Can Dogs Sniff Out Long COVID?

Dogs have been trained to detect acute infections with SARS-CoV-2 using samples such as sweat, saliva, or urine from affected individuals. They detected the infection with high sensitivities and specificities. This is probably based on a unique pattern of volatile organic compounds (VOCs) in the samples of COVID-19 patients. COVID-19 can sometimes result in longer-term health problems, or long COVID. So far, it had been unclear whether dogs can also detect long COVID.

Holger Andreas Volk, University of Veterinary Medicine Hannover and Center for Systems Neuroscience, Hannover, Germany, and colleagues have investigated this question in a pilot study. The team used nine dogs that had previously been trained to detect samples of acute COVID-19 patients. These dogs were confronted with samples of long COVID patients, either compared with negative samples or with samples from acutely infected individuals.

When the dogs were confronted with a long COVID sample and a negative control sample, they reached an average sensitivity (true positive rate) for long COVID of 94.4 % and an average specificity (true negative rate) of 96.1 %. When the dogs were presented with long COVID samples next to acute COVID-19 samples they mostly detected the acute infection, with an average sensitivity for acute COVID-19 of 86.7 % and an average specificity of 95.8 %.

Overall, this means that detection dogs that were trained with samples of acute COVID-19 could also identify long COVID when presented next to negative samples. The results of the test comparing acute COVID-19 samples to long COVID samples, in which the dogs mostly detect the acute infection, indicate that the specific VOC pattern of acute patients might be still present in long COVID samples, but probably not to the same extent.

Detection of Post-COVID-19 Patients Using Medical Scent Detection Dogs—A Pilot Study,
Friederike Twele, Nele Alexandra ten Hagen, Sebastian Meller, Claudia Schulz, Albert Osterhaus, Paula Jendrny, Hans Ebbers, Isabell Pink, Nora Drick, Tobias Welte, Esther Schalke, Holger Andreas Volk,
Front. Med. 2022.
https://doi.org/10.3389/fmed.2022.877259

Also of Interest