There are now many millions of cases globally of human infection with the SARS-CoV-2 virus which causes COVID-19. There is also evidence that many animal species (domestic and wild) may become infected with SARS-CoV-2 from humans infected with the virus [1]. However, the evidence indicates that animals do not play a significant role in infection of humans and that the human COVID-19 pandemic is sustained through human-human transmission [2, 3].
Although many individual domestic animals have now been shown to have been infected with SARS-CoV-2 [1], it is unusual for infected animals to show signs of illness and these have generally been mild. Crucially, there is no evidence that domestic animals are significantly involved in the spread of COVID-19 [1].
The human-animal bond people share with their companion animals is very important and can provide much needed support, comfort and companionship to people in these difficult times, so if possible people and their companion animals should stay together for the benefit of both.
Please note that there are many things that are currently unknown about this virus and the risk it poses to pets and from pets to humans. This information has been prepared with the best and most current information available at the time but things are changing rapidly as the situation evolves. Our information is updated as often as possible.
What animal species can be infected with SARS-CoV-2?
There is evidence of infection (both experimental and natural) of a range of wild and domesticated animals with SARS-CoV-2 [1, 4]. Susceptibility to the virus (how easily a species can be infected with the virus) varies across species. The likelihood of and severity of clinical signs of disease in the infected animal and potential to transmit the virus to other animals, also varies across species. There is more information emerging about this frequently. In addition, the effects of new variants of the virus may vary with different animal species, which highlights the importance of effective and ongoing surveillance of the virus in animals.
Wild and captive wild species
The wild and captive wild species currently known to be susceptible to infection with SARS-CoV-2 include [1, 4, 5]: horseshoe bat, feline species (including tiger, puma, lion, snow leopard, fishing cat, lynx), ferret, mink, hippopotamus, binturong, white-tailed deer, otter, spotted hyena, coatimundi, bushy-tailed woodrat, striped skunk, North American deer mice, Egyptian fruit bats, primates (including macaques, gorilla, savanna monkey), and raccoon dog.
The main concerns relating to SARS-CoV-2 infection of specific wild or captive wild species includes:
- Heightened health and conservation risk to threatened or endangered species such as non-human primates and wild cat species, especially for small and vulnerable populations of these species.
- High susceptibility of mink to SARS-CoV-2 and risk of spreading the virus to other animals including cats and dogs and humans [4]. There have been large outbreaks of SARS-CoV-2 infection in captive mink (these animals are still farmed for fur in many countries) and there is also evidence of infection of wild mink [4]. Although mink were initially infected with SARS-CoV-2 by people with COVID-19, there is evidence that they can also pass the infection to humans [4].
- High prevalence of SARS-CoV-2 infection within white-tailed deer populations in North America raises concerns for the potential risk and public health implications of this species acting as a reservoir of SARS-CoV-2 for humans and other animals [6]. Whilst it is thought that the virus was introduced into the deer population by infected humans, there is no evidence of transmission of SARS-CoV-2 from white-tailed deer to humans, but this is a potential concern. Further research and surveillance is needed to assess the implications of SARS-CoV-2 infection in white-tailed deer [6].
Domestic species
There is evidence of infections of a number of domestic species, either naturally from infected humans or experimentally [1, 4].
For each of the domestic species that have been shown to be vulnerable to infection with SARS-CoV-2, the species’ susceptibility to the virus, likelihood of and severity of clinical signs of disease in the affected animal, and potential to transmit the virus to other animals is summarised below:
- Cat – there is extensive evidence of both experimental and natural infection of cats with SARS-CoV-2, showing that they are highly susceptible to infection [7]. Research suggests that it is relatively common for people who have COVID-19 to infect their companion cats [9]. The evidence suggests that cats are unlikely to develop clinical signs of disease from infection of SARS-CoV-2 and, if they do, these signs are usually mild [3, 7]. However, serious disease has been reported in some cats and there has been a small number of fatalities [7], so there is some health risk to cats from close contact with people with COVID-19. Cats have been shown experimentally to be able to infect other cats but they only shed the virus for a short time [3, 7]. There has only been one report of transmission from a cat to a human; this seems to be a very rare occurrence [8].
- Cattle – the evidence so far suggests that cattle have low susceptibility to the virus. The available information is from studies of experimental infections. These studies show that cattle have only low levels of virus in their bodies and do not seem to transmit the virus or show clinical signs of infection [10]. Therefore, the risk to and risk from cattle who do get infected seems to be low.
