Watch: Cats catch coronavirus
Many people like to snuggle up to their pet, but new research suggests cats may catch the coronavirus while sleeping on their owner's bed.
In April 2021, scientists from the University of Glasgow reported at least two cats had been infected with the virus in the UK.
A study by the University of Guelph, Ontario, now suggests nearly seven in 10 (67%) cats and more than two in five (43%) dogs develop antibodies – infection-fighting proteins that indicate a past infection – after a member of their household tested positive for the coronavirus.
Cats that sleep on their owners' bed are particularly at risk, the results – presented at the European Congress of Clinical Microbiology & Infectious Diseases conference – suggest.
The same is not true for dogs, who tend to nod off further away from their owners' face, reducing their risk of infection, according to the Guelph scientists.
Cats may also have more so-called ACE2 receptors, which the coronavirus uses to enter cells.
"If someone has COVID-19 [the disease caused by the coronavirus] there is a surprisingly high chance they will pass it on to their pet," said study author Professor Dorothee Bienzle.
"Cats, especially those that sleep on their owner's bed, seem to be particularly vulnerable.
"If you have COVID-19, I'd advise you keep your distance from your pet and keep it out of your bedroom.
"I'd also recommend you keep your pet away from other people and pets.
"While the evidence pets can pass the virus on to other pets is limited, it can't be excluded. Similarly, although pets have not been shown to pass the virus back to people, the possibility can't be completely ruled out."
Since the coronavirus outbreak emerged at the end of 2019, experts have been looking at whether animals can catch the infection or develop severe complications.
In March 2020, a Hong Kong dog died after testing "weak positive" for the coronavirus. A tiger in a New York zoo later caught the infection from an asymptomatic keeper, even developing its tell-tale dry cough.
The coronavirus is primarily a human infection, which mainly spreads face to face when a patient expels infected droplets in a cough or sneeze.
The risk of a human transmitting the virus to an animal was thought to be low, but the Guelph scientists have argued it was actually "incompletely defined".
To learn more, the team analysed the blood of 48 cats and 54 dogs from 77 households owned by someone who had endured the coronavirus within the past nine months.
These blood samples were compared against those of 150 cats or dogs from a shelter or "low cost" veterinary clinic.
More than seven in 10 of the cats and 43% of the dogs that were privately owned tested positive for coronavirus antibodies, compared to just 9% of the animals sampled in the shelter and 3% from the veterinary clinic.
Of the owned dogs, one in five (20%) developed symptoms. These were mainly fatigue and a loss of appetite, however, some also endured a cough or diarrhoea. All of the symptoms were mild and resolved quickly.
More than a quarter (27%) of the owned cats showed signs of the coronavirus, typically a runny nose and laboured breathing. Most of the cases were mild, however, three were severe.
The fact that more of the owned animals caught the coronavirus than those from the shelter or veterinary clinic reinforces the belief that pets generally catch the infection from a human, rather than the other way round.
"Fortunately, to date no pet-to-human transmission has been reported," said Dr Els Broens, from Utrecht University in the Netherlands.
Nevertheless, "pets could act as a reservoir of the virus and reintroduce it into the human population", added Dr Broens.
When it comes to animals catching the coronavirus, experts have previously warned against "mass hysteria".
When news of the "weak positive" Hong Kong dog broke, Professor Jonathan Ball from the University of Nottingham stressed "we have to differentiate between real infection and just detecting the presence of the virus".
"The fact the test result was weakly positive would suggest this is environmental contamination or simply the presence of coronavirus shed from human contact that has ended up in the dog’s samples," he said.
The World Health Organization (WHO) has stressed, however, anyone with confirmed or suspected coronavirus should "limit contact with companion and other animals".
"When handling and caring for animals, basic hygiene measures should always be implemented," the WHO states.
"This includes hand washing after handling animals, their food or supplies, as well as avoiding kissing, licking or sharing food."
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