Can dogs detect disease? Studies say…

Can “Spot” spot cancer, diabetes, Parkinson’s disease and more? We’ve rounded up some of what the initial research shows so far — and it’s not just fluff.

“The full potential of dogs to detect human disease is just beginning to be understood,” says Claire Guest, chief executive of a U.K.-based organization called Medical Detection Dogs, which trains “biodetection dogs” (involved in some of the research cited below). “If all diseases have an odor, which we have reason to believe they do, we can use dogs to identify them.”

Sniffing out the latest studies

Several media outlets reported this fall that scientists are currently training dogs to sniff out the scent of malaria, which is on the rise and especially deadly in children. In October, researchers announced at the American Society of Tropical Medicine and Hygiene conference that two dogs correctly detected malaria in children (who appeared healthy, without symptoms) 70 percent of the time.

Following this small “proof of concept” study funded by the Bill & Melinda Gates Foundation, researchers will continue to work on training biodetection dogs and also try to develop a device that could one day mimic what the dog’s nose does — pick up scents or compounds associated with diseases.

What other diseases or conditions might dogs be able to detect? While many of these studies are small and call for additional research, here’s what scientists have found so far:

  • Prostate cancer – In a small 2015 study, Italian researchers found that two German Shepherd explosive detection dogs correctly identified prostate cancer compounds in urine samples 95% of the time (which STAT notes is “more accurate than the prostate-specific antigen test used to screen for prostate cancer”).
  • Colorectal cancer – A 2011 study published in BMJ found that a Labrador retriever specifically trained to detect cancer could identify the breath and stool samples of people with colorectal cancer with high accuracy. The dog would sniff the sample, then sit down if cancer compounds were present. “The accuracy of canine scent detection was high even for early cancer,” the researchers say.
  • Breast and lung cancer – The researchers behind this 2006 study said, “In a matter of weeks, ordinary household dogs with only basic behavioral ‘puppy training’ were trained to accurately distinguish breath samples of lung and breast cancer patients from those of controls.” (How were the dogs trained/rewarded? FOOD!)
  • Melanoma (skin cancer) – A 2004 study (in an animal behavior journal) found that “two dogs demonstrated reliable localization of melanoma tissue samples hidden on the skin of healthy volunteers.” As this article summarizes, a 1989 report in the journal Lancet says a woman’s border collie mix kept sniffing a mole on her thigh (and even tried to bite it off) while ignoring other moles — and said mole turned out to be malignant melanoma.
  • Bladder cancer – In this 2004 “proof of principal” study in the BMJ, six trained dogs had a mean success rate of 41% in correctly selecting urine from patients with bladder cancer (on 22 out of 54 occasions). More research is needed.
  • Parkinson’s disease – Parkinson’s UK and the Michael J. Fox Foundation have teamed up to fund research into biodetection dogs for PD. “Two Labradors and a cocker spaniel will next week start work on swabs from 700 people to spot a smell that appears years before people start experiencing mobility problems,” Parkinson’s UK reported when the research kicked off in summer 2017. Stay tuned.
  • Diabetes and other conditions – Several other studies have shown that dogs may be useful in other types of “biodetection” beyond diagnosis. For example, they could give alerts about oncoming low blood sugar (hypoglycemia) in people with diabetes, or other types of imminent episodes, such as narcolepsy, migraine and seizures.

Seems like dogs are onto something! STAT cautions that “much more work is needed, as dogs haven’t done as well on more rigorous tests in some cases [of cancer detection].”

Why are dogs such super-sniffers?

Dogs are known for their noses, but exactly what is so special about them?

  • Wired reports that dogs’ sense of smell is “powerful enough to detect substances at concentrations of one part per trillion—a single drop of liquid in 20 Olympic-size swimming pools.”
  • “Dogs have something called neophilia, which means they are attracted to new and interesting odors,” according to Guest, of Medical Detection Dogs.
  • Scientists estimate that a dog’s sense of smell is 10,000 to 100,000 times more acute than a human’s, NOVA/PBS reports. “If you make the analogy to vision, what you and I can see at a third of a mile, a dog could see more than 3,000 miles away and still see as well,” says researcher James Walker, the former director of Florida State University’s Sensory Research Institute.
  • Dogs even have an additional organ called the vomeronasal organ (also known as Jacobson’s organ) to help them pick up scents.

Pretty neat! We’ll certainly be nuzzling our pups’ muzzles a little closer now.

What do you think about the potential for dogs to be “biodetectors”? Join PatientsLikeMe or log in today to talk about this topic with the community!

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