Trained sniffer dogs have shown high accuracy in identifying SARS-CoV-2 infections, a finding reported in a Finnish study published in BMJ Global Health. The research highlights how keen canine olfaction can detect very small amounts of volatile compounds released by the body during illness or tissue damage. This sensitivity places dogs among the most perceptive natural detectors, able to pick up biochemical cues that many testing methods might miss.
Initial work trained four dogs over a two week period to spot coronavirus infections, with results that, in some settings, matched the reliability of PCR tests. The study took place during the spring 2020 surge, using a small but carefully chosen cohort under controlled conditions. The aim was to explore whether canine detection could become a viable screening method that complements laboratory testing in real-world scenarios beyond traditional lab environments.
In total, 420 human volunteers contributed skin swab samples for assessment, among which 114 were confirmed positive for coronavirus by PCR. Across seven testing sessions, those samples were presented to the dogs to gauge diagnostic performance. The dogs achieved diagnostic accuracy in the low to mid 90s, with the best performers nearly aligning with PCR results. Even the less accurate dogs showed strong performance within this testing framework, suggesting that canine detection can offer a reliable signal comparable to established molecular tests under certain conditions.
Field testing extended to a real-world setting at Helsinki Vantaa Airport, where dogs were used to screen travelers for covid-19. The level of agreement between canine indications and PCR results remained impressively high, underscoring the potential of trained dogs as a practical screening tool in busy public spaces where rapid results are essential. The findings highlight the dogs’ capacity to function as a first-line diagnostic aid, potentially speeding up the identification of infectious individuals in crowded environments.
Overall, the evidence points to a credible, noninvasive approach that can support SARS-CoV-2 diagnosis. While not intended to replace molecular testing, canine detection can complement current strategies by delivering rapid on-site screening that helps prioritize confirmatory tests and infection control measures. The Finnish study adds a valuable data point to the broader exploration of scent-based diagnostics for respiratory viruses, offering lessons on how animal-assisted screening could integrate with clinical workflows in public health campaigns.
As researchers refine training methods, standardize protocols, and address practical factors such as trainer expertise, odor sample handling, and animal welfare, canine detection remains a promising avenue for strengthening infectious disease surveillance. The results encourage ongoing evaluation across diverse settings and populations to determine broader applicability, reliability, and cost-effectiveness as part of a flexible testing strategy that can adapt to evolving viral dynamics.