Finding virus carriers—especially those with no symptoms—is among the biggest hurdles to addressing the pandemic.

But what if dogs can do that? Scientists in London say that dogs could in fact revolutionize the hunt for Covid-19 by sniffing out subtle odors produced by the virus when within the human body. The London School of Hygiene and Tropical Medicine is crowdfunding a project to train canines to detect healthy-seeming people who haven’t necessarily realized yet they are carriers. If the project is successful, the animal detectives could be working across Britain by the summer.

“It’s very early stages,” says James Logan, head of LSHTM’s Department of Disease Control. “We know diseases have odors — including respiratory diseases such as influenza — and that those odors are in fact quite distinct. There is a very, very good chance that Covid-19 has a specific odor, and if it does I am really confident that the dogs would be able to learn that smell and detect it.”

Dogs with a highly developed sense of smell are already used to diagnose many medical conditions, including Parkinson’s disease and several types of cancer. The LSHTM itself has already trained up animals—labradors and cocker spaniels tend to be especially suited—to detect malaria. Their success rate far exceeds required WHO standards, the center says.

If the project works, the dogs could be deployed to screen staff at hospitals and care homes and, once regular travel resumes, sniff out unwitting carriers at airports and rail stations. Capable of screening thousands of people per day, the dogs could be a key tool for getting daily life back to normal quickly and safely.