What we know — and don’t know — about how COVID-19 affects animals

TVO.org speaks with veterinary internal-medicine specialist Scott Weese about COVID-19’s potential impact on animals and whether vets should be considered an essential service
By Mary Baxter - Published on Mar 23, 2020
Researchers are currently looking into which species may be susceptible. (tock Photos | Living Organism)



Many scientists have stated that the novel coronavirus likely originated in a species of bat. Now that it’s in humans, though, what role might animals play in its transmission?

To find out more about COVID-19’s potential impact on animals, the impact infected animals might have on humans, and whether veterinary practices should be considered an essential service, TVO.org spoke with Scott Weese — the former Canada Research Chair in Zoonotic Diseases at the University of Guelph and a veterinary internal-medicine specialist and chief of infection control at the Ontario Veterinary College.

TVO.org: What is known about COVID-19 and animals?

Scott Weese: It's an unknown. We really don't understand whether there are any risks or what those risks are.

We know, or are pretty confident, this virus came from an animal. Bats are a typical reservoir for coronaviruses, and it looks like there's a type of bat in China this probably came from. The suspicion is that it then went to a mammal, another mammal — pangolins are the leading candidate right now — and then jumped into people.

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The question at this point is, is it a purely human virus, or is it a predominantly human virus? Is there any potential role of animals, or is it purely human-to-human transmission?

Predominantly, this is a human problem, but what we're worried about is animals being vectors of infection or being a reservoir.

We don't want to have it in our domestic- or wild-animal populations. If we look back to the original SARS virus, which is closely related to this one, some domestic animal species were susceptible — at least experimentally.

So there are two questions when it comes to an animal being infected. One is, can they be infected? And the bigger one for us is, can they then pass it on? And [with the] SARS virus, experimentally, cats can pass it on. Dogs are thought to be lower risk.

TVO.org: Could the same hold true with COVID-19?

Weese: If you look at the genetic makeup of this virus and how it probably attaches to cells — cats, ferrets, pigs, and humans are among the species that are highest risk. So dogs aren't thought to be a big risk.

But there was one positive dog in Hong Kong that seemed to have a low-grade infection, with positive tests over multiple days. The amount of virus there seems to have been low, so, hopefully, it was just a bit of an oddball infection rather than something that's more common. But we just don't know at this point. There's been very little animal testing. All the testing resources, not surprisingly, have been directed to humans.

Experimentally, there's work being done in various places around the world looking at species that are susceptible — partly to understand it and partly to have models [for lab testing]. With SARS, and probably with COVID-19, a lot of the common lab animals, like mice and rats, aren't susceptible. So approaches that you use to test things like vaccines and treatments are more challenging because there's not an easy animal model.

I assume that over the next few weeks and months, we'll get more information about the range of species that are susceptible. But, for now, it's prudent to assume that a range could be susceptible until we prove otherwise, as opposed to waiting to see if there's a problem and trying to deal with it after.

TVO.org: How might animals potentially pass on the virus?

Weese: Infection is one thing we're worried about, but they [could be a] a carrier. So if I'm infected, and I cough on my cat, or I pat my cat, and my hands are contaminated, I can put the virus on a cat's hair coat. Then that animal goes and rubs against someone else. We don't know how long it can survive there. We know, on some surfaces, it can survive hours to days.

TVO.org: Are people getting their animals tested for COVID-19?

Weese: There are a couple of labs that are offering testing. We're largely discouraging it. It comes down to, what are you going to do with the result? It's not going to be a whole lot. And we don't want people walking into vet clinics to get tested, because that's just creating unnecessary traffic.

The other thing is, if there's a real reason to test an animal, we have to go on the assumption that it's infected, which means we need to use a higher level of bio-security, like they do with infected human cases. And we don't want to drain through those supplies, and a lot of clinics aren't really set up to do that.

We're trying to do testing on a research basis, on a surveillance basis. It's very difficult to get it done. We want to test animals with infected people so we can start to see whether we're getting transmission over to them, but we really don't want your average person to be thinking they should get their pet tested because they're worried or because it has a cough.

TVO.org: So what are you saying to people about their animals right now?

Weese: Essentially, treat animals like people: If you're being told to stay away from other people, do the same thing with animals. If you don't expose your cat, then we don't have to worry about whether cats are susceptible or not. That can get forgotten. Someone can be under self-isolation, living away from their family, but having their cat go back and forth between them and their family

The same general messaging [applies to farmers]: If you're sick, definitely stay away from livestock.

TVO.org How worried should people be about their animals?

Weese: We think it's probably a small problem. But if it's a problem, a small component still might be relevant. So that's why we're paying attention to it. We don't want people to freak out about their animals. We'd rather just have them do some common-sense things to reduce the risks

The big messaging we're trying to get across is that your average animal is not going to pose much risk. If your animal has been exposed, you probably have been already as well, or you were probably the source. Getting an animal out of a house for COVID-19 risk reasons is rarely going to be necessary.

TVO.org: Should veterinary clinics stay open at this time?

Weese: The World Organization for Animal Health came out with a statement Wednesday supporting veterinary medicine as an essential service. A lot of that's for food, animal production, and for public-health issues.

But in any type of vet practice, there's relevance. One of the big things, really, is human-animal bonds. We're in a pretty tough time for a lot of people, and animals are a bit of a lifeline for many households. And the last thing we want to do is compromise the emotional health and mental health of people by not being able to treat their animals properly.

This is one in a series of stories about issues affecting southwestern Ontario. It's brought to you with the assistance of faculty and students from Western University’s Faculty of Information and Media Studies.

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