SARS-CoV-2 in pets and other domestic animals
COVID-19—or coronavirus disease 2019—is the disease that people get from being infected with the severe acute respiratory syndrome coronavirus 2 (or SARS-CoV-2). Domestic animals do not get COVID-19 like humans do, but under natural conditions, pet cats—and, to a lesser extent, pet dogs—may, albeit rarely, become infected with SARS-CoV-2 after close and prolonged contact with a COVID-19-positive person. In other words, a person with COVID-19 might transmit the virus that causes this disease to pet cats and dogs (and perhaps pet ferrets) in the same way we might transmit it to another person.
However, there is no compelling evidence to date that any domestic animal, including cats, dogs, and ferrets, readily transmits SARS-CoV-2 to other animals, including humans, under natural conditions. Further, the global number of naturally infected animals is far, far less than the number of people with COVID-19, indicating that animals, including pets, are not a driver of the COVID-19 pandemic—the pandemic continues to be driven by human-to-human transmission.
Clinical signs of SARS-CoV-2 infection in cats and dogs
Although cats and dogs with naturally acquired SARS-CoV-2 infections are often asymptomatic, there are several clinical signs compatible with infection, including a combination of any of the following:
- Difficulty breathing or shortness of breath
- Nasal discharge
- Ocular discharge
Testing pets for SARS-CoV-2
Because these are non-specific clinical signs, testing a sick pet for SARS-CoV-2 should ideally be performed only after more common causes of illness have been ruled out. Further, a decision on whether to test an animal for SARS-CoV-2 should be made collaboratively by the pet’s veterinarian in consultation with the owner and in coordination with local, state, and/or federal public health and animal health officials. The CDC has more detailed guidance for state public health veterinarians and state animal health officials regarding testing animals for SARS-CoV-2 infection. And, see more information and resources from the AVMA, including a testing decision flowchart and client handout.
In multiple studies conducted in different laboratories since the start of the pandemic, ferrets—as well as cats—can be readily infected with SARS-CoV-2 after experimental inoculation. Ferrets and cats infected this way may also develop transient mild to moderate abnormal respiratory or gastrointestinal signs and transmit the virus to naïve animals of the same species under controlled conditions.
Dogs, too, can be infected in a laboratory setting, albeit less efficiently and reliably than ferrets or cats. Experimentally infected dogs do not typically develop abnormal clinical signs, nor do they readily transmit SARS-CoV-2 to naïve dogs in these controlled environments. Data regarding experimental infection of other animals are non-existent (e.g., horses), sparse (e.g., cattle, pigs, poultry, rabbits), and at times inconsistent (e.g., pigs, rabbits).
However, we emphasize caution in not overinterpreting the results from only a small number of experimental infection and transmission studies, because:
- Experimentally induced infections do not mirror naturally induced infections. Just because an animal can be experimentally infected via direct intranasal or intratracheal inoculation with high concentrations of purified tissue-cultured virus does not mean that it will easily be infected with that same virus under natural conditions.
- Experimental transmission studies are typically done under ideal conditions that may include use of negative pressure test chambers and unidirectional flow of HEPA-filtered air from the infected to the naïve animal. Such highly controlled conditions do not reflect conditions found outside a laboratory setting. As such, results should not be used as conclusive evidence that an experimentally infected animal can readily transmit COVID-19 under natural conditions.
- The numbers of animals used in these types of experiments is typically small, with conclusions drawn based on data points that are in some cases collected from as few as two animals, making it challenging to draw definitive conclusions regarding all animals of a given species from results of only a few—and in some cases a single—study.
Links to published reports of experimental infection and transmission studies can be found in our compilation of key research articles related to SARS-CoV-2 in non-human animals.
SARS-CoV-2 in farmed, captive, and free-ranging wildlife species
SARS-CoV-2 infection in farmed mink
Mink, including those farmed commercially for fur, are in the same mammalian family (Mustelidae) as ferrets, which are susceptible to experimental inoculation with SARS-CoV-2. As such it was perhaps not surprising when, in late April 2020, government officials in the Netherlands reported the first case of SARS-CoV-2 infection in commercially farmed mink.
Additional reports of SARS-CoV-2 infected farmed mink came later in 2020 from Denmark (June), Spain (July), the U.S. (August), Italy (August), Sweden (October), France (November), Greece (November), Lithuania (November), and Canada (December).
The course of infection in mink varied, with some animals remaining asymptomatic, others developing mild to moderate respiratory or gastrointestinal illness from which they recovered, while still others developed severe illness and died or were euthanized.
In all countries that have reported SARS-CoV-2 infections on commercial mink farms, country- or state-specific surveillance programs and control measures were quickly implemented to control or stop viral transmission. Control measures have ranged from strict on-farm biosecurity and disease reporting requirements only, to depopulation orders for either infected farms or all farms, regardless of infection status.
As surveillance programs continue, both the global number of infected farms and the number of countries with infected farms will no doubt increase. We will update the number of infected mink farms in our summary of naturally occurring SARS-CoV-2 infections in animals.
SARS-CoV-2 transmission between humans and farmed mink
In almost all reports of SARS-CoV-2 infection in farmed mink, the source of infection could be definitively linked to one or more farm employees with COVID-19 who had worked closely with the animals in closed barns. Following an initial human-to-mink transmission event, SARS-CoV-2 was then readily transmitted from mink to mink throughout an affected barn.
In May 2020, results of a study from the Netherlands raised concern that mink-to-human transmission of SARS-CoV-2 may be possible. However, this was only a preliminary study investigating transmission dynamics on a few of the first infected Dutch mink farms. Analyses conducted by Dutch government agencies at that time indicated that the risk for people contracting COVID-19 from infected mink was low.