Detection dogs to identify COVID-19 infection
Detection dogs can detect certain chemical particles and have been suggested to help diagnose several medical conditions and complications, including colorectal cancer, melanoma, bladder cancer, and serious conditions such as hypoglycemia in diabetics. With the need to screen for infectious diseases spreading around the world, especially in crowded places, the study will investigate the applicability of detection dogs to perform such tasks.
German Shepherd (Sarai), German
German Black (Kuzi), and Labrador (Marco) dogs, both male and female, were trained intensively for seven weeks using the entire classical conditioning method. The training method involved the introduction of human specimens obtained from throat and pharyngeal secretions of participants already reported to be positive or negative for SARS-COV-2 infection by RT-PCR, and each dog underwent a conditioning process of about 1000 cycles.
In the meantime, another similar conditioning process was performed on the clothing and masks of COVID-19 patients using three male and three female dogs: a Labrador (Lexi), a Border Gypsy (Sami), and a Golden Retriever (Zhico). In the validation test of the first three dogs, 80 pharyngeal secretion samples consisting of 26 positive and 54 negative samples from different medical centers that underwent RT-PCR testing were single blind method.
In the second validation test of the other three dogs, masks and clothes of 50 RT-PCR positive and 70 RT-PCR negative cases from different medical centers were used.
Results.
According to the validation test using pharyngeal secretions, the detection capability of the detection dog was associated with a sensitivity of 65% and specificity of 89% and managed to identify 17 out of 26 positive samples and 48 out of 54 true negative samples.
The next validation test, using the patient's face mask and clothing, found that 43 of 50 positive samples were correctly identified by the dog, and of the additional 70 negative samples, 65 were correctly negative.
The sensitivity of the test was as high as 86% and its specificity was 92.9%, with positive and negative predictive values of 89.6 and 90.3% respectively.
Eskandari, E., Ahmadi Marzaleh, M., Roudgari, H. et al. Sniffer dogs as a screening/diagnostic tool for COVID-19: a proof of concept study. BMC Infect Dis 21, 243 (2021). Available at: https://doi.org/10.1186/s12879-021-05939-6
Summary
The detection by dogs seems to have been a positive outcome. Some people may wonder if it is possible to infect people by sniffing so many samples during the experiment. However, at the end of the experiment, there was no evidence of infection in the dogs. It is unclear whether this will be the case in the future, but if we can confirm the percentage of false negatives, we may be able to hope for more accurate screening.
Since the study does not specify even the prevalence rate, it cannot be said that it is superior to the existing testing methods, but if it is placed in widely populated areas by extending the training time, etc., there is a possibility that the results can be expected.
There are a lot of mechanical screening methods, but if the accuracy of these methods is not bad, it seems to be a realistic method, although there are a number of obstacles such as human and dog selection.
