Is a Full Body Sniff-Scan by a Trained Dog in Your Future?

Analysis by Dr. Karen Shaw Becker

Story at-a-glance -

  • The canine sense of smell is one of many irreplaceable gifts dogs offer us
  • It may be just a matter of time before scent detection dogs are employed as often as the latest technology in medical offices
  • Cancer-sniffing canines tend to grab all the headlines, but there are likely many other human diseases and disorders that can be detected by dogs as well

Among the countless one-of-a-kind gifts that dogs offer humans is their miraculous sense of smell. Most of us recognize that canines have sharp noses, but the degree to which they’re able to detect “odorant molecules” is rather beyond our comprehension. Some of the specifics of dogs’ super sniffers are described in a 2012 study comparing the canine ability to detect the odor of cancer to laboratory testing:1

  • Dogs possess an extraordinary dimension of their olfactory epithelium (up to 170 cm vs. 10 cm in humans)2 (the olfactory epithelium is a specialized type of tissue inside the nose)
  • They also possess a huge number of olfactory receptors (over 200 million vs. 5 million in humans)
  • There is also a “dense innervation of [dogs’] olfactory mucosa and their ability to ‘sort’ meaningful incoming odors from those that are unwanted or unnecessary”

Bottom line: These very special anatomic features of the canine nose give dogs the ability to detect even minute amounts of a particular odorant — an ability estimated to be one million times more efficient than in humans!

Dogs Are Able to Detect Cancer Odors With a High Degree of Accuracy

In an article for veterinary publication dvm360, researcher Ed Kane, PhD, compiled a sampling of fascinating case reports and studies of dogs detecting human cancer:3

Year Case Report or Study


A 44-year-old woman’s Border Collie-Doberman cross continuously sniffed at her left thigh, which was later biopsied, and a malignant melanoma diagnosed.4


A 66-year-old man’s Labrador Retriever repeatedly sniffed at his leg through his trousers; he was found to have a basal cell carcinoma.5


Two dogs, a 4-year-old Standard Schnauzer and a 6-year-old Golden Retriever, were trained to identify melanoma tissue samples hidden on the skin of healthy volunteers. One of the dogs positively identified samples at first tested negative, but further histologic examination revealed a small number of cancerous cells.6

Six dogs of varying breeds and ages were trained to detect the urine of patients with bladder cancer. The dogs correctly determined bladder cancer urine in 41% of the cases.7


Researchers used a food-reward system to train five household dogs to identify exhaled breath samples of lung and breast cancer patients, distinguishing them from healthy controls. The sensitivity and specificity were 99% for lung cancer patients and 88-98% for breast cancer patients; results were remarkably similar across all four stages of disease.8


A dog was taught to identify ovarian carcinoma samples consisting of 31 different histopathological types of various grades and stages. In double-blind tests, the dog was capable of correctly identifying all cancer samples with 100% sensitivity and 97.5% specificity, as well as discriminating ovarian carcinomas from other gynecological carcinomas with 100% sensitivity, 91% specificity.9


Two dogs were trained to detect ovarian cancer from normal ovarian tissue and distinguish blood plasma of patients with ovarian carcinomas. Tissue test sensitivity was 100% and specificity 95%; blood plasma sensitivity was 100% and specificity 98%.10


A Belgian Malinois was clicker-trained to scent and identify prostate cancer patients from their urine. The dog correctly identified cancer in 31 of 33 patients, with 91% sensitivity and specificity.11

A Labrador Retriever was trained to scent-detect colorectal cancer from breath and watery stool samples. Compared with colonoscopy, dogs showed their ability to detect cancer from breath samples at 91% sensitivity and 99% specificity. With stool samples, sensitivity was 97% and specificity 99%. Accuracy was high even for early cancer.12


Trained dogs successfully detected lung cancer from human breath with sensitivity of 90% and specificity of 72%.13


Two 3-year-old explosion-detection German Shepherds were trained to identify human prostate cancer from specific volatile compounds in urine samples from 362 patients with prostate cancer. For the first dog, sensitivity was 100% and specificity 98%; for the second dog, sensitivity was 99% and specificity 98%.14


Researchers investigated the feasibility of whether dogs could use olfactory cues to discriminate urine samples from dogs with diagnosed urinary tract transitional cell carcinoma versus control dogs.15

Researchers investigated the detection of hepatocellular carcinoma from human breath using canine olfaction. Results showed an accuracy rate of 78%.16

The first item in the above list — the 1989 case report — was also the first published account of the ability of canines to detect cancer, and as you can see, the dog spontaneously sniffed out the disease. It was that first case that planted the seed with scientists that if dogs are able to naturally express the behavior, they can be trained to offer it on command.

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Is a Sniff-Scan in Your Future?

As you read this, formally trained veterinarians are helping to train cancer detection dogs across the globe — in Costa Rica, Canada, Slovenia, Finland, Norway, the U.K., France, Germany, the Netherlands and Poland.

With what looks to be clear evidence that trained sniffer dogs can be as or in some cases more effective than other cancer screening methods, as researcher Michael McCulloch, PhD points out to dvm360, the next step is for entrepreneurs and scientists to collaborate to turn scientific results into a commercial service, if feasible.

While dogs that can sniff out cancer tend to grab the headlines, the keen canine sense of smell also has the potential to be helpful in detecting other diseases with characteristic odors, including:

Urinary tract infections

Gastrointestinal (GI) disorders (e.g., gastritis due to a H. pylori infection)


Psychological disorders

Endocrine disorders (e.g., Cushing’s syndrome)

Thyroid disorders


Candida esophagitis


Alcohol abuse

So, maybe one day in the future while visiting your doctor’s office you’ll be asked to undergo a full body sniff-scan by a four-legged, fur-covered physician’s assistant! I don’t know about you, but I’ll take a wet nose scan any day over the less benign alternatives!

+ Sources and References