Trained dogs can detect the odour of Parkinson’s Disease

A definitive diagnostic test for PD remains elusive, so identification of potential biomarkers may shed light on methods for diagnosis and facilitate early intervention. Excess sebum secretion and skin pathology are recognised symptoms of early PD. It is likely these result in a unique signature of volatile organic compounds that could be used to identify early stages of disease. Numerous medical conditions produce distinctive odours, and dogs have been trained to detect many of these. A single previous study, suggested that dogs can also be trained to detect Parkinson’s Disease. In this study, two dogs were trained to distinguish sebum swabs obtained from drug naïve, and medicated Parkinson’s patients from swabs from control participants. After 38-53 weeks of training on 205 samples (90 target and 115 control), the dogs were tested in a double-blind trial using 60 control and 40 target samples from drug-naïve patients. The dogs both showed high sensitivity (proportion of target samples found 70% and 80%) and specificity (proportion of control samples not alerted to 90% and 98%) of alerting response. This trial supports previous findings that dogs can be trained to reliably detect the odour of PD. We suggest there is a potential for dogs to achieve even higher accuracy with increased exposure and refined training methods and to detect early-stage PD, even prior to diagnosis, as well as hard to diagnose PD cases. Further exploration of the factors which affect dogs’ sensitivity and specificity and sample features which affect accuracy of discrimination are now required. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement We thank Michael J Fox Foundation and Parkinsons UK for funding this study. We also thank the nationwide NIHR recruitment centres for their support and would like to thank the patients carers and participants for providing the samples. We are very grateful to all the participants who took part in this study. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethical approval for this project (IRAS project ID 191917) was obtained by the NHS Health Research Authority (REC reference: 15/SW/0354) I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data supporting the findings of this study are openly available at the University of Bristol data repository, data.bris, at