Our dogs are part of our families, our lives, and our society. Since the beginning of time, they have proved their ability to do whatever their human friends needed or asked from them. For our ancestors, dogs represented an astute hunting partner, a reliable shepherd, a ferocious defender of a man's possessions or loved ones, and an affectionate friend who provided comfort in difficult situations. Dogs are able to perform numerous tasks like humans can, and love like humans cannot. Perhaps based on their adaptability and devotion for humans, dogs have been able to develop new and more sophisticated ways of saving our lives and protecting us from current dangers. Since the beginning of the twenty-first century, helped by the growth of global communications, numerous anecdotal reports of dogs alerting their owners of upcoming seizures, health conditions, and even cancer became a popular subject in the news worldwide. In all these cases, these were pet dogs who had the gift of identifying something was threatening their owners and exhibited anxious behavior and signs of being upset.
Cancer cells exude very low amounts of volatile organic compounds, alkanes and benzene derivatives that are not present in the healthy tissue. Many cancer studies have aimed to detect these by-products of cancer cells by using the most sophisticated tools of scent detection, a mass spectrometer and a dog’s nose. If our beloved dogs can track human scents like any other living creature, why wouldn't they be able to detect diabetes or cancer? A dog’s nose is a very sensitive device with approximately 50 times more scent receptors than humans and able to detect substances in concentrations as small as one part per billion.
In 2004, a research conducted by the British Medical Journal reported that dogs' highly developed sense of smell could detect cancer patients. In 2006, The New York Times published an article about five dogs, three Labradors and two Portuguese Water dogs, trained to detect cancer with a 99 percent accuracy. The study, conducted at the Pine Street Clinic in San Anselmo, California, capitalizes on the exceptional ability of dogs to detect even traces of the substances present in a tumor tissue.
Studies in cancer biomarkers demonstrated that specific volatile organic compounds (VOC) are present in the urine of bladder cancer patients and trained dogs were capable of identifying the cancer samples. Since then, and based on the existence of specific volatile biomarkers associated to different types of cancer, researchers continued to study canine scent detection to detect prostate, colorectal, breast, and ovarian cancer by studying the presence of VOCs in urine, fecal samples, and human breath, places where cancer volatiles may appear during the early stages of the disease. Under Dr. Hideto Sonoda's lead, researches at Kyushu University in Fukuoka in 2011 found in 2011 that a specially trained dog could detect colorectal cancer among patients with up to 98 percent accuracy. This study came to bring empirical and scientific proof to cases like Marine. The latter is a 8-year-old female Labrador retriever trained in St. Sugar Cancer-Sniffing Dog Training Center who has a vast experience in cancer detection. She was able to detect 12 types of tumors by examining patients' breath before the mentioned study.
In 2012, The European Respiratory Journal published a study performed by German researchers at the Schillerhoehe Hospital of Gerlingen which proved that trained dogs can correctly detect lung cancer by detecting volatile organic compounds in human breath. In this study,220 volunteers participated, out of which 60 had lung cancer, 50 had chronic obstructive pulmonary disease (COPD), and the rest were in good health. Two German Shepherds, an Australian Shepherd and a Labrador retriever, tested these patients and accurately identified, with 71 per cent of accuracy, lung cancer in its early stages, when it is still treatable but the lack of symptoms make its diagnosis difficult. The dogs could even discriminate lung cancer from chronic obstructive pulmonary disease, a chronic disease often associated with later development of lung cancer.
Trained dogs can not only recognize VOC, but also behavioral changes such as signs of high blood pressure, heart attack, epileptic, and diabetic seizures. For the latter, dogs can alert their owners of a potential diabetic seizure by detecting ketones, toxic acids whose high concentration in the bloodstream is associated with high blood sugar. In all cases, early detection is the lifesaving key. The creation of electronic devices that have the same abilities a dog's nose has are underway. These will most definitely be an alternative and safe method for detecting diseases with great accuracy. Nevertheless, maybe, in the meantime, it would be interesting to give dogs more space in this field and take advantage of their non harmful and non invasive sniffing method as an additional source, which combined with traditional methods, could potentially contribute to reducing disease diagnosis errors.