The science behind the nose: correlating volatile organic compound characterization with canine biodetection of COVID-19

The SARS-CoV-2 pandemic stimulated the advancement and research in the field of canine scent detection of COVID-19 and volatile organic compound (VOC) breath sampling. It remains unclear which VOCs are associated with positive canine alerts. This study aimed to confirm that the training aids used for COVID-19 canine scent detection were indeed releasing discriminant COVID-19 VOCs detectable and identifiable by gas chromatography (GC-MS).Inexperienced dogs (two Labradors and one English Springer Spaniel) were trained over 19 weeks to discriminate between COVID-19 infected and uninfected individuals and then independently validated. Getxent® tubes, impregnated with the odours from clinical gargle samples, used during the canines’ maintenance training process were also analysed using GC-MS.Three dogs were successfully trained to detect COVID-19. A PCA-X model was created and confirmed the ability to discriminate between VOCs from positive and negative COVID-19 Getxent® tubes with a sensitivity of 78% and a specificity of 77%. Two VOCs were found to be very predictive of positive COVID-19 cases. When comparing the dogs with GC-MS, F1 and MCC correlation scores of 0.69 and 0.37, were observed respectively, demonstrating good concordance between the two methods.This study provides analytical confirmation that canine training aids can be safely and reliably produced with good discrimination between positive samples and negative controls. It is also a further step towards better understanding of canine odour discrimination of COVID-19 as the scent of interest and defining what VOC elements the canines interpret as “essential”.