Trained dogs can sniff out coronavirus from saliva

After just a few days of training, detection dogs can sniff out coronavirus infections. This is according to a new study, published on July 23 and which was piloted by the University of Veterinary Medicine Hannover, the Hannover Medical School and the German Armed Forces. The study established that if well-trained, dogs were able to discriminate between human saliva samples infected with SARS-Cov-2 and non-infected samples with a 94 per cent overall success rate.

“Within randomised and automated 1,012 sample presentations, dogs achieved an overall average detection rate of 94 per cent with 157 correct indications of positive, 792 correct rejections of negative, 33 incorrect indications of negative or incorrect rejections of 30 positive sample presentations,” the study read in part.

Powerful and accurate

Dogs have smell receptors of up to 10,000 times more powerful and accurate than humans. That allows certain trained dogs to sniff out diseases like cancer, malaria and viral infections.

According to the report, detection dogs can be trained in a week to discriminate between samples of people infected and non-infected by Covid-19. Saliva samples and tracheobronchial secretion samples were collected from hospitalised Covid-19 patients that showed clinical symptoms and were diagnosed as SARS-CoV-2 positive using nasopharyngeal swab samples.

Negative control samples were obtained from negative people with no previous history of Covid-19, and the individuals did not have any history of a recent cold or infection.

The study shows that analysis for accuracy and precision revealed a diagnostic sensitivity of 82.63 per cent and a high diagnostic specificity of 96.35 per cent for all dogs.

All dogs had a high diagnostic specificity with a small range in variation, which could be important for population screening to avoid false-positive results.

To avoid a bias concerning hospital-specific smells, positive samples were obtained from two different hospitals to include a variation in a covariate factor, and this appears to have not influenced the results.

Since dogs are susceptible to coronavirus, all samples from Covid-19 patients were inactivated to protect the dogs and their handlers from infection during training.

“Presentation of samples to the dogs was conducted via a device called Detection Dog Training System, which can present samples in a randomised automated manner,” the study says.

For each trial run, only one hole presented a SARS-CoV-2 positive sample at a time while the other six holes presented negative samples. After a successful indication of the hole with the positive sample, the dog was automatically rewarded by the device with food or a ball.