In the spring of 2020, as the novel coronavirus infiltrated the Twin Cities, Hin Lai couldn’t stop thinking about cats and dogs.
Dr. Lee, a veterinary and biomedical researcher at the University of Minnesota, knew that humans were the primary drivers of the epidemic. But he also knew that many people loved to kiss and cuddle their pets, in sickness and in health. They wondered: How transmissible was SARS-CoV-2 to mankind’s best friends?
In March 2020, Dr. Lee learned that two dogs in Hong Kong had received a positive PCR test for the virus. But these tests require the virus to be actively replicated and thus reveal only active infection. Swallowing the muzzles of many pets took Dr. Lee an inordinate amount of time to figure out how easily animals could become infected.
So he pitched the idea to his wife Yuying Liang, a researcher in the same department who leads the lab with him, to test cats and dogs for antibodies, which would reveal past infection with the virus. “I had the idea, but he’s the boss,” Dr. Lee said.
The results of those antibody tests, recently published in the journal envy, suggest that domestic cats are more vulnerable to SARS-CoV-2 infection than dogs.
Fortunately, infected cats appear mild symptoms At most. A biomedical researcher at Colorado State University College of Veterinary Medicine and Biomedical Sciences, Dr. “I’m still a little surprised that cats get infected so easily and yet rarely show any signs of illness,” said Angela Bosco-Lauth. research.
A virologist at Tufts University’s Cummings School of Veterinary Medicine, Dr. There is still no evidence to suggest infected cats or dogs pose a risk to people, said Jonathan Runstadler, who has studied how the coronavirus affects animals but was not involved. new job.
New study supports recent research It may be “quite common” in homes where people test positive for SARS-CoV-2 for cats and dogs to become infected, Dr. Runstadler said.
To test for pet antibodies, the Minnesota researchers needed animal serum, the component of blood that contains antibodies. Dr. Lee contacted Dr. Daniel Heinrich, director of the Clinical Pathology Laboratory at the University’s Veterinary Center. (Dr. Heinrich is also an author on the new study.) Pets passed through the center daily and had their blood tested for a myriad of reasons, including “annual checkups, unrelated illness, inappropriate urination on the wall,” Dr. Lee said.
Those samples are usually discarded. But Dr. Heinrich asked pet owners to allow the serum to be used anonymously in the study, and the researchers received their first handful of samples in April.
The researchers initially examined about 100 samples, and found that about 5 percent of the cat serum contained coronavirus antibodies, while the serum of almost none had. To be on the safe side, Dr. Lee tested hundreds more samples from blood collected in April, May and June, as COVID cases continued to rise in the region.
In the end, the scientists found that 8 percent of cats carried antibodies to the coronavirus, compared with less than 1 percent of dogs, suggesting that cats were more vulnerable to the infection.
Because the pet owners gave consent anonymously, the researchers were unable to ascertain which humans may have transmitted the virus to the various cats and dogs. It was also unclear whether infected pet cats lived indoors or outdoors, or how much the virus spreads from cat to cat, Dr. Lee said.
Researchers do not know why cats seem more sensitive than dogs. One possibility is related to ACE2, a protein on the surface of cells that is a receptor for the coronavirus. The genetic sequence of the human ACE2 protein is more similar to a similar sequence in cats than in dogs.
But animal behavior can also be a factor. A recent study that presented similar conclusions – that cats become infected with the coronavirus more easily than dogs – noted that cats are often more welcome to sleep in beds than dogs. “Maybe it’s because we cuddle cats more,” Dr. Lee guessed. “Maybe we cats kiss more.”
Dr Bosco-Louth said he believes that pets are “unlikely to contribute to the epidemiology of SARS-CoV-2 in the long term.” But there’s still no way to know for sure.
For those who test positive for Covid-19, Dr. Lee recommends distancing yourself from not only humans, but cats and dogs. “You can’t hug them,” he said.
Dr. Li and Dr. Liang do not have cats or dogs in their house. He has a tank of guppies, which, for the time being, seem to be quite safe from the coronavirus.