British researchers are launching a trial to find out if trained dogs can identify COVID-19 patients. Earlier research proved that dogs can pick up odours that contain signatures of cancers, Alzheimer’s disease and even smells signalling infection by influenza viruses.
For the trial, medical staff in London hospitals was told to collect odour samples from COVID-19 patients and healthy people. The idea for the study comes from research proving that tissues produce so-called unique volatile compounds (VOC) and that their concentration changes when someone catches an infection or otherwise becomes ill. Research has also established that the specific odours of volatile organic compounds are present in exhaled breath, urine, faeces, and sweat and dogs are able to reliably distinguish these scents from others.
How can dogs pick up the scent of a disease? Dogs have an extremely refined sense of smell and according to studies, they can detect substances at concentrations as low as parts per trillion, which means they are much more sensitive than our best odour detecting tools, known as olfactometers. A 2016 study used two dogs to identify 3 types of viruses in cattle with impressive results. Although the dogs’ task was made difficult by the introduction of distracting smells very similar to the target odour, they accurately identified the target on 28 occasions out of 34 and on 30 occasions out of 31 runs. This gives confidence to researchers that dogs will be able to perform live detections of asymptomatic and symptomatic Covid-19 patients and screen up to 250 people per hour. If the trial is successful, specially trained dogs could be introduced at transport hubs to filter out infected people, making it possible to resume international air travel, while containing the virus through tracking.