs who live with diabetic patients and warn them before severe hypoglycemia.
What the dog does not replace
A detector dog signals, it does not diagnose. The trials show remarkable but variable success rates depending on the diseases, individuals and training. Canine detection is studied as a complementary screening tool — never as a substitute for a medical examination.
