Dogs can smell Parkinson’s signature on skin: Study
Breakthrough sparked by woman's super-sensitive sense of smell
Two trained dogs detected Parkinson’s disease with high accuracy by smelling skin swabs of patients who had not yet received treatment, adding to growing evidence that scent carries a chemical signature that could help enable early, noninvasive diagnosis.
Bumper, a golden retriever, and Peanut, a black Labrador, were trained for several weeks by Medical Detection Dogs, a U.K. charity, to distinguish between the oily skin secretions — known as sebum — of people with Parkinson’s and those without the disease.
While researchers do not see dogs as diagnostic tools, the study, done in collaboration with the University of Bristol and the University of Manchester, suggests that their “incredible sense of smell” could help with more rapid screening, potentially leading to earlier Parkinson’s treatment, the researchers said.
Dogs have previously been trained to detect other types of disease, such as cancer and malaria. “We are extremely proud to say that once again, dogs can very accurately detect disease,” Claire Guest, CEO and chief scientific officer at Medical Detection Dogs, said in a University of Bristol news story.
The study, “Trained dogs can detect the odor of Parkinson’s disease,” was published as a short communication in the Journal of Parkinson’s Disease. It was partly funded by The Michael J. Fox Foundation for Parkinson’s Research and Parkinson’s U.K.
Dogs smell skin swabs
While Parkinson’s is best known for its motor symptoms, many patients also experience problems with their skin. Changes in sebum may appear long before other Parkinson’s symptoms, providing an early sign that could help diagnose the disease at an early stage.
“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,” Guest said. “Timely diagnosis is key as subsequent treatment could slow down the progression of the disease and reduce the intensity of symptoms.”
The idea to test sebum for changes came after a retired nurse, Joy Milne, noticed changes in her husband’s scent before he was diagnosed with Parkinson’s at age 45. Milne has hyperosmia, or an exceptionally sensitive sense of smell.
“It’s wonderful to be part of this research inspired by Joy Milne,” said Perdita Barran, PhD, a professor at the University of Manchester who has been developing rapid tests for diagnosing Parkinson’s. “Simple, non-invasive skin swabs can be used to diagnose Parkinson’s disease, offering a faster and more accessible method for early detection.”
The researchers trained dogs to detect Parkinson’s based on the scent of sebum.
Bumper was trained for more than 38 weeks (nearly nine months) and Peanut was trained for more than 53 weeks (about one year) using 205 dry skin swabs of people diagnosed with Parkinson’s and those without the disease.
A professional dog trainer used a reward system. When the dogs correctly signaled Parkinson’s after smelling a patient’s skin swab or ignored a control, they received praise and treats. If the response was incorrect, the trainer withheld the reward.
After training, the dogs were presented with 100 new skin swabs from 40 patients, with a median age of 71, who had been diagnosed with Parkinson’s for an average of about two years but had not yet received treatment, and 60 controls.
The researchers looked at sensitivity — the ability to correctly identify Parkinson’s by smelling skin swabs from patients who have the disease — and specificity, the ability to correctly exclude control samples. One dog achieved a sensitivity of 70% and a specificity of 90%, and the other had a sensitivity of 80% and a specificity of 98%.
“The dogs in this study achieved high sensitivity and specificity and showed there is an olfactory signature distinct to patients with the disease,” said Nicola Rooney, PhD, an associate professor at the University of Bristol and the study’s first author. “Sensitivity levels of 70% and 80% are well above chance.”
The findings align with growing evidence that volatile compounds in sebum may carry a chemical signature that indicates the presence of disease and that “dogs can be trained to reliably detect the smell of Parkinson’s,” the researchers wrote.
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