Labrador can detect certain cancer by smell

Japanese researchers have trained an 8-year-old Labrador retriever to diagnose colorectal cancer by smelling a patient’s breath and/or stool. The dog had an overall accuracy of 95 percent when using the breath test and 98 percent for the stool test, according to a study published Monday in the journal Gut.

To train the dog, researchers first let her sniff a breath sample from a patient with colorectal cancer. Then they presented her with a panel of breath samples – one from a cancer patient and four from healthy people. When the dog recognized the sample from the cancer patient, the reward was some quality time with a tennis ball.

In the study, the dog was presented with 36 panels of breath samples. Overall, she correctly identified 91 percent of the samples that were from cancer patients, and she correctly ignored 99 percent of the samples from healthy volunteers.

The dog did a better job evaluating 38 panels of stool samples. In those tests, she correctly flagged 97 percent of the samples from cancer patients and correctly ignored 99 percent of the samples that were disease-free.

The researchers speculate that the dog’s highly developed sense of smell allowed her to pick up a whiff of the chemical compounds that are unique to cancer.