Dogs have held a special place in the hearts of humans for tens of thousands of years. As one of the first domesticated animals, they have practically evolved alongside us, guarding our homes in exchange for tasty morsels, a pat on the head and a warm place to sleep.

As it turns out, dogs are guarding more than our homes – they are also guarding our health.

Dogs were born to sniff; their noses dominate not only their faces (pugs notwithstanding) but also their brains. Even a miniature dachshund puppy has twenty-five times the scent receptors as a human – and bloodhounds twice as many as that. As much as humans see the world as we are, dogs smell the world as it is – and if it’s stinky, they roll in it.

This sharpened sense of smell in canines is a special instrument, and there has long been anecdotal evidence about dogs being able to smell diseases, particularly cancer. Perhaps a lady had a lump on her leg that her dog wouldn’t stop smelling, and when she finally had it examined by a doctor, it turned out to be cancer. Other such stories have percolated through health news columns for years.

But now the proof is finally here. A new study from German researchers showed that dogs are able to detect early-stage lung cancer better than any doctor or any fancy medical equipment.

Tests were held at Schillerhoehe Hospital in Germany with four specially trained dogs: Two German shepherds, a Labrador retriever and an Australian shepherd. Each dog was given a test tube to sniff that contained the breath of some 220 patients, some of whom had lung cancer and some of whom were cancer-free.

Out of 400 samples, the dogs were able to correctly identify the 71 out of 100 patients with lung cancer as well as 372 out of 400 samples that did not have the disease. In addition, the dogs could discern between lung cancer and other lung problems such as chronic obstructive pulmonary disease, as well as sniffing accurately through the breath of patients that just smoked a cigarette.

What does this mean? First of all, cancer of the lungs causes cells to release specific volatile organic compounds, emitted as they undergo mutations caused by tumors. Secondly, these early-stage emissions, while undetectable by medical tests or current diagnostic technology, can indeed be identified by dear old Fido.

Lung cancer is presently the leading cause of cancer deaths in the United States, killing more people than prostate, breast, ovarian, lymph and colon cancers combined. Often a brutal diagnosis that can be very painful and deadly to the patient, detecting lung cancer at an early stage could potentially save the lives of some of the 200,000 diagnosed with the disease each year.

Dogs have long been the appointed guardians of human families and tribes throughout the world, and thanks to the incredible olfactory gifts contained in those wet noses, dogs may prove to be better protectors than we ever imagined.



image: Shilo Urban