ISCAID

SARS-CoV-2 Infections in Cats, Dogs, and Ferrets

Current State of Knowledge for Veterinary Health Care Providers

Updated April 16, 2020 10:00 (EST)

The purpose of this ISCAID document is to provide up-to-date answers for veterinarians to the questions being asked about SARS-CoV-2 in dogs, cats, and ferrets by people around the world. This document is updated as new information becomes available.

  1. Background
  2. Does amplification of viral RNA prove current infection with a coronavirus?
  3. Does the presence of antibodies against a virus document that infection has occurred?
  4. Does the absence of antibodies against a virus prove that infection with a virus did not occur?
  5. What do the ACE2 receptor papers tell us about SARS coronaviruses’ potential to infect different hosts?
  6. What companion animals have been infected experimentally with SARS-CoV-2 to date?
  7. What is the current evidence for SARS-CoV-2 natural infection in domestic cats?
  8. Does SARS-CoV-2 infect non-domestic cats?
  9. Can SARS-CoV-2 be transmitted amongst cats?
  10. What is the current evidence for SARS-CoV-2 natural infection in domestic dogs?
  11. What is the most likely source of SARS-CoV-2 in dogs and cats?
  12. Are all dogs or cats that are exposed to people with COVID-19 infected with SARS-CoV-2?
  13. What methods are used to try to determine whether dogs or cats that have lived with people with COVID-19 are of danger to other people?
  14. How common are subclinical infections in dogs and cats?
  15. How common are clinical SARS-CoV-2 infections in dogs and cats?
  16. Can SARS-CoV-2 live on the hair of dogs or cats and be a fomite for infection of people?
  17. Will bathing dogs or cats or using disinfectant wipes lessen risk of SARS-CoV-2 infection in humans?
  18. Are veterinary health-care providers at risk for developing COVID-19?
  19. How should dogs or cats that are currently housed with a person with COVID-19 be handled?
  20. How should dogs or cats that have been housed with a person with COVID-19 be handled by new care-givers?
  21. How long should a dog or cat that has lived with a person with COVID-19 be quarantined?
  22. Should I administer ivermectin to dogs or cats to attempt to lessen SARS-CoV-2 associated illness or carriage?
  23. What risk does the average dog or cat pose to its owners?
  24. What are the best websites to monitor for new information concerning SARS-CoV2, dogs, ferrets, and cats?
  25. Authors and affiliations
  26. References

 

Background

Enteric coronaviruses of cats and dogs and the mutated strains of feline enteric coronaviruses that can cause feline infectious peritonitis (FIP), and the pantropic canine coronavirus, are alpha-coronaviruses and the canine respiratory coronavirus is a beta-coronavirus.1-3   Most veterinary health care providers are very familiar with these agents which are common in cats and dogs seen in practices around the world.

Shortly after the first outbreak of severe acute respiratory syndrome coronavirus (SARS-CoV-1) was recognized in people over 15 years ago, cats and ferrets were shown to be capable of being infected with this beta-coronavirus and were able to transmit the virus to other cats and ferrets.4-8   No case of SARS-CoV-1 companion animal-to-human transmission was ever demonstrated.8 However, after 2005 no further human cases of SARS were reported and limited research on animal-to-human transmission of SARS-CoV-1 was pursued.

The current pandemic is caused by a new coronavirus, SARS-CoV-2.  The clinical syndrome this virus induces in people is referred to as coronavirus disease 2019 (COVID-19).9 New information is generated and published daily regarding COVID-19.  The purpose of this ISCAID document is to provide up-to-date answers for veterinarians to the questions being asked about SARS-CoV-2 in dogs, cats, and ferrets by people around the world.  For many questions, further information is needed before definitive statements can be made.

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Does amplification of viral RNA prove current infection with a coronavirus?

