Dogs trained to detect people with Covid-19
Researchers at the National Veterinary School of Alfort, outside Paris, trained eight Belgian Malinois shepherd dogs to identify people infected with the coronavirus.
They used odour samples taken from the armpits of more than 360 people, who were both positive and negative for the virus.
The dogs were able to detect the presence of Covid-19 in some of them, and had a 95% overall success rate.
In their paper, the researchers said introducing dog olfactive detection was a cheap, quick and reliable “tool” to either pre-test willing participants or could be a fast-checking option in certain circumstances.
“The first step for such an approach was to determine if the samples we decided to choose (axillary sweat) could allow the dogs to olfactively discriminate between positive and negative people regarding Covid-19.
"This proof-of-concept study provides evidence according to which the axillary sweat of Sars-CoV-2-infected people can be detected by trained dogs.
"The next step is to carry out a validation study with the same dogs of this proof-of-concept study which will provide the sensibility and specificity of the dog’s diagnosis,” said researchers.
They said in their study, like in many others conducted on dog olfactive detection, the performance was defined in accordance with what is called the signal-detection theory.
“A True positive: the dog indicates the target odour by a ‘sit’ response; a False positive: the dog alerts to a non-target position; False negative: the dog fails to exhibit the trained alert in the presence of the target odour; and a True negative: the dog does not alert in the absence of the target odour.
“All trials of the dogs were filmed to check afterwards more precisely their sniffing behaviour.
“This will allow us to determine the duration of each trial before the dog alerts.”
The researchers said using dogs was not new and referred to a hypothesis that was put forward in 1989, that dogs could be used to detect malignant tumours.
They decided to use three types of detection dogs - explosives detection dogs, search-and-rescue dogs as well as colon cancer-detection dogs.