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It was early March when the veterinary clinic in lower Manhattan where I work became inundated with calls from clients concerned about COVID-19. At that time, masks were not yet ubiquitous in public, the trains were still running on their normal schedule, and headstrong individuals could still wander into a bar for happy hour with friends. Yet even then, pet owners were concerned about the possibility that their dogs and cats could contract the novel virus that would come to dominate our collective consciousness. But for all the well-deserved panic that the coronavirus has induced in the human population so far, there’s very little evidence that you should be losing sleep over the possibility that your pet will need a ventilator, yes, even with the recent news about the tiger. Here’s what you need to know to keep your pets, and yourselves, safe.
Which animals have contracted the new coronavirus?
The most recent development in this vein came from the Bronx Zoo in New York earlier this week when a 4-year-old Malayan tiger named Nadia had tested positive for SARS-CoV-2, the virus that causes COVID-19 in people. Nadia was one of seven big cats to develop mild symptoms like those seen in people with the disease, including a dry cough and loss of appetite, after being exposed to a then-asymptomatic zookeeper. No other cats were tested, as drawing blood from an apex predator requires general anesthesia.
These large cats are believed to be the first animals in the U.S. to contract the novel coronavirus (and the first confirmed case globally in which an animal became sick from human transmission of the virus). But similar stories about pets have littered the headlines in recent weeks. On March 4, reports emerged from Hong Kong that a 17-year-old Pomeranian tested “faint positive” for the virus on repeat oral and nasal swabs. About two weeks later, a second dog from Hong Kong tested positive, this time a young German shepherd. In Belgium, on March 27, researchers detected the virus in the vomit and feces of a domestic house cat that showed respiratory and gastrointestinal symptoms. Four days later, Hong Kong announced yet another cat had tested positive.
That sounds … concerning.
Not so fast. If you consume news media like most Americans, these headlines may have you anticipating a wave of infected dogs and cats to follow the one seen in people. However, there are some important points to note that may get lost in a superficial reading of these case reports.
First, all of these animals were tested after being in sustained proximity to their corona-positive owners. So, that adds evidence behind our current understanding that it’s not likely that pets will contract the novel coronavirus from simply joining you outside on your evening walk, for example, or from other sources of infection that seem to be associated with lower viral “doses.” Being cooped up with an infected person is one of the best ways to get exposed to a high number of viral particles, short of working at a hospital.
Second, both dogs and the Hong Kong cat were asymptomatic, and the Belgian cat’s symptoms have not definitively been linked to SARS-CoV-2. Furthermore, none of these animals actually died from the virus (the geriatric Pomeranian died shortly after release from quarantine, from unrelated issues). Throw in a study out of Wuhan, China, that found antibodies to the virus in asymptomatic feral cats there, and we’re left with a sense that most pets (and maybe all dogs) who become infected never develop symptoms.
What all this means is that dogs are probably what virologists call “aberrant hosts” for this virus, meaning while the virus can infect these species, conditions in the dog body are not very hospitable for the virus. Therefore, symptoms in aberrant hosts are absent or mild, and transmission to other aberrant hosts (other dogs) or even back to the original host (people) is highly unlikely to occur. Cat-to-cat transmission is possible in the laboratory setting but has not been observed in the real world. As far as the novel coronavirus is concerned, pets seem to be a disappointing dead end.
Could the coronavirus mutate over time into strains for dogs or cats?
Probably not. In general, viruses have been known to adapt to aberrant hosts over time (with a proportional loss of their ability to infect the original host species), but fortunately coronaviruses seem to be quite slow to mutate, in contrast with, say, the seasonal flu.
So how worried should pet owners be?
Not very. Epidemiologists generally agree that while SARS-CoV-2 was originally transmitted to people from bats, likely through an intermediate species, animals broadly do not play an important role in the COVID-19 transmission chain. There’s certainly no need to surrender your pets out of fear that you’ll catch the virus (although at least one group of researchers is recommending we practice social distancing from certain great apes). Research is ongoing, but currently there’s just no evidence that dogs and cats have the ability to infect people. “I think it’s far more likely that they’ll get it from the person that’s shedding large amounts of virus, rather than the other way around,” said Melissa Kennedy, a virologist at the University of Tennessee College of Veterinary Medicine.
It sounds like dogs are fine. But say my cat starts coughing …
A coughing cat should be examined by a vet (but please call first!). Respiratory diseases and other causes of cough, like heart disease, are very common in cats and should certainly be given medical attention if noticed. It’s just extremely unlikely that the new coronavirus is the cause. If you believe the animal has been in close contact with a person with COVID-19, please let the staff know; just because cats aren’t likely to contract the virus doesn’t mean we can’t pick it up off their coat in the same way we might pick it up off a doorknob. And before you ask, no, we cannot test your animal for SARS-CoV-2.
Karen A. Terio, the chief of the Zoological Pathology Program at the University of Illinois veterinary college, thinks cats likely have a low chance of having it, anyway. “Given the number of people in this country that have been infected with the virus and have become ill, and the number of people in this country that own domestic cats,” she told the Times, “it seems fairly improbable that cats are an important source of the virus for people if the first case we’re diagnosing it in is a tiger.”
What do I do with my pets if I get COVID?
If you feel sick, you should consider distancing yourself from your cats or ferrets, given their possible susceptibility, if that’s an option for you. If you have COVID-19 and have already spent time around your pets, possibly infecting them, your pets should be quarantined with you to minimize risk of viral particles on the animal’s body infecting another person.
It’s true that many people might be asymptomatic carriers of the virus. Even if you feel fine, continue the usual safe practices like hand-washing. Because the virus is respiratory in nature, you may also want to avoid kissing cats (for their sake, not yours).
Is there any evidence that pets other than dogs and cats could be susceptible?
Since the SARS epidemic in 2003, we have known that the physiology of cats and ferrets makes them more susceptible to certain coronaviruses. A more recent study confirmed experimentally that in ferrets, the novel coronavirus can infect the upper respiratory system but does not cause severe disease or death. Orangutans and some bat species are also theorized to be susceptible, although hopefully you’ve learned from Tiger King that wild animals don’t belong in private custody.