Trained scent detection dogs screening for those with COVID-19 showed similar or better success rates than standard polymerase chain reaction tests, according to findings from a literature review published in the February issue of Journal of Osteopathic Medicine.
Researchers conducted a narrative review of four peer-reviewed studies that considered the use of scent detection dogs to identify volatile organic compounds associated with COVID-19. The fourth study is ongoing and results were not yet available for this literature review.
Here are findings from the researchers' assessment of three peer-reviewed studies:
1. The first study, conducted by researchers from France and Lebanon, found eight previously trained scent detection dogs had a success rate between 83 and 100 percent when screening for COVID-19. The dogs were trained for four days to sit in front of a positive COVID-19 sample box, and were then presented with gauze samples that had been soaked in sweat from the armpits of patients across different hospitals. While the COVID-19 virus doesn't have a smell itself, researchers hypothesized that the infection prompts metabolic changes, resulting in a distinctive sweat odor able to be detected by dogs.
2. In the next study, a research team in Germany used COVID-19 virus samples collected from the saliva or tracheobronchial secretions of infected patients, and trained scent detection dogs for one week to identify the virus' presence. Afterward, the dogs were able to successfully detect COVID-19 in the majority of sample presentations. Of 1,012 samples, there were 157 correct indications of a positive, 792 correct rejections of a negative, 33 false positives and 30 false negatives.
3. The third study was conducted in three phases, with the third phase ongoing. In earlier phases, a research team in Colombia exposed six scent-trained dogs to volatile organic compound samples collected from respiratory secretions of positive COVID-19 patients. The dogs were safely exposed using a device developed by the research team. The sensitivity and selectivity rates of the dogs' ability to detect COVID-19 was 95.5 percent and 99.6 percent, respectively.
"Trained scent detection dogs could, in principle, be used to non-intrusively screen and identify individuals with various stages of COVID-19 infections in hospitals, senior care facilities, schools, universities, transportation centers like airports and train stations, and even large public gatherings for sporting events and concerts," authors of the literature review said, adding that further research with larger sample sizes is needed.