Dogs could soon be used to sniff out Parkinson’s disease years before symptoms start to show.

Scientists are trying to discover which odour molecules are linked to the disease so that dogs can be trained to spot the illness.

Researchers at Manchester University first began to believe Parkinson’s might have a discernible odour when a woman in Perth, Scotland, with a highly sensitive sense of smell claimed she detected a change in the odour of her husband six years before he was diagnosed with the condition.

Joy Milne claimed her husband’s smell changed subtly years before any difficulty with movement started to emerge.

When researchers conducted tests with Mrs Milne they found she was able to identify people living with Parkinson’s from people without the condition by smelling skin swabs taken from both groups.

In one case, Mrs Milne identified an individual who had Parkinson’s but at the time had not been diagnosed with the condition, because they had no symptoms.