A stray cat on the streets of an empty Istanbul.
Getty/Anadolu AgencyCoronaviruses have lived and thrived in animals for thousands of years, but only a handful have been known to make the jump from animal to humans and cause illness. The coronavirus at the center of the current pandemic, SARS-CoV-2, did just that and has proven to be incredibly successful at spreading from human to human. As of early April -- just four months after it was first detected -- the virus had infected over 1 million people and spread to over 180 countries.
It turns out SARS-CoV-2 can hijack animal cells, too. Scientists believe the disease originated in Chinese horseshoe bats before it jumped into an intermediary animal and, from there, found its way into humans. The virus is able to inject itself into cells by binding to a cell surface protein known as ACE2, which is present in many species of animal.
Some media reports have shown that the coronavirus can infect our companion animals -- and more exotic species like tigers and lions -- but cases are rare. It appears that transmission of the disease from human to animal is low with a tiny number of cases reported since the outbreak's early days. Importantly, there is no evidence pets can transmit to their owners. The World Health Organization states there is "no evidence that a dog, cat or any pet can transmit COVID-19."
Still, pet owners are understandably worried about the health of their companions and how COVID-19 might affect them. We've gathered everything you need to know about coronavirus and your pets here, along with emerging research in how animals may spread or be affected by the coronavirus. If you have additional questions, you can reach out via email or give me a nudge on Twitter.
Where did the coronavirus come from?
This coronavirus, SARS-CoV-2, is what's known as a zoonotic disease: It jumped from an animal species into humans.
Studying the genetic makeup of the coronavirus and comparing it to a library of previously known coronaviruses, experts suggest the virus likely arose in Chinese horseshoe bats, before jumping to an intermediary species in close contact with humans. Some scientists believe the intermediary could be the pangolin, a scaly, ant-eating mammal that has been shown to harbor coronaviruses in the past and is one of the most illegally trafficked animals in the world.
Pangolins were sold at a Chinese live animal market often cited as the "epicenter" of the outbreak, but prestigious medical journal The Lancet published an extensive report on patients infected with the disease, noting that the very first patient identified had not been exposed to the animal market.
Whatever the origin story of SARS-CoV-2, we know coronaviruses are able to establish residency in all manner of species -- whether they cause disease or not is a question still requires an answer and it's an important one. Epidemiologists will want to know which species can harbor the virus so they can better understand where it may persist in the environment and how likely it is to jump back to humans in the future.
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Can the coronavirus infect cats and dogs?
Coronaviruses are not particularly hard to please when it comes to potential hosts -- they've been detected in many mammal and bird species, including dogs and cats, as well as livestock like cows, chickens and pigs.
There have been several reports providing evidence of SARS-CoV-2 infection in household pets. A 17-year-old dog in Hong Kong repeatedly tested "weakly positive" for coronavirus in March and later died. A cat in Belgium tested positive for the disease on March 24.
"These pets were living with infected human owners, and the timing of the positive result demonstrates human-to-animal transfer," said Jacqui Norris, a veterinary scientist at the University of Sydney in Australia. "Virus culture on these pets was negative, meaning that an active virus was not present."
A study by researchers at the Harbin Veterinary Research Institute in China, published in the journal Science on April 8, examined the susceptibility of a number of species to COVID-19, including cats and dogs, using a small number of animals.
The results demonstrated that cats can be infected with the coronavirus and may be able to spread it to other cats via respiratory droplets. The team placed infected animals in cages next to three animals without the disease and found, in one case, the virus had spread from cat to cat. The felines didn't show any outward signs of illness, however.
Dogs appear to be more resistant. Five 3-month-old beagles were inoculated with SARS-CoV-2 via the nasal passage and housed with two dogs not given the virus. After a week, the virus was not detected in any dogs, but two had generated an immune response. The two dogs that did not receive the virus did not acquire it from their kennel mates.
One of the key takeaways, as highlighted by Nature, is that these experiments were performed in a laboratory setting and that high doses of the coronavirus were used to infect the animals, which likely does not reflect real-life conditions. Nevertheless, cats do appear prone to infection, and the authors note further monitoring should be considered.