Amplification of viral nucleic acids (including SARS-CoV-2) by molecular methods only documents that the virus is present, but does not confirm the virus is alive (able to replicate in human or animal cells).  Virus isolation (culture) must be used to prove the presence of infectious virus.  However, if viral nucleic acids are amplified multiple times over time from the same host or are present in high levels, infection may have occurred.

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Does the presence of antibodies against a virus document that infection has occurred?

If serum antibodies are present against an agent transmitted across mucosal surfaces like the respiratory and gastrointestinal tracts, it can generally be assumed that live virus entered the body and induced an immune response.  In general, if non-viable organisms are ingested or contact respiratory mucosal surfaces, antibody responses do not develop.  As antibody assays are developed for agents like SARS-CoV-2, it is important that the specificity of the assay is known.   The assay should detect antibodies only against the agent in question and not against related organisms.

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Does the absence of antibodies against a virus prove that infection with a virus did not occur?

In acute infections, serum antibodies may still be below the detectable limit in some assays.  In addition, low level infections may not always induce antibody responses.  For example, failure to seroconvert was noted in some asymptomatic humans infected with Middle East respiratory syndrome coronavirus (MERS-CoV).10

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What do the ACE2 receptor papers tell us about SARS coronaviruses’ potential to infect different hosts?

The studies with SARS-CoV-1 over 12 years ago and the current work with SARS-CoV-2 suggest that the receptor binding domains that the viruses use to enter cells are very similar for several mammalian species, including cats, ferrets, dogs, and people.11,12  These findings were amongst the first used to suggest that SARS-CoV-2 virus may have the potential to infect species other than humans.

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What companion animals have been infected experimentally with SARS-CoV-2 to date?

Data from several studies became available recently reporting infectivity of SARS-CoV-2 to cats, ferrets, dogs (as well as number of other species).13-15  In these studies, infection after experimental inoculation was documented in all 3 of these companion animal species, with the virus replicating poorly in dogs in one study.14

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What is the current evidence for SARS-CoV-2 natural infection in domestic cats?

The first naturally exposed cat positive for SARS-CoV-2 RNA (samples obtained from the cat’s feces and vomitus) lived in Belgium with a person with COVID-19.16 The clinical signs of disease, which may have been related to the viral infection, resolved.  Whether the cat also developed serum antibodies has not been reported to date.

Recently, a SARS-CoV-2 qRT-PCR positive cat owned by a person with COVID-19 (out of a total of 17 cats tested from different owners) was reported in Hong Kong while the cat was under quarantine.17  The cat was positive by PCR on 3 occasions in nasal and oral samples collected every two days but showed no signs of illness during the period it tested qPCR positive.

A pre-print of a manuscript was made available recently that reported SARS-CoV-2 antibody test results from 102 cats collected during the COVID-19 outbreak in Wuhan (January to March 2020) and those from 39 cats collected prior to the outbreak in 2019.18 Antibodies against the virus were detected by both ELISA and virus neutralization in 11 of 102 cat samples from the outbreak period, but none of the samples from cats tested positive prior to the outbreak.  SARS-CoV-2 RNA was not amplified from any of the tested cats.  Presence of serum antibodies provides further evidence that cats exposed to people with COVID-19 can become infected.

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Does SARS-CoV-2 infect non-domestic cats?

The Wildlife Conservation Society’s Bronx Zoo in New York, USA reported a resident 4-year-old female Malayan tiger was PCR positive for SARS-CoV-2 after being presented with cough and decreased appetite.19 This suggests the tiger was infected with SARS-CoV-2 with resulting clinical illness. The cat was cared for by in part by a person who was infected with the virus.  Although three other tigers and three African lions also had a dry cough, these cats were not sampled due to the associated risks with collecting samples under anesthesia. The four tigers lived with one clinically unaffected Amur tiger. Three other tigers and other non-domestic cats at the zoo were not showing signs of illness at the time of the report.

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Can SARS-CoV-2 be transmitted amongst cats?

