Dogs can detect Covid-19 from sweat samples

> The percentages of success of the dogs to find the positive sample in a line containing several other negative samples or mocks (2 to 6) were 100p100 for 4 dogs, and respectively 83p100, 84p100, 90p100 and 94p100 for the others, all significantly different from the percentage of success that would be obtained by chance alone.

> We conclude that there is a very high evidence that the armpits sweat odour of COVID-19+ persons is different, and that dogs can detect a person infected by the SARS-CoV-2 virus.

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> For each involved dog, the acquisition of the specific odour of COVIS-19+ sweat samples required from one to four hours, with an amount of positive samples sniffing ranging from four to ten.

> Once the training period was considered as completed by the dog’s handler, the dog was not anymore in contact with any sample prior to a trials session, and the data collection regarding the success or failure to detect a COVID19+ sweat odour started.

> At that time, the dog must alert for COVID19+ sweat odour contained in one box only, out of 3,4, 6 or 7 boxes(depending on the study site) presented in a line. The other boxes contained negative samples or mocks, but always with only mock in the line.

> A “trial” consisted of one dog detecting the presence of the COVID-19+ in one box out of the 3, 4, 6 or 7 boxes. One positive sample could be used several times at different spots in the line for the same dog (3 times maximum). All the trials are independent from each other, which means that for each trial, the location of the COVID-19 positive box was randomly assigned by using a randomization dedicated wellsite.

> A success was defined if the dog alerts the one box containing the COVID-19+ sweat sample. A failure was defined if the dog alerts on any of the other boxes. Trials were registered from the moment dogs recognized positive sample among other samples (mock or negative ones) without having sniffed any of them previously to the test. If the dog marks first a negative sample, the trial is considered as failed even if he marks the positive afterwards.

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> In our proof-of-concept study, two negative samples, according to our described inclusion criteria for negative samples, were marked positive by two dogs; the information was immediately sent to the concerned hospital through the anonymous samples codes, and PCRs that were redone on the patients gave positive results.