- Dog – the experimental evidence indicates that dogs’ susceptibility to infection with SARS-CoV-2 is low. Despite this, there is extensive evidence of natural infection of dogs with SARS-CoV-2 from infected people and the number of cases of infections in dogs is thought to be significantly higher than reported [9]; this is likely to be simply because so many dogs live as companions in close contact with people who are infected with and shedding the virus. Research suggests that it is relatively common for people who have COVID-19 to infect their companion dogs [9]. Dogs do not commonly show clinical signs associated with SARS-CoV-2 infection but, when present, clinical signs have generally been mild [1, 9, 10]. Dogs seem to shed minimal amounts of the virus when infected and are thought to pose a low risk of infection to other animals and people.
- Ferret – there is extensive evidence that ferrets are susceptible to natural and experimental infection with SARS-CoV-2 [4]. Infected ferrets usually show mild clinical signs related to SARS-CoV-2 infection although more serious disease and even euthanasia has been reported [11]. Infected ferrets shed the virus and have been shown to be able to transmit SARS-CoV-2 to other ferrets [4]. There have been reports of infected people transmitting SARS-CoV-2 to their companion ferrets [12, 13].
- Hamster – Golden Syrian hamsters have been shown to have high susceptibility to the virus in experiments, can show signs of disease (none to very mild in some cases) and spread between hamsters has been documented [14]. Natural infection of hamsters being sold as companion animals has also been documented [5].
- Rabbits – the available evidence shows that some rabbits can be experimentally infected with SARS-CoV-2 but do not become sick and only shed low amounts of the virus [15].
The following domestic species do not seem to be vulnerable to infection with SARS-CoV-2 based on the available information:
- Horses – The limited evidence available indicates that horses are not susceptible to infection with SARS-CoV-2 [10, 16]. More surveillance and evidence are needed to confirm that the potential risk to and risk from horses is very low, as is suggested.
- Poultry – Experimental evidence suggests that poultry (chicken, ducks, and turkeys) are not susceptible to infection with SARS-CoV-2 [1, 4].
- Pigs – the evidence suggests that very low susceptibility to infection with SARS-CoV-2 and there is no evidence that they develop clinical signs associated with infection or transmit the virus [4, 17].
- Sheep, goats, and alpacas – The limited evidence available suggests that sheep, goats, and alpacas are not susceptible to infection with SARS-CoV-2 [10]. More surveillance and evidence are needed to confirm that the potential risk to and risk from these species is truly very low, as is suggested.
It is advised by the Australian Animal Health Committee that commercial entities who develop tests for SARS-CoV-2 infection in animals should reference the OIE Considerations on monitoring SARS-CoV-2 in animals, and carefully consider the circumstances when testing may support human and animal health and welfare outcomes. The RSPCA is not aware of any commercial entities that have developed validated tests for animals which are available in Australia. While SARS-CoV-2 is not specifically listed on the National list of notifiable animal diseases, it has not been previously confirmed by laboratory testing in animals in Australia. Therefore, diagnostic test results for SARS-CoV-2 should be reported to the relevant jurisdictional Chief Veterinary Officer [18].
Since there is evidence of cats and dogs becoming infected with the SARS-CoV-2 virus from humans who have COVID-19 and some (albeit low) risk to some individual animals, it is important to take some precautionary steps to protect our companion animals such as those below:
- People without symptoms of COVID-19 should continue to practice good hygiene during interactions with animals. This includes washing hands before and after such interactions and when handling animal food, waste, or supplies.
- People who are infected with SARS-CoV-2 should eliminate or limit contact with animals as well as other people. Someone else should care for any animals, including companion animals.
- If a companion animal has been exposed to SARS-CoV-2, as a precaution they should be kept in the house and not allowed to interact with other people or animals.
- If a companion animal has been exposed to SARS-CoV-2 and is sick, their veterinarian should be contacted for advice; the animal should not be taken to the veterinary clinic unless the veterinarian has advised this and can take precautions.
The Australian Veterinary Association currently advises that COVID-19 vaccination of animals in Australia is not required and there are no approved animal COVID-19 vaccines registered in Australia. The Australian government monitors this situation closely through monitoring emergence of new research and advice from global organisations, such as the OIE, and will modify its advice if required.
