Life-saving pets: Cats and dogs that find cancer

You've heard of drug-sniffing dogs; now come cancer-sniffing dogs. In the past decade, scientists have been studying dogs to see if they can detect the presence of tumors before conventional tests do. The answer, according to numerous recent studies, is yes. Specially trained dogs have been found to know by smell when someone has lung, colon, or even skin cancer. The most recent research on cancer-detecting dogs, published in the European Respiratory Journal in 2011, found that four trained dogs were able to detect cancer in 71 of 100 samples from lung cancer patients. Meanwhile, when given samples from the breath of people known not to have lung cancer, the dogs had a "false positive" ratio of just 7 percent.

Another study, this one in Japan, found that dogs could detect colon cancer with close to 90 percent accuracy using both breath and stool samples, while a study in Cambridge, England, is testing if dogs can detect prostate cancer from urine samples. And a dermatologist in Tallahassee, Florida, has conducted experiments to see if bomb-sniffing dogs can also detect melanoma, finding in his informal trials that they have 99 percent accuracy. Experts don't know exactly how dogs know when someone has cancer, but they suspect that dogs, with their keen sense of smell, are able to detect subtle changes in volatile organic compounds (VOCs) that function as chemical signatures in the body.

Cats have also been known to alert their owners to breast cancer and lung cancer, though the reports so far are just anecdotal and no studies have confirmed them. In one case reported by the CBC news in Winnipeg, Canada, a newly arrived stray cat jumped repeatedly against a woman's chest until she had her doctor check her for breast cancer, at which point it turned out she had a tiny tumor in the exact spot the cat had indicated.

Takeaway tip: There's not one among us who doesn't fear cancer and wouldn't appreciate an early warning system. Ask at your local hospital or cancer center whether studies with cancer-sniffing dogs are in progress and offer to participate.