Dogs can be trained to sniff out COVID-19, randomized trial finds
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Trained dogs were able to identify samples from people with COVID-19 with 92% accuracy in a randomized trial conducted in Finland, researchers reported.
Anu Kantele, MD, PhD, an assistant professor of medicine at the University of Helsinki, told Healio that the study was prompted by a need to be able to screen large crowds during the pandemic.
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Kantele was contacted by Anna Hielm-Björkman, DVM, PhD, CVA, from the university’s department of equine and small animal medicine.
“I became immediately enthusiastic about the idea since I have always admired the scenting ability of my own dogs,” Kantele told Healio.
Kantele and colleagues conducted a randomized triple-blinded validation trial and a real-life study at the Helsinki-Vantaa International Airport using four dogs three Labrador retrievers and one white shepherd trained to detect COVID-19 using skin swabs from people tested for SARS-CoV-2 infection by reverse transcriptase PCR (RT-PCR).
The researchers explained that the controlled triple-blinded validation study was made up of four identical sets of 420 parallel samples from 114 people who tested positive and 306 samples from people who tested negative by RT-PCR. They randomly presented the samples to each dog over seven trial sessions. Then, in the real-life part of the trial, the dogs screened skin swabs from 303 incoming passengers at the airport who were all concomitantly examined by nasal swab.
The study demonstrated that the dogs detected COVID-19 with an overall accuracy of 92% (95% CI, 90%-93%), a sensitivity of 92% (95% CI, 89%-94%) and a specificity of 91% (95% CI, 89%-93%) compared with RT-PCR.
“For me, a particularly impressive finding was that they did not perform equally well if the patient had been infected with a variant virus,” Kantele said.
Specifically, their accuracy was 89% for confirmed wild-type virus vs. 36% for the alpha variant (OR = 14; 95% CI, 4.5-43.4). Kantele said the reason for this was simple.
“The dogs had been trained initially with the wild-type virus and their discriminatory power was so incredible that they could tell that this is not exactly what I was supposed to identify,” she said. “In order to cover the variants, the dogs need a 2-day retraining.”
Kantele said having dogs available to sniff for COVID-19 in airports would cost “much, much less” than performing PCR tests.
“The dogs could sniff all the incoming passengers and tell the results immediately,” she said. “Dogs may provide solutions to a variety of clinical problems, so we definitely should explore this possibility not only with COVID but other diseases as well.”
Dogs have also been trained to sniff out Clostridioides difficile, cancer and malaria, among other infections and diseases.
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