A proof-of-concept study has found that trained dogs can smell the SARS-CoV-2 virus in urine samples with 96 percent accuracy. It is known that dogs are able to sniff out smells of various ailments. Many past studies have confirmed that dogs can detect a strong signature of the SARS-CoV-2 virus in sweat and saliva samples. In fact, dogs have been deployed at a Dubai airport to detect COVID19. However, it is unclear whether dogs can identify the virus in the samples of people who have a lower viral load. A team of experts has trained eight Labrador retrievers and one Belgian Malinois to detect the scent of a synthetic substance that is known as the Universal Detection Compound (UDC). The UDC is a smell that cannot be found in the environment. They have kept the UDC on one of the 12 ports of a scent wheel and rewarded the dogs whenever they have successfully identified the port containing UDC. Once dogs have been trained to identify UDC, experts have used the scent wheel to instruct the dogs to react to urine samples taken from the COVID19 positive patients. These samples have been taken from two adults and five kids who have tested positive for the SARS-CoV-2 virus. Experts as well have taken samples from six children who have turned out to be negative for COVID19. The findings of the study have been released in the journal called PLOS One.
During the training, dogs have been given two situations. In the first scenario, the scent wheel has the target odor in one port and a distracting odor in the others. In the second scenario, the scent wheel has included only distracting odors. Experts have inactivated the virus via heat or detergent so it is harmless to dogs. The authors of the study have revealed that after three weeks of training, dogs have been able to detect the SARS-CoV-2 virus in the samples with 96 percent precision on average. They have said that that the overall specificity has been 99 percent, which means that there have been false positives hardly. However, there have been some false negatives with 68 percent of overall sensitivity. Scientists have said that the low percentage of sensitivity might be due to the strict way of conducting the test. They have said that if the dogs pass a positive port without reacting, it has been labeled as a miss. The senior author of the study, Dr. Cynthia Otto, who is also the director of the University of Pennsylvania School of Veterinary medicine Working Dog center has said that dogs need to be particular about smelling the odor of the infection. They need to simplify the background odors of different people as well, which is not a simple task. She has said that dogs have been struggling a bit in the trial initially. They tend to differentiate between the scents of actual patients but not between the infection types. These dogs have been a little confused by a sample of a patient who has recently recovered from the disease and has tested negative. However, there has been something in patients’ samples that dogs have been zeroing in on.
Some health experts have said that as the dogs have been trained on the same sample from the same patients again and again, they have not been able to generalize to entirely new samples. Therefore, it might not be suitable for real-world applications. They have said that in the future, dogs should be trained on diverse samples from different patients for better outcomes. Now, scientists are going to conduct a study called the T-Shirt Study. In this study, dogs will be trained to identify whether or not someone has contracted the SARS-CoV-2 virus or has been vaccinated through the odors left on the clothes people have been wearing overnight. The senior author of the study Dr. Cynthia Otto has said that the team is going to include many more samples in this study.