Finland pioneers using sniffer dogs to test for coronavirus

There are four dogs 'on duty': two of them working with their handlers, while the two others are resting.

The dogs are of different breeds, ages and sizes and are owned by members of the Finnish Odour-Separation Dog Association, Wise Nose.

The only reward the Covid-19 dogs gets - in addition to having an interesting job - is a freeze-fried meat delicacy when it marks a positive corona-sample.

Their handler sets out an extra 'positive' sample if there is too long a time-gap between positive samples, to keep their motivation high. So far, only one percent of tested passengers have come back as positive.

Some 16 dogs were tested for the research study and training, run by Helsinki University, last spring.

The purpose was to teach the dogs to distinguish the smell of coronavirus molecules from other smells, so that the dogs could be used at airports and other border crossings to assist in detecting arriving passengers carrying Covid-19.

The best trainee was a light greyhound mix, named Kössi, who was found in a cardboard box next to a highway in Spain seven years ago and brought to Finland by its new owner.

Kössi had earlier learnt to identify cancer, bedbugs and mould, among other smells. It took Kössi only seven minutes to learn to detect corona, after which it always chose the right sample.

Out of the 16 dogs only 10 were selected to contribute to the pilot project at Vantaa airport. The remaining six were not suited to work in a noisy environment with many people.

So far the results of using dogs to sniff corona have been outstanding.

They can detect a coronavirus in a person earlier and more reliably than PCR-tests analysed in the laboratory.

And they can do it fast - in about a minute. One of the more disturbing findings is that sometimes they can "mark" a sample from a person who has had corona, but has been declared healthy.

The science of odours has not yet been able to identify what the corona odour consists of, and why somebody can emit that smell long after recovering from the disease. This is not the case for cancer, where a recovered cancer patient stops 'smelling' of cancer.

Testing process

In order not to expose the dogs and their handlers to potentially sick people, a passenger who wants to participate in the testing pilot, gets a sample container and a sterile gauze.

He or she then wipes his armpit or neck with the gauze, places it in the sample container, and hands it through a hatch to the handler.

The handler arranges the new container, plus four similar containers with negative corona-tests, in a random order on the floor and asks the dog to check the samples. If the dog marks a sample as positive, the passenger will be instructed to contact nearby medical staff for follow up.

The training of the 10 dogs and their handlers was funded by the private Finnish Veterinary Center Evidensia which also provided health services and nutrition to the dogs and financial support to their handlers.

However, expenses for the pilot project at Helsinki-Vantaa airport are paid by the Finnish state. There are still many unanswered questions - like how many hours the various dogs are able to work, and how to separate those who already have recovered from Covid and those who have been recently infected.

The current discussion among health authorities is how to ensure such 'corona-dogs' have an official status, in line with dogs employed by customs authorities and police or used as service dogs helping blind or people suffering from epilepsy or diabetes.

This would require a change in Finland's Infectious Diseases Act and ensure further funding for using them.

Many countries have shown interest in the Finnish experiment, among them the United Arab Emirates. Currently the veterinary department of the Helsinki University is assisting 10 international research groups getting started with similar projects.