Weird Fact: Dogs can smell cancer in humans.

New research out of Germany shows that dogs can smell lung cancer on your breath. The scientists trained two German Shepherds, a Labrador Retriever and an Australian Shepherd to smell breath samples from glass tubes and lie down in front of the cancerous ones.

Dogs Can Smell Cancer

Dogs have up to 300 million scent receptors which enable them to smell cancer in humans

The dogs correctly identified 71 out of 100 of the cancer patients, and 372 out of 400 who were perfectly healthy.

Other studies have found that dogs can reliably detect breast cancer, bowel cancer, ovarian cancer, bladder cancer, prostate cancer and skin cancer.

But how do they do it?


How Dogs Smell

Just as we depend heavily on our vision to interpret the world, dogs rely on their sense of smell.

Not only are their faces closer to the ground where all the interesting scents lie, but they also have millions more scent-detecting cells, called turbinates, in their noses.

Take a trip up a dog’s nostril and you’ll find a thick, folded membrane full of scent cells and nerves which deliver the data to the brain. In humans this organ is about the size of a postage stamp. In dogs, it can be up to 60 times as big, almost the size of an A4 sheet of paper.

And because of the huge amount of sensory data coming in, dogs dedicate more of their brains to interpreting smells – about 40 times as much as humans. This gives them the apparently miraculous ability to detect smells that form only one part in a trillion.


Calling Dr Fido

For dog owners, this could lead to a chance early detection of cancer. For instance, one woman was bemused to find her dog obsessively licking a mole on her leg for weeks, and after getting it checked out by a doctor, discovered the mole was malignant and her dog knew all along.

However, the ability of dogs to smell cancer isn’t 100% foolproof, and most pet dogs aren’t trained to communicate this kind of information anyway. So what is the real value of this remarkable skill?

Experts say that we will never see dogs performing medical diagnosis. But their talent isn’t going to waste. Future trials may help scientists identify the volatile organic compound or pattern compounds that is associated with lung cancer. This would fast-track the creation of better diagnostic tests and save many more lives through early detection.

Just another reason to love dogs 🙂


Chatback: Has your dog ever appeared to diagnose something wrong with you?