The experimental inoculation study in domestic cats documented transmission to some of the in-contact cats.14   Whether the dose used to infect the primarily inoculated cats in this report is achieved under natural conditions (e.g., from contact with a person with COVID-19) is not currently known.  The small number of animals used also suggest caution when interpreting the results of the study.  Transient illness in 3 other lions and 3 other tigers in the Bronx Zoo at the same time infection was documented in one tiger may support the findings of the domestic cat experimental study.19   However, further studies will be required to determine whether exotic cats are more susceptible to the SARS-CoV-2 virus than domestic cats.

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What is the current evidence for SARS-CoV-2 natural infection in domestic dogs?

A total of 33 dogs that had lived with people with COVID-19 have been tested to date during quarantine in Hong Kong with only 2 dogs confirmed positive by qRT-PCR.  Both of those dogs seroconverted and neither had recognizable clinical signs of disease.17 These findings when combined with an experimental infection study suggest that dogs are difficult to infect with SARS-CoV-2.

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What is the most likely source of SARS-CoV-2 in dogs and cats?

If a dog or cat is infected, it is most likely to be from exposure to an infected person, early in the course of their disease, when the viral levels are the highest.20

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Are all dogs or cats that are exposed to people with COVID-19 infected with SARS-CoV-2?

At this time, it is unclear what proportions of dogs or cats exposed to SARS-CoV-2-infected people will become infected.  The degree of contact between owners and their pets may vary greatly.  The data from the Hong Kong cats and dogs belonging to COVID-19 patients showed that 1 of 18 cats (5.6%) and 2 of 32 dogs (6.3%) became infected and none showed clinical signs of disease.17  In another recent report, 20 veterinary students with confirmed SARS-CoV-2 infection (2 students) or compatible clinical signs (11 of the other 18 students) were in close contact with 9 cats and 12 dogs.21  None of the dogs and cats became infected.  Based in these results, it appears that < 10% of naturally exposed dogs and cats become infected.

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What methods are used to try to determine whether dogs or cats that have lived with people with COVID-19 are of danger to other people?

Multiple research and public health groups around the world continue to evaluate the published literature and social media for evidence that dogs or cats living with people with COVID-19 are capable of passing the virus to others.  To date, there is no evidence to suggest that dogs or cats can be a source of SARS-CoV-2 for people.22

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How common are subclinical infections in dogs and cats?

Asymptomatic SARS-CoV-2 infections of people have now been documented.23-26 In a study in Singapore, 6.4% of human cases were likely due to pre-symptomatic transmission events.26  These transmission events likely occurred 1 to 3 days prior to symptom onset.26  In a study of one of the cruise ships with a large number of COVID-9 cases, it was estimated that 17.9% of infected people remained asymptomatic.23  Results from the quarantined animals in Hong Kong suggest that when infections do occur in animals, they are subclinical, and that these infections are uncommon (< 10%), even if from a home with an infected human.17  However, many more dogs and cats will need to be tested before more accurate estimates can be made.

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How common are clinical SARS-CoV-2 infections in dogs and cats?

Clinical illness in naturally infected dogs has not been documented and only one case has been described in domestic cats. The infected large cats at the Bronx zoo also showed signs.  Since there have been over 2 million human cases of COVID-19, it appears clinical infections in dogs are cats are very uncommon.  However, the number of dogs and cats with clinical illness that were exposed to SARS-CoV-2 infected people that have been evaluated to date are small.  More information is needed before more accurate estimates can be made.  Two commercial laboratories in the United States have been evaluating samples from clinically ill dogs and cats since the pandemic entered the United States with no positive cases identified to date.27,28   However, it is unknown how many of the animals tested were known to have been in contact with people positive for SARS-CoV-2 infection.

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Can SARS-CoV-2 live on the hair of dogs or cats and be a fomite for infection of people?

On a porous surface like cardboard, the virus did not live past 24 hours in one study.29 This may partially explain why there is currently no evidence for cats or dogs serving as a fomite and passing SARS-CoV-2 to a human.   However, further data will need to be collected before definitive statements can be made as there has been no investigation of haircoat contamination or the potential human impacts.