IDEXX Reference Laboratories, a consortium of testing labs across the globe, announced in March that it had created a testing kit for felines and canines. After running tests on over 4,000 specimens from the US and South Korea, it found no positives. The US Department of Agriculture has stated it will not test companion animals unless testing is agreed upon by animal and public health officials due to "a link to a known human case of COVID-19."
Can other animals be infected by SARS-CoV-2?
Many species are susceptible to infection because they contain a protein known as angiotensin-converting enzyme 2, or ACE2.
That's because the virus itself is covered in spiky projections that can to latch onto ACE2 proteins on the surface of animal cells. The coronavirus "spikes" then lock into place and hijack the cell to replicate.
Using computer databases and modeling, researchers have examined the genes of species to find out if the ACE2 protein in their cells can be used by SARS-CoV-2. A recent study, published in the journal Microbes and Infection on March 19, showed SARS-CoV-2 could grab onto the ACE2 receptor of many different species -- including bats, civet cats and pigs -- and predicted it may also be able to do so in goats, sheep, horse, pangolins, lynx and pigeons.
The research undertaken by the Harbin Veterinary Research Institute in China suggests that the virus replicates poorly in chickens, ducks and pigs.
The first confirmed case of coronavirus in an animal in the US was documented on April 5, when 4-year-old Nadia, a Malayan tiger at the Bronx Zoo, was found to have contracted the virus, likely from an infected but asymptomatic zookeeper.
Can I get COVID-19 from my pet?
There's still a lot we don't know about transmission of SARS-CoV-2, but the most important point to reiterate: There is a lack of evidence the coronavirus is spread by pets and companion animals to humans.
"There is absolutely no evidence whatsoever that companion animals play any role in the epidemiology of this disease," said Trevor Drew, director of the Australian Animal Health Laboratory. Drew and his colleagues at the AAHL are testing vaccines in ferrets in pre-clinical trials to assess safety and efficacy of new treatments. Ferrets are used in the trial because they are particularly susceptible to infection by the coronavirus. However, even ferret owners are unlikely to get the disease from their furry friends according to Drew.
He notes that the researchers at the AAHL are not seeing "overt clinical disease" in their ferrets, but "they do seem to have a slight temperature and they do replicate the virus." It may be that SARS-CoV-2 can infect these animals, but cannot replicate enough to cause the set of symptoms which define human COVID-19.
You may also be wondering if you can pick it up from your pet's fur? The risk is low -- but not zero -- because the coronavirus can survive on surfaces and is able to be transmitted via droplets. Theoretically, it might persist on fur, so you should always wash your hands before and after you interact with them if you're feeling unwell.
"People appear to pose more risk to their pets than they do to us," said Glenn Browning, a veterinary microbiologist at the University of Melbourne, Australia.
How can I protect my pets?
If you are feeling unwell and believe you may have contracted COVID-19, the first thing you should do is get tested. If you suspect you are unwell, the recommendation from the US Centers for Disease Control and Prevention is to "restrict contact with pets and other animals, just like you would around other people."
The best method of protection remains prevention. There are a huge number of resources available from the WHO on reducing your risk of infection, and the key measures are outlined below:
- Wash your hands: For 20 seconds and no less! You can get some handy handwashing tips here.
- Maintain social distancing: Try to keep at least 3 feet (1 meter) away from anyone coughing or sneezing.
- Avoid touching your face, eyes or mouth: A difficult task, but this is how the virus initially gets into the body.
- Respiratory hygiene measures: Cough and sneeze into your elbow!
If you are sick, you may consider quarantining your pets at home and limiting your contact with them as much as possible. You don't have to isolate them, but try to limit them to one or two rooms in the home, wear a mask when around them and -- yes, we're saying it again -- wash your hands.
Is there a vaccine for COVID-19 in dogs and cats?
As with humans, there is no vaccine available against COVID-19 at this time. There is a canine coronavirus vaccine, but it is directed against another member of the coronavirus family and does not provide protection against COVID-19 (Note: The Australian Veterinary Association does not recommend it even for that virus).
There are many clinical trials underway in humans, and a range of different treatment options. While some could theoretically be tweaked for different species (and some will even be tested in them), the most promising vaccines in development right now are being designed solely for use in humans.
Originally published in April and updated with new information regularly
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