Can a dog smell if you’re infected with the new coronavirus? The truth may not be so simple.

According to the World Health Organization (WHO), more than 19.7 million people have been infected with the virus worldwide, possibly more than 20 million this week. Around the world, how to control the spread of the epidemic, and how to control the expansion of the outbreak at the same time gradually return to normal life, is a very concerning topic.

We know that rapid detection of new coronavirus infections, isolation of infected patients and follow-up isolation of people they come into contact with are among the important means of controlling the spread of the epidemic. In order to develop a faster and more convenient detection of new coronavirus, many scientists explore the application of innovative technologies in the detection of new crown viruses, including next-generation sequencing technology (NGS), CRISPR gene editing technology, iso-warm PCR technology, microfluidic technology and so on.

Some scientists, on the other hand, have turned their attention to the “best friend” of human history, the dog. In an exploratory study published in the journal BMS Journal of Journal Of Bio Disease, eight test dogs were able to find samples of saliva or bronchial secretions from patients infected with the new coronary virus in a random double-blind, controlled-out group of patients after just a week of training. Their detection sensitivity reached 82.63 percent and their specificity reached 96.35 percent. The study sparked a widespread media debate. So, can detection dogs really become a fast and effective detection method for the new coronavirus?

Can a dog smell if you're infected with the new coronavirus? The truth may not be so simple.

The mechanism and potential of new crown virus infection were detected in dogs.

We all know that dogs have a very sensitive sense of smell, and people use their keen sense of smell have trained them to search for many things by smell. For example, drug search dogs, search for missing people rescue dogs, can be through the smell to find very deep hidden items or people. The use of dogs’ olfactory to detect disease is not a new concept, as early as 1989, The Lancet published an article using the dog’s sense of smell to detect melanoma. Scientists have long known that disease causes changes in the composition of volatile substances secreted, which forms the basis for using dogs’ sensitive noses to detect disease.

Can a dog smell if you're infected with the new coronavirus? The truth may not be so simple.

For the study, the researchers trained eight test dogs using samples from COVID-19 patients who diagnosed and showed symptoms and volunteer samples tested by RT-PCR for new coronavirus infections. If they were able to identify one of the seven samples that belonged to COVID-19 patients, they would be rewarded. After seven days of training, the dogs found that the success rate of COVID-19 patients increased from 50 percent on the second day of training to 81 percent, indicating that they did learn the “smell” of the new coronavirus-positive samples through training.

After training, the eight dogs were tested in a random double-blind, controlled group, and the researchers randomly provided samples from PATIENTs with COVID-19 or no new coronavirus estoccotic strain on machines. After 1012 random and automated samples were presented, 8 test dogs correctly found 157 positive samples of new coronavirus, 792 positive samples were correctly found, 33 error-positive samples, 30 error-judgement negative samples were found. Calculated, the diagnostic sensitivity of the detection dog was 82.63% (95% CI, 82.02%-83.24%), and the specificity reached 96.35% (95% CI:96.31%-96.39%). The detection specificity of all eight detection dogs did not change much, but their detection sensitivity was significantly different.

Can a dog smell if you're infected with the new coronavirus? The truth may not be so simple.

The specificity and sensitivity of the positive samples of the new coronavirus were found in 8 detection dogs.

Given that the current “gold standard” RT-PCR for testing for new coronavirus infections also has a false positive rate of 2.3-6.9 percent, the dog’s performance is worth affirming, the researchers said in a discussion session of the paper. This test, if perfected, may, in some cases, be an effective way to aid RT-PCR or replace RT-PCR testing to quickly screen new coronavirus-infected people.

Scientists in the UK have launched a study to test whether six dogs can accurately identify asymptomatic patients infected with the new coronavirus after eight weeks of training. The researchers’ idea is that they could become a quick, non-invasive test for asymptomatic infections at airport testing points.

Testing dogs found the challenges and limitations of the new crown virus infection.

Since testing dogs have shown a welcome performance in the test spotting positive samples of the new coronavirus, will they be seen in public places such as airports in the future? The researchers say real-world applications are very different from the environment in scientific research, which adds to the challenge of detecting dog performance.

Training dogs to find positive samples of new coronavirus, found missing persons are also good, all use positive reinforcement (positive reinforcement) means. Simply put, when the test dogs choose the right target, they are encouraged or rewarded, and they may be toys or food. During the experiment, because there were always positive samples of the new coronavirus, and because the test dogs were able to reward them within a short period of time, they were able to actively reinforce them.

However, in real-world applications, testing dogs may need to find a positive sample out of thousands of negative samples, which can be a tedious task for them without reward. What’s more, in real-world cases, even if the test dog makes the right choice, the tester cannot confirm that they are correct (because other tests such as RT-PCR, such as the sample found by the test dog, are confirmed). This delay can “discourage” the motivation of test dogs by failing to be rewarded in a timely manner after making the right choice.

Can a dog smell if you're infected with the new coronavirus? The truth may not be so simple.

Photo credit: Image by 85 Miranda from Pixabay.

As mentioned earlier, the idea of using test dogs to find cancer patients has a long history, but the use of test dogs to screen cancer is still not widely used. In 2017, Austrian scholar Dr Klaus Hackner wrote in Journal of Breath Research that test dogs did not perform well on cancer samples in simulated real-world scenarios where researchers did not know which sample was positive and could not be rewarded in time.

In addition, the use of test dogs to detect new coronavirus infections also face other challenges, such as even trained test dogs can fluctuate in physiological status, which can directly affect the accuracy of their detection. Moreover, whether a positive sample of the new coronavirus can infect test dogs is still a question that has not been answered for sure. If dogs are infected with the new coronavirus, will their sense of smell be affected, and will they become a new source of infection?

Use volatile organic compounds to detect the future of disease.

The disease causes changes in the composition of volatile organic compounds (VOC) in the patient’s sample, which is the root cause of the disease sample spotting dogs. If we can detect changes in the VA characteristics of patients caused by the new coronavirus infection, it is possible to design “electronic noses” that simulate detection dogs for rapid detection. Using gas chromatography and ion migration spectrum using a combination of gas chromatography and ion migration spectrum, researchers in Germany can distinguish patients with the new coronavirus from those with influenza A by examining breath samples from patients.

Even if testdogs don’t quickly become an effective way to quickly detect new crowns in the real world, they could help scientists discover VOC characteristics associated with different diseases, contributing to the design of more effective and convenient noninvasive disease detection methods.