Dogs have incredibly strong scent receptors. Think you have a superior snout? Well, you might take pride in your palette, but there really is no comparison. We have 6 million scent receptors. Dogs have 300 million. To put it in terms we understand, Alexandra Horowitz, a dog-cognition researcher at Barnard College, writes in her book Inside of a Dog, that “while we might notice if our coffee has had a teaspoon of sugar added to it, a dog could detect a teaspoon of sugar in a million gallons of water, or two Olympic-sized pools worth.” 

Everyone knows that dogs can detect odors of drugs, made popular by TV shows such as “Cops” and “Live PD”. These K-9 units utilize their companions’ noses in order to catch even the smallest remnants of illegal substances. But another truly amazing feat of some breeds is the ability to detect cancers. 

Some dogs work in lab environments dealing with vials of blood. Specifically in the detection of ovarian cancers, volatile organic compounds or VOC’s, give off a certain odor that dogs can detect. Even the smallest quantities of tainted VOC’s can be found by a dog trained to alert. 

But why can dogs smell these altered cells? Some scientists believe that all creatures have evolved to detect death and disease in order to prevent contamination and the spread of infection. Many animals will not eat rotting carcases, and those that do have evolved gastro-intestinal biomes in which their bacteria is equipped to handle the diseases that may be present. Wolves in the wild will kill sick individuals in order to save the pack. They can smell the change in their pack member’s biology, and will either kill or exile the sick member in order to keep the majority safe and healthy. Just as infections smell, so do other illnesses; the difference is that humans just can’t detect the scent.

Many dog breeds have been trained to detect these odor signatures in a patient’s breath, urine, skin samples, blood samples, and sweat. Specifically Bloodhounds, German Shepherds, and some terrier breeds have been used to target specific cancers. A study was published in the Journal of Urology to see just how accurate dogs can be when detecting prostate cancers. Two female German Shepherd Dogs, who were previously trained in explosion detection, were also trained to detect VOC’s in urine samples. They had a sample group of 902 patients. 362 of them had varying stages of prostate cancer, while 540 of them were completely cancer-free. The results of the study shocked even the scientists performing it. Dog 1 had a 100% sensitivity rate. She had found every case of cancer, no matter the severity. Dog 2 had a 98.7% sensitivity rate. The fact that they each had such a selective, precise way of detecting the cancer was truly jaw-dropping. 

Many doctors are hopeful that the medical field will begin to expand its use of canines and their amazing noses. They already acknowledge that owning a pet supports healthy living habits and increases overall happiness. Hopefully we will continue to partner with our pets in order for all to live longer, healthier lives.