Since June, Sarah Hamer and her team at Texas A&M University have tested hundreds of animals from households where people have contracted Covid-19. Of course, they wiped dogs and cats, but also hamsters and guinea pigs looking for signs of infection. “We are open to everything,” said Hamer, a professor of epidemiology who has found at least 19 cases of infection.
One pet that tested positive was Phoenix, a 7-year-old partly Siamese cat owned by Kaitlyn Romoser who works in a university laboratory. The 23-year-old Romoser had Covid-19 twice, once in March and again in September. The second time she was much sicker, she said, and Phoenix was her constant companion.
“If I had known that animals just got it everywhere, I would have tried to distance myself, but he will not distance himself from me,” said Romoser. “He sleeps with me in my bed. There was absolutely no social distancing.”
Across the country, veterinarians and other researchers are searching the animal kingdom for signs of the virus that is causing Covid-19. In the United States, at least 2,000 animals have been tested for the coronavirus since the pandemic began. Cats and dogs exposed to sick owners represent the majority of animals tested and 80% of positive cases found.
However, scientists have set up a wide network to study other endangered animals. In states from California to Florida, researchers have tested species ranging from farmed minks and zoo cats to unexpected creatures like dolphins, armadillos, and anteaters.
Fur farm outbreaks
The US Department of Agriculture maintains an official list of confirmed Covid-19 cases in animals, which is several dozen. But that list is a large number of actual infections. In Utah and Wisconsin, for example, more than 14,000 mink have died in the past few weeks after contracting Covid-19 infections that were originally human-transmitted.
So far, there is limited evidence that animals transmit the virus to humans. Veterinarians emphasize that pet owners do not appear to be at risk from their furry companions and should continue to love and care for them. However, scientists say continued testing is a way to stay vigilant in the face of a previously unknown pathogen.
“All we know is that as a family, coronaviruses infect many species, mainly mammals,” said Dr. Peter Rabinowitz, professor of environmental and occupational medicine and director of the Center for Health Research at the University of Washington in Seattle. “It makes sense to take a cross-species approach and look at a broad spectrum.”
Much of the testing is based on scientific curiosity. Since the beginning of the pandemic, it has been a great mystery how the virus, which is believed to have come from bats, spread to humans. One leading theory is that it jumped to an as-yet-unknown intermediate species and then to humans. In April, a 4-year-old Malay tiger tested positive for Covid-19 at the Bronx Zoo in a unique case after seven large cats showed signs of respiratory disease. The tiger, Nadia, got the virus from a janitor, federal health officials said. It was also confirmed that four other tigers and three African lions were infected.
In Washington state, the site of the first US human outbreak, scientists rushed to design a Covid-19 test for animals in March, said Charlie Powell, spokesman for the Washington State University College of Veterinary Medicine. “We knew warm-blooded animals housed together would develop cross-infection,” he said. Animal testing uses different reagents than animal testing so it doesn’t compromise human supplies, Powell added.
Infections remain rare in animals
Since spring, the Washington Animal Disease Diagnostic Laboratory has tested nearly 80 animals, including 38 dogs, 29 cats, two ferrets, a camel, and two tamanduas, a type of anteater. The lab also tested six minks after the Utah outbreak, five of which were responsible for the lab’s only positive tests.
In total, nearly 1,400 animals have been tested for Covid-19 through the National Animal Health Laboratory Network or private laboratories, said Lyndsay Cole, spokesman for the USDA Animal and Plant Health Inspection Service. More than 400 animals were tested by the National Veterinary Services Laboratories. At least 250 more were tested in academic research projects.
The vast majority of tests were performed on domestic cats and dogs with suspicious respiratory symptoms. In June, the USDA reported that a dog in New York became the first dog to test positive for the coronavirus after getting sick and having difficulty breathing. The dog, a 7-year-old German Shepherd named Buddy, later died. Officials discovered that he got the virus from its owner.
Neither the Centers for Disease Control and Prevention nor the USDA recommend routine testing for pets or other animals – but that hasn’t stopped owners from asking questions, said Dr. Douglas Kratt, president of the American Veterinary Medical Association.
“The questions have become a little more consistent in my practice,” he said. “People want to know about Covid-19 and their pets. Can your pet pick it up at a clinic, boarding school, or dog daycare?”
The answer so far is that humans are the main source of infection in pets. Last month, a small, unpublished study from the University of Guelph in Canada found that cats and dogs appeared to be infected by their sick owners, as measured by antibodies to the coronavirus found in their blood.
In Texas, Hamer began testing animals from households in which someone had caught Covid-19 to learn more about transmission routes. “At the moment we are trying very hard to describe what happens in nature,” she said.
So far, most animals – including the phoenix, Romoser’s cat – have shown no signs of illness or disease. So far, this has been the case for many animal species that have been tested for Covid-19, according to veterinarians. Most nonhuman creatures appear to survive Covid-19 infection with mild symptoms such as runny nose and lethargy, if any.
Still, owners should follow best practices to avoid Covid-19 infection in pets as well, Kratt said. Don’t let pets come into contact with unfamiliar animals, he suggested. Owners should wash their hands frequently, avoiding mumbling and other very close contact if possible.
Cats appear to be more prone to Covid-19 than dogs, researchers said. And minks, bred for their fur in the US and elsewhere, appear to be quite vulnerable.
In the meantime, the list of creatures tested for Covid-19 – whether for disease or science – is growing. 22 animals were tested in Florida earlier this month, including three wild dolphins, two civets, two cloudy leopards, a gorilla, an orangutan, an alpaca, and a baby bush.
In California, 29 animals had been tested by the end of September, including a meerkat, a monkey and a coatimundi, a member of the raccoon family.
In Seattle, a last-minute plan to test orcas or killer whales in Puget Sound was canceled after a member of the scientific team was exposed to Covid-19 and had to be quarantined, said Dr. Joe Gaydos, a senior wildlife veterinarian and scientific director of the SeaDoc Society, a conservation program at the University of California-Davis. The group missed their September window to locate the animals and obtain breath and stool samples for analysis.
Nobody believes marine animals will play a huge role in the pandemic that is decimating the human population, Gaydos said. However, it is important to test many creatures on land and at sea.
“We don’t know what this virus will or can do,” Gaydos said.
KHN (Kaiser Health News) is a non-profit health news service. It is an editorially independent program of the KFF (Kaiser Family Foundation) that is not affiliated with Kaiser Permanente.