Lessons learned from the pets who were diagnosed with SARS-CoV-2
Back in March (a lifetime ago), the first pet was diagnosed with SARS-CoV-2 in Hong Kong. It’s been nearly seven months now, and many other pets—and tigers, lions, and minks—have joined the SARS-CoV-2–positive ranks.
With each new story about a diagnosed pet comes a flurry of anxiety from pet owners. News of SARS-CoV-2–positive dogs in particular may raise clients’ concern because they’re the pets who seem to die after they get diagnosed, although some had a preexisting condition that was the likely cause of death (like Buddy in New York). But more cats have actually been diagnosed with SARS-CoV-2. Which makes sense, as they’re known to be susceptible to coronaviruses.
And with every new pet diagnosed, weary veterinarians have to mollify worried clients.
NEWStat asked Meghan Davis, DVM, MPH PhD, an associate professor in the Department of Environmental Health and Engineering at Johns Hopkins’ Bloomberg School of Public Health, about the current thinking on SARS-CoV-2 and COVID-19 infection in pets.
Davis acknowledges that while it’s possible for pets—particularly cats and ferrets—to become infected with the SARS-CoV-2 virus, it “appears to be uncommon. In the United States, fewer than 40 dogs or cats have tested positive, [according to] the National Veterinary Services Laboratories.”
The United States Department of Agriculture Animal and Plant Health Inspection Service keeps a list of those animals, updated as of September 14, and notes that most who have tested positive have had known exposure to a human who tested positive for COVID-19.
But have any of them died? Yes, a handful, but it’s hard to say from what—most had underlying preexisting health conditions. And that’s where it gets tricky.
Regarding symptoms, Davis says that some, but not all, of the pets who tested positive have had symptoms: “For example, the first pets to test positive in the United States were two cats from unrelated households in New York State: both had mild respiratory illness.” Both recovered. “More recently, a dog in North Carolina died after a sudden respiratory illness and was found to be positive for SARS-CoV-2, although it’s not yet publicly confirmed whether the virus caused the dog’s death.”
In other cases, Davis says pet animals who’ve tested positive for SARS-CoV-2 have had symptoms that may or may not be related to the novel coronavirus. For example, a Georgia dog with neurological symptoms who tested positive earlier this year also had a brain tumor, which a necropsy later confirmed was the cause of death.
Davis says it’s also important to note that because pets are not undergoing the same kind of surveillance testing that’s being done for people, testing pets is often based on either the presence of symptoms or concern with the pet’s proximity to a human with COVID-19. “This means that it would not be appropriate to use the number of symptomatic cases among those tested to estimate how often pets may have symptoms when they are positive for SARS-CoV-2,” Davis cautions.
“Given how few pets have tested positive compared to the large number of people who have been diagnosed with COVID-19, pets appear to be at much lower risk than their owners for COVID-19.”
“Most pets who get SARS-CoV-2 will be exposed to and catch the virus from their owners.” She echoes the advice that worried owners should not relinquish their pets. COVID-positive people just need to keep their distance from pets.
Christine Petersen, DVM, PhD, director of the Center for Emerging Infectious Diseases at the University of Iowa, concurs with Davis that pets who test positive are likely to have caught the virus from their owners: “We need to remember that our pets, who live closely with us and literally sleep in our beds can be exposed to high amounts of viruses.” And not just the novel coronavirus—any virus.
Cats in particular who sleep on their infected owner’ chest can be breathing in infected droplets all night long. “So the pet can test positive because the virus is literally in their bodies [but] that doesn’t necessarily mean they’re sick,” Peterson says. She also noted that some of the dogs who were diagnosed with SARS-CoV-2 are brachycephalic, so “they already had deficits in their respiratory systems.”
In many of these cases, pets exposed to the virus have existing immunodeficiencies or preexisting health issues. That Georgia dog who died who tested positive and died of a brain tumor is a good example.
As Peterson put it, “The pet didn’t die of SARS-CoV-2. They died with SARS-CoV-2.”
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