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Will bathing dogs or cats or using disinfectant wipes lessen risk of SARS-CoV-2 infection in humans?

SARS-CoV-2 is easy to kill with detergents and so if dog and cat hair was proven to be a fomite, bathing or disinfectant wipes would likely be beneficial if the procedure could be applied safely.  In the absence of data proving or denying a positive effect and since SARS-CoV-2 infection of people from contact with a dog or cat has not been documented, some groups have stated that dogs or cats exposed to people with COVID-19 do not need to be bathed.30

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Are veterinary health-care providers at risk for developing COVID-19?

SARS-CoV-2 infection is always a possible risk in the veterinary profession due to interactions with other people.  To date, there is no evidence suggesting that cats or dogs can infect people with the virus as fomites or from having a primary infection.  In one occupational risk reference, veterinary health-care providers were not listed.31

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How should dogs or cats that are currently housed with a person with COVID-19 be handled?

Healthy dogs and cats should remain in the home.  However, owners with COVID-19 should minimize contact with their pets.  If contact is necessary, the American Veterinary Medical Association and Centers for Disease Control and Prevention recommend that “if you have a service animal or you must care for your pet, then wear a facemask; don’t share food, kiss, or hug them; and wash your hands before and after any contact with your pet or service animal.  You should not share dishes, drinking glasses, cups, eating utensils, towels, or bedding with other people or pets in your home.”30   If there is a COVID-positive person in a household, quarantining from other members of the household is also indicated.  The exposed companion animals also should not be allowed to move between the quarantined area of infected versus noninfected members of the household.

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How should dogs or cats that have been housed with a person with COVID-19 be handled by new care-givers?

While transmission of SARS-CoV-2 from exposed pets to people has not been documented, caregivers for dogs or cats that have lived with people with COVID-19 should minimize contact with the pet including dishes, and other items in-contact with the pet.  If contact is necessary, then the caregiver should wash their hands before and after handling the pet and minimize direct contact with the animal.  To date, an international consensus on whether to wear a face mask and eye protection when handling the pets has not been achieved.

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How long should a dog or cat that has lived with a person with COVID-19 be quarantined?

Since there has been minimal sequential testing of dogs and cats, recommendations for length of quarantine cannot be stated definitely.  However, based on results in people and in dogs, quarantine for a maximum period of 14 days after the last exposure to a known infected person is recommended the most.

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Should I administer ivermectin to dogs or cats to attempt to lessen SARS-CoV-2 associated illness or carriage?

A pre-print of a manuscript showing ivermectin to inhibit SARS-CoV-2 in vitro was recently made available leading to questions about the use in animals.32  ISCAID believes there is not enough information to make recommendations of how to use this information in clinical practice since optimal doses for this purpose are unknown and since illness in dogs or cats potentially related to SARS-CoV-2 from natural infection has been non-existent or apparently self-limited.

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What risk does the average dog or cat pose to its owners?

If a pet has been socially distanced from other animals and people, as is recommended, the only way a pet can be exposed to SARS-CoV-2 is from its owner.  Thus, the chances of a pet bringing SARS-CoV-2 into a household are low and can be negligible if physical distancing is used. The main concern about pets as sources of infection are when pets are moved outside of the home and have contact with people and other animals.

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What are the best websites to monitor for new information concerning SARS-CoV2, dogs, ferrets, and cats?

While there are many great sources of information, the following websites are recommended for veterinary health care providers.  Information for pet owners are available at most of these sites and also on www.iscaid.org.

Recommended websites

 AVMA

Centers for Disease Control and Prevention (CDC)

World Health Organization (WHO)

World Organization for Animal Health (OIE)

World Small Animal Veterinary Association

Worms and Germs Blog (Dr. Scott Weese; University of Guelph)

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 Authors and Affiliations

Vanessa Barrs BVSc(hons), PhD, MVetClinStud, FANZCVS, Chair Professor of Companion Animal Health, Department of Veterinary Clinical Sciences, Jockey Club College of Veterinary Medicine, City University of Hong Kong.

