According to research published on Monday, dogs can be trained to detect more than 90 per cent of COVID-19 infections even when patients are asymptomatic. The authors of the research hope that this revelation could help to replace the need to quarantine new arrivals.
Dogs have already shown that they can sniff out maladies such as cancer, malaria and epilepsy using their remarkable sense of smell – which can pick up the equivalent of half a teaspoon of sugar in an Olympic-sized swimming pool.
Dogs detecting SARS-CoV-2 have been proven by several previous studies. Researchers from the London School of Tropical Medicine wanted to find out if dogs could detect a unique odour given off from chemical compounds associated with patients who are COVID positive but do not show symptoms.
Clothes and face masks from people who had tested positive for mild and symptomatic SARS-CoV-2 were gathered for the research. Socks of 200 COVID-19 patients were collected and placed in labs for six dogs, who were to be trained to indicate either the presence or absence of the chemical compound.
In a classic case of conditioning, dogs were needed to be trained to not detect ‘false positive’ if there were no COVID-19 samples in a given test. “This means that the dog fully understands and gets a reward for a correct negative as well as a correct positive,” said Claire Guest, from the school’s Faculty of Infectious and Tropical Diseases.
The experiment was concluded with the proven hypotheses that dogs were successful in identifying SARS-CoV-2 sample between 94 and 82 per cent. The researchers then modelled how these success rates could help detect asymptomatic Covid 19 cases.
They found that if dogs are used at terminals of airports to screen arrivals, the result can be 2.24 times lower rate of transmission than PCR tests alone.
The need for travellers to quarantine disrupts every arrival even though the majority are not COVID positive. The authors of the research, which has yet to be peer-reviewed, hoped that their finding could help replace the quarantine method.
“The key thing is that dogs are significantly quicker than other tests,” said co-author James Logan. “What we’re suggesting is that dogs would give the first initial screening, and then those (arrivals) that were indicated as positive would then receive a complimentary PCR test.”
Out of a full plane arrival – around 300 people – less than one per cent were statistically likely to be carrying SARS-COV-2, said the team. Significant inconvenience is caused as all 300 would need to isolate under the current quarantine regulations employed by some countries.
The paper stated that given the sensitivity of trained dogs, a maximum of 35 people on board would be indicated as positive. Only 3 out of these would be expected to return a positive PCR test. “This is a really important start and could lead to a useful, usable system,” said Mick Bailey, professor of Comparative Immunology at the University of Bristol, who was not involved in the research.
“But there’s a lot more validation needs to be done before we could be confident that the dogs can reliably and specifically detect asymptomatic SARS-CoV-2 infection in people in airports and train stations.”