Bumper, the Golden Retriever in the study, smells a swab for the experiment. (Credit: Medical Detection Dogs UK)

In A Nutshell

Two trained dogs detected Parkinson’s disease with up to 80% sensitivity and 98% specificity by sniffing skin swabs.

Parkinson’s patients produce sebum (skin oil) with a unique scent signature linked to the disease.

There’s currently no definitive test for Parkinson’s. Early scent detection could help doctors screen for the disease sooner.

Researchers hope to refine training or build electronic “noses” that mimic dogs’ remarkable sniffing skills.

BRISTOL, England — Two specially trained dogs have proven they can detect Parkinson’s disease simply by smelling skin swabs, achieving accuracy rates that rival expensive medical tests. In a rigorous study, the canines correctly identified the neurological condition in 70% and 80% of patients while maintaining over 90% accuracy in ruling out healthy individuals—a breakthrough that could change how doctors screen for a disease that currently has no definitive diagnostic test.

Getting a Parkinson’s diagnosis today means waiting for telltale symptoms like tremors and stiffness to appear, often years after brain damage has already begun. Doctors rely on observing these physical signs because current medical tests are either invasive, expensive, or unreliable. But dogs possess a secret weapon: noses that are 10,000 times more sensitive than humans, capable of detecting molecular changes invisible to our senses.

How Dogs Were Trained to Detect Parkinson’s from Skin Swabs

Researchers from the Universities of Bristol and Manchester, in collaboration with Medical Detection Dogs in the UK, discovered that Parkinson’s patients produce different oils on their skin compared to healthy people. These oils, called sebum, carry a distinct scent that trained dogs can learn to recognize from simple cotton swab samples taken from patients’ backs.

Starting with ten candidate dogs, researchers quickly learned that medical detection work isn’t for every canine. After initial screening, only five showed promise, and as training intensified over nearly a year, three more dropped out. The final two, a two-year-old male Golden Retriever and a three-year-old male Labrador-Golden Retriever mix, proved exceptional at the task.

Dog training was methodical and demanding. Over 38 to 53 weeks, the animals learned to distinguish between 205 different skin samples from people with and without Parkinson’s. Trainers rewarded correct identifications while ignoring samples from healthy individuals, teaching the dogs to alert only when they detected the disease’s unique scent signature.

Peanut, the Labrador retriever from the study. (Credit: Medical Detection Dogs UK) Double-Blind Trial With Over 90% Accuracy

The real test came when researchers presented the dogs with 100 completely new samples during double-blind trials, meaning neither the handlers nor researchers knew which samples contained the target scent. This eliminated any possibility of unconscious human cues influencing the dogs’ behavior.

Results, published in the Journal of Parkinson’s Disease, were impressive. The first dog correctly identified 28 out of 40 Parkinson’s samples (70% sensitivity) and properly dismissed 54 out of 60 healthy samples (90% specificity). The second dog performed even better, catching 32 out of 40 Parkinson’s samples (80% sensitivity) and correctly ignoring 59 out of 60 control samples (98% specificity).

These accuracy rates surpass many current medical detection scenarios. Dogs trained to detect bladder cancer, for example, achieved only 41% accuracy in previous studies. The Parkinson’s detection rates also compete with some laboratory tests and brain imaging procedures currently used in hospitals.

Both dogs showed remarkable agreement on which samples were easier to identify, indicating that some patients may produce stronger scent signatures than others. Research focused exclusively on drug-naive patients — those who hadn’t yet started Parkinson’s medications — ensuring cleaner scientific results about the disease’s natural scent profile.

Bumper smells a swab for the Parkinson’s disease detection study. (Credit: Medical Detection Dogs UK) What Exactly Are Dogs Smelling in Parkinson’s Patients?

Parkinson’s disease changes more than just movement. It also alters how the body produces skin oils. Patients often develop seborrheic dermatitis, a condition involving excessive production of sebum that’s chemically different from healthy individuals. This altered sebum composition can appear even before the characteristic motor symptoms of Parkinson’s emerge.

The changed sebum creates volatile organic compounds (essentially odor molecules) that produce a distinctive scent signature. While human noses can’t detect these subtle differences, dogs can identify molecular changes occurring at the cellular level. The discovery builds on earlier observations by Joy Milne, a Scottish woman with hyperosmia (an enhanced sense of smell) who noticed her husband’s scent change years before his Parkinson’s diagnosis.

Parkinson’s disease also changes the way the body produces skin oils, making it easier for detection dogs to learn the “scent” of the condition. (© Feng Yu – stock.adobe.com) Could Medical Detection Dogs Help Diagnose Parkinson’s Earlier?

While dogs won’t replace neurologists, they could serve as valuable screening tools, especially in areas where movement disorder specialists are scarce. Early detection could enable earlier treatment and potentially slow disease progression.

Research also points toward developing electronic sensors that could detect the same chemical signatures dogs identify. Such devices could deliver rapid, non-invasive screening that complements existing diagnostic methods without the substantial costs and time requirements of training detection dogs.

Challenges remain, however. Training detection dogs requires significant time and resources — nearly a year of intensive work per animal — and only a small percentage of candidates prove suitable. The study also couldn’t determine what specific factors made some samples easier to detect than others, limiting understanding of how consistent this detection method might be across different patients.

Despite these limitations, the study could yield a significant advance in Parkinson’s disease detection. It turns out humanity’s oldest companion may become an unexpected ally in diagnosing one of our most challenging neurological conditions.

Peanut, the Parkinson’s disease detection dog. (Credit: Medical Detection Dogs UK)

Disclaimer: This article summarizes findings from the paper “Trained dogs can detect the odor of Parkinson’s disease.” The results reflect early-stage research and should not be used as medical advice. Always consult qualified healthcare professionals for diagnosis or treatment of Parkinson’s disease or any other health condition

Paper Summary Methodology

Researchers trained two dogs over 38-53 weeks using 205 skin swab samples collected from people with Parkinson’s disease and healthy controls. After training, the dogs underwent double-blind testing with 100 new samples (40 from Parkinson’s patients, 60 from controls) that neither the dogs nor handlers had encountered before. Samples were collected using cotton swabs on participants’ backs to capture sebum, the oily skin secretion that previous research suggested carries a distinctive scent in Parkinson’s patients.

Results

Dog 1 achieved 70% sensitivity (correctly identifying Parkinson’s samples) and 90% specificity (correctly dismissing control samples). Dog 2 performed better with 80% sensitivity and 98% specificity. Both dogs performed significantly better than chance, and their agreement on certain samples was higher than expected, suggesting some samples were easier to identify than others.

Limitations

The study involved only two dogs from an initial pool of ten candidates, indicating that not all dogs are suitable for this type of detection work. The training process was lengthy and resource-intensive. The study used only drug-naive Parkinson’s patients, so the impact of medications on scent detection remains unknown. Sample sizes were relatively small, and researchers couldn’t identify specific factors that made some samples harder to detect than others.

Funding and Disclosures

The research was funded by the Michael J Fox Foundation and Parkinson’s UK, with additional support from EPSRC and BBSRC grants. The authors declared no conflicts of interest related to the research, authorship, or publication of the article.

Publication Information

“Trained dogs can detect the odor of Parkinson’s disease” by Nicola Rooney et al., published in the Journal of Parkinson’s Disease on July 14, 2025. The study was conducted by researchers from Medical Detection Dogs, University of Bristol, University of Manchester, University of Edinburgh, and other UK institutions.