The COVID-19 pandemic has increased anxieties for everyone, including pet owners. The disease’s zoonotic, animal origins and the diagnoses of some dogs, cats and other animals like tigers since the outbreak has contributed to those anxieties.
The UC Davis School of Veterinary Medicine has some of the world’s leading experts on zoonotic diseases, including coronaviruses. On the UC Davis LIVE: COVID-19 livestream last Thursday (Aug. 27), two of the UC Davis experts, Niels Pedersen and Jane Sykes, assuaged animal owners’ fears of the COVID-19-causing SARS-CoV-2 possible effects on people’s beloved pets. The panelists are pictured above, clockwise from top left: Pedersen; Soterios Johnson, host of UC Davis LIVE: COVID-19; and Sykes.
How COVID-19 affects different species
Coronavirus infections of dogs, cats and other pets “are quite uncommon given the scope of this infection worldwide in people,” said Sykes, chief veterinary medical officer of the William R. Pritchard Veterinary Medical Teaching Hospital and associate dean of Veterinary Medical Center Operations at the School of Veterinary Medicine. As a clinician and researcher, she specializes in infectious diseases of dogs and cats.
“There’s no known documented transmission of disease from pets back to people,” Sykes said. “The most likely reason that animals aren’t passing COVID-19 back to humans is that dogs and cats don’t shed enough of the virus to infect us.”
Professor Emeritus Pedersen said: “Once coronaviruses establish themselves in a host, they don’t jump around; they are host-specific.”
It all depends on the match
Pedersen’s research career has focused on viruses that cause disease in cats, including coronaviruses. Coronaviruses can be carried benignly in a reservoir species such as bats and then jump directly to infect a susceptible host species — humans in the case of COVID-19 — or travel to the host through an intermediary such as pangolins.
A coronavirus may touch other species along the way, such as dogs or cats, or even tigers in the case of COVID-19, but if those species aren’t a good match, they aren’t likely to cause much effect or be easily transmittable. For instance, a coronavirus that Pedersen has studied extensively, feline infectious peritonitis, or FIP, can be deadly to cats but is benign to humans.
This evolutionary search for survival not only means that coronaviruses search for optimal host species, but that they tend to be deadliest when they first infect a susceptible species, Pedersen said. “There’s an old saying among virologists that viruses do not like to kill their hosts; they don’t even like to make them sick," he said. "And so the suspicion is that SARS-CoV-2 is already on its way there with humans with mutations that reduce virulence and increase infectivity.”
Enjoy human-animal bond
Pets have low susceptibility to the disease and are at less risk for a serious reaction than humans, Sykes said, so owners don’t need to take any particular precautions to protect their pets. “We want people especially in this quarantine time to enjoy the human-animal bond, and participate in activities like walking your dog,” she said.
“Really what you want to be doing is physical distancing as you would be doing normally. You don’t want to get close to people and spend time with them while they’re petting your dog.”
The pets that have been diagnosed with coronavirus caught it from their owners, Sykes said, so to best protect your pet, you need to protect yourself from contracting COVID-19 or a secondary condition that would weaken your immune system, such as the flu.
Hope for a vaccine?
Coronaviruses exist in most species, and are similar enough that a drug effective against one may also be effective against another. Pedersen tested a drug compound that successfully treated cats with FIP in a clinical study, but it has not yet been made legally available for cat owners because, according to Pedersen, it or related compounds may also be effective in humans for treating or preventing COVID-19. The compound owners are focused on testing it against COVID-19 before releasing it for feline treatments.
Another FIP drug, one that Pedersen successfully tested in partnership with Kansas State University, is being launched for clinical trials in Canada. “So here are two drugs being tested and used in cats that are now on the brink of being tested in humans for C19 in humans,” he said.
Sykes and Pedersen’s discussion with host Soterios Johnson also covered COVID-19 and domestic animals, like cows, chickens and pigs as well as deeper dives into the topics above. See the entire program, above