In the Ruhr area, a therapy dog helps Parkinson’s patients.

In many cases, dogs can smell whether a person has Parkinson's disease. In one study, two dogs trained to detect this odor were able to reliably determine from skin swabs whether a person suffered from the neurodegenerative disease.

"Identifying diagnostic biomarkers for Parkinson's, particularly those that can predict disease progression or contribute to earlier diagnosis, is the subject of intensive research," said lead author Nicola Rooney of the University of Bristol in a university press release. Diagnosing the disease, in which nerve cells in the midbrain die, is difficult and based on symptoms. Early detection opens the possibility of initiating treatment at an early stage.

Although previous studies have shown that dogs can sniff out Parkinson's disease, the study authors noted that the conditions under which these results were obtained were not always clear. Now, the scientists tested the ability to detect Parkinson's disease by smell in two dogs: a Golden Retriever and a Labrador-Golden Retriever mix.

They first trained the animals with 90 sebum samples from Parkinson's patients who were not taking anti-Parkinson's medication. In the double-blind study, the two animals then examined 40 samples from Parkinson's patients and 60 from people without the disease. These samples were similar to the patients in terms of age, gender, body mass index, and smoking status.

The two dogs correctly identified 70 and 80 percent of people suffering from Parkinson's disease, respectively. The two animals were even more reliable—one in 90 percent of cases, the other in 98 percent—when the sebum smear did not come from a patient, as Rooney's team reports in the Journal of Parkinson's Disease. The researchers do not know how the dogs were guided in this process.

Although the team writes that they do not believe that dogs could be used in diagnostics, Lars Timmermann, Director of the Department of Neurology at Marburg University Hospital, sees things differently: He can certainly imagine dogs being used in the early diagnosis of Parkinson's disease.

"A sniffing dog is a friendly, simple, and affordable way to detect Parkinson's disease at an early stage and subsequently treat it," said the former president of the German Society of Neurology (DGN). The high accuracy in identifying people without Parkinson's disease can largely prevent people from being burdened by a misdiagnosis.

The neurologist points out that dogs are already being used in Parkinson's therapy. For example, the therapy dog Ludwig is being used to treat Parkinson's patients at the Knappschaft Kliniken Bottrop.

Parkinson's disease is a neurological movement disorder that primarily affects older people. Also known as shaking palsy, the disease is caused by the death of specific nerve cells in the brain. These cells then no longer produce dopamine, which the body normally uses to control movement. Numerous disorders result: tremors, tense muscles, and gait and balance disorders. Parkinson's disease is the second most common neurodegenerative disease in Germany after Alzheimer's disease.