Study shows dogs can detect Covid, raising hopes for fewer quarantines

Dogs can be trained to detect more than 90 percent of Covid-19 infections even when patients are asymptomatic, according to research published on Monday. The news could mean fewer travellers having to quarantine. 

Sniffer dogs being used at airport Lehtikuva/via REUTERS

Researchers from the London School of Hygiene and Tropical Medicine conducted an experiment to see if dogs could detect a distinctive odour emanating from someone who is Covid positive but who doesn't show symptoms.

Samples of socks and face masks of 200 Covid-19 cases were collected and arranged in lab tests for six dogs that had been trained to indicate either a presence or absence of the chemical compound.

Overall, the dogs were successfully able to identify between 94 and 82 percent of SARS-CoV-2 samples.

Dogs are already in use to help detect Covid but this research is the first to try to measure the efficiency of sniffer dogs compared to PCR tests.

The researchers then modelled how effectively these success rates, combined with traditional PCR tests, could help detect mild or asymptomatic Covid-19 cases.

They found that using dogs to screen arrivals at terminuses such as airports could detect 91 percent of cases, resulting in a 2.24 times lower rate of transmission than with PCR tests alone.

Authors of the research, which has yet to be peer-reviewed, said they hoped it could eventually replace the need for travellers to quarantine - which necessarily disrupts every arrival even though the vast majority are not Covid positive.

Dogs give quicker results

"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 [arriving passengers] who were indicated as positive would then receive a complimentary PCR test."

The team said that out of a plane full of arrivals around 300 people - less than one percent - were statistically likely to be carrying SARS-CoV-2.

Under current quarantine regulations employed by some countries, all 300 would need to isolate, causing significant inconvenience.

Meanwhile Thailand on Friday deployed dogs trained to detect coronavirus infections by sniffing samples of human sweat.

Three of six trained Labradors made their debut at Bangkok's Chulalongkorn University after trials that the project leader said had shown a success rate of about 95%, with about 2,000 samples sniffed this month.

The dogs are not required to smell the humans directly. Sweat samples are collected from humans and stored in small metal containers for the dogs to inspect one-by-one.

Thailand is fighting its most severe outbreak yet, with cases quadrupling to 123,066 and deaths increasing seven-fold since the start of April to 735.