Jeff Bender DVM, MS DACVPM, Professor and Hospital Epidemiologist, School of Public Health and College of Veterinary Medicine University of Minnesota, United States and Adjunct Professor Chiang Mai University, Thailand; member ISCAID.

Jonathan Dear DVM, MAS, DACVIM, Assistant Professor of Clinical Internal Medicine, University of California, Davis; President, ISCAID.

Michael R. Lappin, DVM, PhD, DACVIM, Director, Center for Companion Animal Studies, Colorado State University, Charter Member, ISCAID.

Jane Sykes, BVSc(Hons) PhD DACVIM, Professor of Small Animal Internal Medicine (Infectious Diseases) and Chief Veterinary Medical Officer, University of California-Davis; Founder, ISCAID.

Jason Stull, VMD, MPVM, PhD, DACVPM; Assistant Professor. The Ohio State University; University of Prince Edward Island; member ISCAID.

Séverine Tasker BSc BVSc DSAM PhD DECVIM-CA FHEA FRCVS.  Honorary Professor of Feline Medicine, Bristol Veterinary School, University of Bristol; Chief Medical Officer, Linnaeus Group, UK.

Scott Weese, DVM, DVSc Guelph, DACVIM, Professor, Ontario Veterinary College, University of Guelph.   Charter Member, ISCAID.

