Double-blinded test–retest reliability assessment in laboratory
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The prime contribution of the current paper lies in answering the empirical question of whether trained sniffer dogs’ ability is relatively stable over time in a laboratory setting. The current results support such possibility, at least in two of the three dogs involved. The dogs’ ability was analysed through test–retest reliability, in order to verify whether their performance achieved the same results when repeated after a short period of time. According to the results, Otto and Nala had high Se and Sp, which remained high, or even increased in the case of Nala, between the test and the retest. By contrast, Helix had the highest test’s Se and Sp (100%) but was markedly less successful during the retest. It could be useful to report thatDuring the laboratory test, the three trained dogs showed an overall sensitivity rate of 93% (90–100%), and an overall specificity rate of 99%, which ranged from 98 to 100%. These values fall within the upper end of published ranges. In fact, in studies conducted recently on olfactory detection of COVID-19 in sweat samples by sniffer dogsThe high sensitivity and specificity and low inter-dog difference observed in the present study likely originate from two conditions: (1) the “ubiquitous” recruitment system and the rigorous sample collection, and (2) the consistent high-quality training performed.In our study, positive and negative samples were collected from both hospitals and outside hospitals, symptomatic and asymptomatic volunteers, vaccinated and non-vaccinated, so that the actual target population could be accurately covered and potential misleading of dogs due to hospital-associated odours avoided. In addition, as recommendedFollowing the example of Kantele et al.