Veterinarian latex loves dong injection dog vet holds syringe hands.

In February 2020, a woman in Hong Kong was diagnosed with Covid-19. Two other people in her home soon tested positive for the virus, as did one unexpected member of the household: an elderly Pomeranian. The 17-year-old dog was the first pet known to catch the virus.

But not the last. A German shepherd in Hong Kong soon tested positive, too, as did cats in Hong Kong, Belgium and New York. The cases were exceedingly mild. The animals had few or no symptoms and experts concluded that humans had spread the virus to the pets, rather than vice versa.

Over the past year, coronavirus vaccines have gone into billions of human arms and into the fuzzy bodies of zoo animals.  Zoos, which look after a relatively small number of often rare and high-value animals, clearly want to protect the species in their care. COVID-19 has caused a handful of animal deaths in zoos to date—including three snow leopards at a children’s zoo in Nebraska and two lions at a zoo in India. 

About 260 animals in San Diego Zoo and Safari Park, including lions, bears and ferrets have now received an experimental Covid-19 vaccine for animals by veterinary pharmaceutical company Zoetis.

Largely left behind, however, are domestic cats and dogs. Many pet parents are concerned.

No history of dogs or cats spreading virus to humans

Scientists think that a pet Covid vaccine is feasible. Research teams say that they have developed promising cat or dog vaccines and the shots that zoo animals are receiving were initially designed for dogs.

But vaccinating pets is simply not a priority, experts said. Although dogs and cats can catch the virus, studies suggest that our pets play little to no role in its spread and rarely fall ill themselves. “A Covid vaccine is quite unlikely, I think, for dogs and cats,” Dr Will Sander, a veterinarian at the University of Illinois Urbana-Champaign, said. “The risk of disease spread and illness in pets is so low that any vaccine would not be worth giving.”

 “To date, there hasn’t been any documented cases of dogs or cats spreading the virus to people,” Dr Elizabeth Lennon, a veterinarian at the University of Pennsylvania, said. “But the prospect of a pet pandemic sparked interested in an animal vaccine.”

Lions and tigers are more prone to be infected with the coronavirus

Zoetis has now committed to donating 26,000 doses – enough to vaccinate 13,000 animals – to zoos and animal sanctuaries in 14 countries. The development means that many zoo-dwelling cats, like lions and tigers, are getting vaccinated, while their domestic cousins are not.

In part, that’s because these species appear to be more susceptible to the virus; some have died after becoming infected, although the cause of death is often difficult to conclusively determine. 

“The big cats seem to be getting sicker than the house cats,” Lennon said. 

Moreover, there is no evidence that cats or dogs spread the virus to humans and there are few signs that they readily transmit it among themselves. Stray cats, for instance, are much less likely to have antibodies to the virus than cats that live with people, suggesting that the animals are largely getting the virus from humans, rather than from each other.

According to the World Organisation for Animal Health, there is currently no evidence showing that animals play a role in spreading the virus to humans.

Therefore, the risk of humans contracting the Sars-CoV-2 virus from animals is very low. If the virus turns out to be more prevalent, virulent or transmissible in dogs or cats than is currently known, that would make the case for a vaccine more compelling, scientists said.

For now, there are steps that pet parents can take to protect their animals. People who test positive for the virus should isolate from their pets, if possible, or wear a face mask while caring for them. If the pet is a suspected or confirmed case, consult a vet immediately. This article originally appeared in The Irish Times.

Scientists believe that the risk of disease spread and illness in pets is so low that any vaccine would not be worth giving.