Study confirms cats can become infected with COVID-19
By UNIVERSITY OF WISCONSIN-MADISON
 |
| "You want me to wear a mask? Are you out of your mind?" Photo by Will Collette |
Professor of Pathobiological Sciences at the University of
Wisconsin School of Veterinary Medicine Yoshihiro Kawaoka led the study, in
which researchers administered to three cats SARS-CoV-2 isolated from a human
patient.
The following day, the researchers swabbed the nasal passages of the cats and were able to detect the virus in two of the animals. Within three days, they detected the virus in all of the cats.
The following day, the researchers swabbed the nasal passages of the cats and were able to detect the virus in two of the animals. Within three days, they detected the virus in all of the cats.
The day after the researchers administered virus to the first
three cats, they placed another cat in each of their cages. Researchers did not
administer SARS-CoV-2 virus to these cats.
Each day, the researchers took nasal and rectal swabs from all six
cats to assess them for the presence of the virus. Within two days, one of the
previously uninfected cats was shedding virus, detected in the nasal swab, and
within six days, all of the cats were shedding virus. None of the rectal swabs
contained virus.
Each cat shed SARS-CoV-2 from their nasal passages for up to six
days. The virus was not lethal and none of the cats showed signs of illness.
All of the cats ultimately cleared the virus.
“That was a major finding for us — the cats did not have
symptoms,” says Kawaoka, who also holds a faculty appointment at the University
of Tokyo. Kawaoka is also helping lead an effort to create a human COVID-19
vaccine called CoroFlu.
The findings suggest cats may be capable of becoming infected with the virus when exposed to people or other cats positive for SARS-CoV-2. It follows a study published in Science by scientists at the Chinese Academy of Agricultural Sciences that also showed cats (and ferrets) could become infected with and potentially transmit the virus. The virus is known to be transmitted in humans through contact with respiratory droplets and saliva.
“It’s something for people to keep in mind,” says Peter Halfmann,
a research professor at UW–Madison who helped lead the study. “If they are
quarantined in their house and are worried about passing COVID-19 to children
and spouses, they should also worry about giving it to their animals.”
Both researchers advise that people with symptoms of COVID-19 avoid contact with cats. They also advise cat owners to keep their pets indoors, in order to limit the contact their cats have with other people and animals.
Kawaoka is concerned about the welfare of animals. The World
Organization for Animal Health and the Centers for Disease Control and
Prevention say there is “no justification in taking measures against companion
animals that may compromise their welfare.”
Humans remain the biggest risk to other humans in transmission of
the virus. There is no evidence cats readily transmit the virus to humans, nor
are there documented cases in which humans have become ill with COVID-19
because of contact with cats.
There are, however, confirmed instances of cats becoming infected
because of close contact with humans infected with the virus, and several large
cats at the Bronx Zoo have also tested positive for the virus.
For instance, according to an April 22 announcement from the U.S.
Department of Agriculture, two cats in two private homes in New York state
tested positive for COVID-19. One had been in a home with a person with a
confirmed case of the viral disease. The cats showed mild signs of respiratory
illness and were expected to make a full recovery.
Additional cats have also tested positive for COVID-19 after close
contact with their human companions, says Sandra Newbury, director of the
UW–Madison Shelter Medicine Program.
Newbury is leading a research study in several states in the U.S. to test animal-shelter cats that might have previously been exposed to human COVID-19 cases.
Newbury is leading a research study in several states in the U.S. to test animal-shelter cats that might have previously been exposed to human COVID-19 cases.
“Animal welfare organizations are working very hard in this crisis
to maintain the human-animal bond and keep pets with their people,” says
Newbury. “It’s a stressful time for everyone, and now, more than ever, people
need the comfort and support that pets provide.”
“It’s something for people to keep in mind,” says Peter
Halfmann, who helped lead the study. “If they are quarantined in their house
and are worried about passing COVID-19 to children and spouses, they should
also worry about giving it to their animals.”
Newbury has worked with the CDC and the American Veterinary
Medical Association to develop recommendations for
shelters housing potentially exposed pets, which they may do while owners are
hospitalized or otherwise unable to provide care because of their illness.
The UW–Madison study helps confirm experimentally that cats can become infected, though the risk of natural infection from exposure to SARS-CoV-2 seems to be quite low, Newbury says. Of the 22 animals the program has tested, none have had positive polymerase chain reaction tests for the virus, she adds.
The UW–Madison study helps confirm experimentally that cats can become infected, though the risk of natural infection from exposure to SARS-CoV-2 seems to be quite low, Newbury says. Of the 22 animals the program has tested, none have had positive polymerase chain reaction tests for the virus, she adds.
“Cats are still much more likely to get COVID-19 from you, rather
than you get it from a cat,” says Keith Poulsen, director of the Wisconsin
Veterinary Diagnostic Laboratory, who recommends that pet owners first talk to
their veterinarians about whether to have their animals tested. Testing should
be targeted to populations of cats and other species shown to be susceptible to
the virus and virus transmission.
With respect to pets, “we’re targeting companion animals in
communal residences with at-risk populations, such as nursing homes and
assisted living facilities,” Poulsen says. “There is a delicate balance of
needing more information through testing and the limited resources and clinical
implications of positive tests.”
So, what should pet owners do?
Ruthanne Chun, associate dean for clinical affairs at UW
Veterinary Care, offers the following advice:
If your pet lives indoors with you and is not in contact with any
COVID-19 positive individual, it is safe to pet, cuddle and interact with your
pet.
If you are COVID-19 positive, you should limit interactions with
your pets to protect them from exposure to the virus.
Additional guidance on managing pets in homes where people are
sick with COVID-19 is available from the American Veterinary
Medical Association and CDC,
including in this FAQ from AVMA.
“As always, animal owners should include pets and other animals in
their emergency preparedness planning, including keeping on hand a two-week
supply of food and medications,” she says. “Preparations should also be made
for the care of animals should you need to be quarantined or hospitalized due
to illness.”
References: “Transmission of SARS-CoV-2 in Domestic Cats” by Peter
J. Halfmann, Ph.D.; Masato Hatta, D.V.M., Ph.D.; Shiho Chiba, Ph.D.; Tadashi
Maemura, D.V.M., Ph.D.; Shufang Fan, Ph.D.; Makoto Takeda, M.D., Ph.D.; Noriko
Kinoshita, M.D.; Shin-ichiro Hattori, Ph.D.; Noriko Kinoshita, M.D. and
Shin-ichiro Hattori, Ph.D., 13 May 2020, New England Journal of Medicine.
DOI: 10.1056/NEJMc2013400
DOI: 10.1056/NEJMc2013400
The study was supported by the U.S. National Institute of Allergy
and Infectious Diseases and by the Japan Agency for Medical Research and
Development.
