Can Dogs Tell if You Have Cancer by Smelling Your Breath?

The Art of Racing in the Rain, a New York Times best-seller, is narrated by a family's dog, whose aspiration is to be reincarnated as human. In the book, (spoiler alert if you haven't read it) he is able to sniff out a cancerous tumor in his master's wife's brain before anyone else knows about it. Current research shows, this idea may not be too far fetched.

Though not an entirely new concept, research is continuing to confirm the accuracy with which dogs can smell cancer. A study by researchers at the Schillerhoehe Hospital in Germany showed that dogs correctly identified lung cancer 71 percent of the time.

Published in the European Respiratory Journal, out of 220 volunteers who gave breath samples -- a mix of healthy individuals and those with lung cancer or chronic obstructive pulmonary disease -- dogs correctly identified cancer 71 patients with confirmed lung cancer. As the study states, early detection is key to a positive prognosis.

According to BBC [via Science Daily and the European Lung Association], the dogs were able to detect cancer even amidst tobacco smoke, food odors and other medications, which may have been on the patients breath when the sample was given. With few early detection techniques for lung cancer -- the number one most common cause of death from cancer worldwide -- this method relies on a sample of exhaled breath from the patient and the theory that dogs are smelling volatile organic compounds (VOCs) that are produced in the presence of cancer.

Dr Thorsten Walles, the report's author from Schillerhoehe Hospital, said: "In the breath of patients with lung cancer, there are likely to be different chemicals to normal breath samples and the dogs' keen sense of smell can detect this difference at an early stage of the disease.

"Our results confirm the presence of a stable marker for lung cancer. This is a big step forward."

The use of sniffer dogs was first suggested in 1989 and studies since have shown they can identify a variety of cancers, not just lung. This news report from a local Fox network in Florida earlier this August, tells the story of a dog who the owner believes alerted her to the presence of stage-four lung cancer.

Researchers are developing an electronic "nose" to mimic the accuracy and sensitivity of a dog's smelling ability to one day detect the same chemical the dog identifies as cancer. But, the chemical that tips the dog off has not yet been identified by researchers. BBC reports Laura McCallum, the science information office for Cancer Research UK as saying: "Although there are now some intriguing studies suggesting that dogs may be able to smell cancer in some situations, we're still a long way from understanding exactly which 'smelly molecules' they are detecting and if these studies are accurate."