A dog's highly sensitive nose can tell it a lot about the people it meets. Medical studies show that dogs can detect at least some kinds of cancer in humans.
Properly trained dogs can detect lung cancer and breast cancer simply by sniffing a person's breath. Dogs have been documented being able to sniff a skin lesion and tell whether it's a skin cancer melanoma.
The dogs are detecting changes in the skin chemistry where the lesions occur. With patients suffering lung and breast cancers, the dogs smell biochemical markers in their breath. Scientists explain that cancer cells give off different waste products than do other cells, and to a dog's keen nose, those products have a noticeable smell.
At their 2014 annual meeting, members of the American Urological Association heard the results of a study that found that trained dogs are 98 percent accurate at detecting prostate cancer by smelling urine samples. Dogs also are being used to detect ovarian cancer by smelling "volatile organic compounds" [source: MNT].
Does this mean that the next time you go for a physical, your doctor is likely to have you screened by a dog? Probably not. But since early detection can be so crucial in surviving cancer, scientists continue to study dogs' ability to sniff out cancer. How does this gift work? How extensive is it? Can it be duplicated with medical instruments? Research in this area is ongoing.