If you are facing challenges caring for your animals, please get in touch with your local RSPCA to discuss options; we are here to offer support and help if possible.
References
[1] World Organisation for Animal Health (OIE) (2022) COVID-19 – Events in Animals. Available online: https://www.oie.int/en/what-we-offer/emergency-and-resilience/covid-19/#ui-id-3 (accessed on 20.1.2022).
[2] World Organisation for Animal Health (OIE) (2020) Questions and Answers on the 2019 Coronavirus Disease (COVID-19). Available online: https://www.oie.int/en/what-we-offer/emergency-and-resilience/covid-19/#ui-id-2 (accessed on 24.2.2022).
[3] Bosco-Lauth AM, Hartwig AE, Porter SM et al (2020) Experimental infection of domestic dogs and cats with SARS-CoV-2: Pathogenesis, transmission, and response to reexposure in cats. Proceedings of the National Academy of Sciences of the United States of America 117: 26382–26388.
[4] Fenollar F, Mediannikov O, Maurin M et al (2021) Mink, SARS-CoV-2, and the Human-Animal Interface. Frontiers in Microbiology 12: 663815.
[5] World Organisation for Animal Health (OIE) (2022) SARS-CoV-2 in animals – situation report 9. Available online: https://www.oie.int/app/uploads/2022/02/sars-cov-2-situation-report-9.pdf (accessed on 17.2.2022).
[6] World Organisation for Animal Health (OIE) (2021) OIE Statement on monitoring white-tailed deer for SARS-CoV-2. Available online: https://www.oie.int/en/oie-statement-on-monitoring-white-tailed-deer-for-sars-cov-2/ (accessed on 20.1.2022).
[7] Hosie MJ, Hofmann-Lehmann R, Hartmann K et al (2021) Anthropogenic infection of cats during the 2020 covid-19 pandemic. Viruses 13: 185.
[8] Sila T et al (2022) Suspected Cat-to-Human Transmission of SARS-CoV-2, Thailand, July–September 2021. Emerging Infectious Diseases 28(7): 1485-1488.
[9] Hamer SA, Pauvolid-Corrêa A, Zecca IB et al (2021) SARS-CoV-2 infections and viral isolations among serially tested cats and dogs in households with infected owners in Texas, USA. Viruses 13: 938.
[10] Bosco-Lauth AM, Walker A, Guilbert L et al (2021) Susceptibility of livestock to SARS-CoV-2 infection. Emerging Microbes & Infections 10: 2199–2201.
[11] Kutter JS, de Meulder D, Bestebroer TM et al. (2021) SARS-CoV and SARS-CoV-2 are transmitted through the air between ferrets over more than one meter distance. Nature Communications 12: 1653.
[12] Giner J, Villanueva‐saz S, Tobajas AP et al (2021) SARS‐CoV‐2 seroprevalence in household domestic ferrets (Mustela putorius furo). Animals 11: 667.
[13] Račnik J, Kočevar A, Slavec B et al (2021) Transmission of SARS-CoV-2 from human to domestic ferret. Emerging Infectious Diseases. 27:2450–2453.
[14] World Organisation for Animal Health (OIE) (2020) OIE Technical Factsheet – SARS-CoV-2 Available online: https://www.oie.int/fileadmin/Home/eng/Our_scientific_expertise/docs/pdf/COV-19/A_Factsheet_SARS-CoV-2.pdf (accessed on 20.1.2022).
[15] Mykytyn AZ, Lamers MM, Okba NMA et al (2021) Susceptibility of rabbits to SARS-CoV-2. Emerging Microbes and Infections 10: 1–7.
[16] Cerino P, Buonerba C, Brambilla G et al (2021) No detection of SARS-CoV-2 in animals exposed to infected keepers: results of a COVID-19 surveillance program. Future Science OA 10.2144/fsoa-2021-0038.
[17] Pickering BS, Smith G, Pinette MM et al. (2021) Susceptibility of domestic swine to experimental infection with severe acute respiratory syndrome coronavirus 2. Emerging Infectious Diseases 27: 104–112.
[18] Animal Health Committee (AHC) of the National Biosecurity Committee (NBC) (2020) Policy statement on COVID-19 diagnostic testing and surveillance in animals. Available online: https://www.awe.gov.au/agriculture-land/animal/health/committees/ahc. Accessed 13.5.2022.