COVID-19: Dogs Capable of Smelling Enclosure in Patients

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A scientific project aims to demonstrate the ability of trained dogs to detect Covid-19 through the sweat of patients. The success rates are promising, making this screening technique an invaluable aid to clinicians alongside conventional diagnostic tests.

This is a route being studied for the early detection of breast cancer and, it has been a hope for the detection also of carriers of Covid-19 (or SARS-CoV2): it is committed to exceptional olfactory ability of dogs.

The project started in March entered a new phase

A study published in the scientific journal Plos One evokes the Nosaïs-Covid19 project that aims to demonstrate the ability of dogs to detect Covid-19 and carried out by Pr Dominique Grandjean, professor-researcher at the Escuela Nacional de Veterinaria de Alfort (EnvA ). The project, also carried out in Lebanon, began in March but entered a new phase with the publication of this study with very encouraging results.

The aim was to evaluate whether the trained dogs could detect sweat samples from symptomatic COVID-19 positive individuals (PCR test positive) and from asymptomatic COVID-19 negative individuals. Six dogs trained for one to three weeks (three explosives detection dogs, one search and rescue dog, and two colon cancer detection dogs) participated. At the same time, it recruited 177 people from five different hospitals: 95 symptomatic COVID-19 positive people and 82 asymptomatic COVID-19 negative people. Collection of sweat samples from the armpits of each person.

Snorting volatile organic compounds in sweat

"Our hypothesis is based on the possible excretion of specific catabolites in sweat, induced by cellular actions of SARS-CoV-2 or replications in the cells of the organism, through the apocrine sweat glands, generating organic compounds in volro-sedile dogs to detect" say the study researchers.

In general, many studies have shown that dogs can detect VOCs in breath, urine, tears, saliva, feces, and sweat. For animal safety, the samples are not used in training or testing sessions within 24 hours of harvest.

The dogs were trained to work on a series of cones, used as sample holders and to mark the olfactory cone containing the positive COVID-19 sample by sitting in front of it after sniffing it. The training method is based on positive reinforcement: the dog receives his toy for each correct marking. During the testing sessions, each test was conducted in a room containing 3 or 4 cones with a positive COVID-19 sample randomly placed behind a cone, as well as a negative COVID-19 sample while the others the cones were empty. During the test, a positive sample can be used up to a maximum of three times for a dog.

Between 76% and 100% success

The results showed that "the success rate per dog (the number of correct prompts divided by the number of trials) ranged from 76% to 100%," the researchers add. "In a context where there is a lack of diagnostic tests available for mass screening for SARS-CoV-2, explore the possibility of using dog odor detection as a fast, reliable, and inexpensive tool to pre-screen people for a check. rapid in certain circumstances is significant. "

The latter specify that during the testing sessions two samples taken from individuals a priori negative for COVID-19 were marked on several occasions by two dogs. The information was immediately sent to the corresponding hospital and again PCR tests are carried out on these two people who tested positive for the infection. "False negative RT-PCR tests are not uncommon, but these two events support our working hypothesis," the scientific team notes. But she specifies that although dogs trained their ability to correctly distinguish between positive and negative COVID-19 individuals, they should not be viewed as a perfect diagnostic method, but rather as a complementary tool when testing for COVID-19. diagnostics are not readily available or do not have a high level of precision.

The study has the support of the World Health Organization (WHO), an agreement was established there to award a grant and the creation of a working group with the World Organization for Animal Health.

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