A pair of specially trained dogs has shown that Parkinson’s disease leaves a telltale scent on human skin. This scent is strong enough for a canine nose to detect with remarkable accuracy.
This discovery could open the door to faster, cheaper, and entirely non‑invasive screening for a condition that currently lacks an early diagnostic test.
The study brought together Medical Detection Dogs in Milton Keynes with scientists from the Universities of Bristol and Manchester.
Over several months, the charity’s trainers conditioned two retriever-type dogs to recognize the odor that clings to sebum. This oily substance, which our skin naturally produces, changes when Parkinson’s disease (PD) is present.
Training dogs to detect disease
During training, the canines encountered more than 200 gauze swabs. Some were taken from recently diagnosed patients, others from volunteers with no neurological illness, and a few from people living with different conditions.
Each pad was clipped to a stand. When a dog paused and pointed at a positive sample, the handler quietly clicked and offered a reward.
In the final double-blind trial – where neither the dog handler nor the overseeing scientist knew which positions held a patient’s swab – the dogs showed sensitivity of up to 80 percent and specificity of up to 98 percent.
Moreover, they were also able to detect Parkinson’s in swabs from people with multiple health conditions.
The scent of Parkinson’s
Dog noses are legendary, but Parkinson’s researchers turned to them for a very specific reason. Excess sebum and a change in body odor often precede the familiar motor symptoms – shaking, slowed movement, and rigid muscles – by years.
A Scottish nurse named Joy Milne famously noticed a musky shift in her husband’s scent long before his diagnosis. Her observation inspired scientists to hunt for molecular fingerprints in skin oil.
A laboratory method based on mass‑spectrometry is inching forward, yet requires expensive instruments and trained personnel. Canines offer a shortcut.
“We are extremely proud to say that once again, dogs can very accurately detect disease,” said Claire Guest, CEO and Chief Scientific Officer at Medical Detection Dogs.
“There is currently no early test for Parkinson’s disease and symptoms may start up to 20 years before they become visible and persistent leading to a confirmed diagnosis.”
“Timely diagnosis is key as subsequent treatment could slow down the progression of the disease, and reduce the intensity of symptoms.”
Detection rates that rival medical tests
Even seasoned neurologists can misclassify early Parkinson’s, and imaging scans or spinal fluid assays are costly. By contrast, the gold-coated sensitivity and specificity reported here exceed those of many existing point-of-care tests in medical use.
“Identifying diagnostic biomarkers of PD – particularly those that may predict development or help diagnose disease earlier – is the subject of much ongoing research,” said lead author Nicola Rooney, an animal behavior specialist at the University of Bristol.
Rooney noted that the dogs in the study achieved high sensitivity and specificity and showed there is an olfactory signature distinct to patients with the disease.
“Sensitivity levels of 70 percent and 80 percent are well above chance, and I believe that dogs could help us develop a quick, noninvasive, and cost-effective method to identify patients with Parkinson’s disease.”
Blinded trials confirm the results
To guard against subconscious cues or handler bias, the researchers also presented every testing line in reverse order.
A computer kept track of which sample sat where, and only after the dog’s choice did researchers learn whether to dispense a treat.
This rigorous protocol mirrors clinical trial standards and boosts confidence that the animals relied on smell alone.
Dogs help build smell sensors
Dogs will never replace neurologists, but the findings give chemists a shortlist of volatile molecules to capture with sensors.
“This study adds to the growing body of evidence showing that simple, noninvasive skin swabs can be used to diagnose Parkinson’s disease,” said Perdita Barran, a professor of analytical chemistry at the University of Manchester.
Professor Barran’s lab is already dissecting the swab chemistry; the canine results confirm those molecules belong on the diagnostic radar.
Dogs and other neurological diseases
Researchers and dog trainers are beginning to explore how these animals can detect other neurological diseases like Alzheimer’s, multiple sclerosis, and even conditions like migraines or autism-related sensory episodes.
In the case of Alzheimer’s, for example, people in early stages of the disease may emit subtle changes in body odor – things a human nose would never catch, but a dog’s nose picks up with ease.
These scent cues could one day help in screening or early detection, well before symptoms become obvious.
There are also stories of dogs acting differently before their owners have a migraine or during MS flare-ups – becoming restless or unusually attentive – as if they sense something’s coming.
Some families of children with autism even report that service dogs notice sensory overload before it escalates, helping calm things down before a meltdown.
Expanding the science of scent
Future trials aim to include people with REM sleep behavior disorder – a risk state for Parkinson’s – to see whether dogs can spot the disease before a neurologist could.
Parallel chemical analyses will hunt for the exact compounds responsible for the odor. If those molecules prove consistent worldwide, engineers could embed them in low‑cost sensor chips.
For now the message is hopeful: a straightforward skin swab carries hidden information about neurodegeneration, and a dog’s nose can read it.
That knowledge could accelerate the quest for a rapid, painless test. It would offer one more tool to bring Parkinson’s onto clinicians’ radar while there is still time to slow its march.
The study is published in the Journal of Parkinson’s Disease.
—–
Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.
Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.
—–
-
-
-
-
