That smells like Corona! A study shows that the fine nose of trained sniffer dogs can also identify post-Covid-19 patients in addition to acutely infected people. According to the researchers, this illustrates the far-reaching potential of the animal diagnostic method: it could benefit the detection and study of persistent infections or long-lasting metabolic changes in the so-called Long Covid.
The sensitivity of the dog’s nose is legendary – for thousands of years, humans have been using the amazingly fine sense of smell of their “best friend”. In recent years, the medical potential of sniffer dogs has also become increasingly clear: they can detect diseases such as various types of cancer, malaria and bacterial and viral infections in humans by the smell of body fluids. The animals perceive volatile organic compounds that the body forms in connection with the disease.
Several studies have already shown that dogs can be trained to detect an acute Sars-CoV-2 infection with high accuracy. The animal detection method has already shown its potential in practical use. The focus of the study by the research team led by the University of Veterinary Medicine Hanover was now the question of the extent to which sniffer dogs can also detect a notorious secondary condition of Sars-CoV-2 infections: Long Covid. Patients still complain about various symptoms of the disease months after their actual recovery.
Also a nose for Long Covid
Trained corona detection dogs were used in the study, which can identify acute Covid 19 patients with a hit rate of over 90 percent based on the smell of various body fluids. The scientists again confronted these animals in various combinations with odor samples from people acutely affected by Covid-19 and from long-Covid patients and to control healthy people.
The evaluation of the results clearly confirmed that the animals are able to sniff out Long Covid: They were able to distinguish the samples from Long Covid patients from the healthy control with a hit rate of over 90 percent. “Our study now makes it clear that dogs can recognize the unique patterns of volatile organic compounds not only in acute Sars-CoV-2 infected people, but also in post-Covid-19 patients,” summarizes co-author Holger Volk from the foundation University of Veterinary Medicine Hanover. His colleague Claudia Schulz adds: “The sniffer dogs succeed in this, even if conventional detection systems such as PCR and antibody tests can no longer make any statements about the disease,” says the scientist.
Potential for studying the pathophysiology of Covid-19
Interestingly, as the researchers further report, when directly choosing between acute Sars-CoV-2 cases and long-Covid samples, the dogs almost exclusively showed the current infections as positive. This result thus indicates that the disease-specific odor of acute Covid-19 is still present in many long-Covid cases, but apparently not to the same extent as in samples from acutely infected patients, the scientists explain. This could mean that after some Covid-19 diseases, a hidden infection persists or long-lasting metabolic changes become established as a result of the infection. “Although post-Covid patients usually no longer pose an infection risk, the diagnosis enables optimized treatment of the patients and opens up new possibilities for better understanding this complex viral disease in the future,” says Schulz.
As the scientists emphasize, the investigation has so far been a pilot study: “More extensive work should now clarify to what extent the sensitivity of the medical detection dogs can vary in the course of the infection,” write the researchers. One question is, for example, whether the type of symptoms affects the dogs’ ability to recognize something. In addition, further studies should characterize the disease-specific volatile compounds that occur in Sars-CoV-2 infections. “Basically, the current study is further proof of the potential that sniffer dogs have in investigating the pathophysiology of Covid-19,” concludes co-author Friederike Twele from the University of Veterinary Medicine Hannover.
Source: Foundation of the University of Veterinary Medicine Hanover, specialist article: Frontiers in Medicine, doi: 10.3389/fmed.2022.877259