Dogs can smell parkinson's disease years in advance

The main study was published in 2025 in the Journal of Parkinson's Disease.

The research involved:

• University of Bristol
• University of Manchester
• Medical Detection Dogs

How the experiment was carried out

The dogs did not sniff people directly but skin samples (sebum).

Sebum is an oily substance produced by the sebaceous glands in the skin. In Parkinson's disease its composition changes and it takes on a specific odour.

Steps in the experiment:

1. Skin swabs were taken from people's backs or necks.
2. The samples were placed in special containers on a stand.
3. The dogs were trained to indicate the sample that "smells of Parkinson's".
4. The test was double-blind: neither the trainer nor the dogs knew where the real sample was.

The dogs were rewarded when they correctly indicated the sample.

The results were surprisingly good:

• 80% sensitivity
  → the dogs correctly identified 80% of the people who have Parkinson's disease
• 98% specificity
  → in 98% of cases they correctly indicated that healthy people did not have the disease

The dogs were able to recognise the disease even when the patients had other health problems, which means the odour is not a coincidence.

Parkinson's disease causes changes in the skin's metabolism:

• increased production of sebum
• changes in volatile organic molecules
• a different chemical composition of the skin's oils

Dogs can detect these molecules because they have around 300 million scent receptors (humans have around 6 million).

At present there is no simple test for the early detection of Parkinson's disease.

If the disease is detected earlier:

• therapy can begin sooner
• the progression of symptoms can be slowed
• patients' quality of life can be better.

That is why scientists are trying to:

• identify the chemical odour biomarkers
• build an electronic "nose" (sensor) that would imitate the dogs.