Detecting Parkinson’s Disease Through Canine Scent

Two specially trained dogs have revealed that Parkinson’s disease produces a distinctive scent on human skin—detectable with surprising precision by canine noses.

This breakthrough could lead to quicker, more affordable, and non-invasive diagnostic options for a condition that currently lacks an early detection method.

The research involved collaboration between Medical Detection Dogs in Milton Keynes and scientists from the Universities of Bristol and Manchester.

Over several months, trainers worked with two retriever-type dogs to identify the odor associated with sebum—a natural oily substance produced by our skin—altered in the presence of Parkinson’s disease (PD).

Teaching Dogs to Sniff Out Disease

Throughout their training, the dogs were presented with over 200 gauze swabs, which included samples from recently diagnosed patients, volunteers without neurological conditions, and those with various other ailments.

Select samples were attached to stands. When a dog indicated a positive sample, the handler responded with a click and a treat.

In a final double-blind test—where neither the dog handler nor the scientist knew which samples were which—the dogs achieved an impressive sensitivity of 80 percent and specificity of 98 percent, even identifying Parkinson’s in swabs from individuals with other health issues.

The Unique Scent of Parkinson’s

While dog noses are famously keen, researchers sought their help for a compelling reason. Elevated sebum levels and changes in body odor may occur years before the motor symptoms—like tremors and rigidity—become noticeable.

A Scottish nurse, Joy Milne, famously recognized a musky change in her husband’s scent long before he was diagnosed, prompting scientists to search for molecular indicators in skin oils.

Although lab methods using mass spectrometry are developing, they require costly equipment and trained staff. Dogs might provide a more straightforward solution.

“We’re proud to confirm that dogs can accurately detect disease,” stated Claire Guest, CEO and Chief Scientific Officer at Medical Detection Dogs. “Currently, there is no early test for Parkinson’s, and its symptoms can start up to 20 years prior to diagnosis.”

“Early diagnosis is critical as treatments can potentially slow disease progression and lessen symptoms.”

Detection Rates Outshining Typical Medical Tests

Even experienced neurologists can misdiagnose early Parkinson’s, and tests like imaging and spinal fluid analysis can be expensive. In contrast, the high sensitivity and specificity reported here surpass many existing point-of-care methods.

“Identifying biomarkers of PD that could signal earlier detection is an ongoing area of research,” noted lead author Nicola Rooney, an animal behavior specialist at the University of Bristol.

Rooney emphasized that the dogs demonstrated a distinct olfactory signature linked to the disease, achieving sensitivity levels above chance, which is promising for developing a quick, non-invasive diagnostic option.

Confirming Results with Blinded Trials

To prevent any unconscious bias, researchers also alternated the order of sample presentation. A computer tracked sample locations, revealing results only after the dog’s selection.

This rigorous approach aligns with clinical trial standards, affirming that the dogs relied solely on their sense of smell.

Canines Contributing to Smell Sensor Development

Recognizing that dogs won’t replace neurologists, this research provides chemists with a list of volatile molecules to target with sensors.

“This study adds to growing evidence that simple skin swabs can diagnose Parkinson’s,” remarked Perdita Barran, a professor of analytical chemistry at the University of Manchester. Her lab is analyzing swab compositions, confirming their relevance in diagnostics.

Exploring Other Neurological Conditions

Researchers and trainers are now investigating using dogs to detect other neurological disorders such as Alzheimer’s, multiple sclerosis, and even migraine episodes. Early stages of Alzheimer’s might also alter body odor—subtle changes that could easily go unnoticed by humans but are picked up by dogs.

There have even been reports of dogs acting restlessly before their owners experience migraines or MS flare-ups, suggesting a unique sensitivity to impending symptoms.

Additionally, families with children on the autism spectrum have observed service dogs detecting sensory overload before it escalates, helping to calm situations before they become overwhelming.

Advancing Scent Science

Future studies aim to include individuals with REM sleep behavior disorder—a precursor to Parkinson’s— to see if dogs can identify the disease earlier than a neurologist. Concurrent chemical analyses will seek out precise compounds responsible for the distinctive odor. If consistent globally, these molecules could be developed into affordable sensor technology.

The takeaway is encouraging: a simple skin swab may contain vital information about neurodegeneration, readable by a dog’s nose. This could speed up efforts for a quick, painless test, offering another means to put Parkinson’s on the radar before it progresses.

The study has been published in the Journal of Parkinson’s Disease.