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References

  1. Pedersen NC. An update on feline infectious peritonitis: virology and immunopathogenesis. Vet J. 2014;201(2):123–132. doi:10.1016/j.tvjl.2014.04.017
  2. Zicola A, Jolly S, Mathijs E, et al. Fatal outbreaks in dogs associated with pantropic canine coronavirus in France and Belgium. J Small Anim Pract. 2012;53(5):297–300. doi:10.1111/j.1748-5827.2011.01178.x
  3. Priestnall SL, Mitchell JA, Walker CA, Erles K, Brownlie J. New and emerging pathogens in canine infectious respiratory disease. Vet Pathol. 2014;51(2):492–504. doi:10.1177/0300985813511130
  4. WHO issues consensus document on the epidemiology of SARS. Wkly Epidemiol Rec. 2003;78(43):373–375.
  5. Martina BE, Haagmans BL, Kuiken T, Fouchier RA, Rimmelzwaan GF, Van Amerongen G, et al. SARS virus infection of cats and ferrets. Nature. 2003;425:915 10.1038/425915a
  6. Osterhaus AD1, Fouchier RA, Kuiken T.  The aetiology of SARS: Koch’s postulates fulfilled. Philos Trans R Soc Lond B Biol Sci. 2004;359:1081-1082.
  7. van den Brand JM, Haagmans BL, Leijten L, van Riel D, Martina BE, Osterhaus AD, Kuiken T.  Pathology of experimental SARS coronavirus infection in cats and ferrets. Vet Pathol. 2008;45:551-562.
  8. Lun ZR, Qu LH.  Animal-to-human SARS-associated coronavirus transmission? Emerg Infect Dis. 2004;10:959.
  9. Rothan HA, Byrareddy SN. The epidemiology and pathogenesis of coronavirus disease (COVID-19) outbreak [published online ahead of print, 2020 Feb 26]. J Autoimmun. 2020;102433. doi:10.1016/j.jaut.2020.102433
  10. Okba NMA, Raj VS, Widjaja I, et al. Sensitive and specific detection of low-level antibody responses in mild Middle East Respiratory Syndrome Coronavirus Infections. Emerg Infect Dis. 2019;25:1868–1877. doi:10.3201/eid2510.190051
  11. Guo H, Guo A, Wang C, Yan B, Lu H, Chen H.  Expression of feline angiotensin converting enzyme 2 and its interaction with SARS-CoV S1 protein. Res Vet Sci. 2008 Jun;84(3):494-6. Epub 2007 Jul 20.
  12. Luan J, Lu Y, Jin X, Zhang L. Spike protein recognition of mammalian ACE2 predicts the host range and an optimized ACE2 for SARS-CoV-2 infection [published online ahead of print, 2020 Mar 19]. Biochem Biophys Res Commun. 2020;S0006-291X(20)30526-X. doi:10.1016/j.bbrc.2020.03.047.
  13. Young-Il Kim, Seong-Gyu Kim, Se-Mi Kim, et al.  Infection and rapid transmission of SARS-CoV-2 in ferrets.  Cell Press.  Journal pre-proof DOI: 0.1016/j.chom.2020.03.023
  14. Jianzhong Shi, Zhiyuan Wen, Gongxun Zhong1, et al.  Susceptibility of ferrets, cats, dogs, and different domestic animals to SARS-coronavirus-2.  bioRxiv preprint doi: https://doi.org/10.1101/2020.03.30.015347.
  15. COVID-19 update (88): Germany, animals, research, pig, chicken, bat, ferret.  ProMed.   Published Date: 2020-04-07 17:39:16.  Archive Number: 20200407.7196506
  16. http://www.afsca.be/wetenschappelijkcomite/adviezen/2020/_documents/Spoedraadgeving04-2020_SciCom2020-07_Covid-19gezelschapdieren_27-03-20.pdf
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  18. Qiang Zhang Q, Zhang H, HuangK, et al. SARS-CoV-2 neutralizing serum antibodies in cats: a serological investigation.  bioRxiv preprint doi: https://doi.org/10.1101/2020.04.01.021196.
  19. https://content.govdelivery.com/accounts/USDAAPHIS/bulletins/285036f
  20. Zou L, Ruan F, Huang M, et al. SARS-CoV-2 Viral load in upper respiratory specimens of infected patients. N Engl J Med. 2020;382(12):1177–1179. doi:10.1056/NEJMc20017
  21. Temmam S, Barbarino A, Maso D,  Absence of SARS-CoV-2 infection in cats and dogs in close contact with a cluster of COVID-19 patients in a veterinary campus.  https://doi.org/10.1101/2020.04.07.029090.
  22. http://www.syreaf.org/covid-19-and-animals/
  23. Mizumoto K, Kagaya K, Zarebski A, Chowell G. Estimating the asymptomatic proportion of coronavirus disease 2019 (COVID-19) cases on board the Diamond Princess cruise ship, Yokohama, Japan, 2020. Euro Surveill. 2020;25(10):2000180. doi:10.2807/1560-7917.ES.2020.25.10.2000180
  24. Kimball A HK, Arons M, et al. Asymptomatic and Presymptomatic SARS-CoV-2 Infections in Residents of a Long-Term Care Skilled Nursing Facility — King County, Washington, March 2020. MMWR Morbidity and mortality weekly report. 2020; ePub: 27 March 2020.
  25. Pan X, Chen D, Xia Y, et al. Asymptomatic cases in a family cluster with SARS-CoV-2 infection. The Lancet Infectious diseases. 2020.
  26. Presymptomatic transmission of SARS-CoV-2 – Singapore January 23 – March 16, 2020. MMWR 69 April 1, 2020 pre-release.
  27. https://www.idexx.com/en/about-idexx/news/no-covid-19-cases-pets?
  28. https://www.antechdiagnostics.com/news
  29. van Doremalen N, Bushmaker T, Morris DH, et al. Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1 [published online ahead of print, 2020 Mar 17]. N Engl J Med. 2020;10.1056/NEJMc2004973. doi:10.1056/NEJMc2004973
  30. https://www.avma.org/resources-tools/animal-health-and-welfare/covid-19
  31. Koh D. Occupational risks for COVID-19 infection. Occup Med (Lond). 2020;70(1):3–5. doi:10.1093/occmed/kqaa036.
  32. https://www.sciencedirect.com/science/article/pii/S0166354220302011?via%3Dihub

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