Cancer-sniffing Dogs
Cancer-sniffing Dogs
LWA/Dann Tardif/Blend Images/Corbis | Darwin Wiggett/First Light/Corbis | Markus Altmann/Corbis
While some aspects of dog senses are still a mystery to us, we do know that when it comes to smell, they're probably picking up on volatile organic compounds (VOCs) in the air. These microscopic chemicals exist in both gaseous and liquid states, and they're emitted by both biological and man-made substances. We can smell them, too; in recent years, things like paint have been criticized for the potentially toxic VOCs that they emit. Due to their superior sense of smell, dogs can detect VOCs in extremely tiny amounts. Exactly how well they can sniff out something depends not only on the breed but also on the individual dog -- some dogs are just better at it than others.
Going on this knowledge, several researchers in the past decade have successfully trained dogs to sniff out cancer. The first study read by Dr. Lichtenfeld took place in 2004 in England and was published in the British Journal of Medicine. Six dogs were trained to detect urine samples that belonged to patients known to have bladder cancer. While their 41 percent success rate wasn't amazing, it was higher than the 14 percent "coincidence rate" determined by the researchers. Since then, dogs have been trained to discern other forms of cancer, including skin, prostate, lung, breast and colorectal cancers, with increasing rates of success.
Two years after the bladder cancer study, researchers at the Pine Street Foundation in California trained dogs to sniff out both breast and lung cancer. Rather than sniffing urine samples, however, the dogs smelled breath samples from the patients. The results were startling -- they had an 88 percent success rate with breast cancer and a 97 percent accuracy rate with lung cancer. The most impressive study took place early in 2011, in which dogs in Japan detected colorectal cancer with 98 percent accuracy by sniffing breath samples. This is more accurate that the traditional diagnostic tests for the disease.
So far, the cancer-sniffing dog phenomenon has only been used in research, but scientists are hoping to identify and isolate the exact compounds dogs are detecting to create electronic cancer-sniffing devices. Up next, more health problems that dogs are helping people with right now.
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