VANCOUVER -- Cat and dog owners who cuddle their pets when infected with COVID-19 could end up making the animals sick with the virus, according to a Canadian study.

The study said that while it was already known that animals including cats, dogs, ferrets and hamsters seem to be susceptible to COVID-19, transmission may be happening more often than previously thought.

The research, published this month in the journal Emerging Infectious Diseases, involved 69 cats and 49 dogs, including pets and animals from shelters and neuter clinics.

Pet owners were also asked to fill out an online survey about the nature of their interaction with their animals.

"These data indicate relatively common transmission of SARS-CoV-2 from humans to animals and that certain human-animal contacts -- example, kissing the pet, pet sleeping on the bed -- appear to increase the risk," said the study.

"We inferred that infections in dogs and cats reflect direct transmission from humans to animals, given the pandemic nature of this virus in humans and limited contact of most household pets with other animals."

Dogs and cats that lived in shelters showed lower rates of COVID-19 infection compared with those that lived with humans, said study co-author Prof. Scott Weese of the University of Guelph's Ontario Veterinary College.

"It was a fairly substantial difference as we would have expected," said Weese.

Lead author Prof. Dorothee Bienzle from the University of Guelph's pathobiology department said results suggest that cats have a higher rate of COVID-19 infection than dogs.

"It has to do with how well the virus latches on to the receptor in the cat or dog's respiratory system," said Bienzle.

The high prevalence of COVID-19 antibodies in cats surprised researchers, she said.

"We did not expect quite that many," she said. "Over half of the cats that live in a household of a person who had COVID had antibodies. That's very high."

Animals infected with COVID-19 show symptoms similar to humans who fall sick with the virus, she said.

"They don't have any appetite, they feel crummy, they sleep more, they might sneeze and cough," she said.

Weese said cats are able to pass on the infection to each other, and also to humans.

A veterinarian in Thailand was diagnosed with COVID-19 in August 2021, after being sneezed on by an infected cat owned by a patient who had tested positive for the virus, he said. Genetic analysis showed that the virus was transmitted from the cat owner to the pet and onto the veterinarian, Weese said.

There is also evidence that minks infected by humans can pass the virus on to other people, he said.

Transmission from humans to animals can be minimized by owners keeping their distance, wearing a mask and taking other precautions, just as they would to prevent infecting a person, he said.

"Ideally, what we want to do is keep it from spreading as much as possible so people can limit the contact they have with animals when they're infected," he said. "That's ideal."

This report by The Canadian Press was first published June 26, 2022.