It may be hard to believe, but researchers are concerned that our sweet, fluffy doggy friends are a “potential reservoir” for future flu pandemics. As Rachael Rettner reports for Live Science, a new study has found that influenza viruses from pigs—which have previously transmitted dangerous strains of the flu to humans—can jump into dogs. What’s more, canine flu viruses are becoming increasingly diverse.
Scientists are worried about these findings because of the way that animal viruses have spread to humans in the past. Influenza can jump between different animals; the trouble for humans starts when flu strains exchange genes with other infectious diseases in the animal host, according to the Independent’s Alex Matthews-King. If these new strains pass to humans, who have not been previously exposed to them and therefore do not have immunity against them, the health consequences can be severe.
H1N1, or swine flu, which was the cause of a 2009 pandemic, actually originated in birds. An avian virus “jumped to pigs, exchanged some of its genes with previously circulating swine viruses and then jumped from pigs into humans,” according to a statement by the American Society for Microbiology. And now scientists are seeing this pattern again—except this time, the viruses are jumping from pigs to dogs.
For the new study, published recently in mBio, researchers sequenced the genomes of 16 influenza viruses obtained from dogs in the Guangxi region of China. The dogs were pets and had been brought to the vet after exhibiting respiratory symptoms consistent with canine influenza. There are two main types of canine influenza: H3N8, which was transferred from horses to dogs, and H3N2, which was transferred from birds to dogs. These viruses have never been reported in humans, according to the CDC.
The researchers, however, discovered that the sickly pups in China harbored two types of H1N1 swine flu viruses. They also found three new canine influenza viruses, which resulted from the mixing of swine flu and canine flu strains.
“In our study, what we have found is another set of viruses that come from swine that are originally avian in origin, and now they are jumping into dogs and have been re-assorted with other viruses in dogs,” Adolfo García-Sastre, study co-author and director of the Global Health and Emerging Pathogens Institute at the Icahn School of Medicine at Mount Sinai in New York, says in the statement. “They are starting to interact with each other. This is very reminiscent of what happened in swine ten years before the H1N1 pandemic.”
Before the dog owners among us start to panic, it’s worth reiterating that to date, no human has contracted canine flu. Scientists don’t know if new strains of dog flu viruses would spread among humans if, hypothetically, a person were to contract one in the future. The study was also relatively localized; researchers can’t be certain that similar viral mixing is happening in dogs around the world.
“What this study provides is evidence that dogs can be naturally infected with multiple strains of viruses, most notably viruses from pigs, which are a known reservoir of influenza viruses that can infect us,” Jonathan Ball, a professor of molecular virology at the University of Nottingham who was not involved with research, tells the Independent’s Matthews-King.
“This increases the potential threat of dogs acting as mixing vessels for the production of new strains of virus that might, just might, in the future spill over into humans,” Ball says.
The study authors acknowledge in their report that “further research is greatly needed to assess the pandemic risk” of flu viruses in dogs. But they also say that it is important to start thinking about how a dog flu pandemic would be managed if one were to break out.
In the United States, avian flu outbreaks have been brought under control by culling poultry. Perhaps anticipating that this solution would not be quite as well received when it comes to doggos, García-Sastre notes in the statement that there have been "attempts to restrict influenza virus in pigs through vaccination and one could consider vaccination for dogs."