Covid sniffer dogs could work summer events in France Trained sniffer dogs can be educated to react to the smell of Covid within two or three days using a sample manufactured in a laboratory 25 May 2021 By Brian McCulloch Sniffer dogs to detect Covid-19 are being trained to be used in France this summer, 18 months after French researchers showed that they were reliable. Professor Dominique Grandjean of the Ecole Vétérinaire d’Alfort-EnvA is a world expert on the use of sniffer dogs to detect illnesses, and realised that trained sniffer dogs could be used to detect if people had the disease.