MILWAUKEE – Since COVID-19 spread last year, its effects have spread across oceans and borders – and even across species.
What you need to know
- A preprint study identified four dogs and four cats with COVID-19 antibodies
- Research shows that pets can get infection from humans, but they don’t show many symptoms
- Cats and dogs are unlikely to spread the virus, but minks and ferrets are more worrying
- If you test positive for COVID-19, experts recommend staying away from your pets
“People don’t live in a vacuum,” said Keith Poulsen, director of the Wisconsin Veterinary Diagnostic Laboratory at UW-Madison. “If you have an infectious disease, we have mammalian households, and that includes humans, dogs, cats.”
For a year now, Poulsen and his laboratory have been testing animal samples from across the country to find out if our furry friends can get infected with the SARS-CoV-2 virus – and if they could transmit it back to humans.
Part of this work was part of a household carryover study conducted by the Centers for Disease Control and Prevention, the results of which were published in an online preprint last week.
According to the results, dogs and cats could become infected with the SARS-CoV-2 virus after staying in a household with a sick person. But for the most part, the pets don’t show many symptoms and appear unable to transmit the virus back to humans, Poulsen explained.
“Having someone in your home is not a 100% guarantee [with COVID-19] that everyone in the house gets it even though you are at considerable risk, ”he said. “And it’s the same for pets.”
The study began as an offshoot of the CDC’s work on the spread of the virus in households, said Ailam Lim, head of the laboratory’s virology department.
At the beginning of the pandemic, CDC researchers collected samples from Milwaukee and Salt Lake City to see how often an infected person would make other people in the home sick. However, after Lim discovered that many of these houses were also home to domestic animals – and the first evidence suggested that domestic animals could catch the virus as well, as in the case of an infected police dog in Hong Kong – the scientists began looking beyond their own species.
So the researchers not only collected swabs in human noses, but also collected various samples from dogs and cats in the households.
Of the dozen of pets that were sampled in the study, eight animals – four dogs and four cats – showed SARS-CoV-2 antibodies in blood tests, according to the study. And a sample from a dog’s fur also tested positive for viral RNA.
This means that people may transmit the coronavirus to pets more often than previously thought, the researchers write.
But pet owners shouldn’t worry too much, said Wisconsin State Veterinarian Darlene Konkle, who was consulted as part of the study. In this research and in other cases, even cats and dogs that test positive for SARS-CoV-2 are not prone to getting very sick.
“I think a lot of pet owners were initially concerned about whether or not their dog or cat might get COVID, you know, might get COVID or die from COVID,” Konkle said. “Some of the information that came out similar to that in this study really helped people understand that they don’t need to be afraid.”
The most common signs of infected animals are breathing difficulties like a runny nose or sneezing, Konkle said. But it’s rare for pets to actually need treatment for an infection, Poulsen explained, and the death rate for most animals appears to be near zero.
Another good news: cats and dogs seem unable to pass the virus on to humans. While other research by UW Madison scientists has shown that cats may shed the virus and even infect other cats with COVID-19, the levels don’t seem high enough to make people sick, Poulsen explained.
“We know that animals can harbor the virus. And we know cats aggravate the virus more than dogs, ”Poulsen said. “But we still don’t believe that any of the pets in people’s homes or in their homes will pose a significant risk of human infection.”
This is a relief for individual pet owners and also for the future of the pandemic, emphasized Lim. If dogs and cats could return infections to humans, our furry friends could serve as a “reservoir” and give the virus space to continue to admit even after herd immunity has been achieved circulate and mutate.
But with the results we’ve seen so far, the scientists say this isn’t a huge problem when it comes to our most common household companions. Experiments have also shown that key farm animals such as cows, chickens and pigs appear to be resistant to COVID-19 infection.
There are a few exceptions, however: mink and ferret appear to be more susceptible to the virus than other species.
Poulsen said his concerns about mink harboring the virus are “much higher” than for dogs and cats. In Denmark, where the government ordered farmers to kill millions of minks, the animals appeared to be spreading a mutated form of the virus back to their human handlers.
The difference between the species’ susceptibility has to do with the receptors in their lungs, Poulsen explained. Mink and ferret have receptors almost the same as humans – making them prone to “grabbing these coronaviruses to cause disease,” he said.
In Wisconsin, two mink farms saw COVID-19 cases among their animals, Konkle said. In contrast to the mild reactions of cats and dogs, the symptoms of mink are much more evident, she said; Thousands of animals died on a Taylor County farm.
These farms are still being monitored but are no longer seeing clinical signs or deaths in their mink, Konkle said.
Poulsen said mink and pet watching can be a useful tool in managing the virus and tracking its life cycle – from “epidemic to endemic to hopefully disease-free”.
Monitoring animals for COVID-19 antibodies could be another “guardian” telling us how the virus moves through a population, he said. And it will also be important to keep an eye on variants in animals, emphasized Konkle. In another preprint recently worked with by Lim, researchers found that a dog and a cat in Texas had tested positive for variant B.1.1.7 originally discovered in the UK
For the everyday pet owner, however, the science so far is encouraging. The researchers agreed that people shouldn’t worry that their dogs and cats will get really sick from COVID-19 – or stress about getting the virus from their pets.
If you test positive for COVID-19, it’s still a good idea to take some precautionary measures, such as trying to keep a little distance with your furry friends or wearing a mask while you feed them . Even though your pets may not get very sick, they can still get the virus, Lim pointed out, so caring for them as another member of the household can be helpful.
Of course, it’s hard to explain to your dog that you’re in quarantine, Poulsen said. And pets are an important source of social support, especially during these isolating times. However, studies like this remind us that our health affects the other living things around us – and vice versa.
“We care about our environment,” said Poulsen. “We are dealing with other types of animals, whether they are pets, food, or wildlife. And then we have human health there too, so we all interact. “