Cats can be infected with the coronavirus that causes COVID-19 and pass it on to other cats, but dogs aren’t really susceptible to the infection, according to Chinese researchers. The team at Harbin Veterinary Research Institute in China also concludes that chickens, pigs and ducks are not likely to get the virus.
Scientists say the results are interesting, but cat owners shouldn’t be alarmed yet. The results are based on laboratory experiments in which a small number of animals have been deliberately infected with high doses of the virus, SARS-CoV-2, and do not represent actual interactions between people and their pets. says virologist Linda Saif of The Ohio State University at Columbus. There is no direct evidence that infected cats secreted enough coronavirus to infect people, she said.
With the coronavirus spreading rapidly around the world, some have questioned whether the virus can pass between pets and humans. So far, there have been a few reports of infection of pets: a cat in Belgium and two dogs in Hong Kong. “Cats and dogs are in close contact with humans, and it is therefore important to understand their sensitivity to SARS-CoV-2 for the control of COVID-19”, write the authors of the latest study, a prepublication published on bioRxiv March 31.
The team, led by virologist Bu Zhigao, infected five domestic cats with SARS-CoV-2 through the nose. When two of the cats were euthanized six days later, the researchers found viral RNA, as well as infectious viral particles, in their upper respiratory tract.
The other three infected cats were placed in cages next to three uninfected felines. The team later detected viral RNA in one of the uninfected cats, suggesting that they contracted the virus from infected cats through respiratory droplets. The four cats also produced antibodies against SARS-CoV-2. Surveillance for SARS-CoV-2 in cats should be considered as part of efforts to eliminate COVID-19 in humans, note the authors in the preprint, which has not been peer review.
But Saif says that none of the infected cats showed symptoms of illness and that only one of the three cats exposed to infected animals caught the virus. “This suggests that the virus may not be highly transmissible in cats,” she says. In addition, the mode of transmission is unclear since the study does not describe how the cages were set up and uninfected cats could have contracted the virus from contaminated feces or urine.
More tests are needed when cats are infected with different doses of the virus to see, for example, if they can spread it to other cats, she says.
The results suggest that cats should be considered an element in the effort to control COVID-19, but that they are not a major factor in the spread of the disease, explains Dirk Pfeiffer, epidemiologist at City University of Hong Kong. “The attention paid to the control of COVID-19 must therefore undoubtedly remain firmly attached to reducing the risk of human-to-human transmission.”
Previous studies on the virus that caused severe acute respiratory syndrome, SARS, have shown that cats can become infected with SARS-CoV and pass it on to other cats. But “there was no evidence that during the SARS pandemic, SARS-CoV spread to domestic cats or was transmitted from cats to humans,” says Saif.
The United States Centers for Disease Control and Prevention recommends that people infected with COVID-19 limit contact with their pets, including avoiding petting, licking, and sharing food and utensils.
“These are precautionary measures, as would be advised for any new emerging disease where only limited information is available,” says Saif.
The researchers also found that ferrets are also very susceptible to infection with the SARS-CoV-2 coronavirus, which they believe makes them an appropriate model for testing potential vaccines and drugs. Several laboratories have already started researching COVID-19 on them.
Dogs, however, were less susceptible to the virus. The researchers infected five young dogs and discovered that two viral RNAs excreted in the feces, but none contained an infectious virus.
Similar investigations in pigs, chickens and ducks have not identified any viral RNA in animals deliberately infected with the virus or in those exposed to infected animals.
These results suggest that none of these species plays a role in the epidemiology of COVID-19 infection, says Pfeiffer.