Pet dogs of various breeds can be trained to detect scents linked to Parkinson鈥檚 disease with nearly 90 per cent accuracy. With further research, this may be a relatively conclusive and inexpensive way of diagnosing the condition that enables earlier access to treatments.
People with Parkinson鈥檚 disease have hundreds of unique chemicals in their sebum, the oily substance that hydrates the skin. With the condition having no set test, it has been suggested that these chemicals could be used to aid diagnosis.
Dogs, , have previously been found to detect scents relating to , and . The breeds typically used include Labrador retrievers and different shepherd dogs, with animals being considered for such roles tending to be raised in expensive training centres.
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Seeking a new approach, Lisa Holt and Samuel Johnston at the charity PADs for Parkinson鈥檚 in Washington state recruited 23 pet dogs of 16 breeds. These included breeds that have previously been used to detect different medical conditions, as well as those that generally aren鈥檛 raised for this purpose, such as Pomeranians and English mastiffs.
Forty-three people who had been diagnosed with Parkinson鈥檚 disease and 31 volunteers with no known medical conditions provided sebum samples, either via T-shirts worn overnight or swabs of their upper backs.
Each dog was put through a training programme lasting at least eight months. They were trained to communicate when they identified a Parkinson鈥檚 sample by sitting, barking, tapping a paw or bobbing their nose. To incentivise them, each sniffing sample provided by a participant with Parkinson鈥檚 disease was paired with a reward, such as food or a toy.
Once their training was complete, the dogs were exposed to sebum samples they hadn鈥檛 previously encountered. Their owners weren鈥檛 aware if the samples were from someone with or without Parkinson鈥檚.
Overall, the dogs identified the samples from someone with Parkinson鈥檚 disease with 86 per cent accuracy, on average, and didn鈥檛 respond to the healthy volunteers鈥� samples 89 per cent of the time.
Testing of the training programme is continuing at the Alfort National Veterinary School in France, says Holt. 鈥淥nce that training was done, it would then be possible to test whether dogs could identify Parkinson鈥檚 at a much earlier stage, when the full suite of symptoms are not yet present,鈥� she says. The researchers hope that odorants relating to Parkinson鈥檚 disease could one day be packaged into a training aid for dogs.
鈥淢any dog studies for disease detection are proof of principle, with just two dogs, for example,鈥� says at the University of Bristol, UK. 鈥淭his study shows training can be successful with a variety of home-housed dogs.鈥�
But despite testing several breeds, the dataset isn鈥檛 large enough to conclude which ones detect Parkinson鈥檚 best, she says.
bioRxiv
