As COVID-19 (SARS-CoV-2) continues to grip the world, we are increasingly finding out more about how the virus works. Animals are often brought up due to pet owners worried about their pets, farmers worried about their livestock, and people generally worried about transmission from an animal. Preliminary information about COVID-19’s transmissibility, its origins, and the more recent reports of mass cullings, or selective slaughter, of mink farms in The Netherlands and Denmark have raised the question, what exactly is COVID-19’s relationship with animals? 

As COVID-19 was first making its presence known in the Chinese city of Wuhan, the world was scrambling to find out where this coronavirus variant originated. Wuhan’s Huanan Seafood Wholesale Market was one of the first sources of multiple person infections. However, after animal samples were collected, Chinese officials determined this was not the origin of the disease but the location of a superspreader event((Team, The Novel Coronavirus Pneumonia Emergency Response Epidemiology. “The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China.” Chinese Journal of Epidemiology 41, no. 02 (February 17, 2020): 145–51. https://doi.org/10.3760/cma.j.issn.0254-6450.2020.02.003.)). Bats have been known to be reservoirs for many viruses including coronaviruses, the family of viruses including COVID-19((Berger, Kevin. “The Man Who Saw the Pandemic Coming.” Nautilus, March 12, 2020. http://nautil.us/issue/83/intelligence/the-man-who-saw-the-pandemic-coming.)). Two coronaviruses including the 2003 SARS (Severe Acute Respiratory Syndrome) outbreak and MERS (Middle East Respiratory Syndrome) which appeared in 2012 have originated from bats with the former moving from bats to civets, a type of small mammal native to southeast Asia, to humans and the latter moving from bats to camels to humans((Welle (www.dw.com), Deutsche. “Coronavirus: From Bats to Pangolins, How Do Viruses Reach Us? | DW | 26.03.2020.” DW.COM. Accessed January 28, 2021. https://www.dw.com/en/coronavirus-from-bats-to-pangolins-how-do-viruses-reach-us/a-52291570.)). The origin of SARS-CoV-2 is still unknown although the illegally traded pangolin, a small scaly anteater-like animal, has been suggested as a possible intermediary source((Welle (www.dw.com), Deutsche. “Coronavirus: From Bats to Pangolins, How Do Viruses Reach Us? | DW | 26.03.2020.” DW.COM. Accessed January 28, 2021. https://www.dw.com/en/coronavirus-from-bats-to-pangolins-how-do-viruses-reach-us/a-52291570.)).

It has now been over a year since COVID-19 was originally identified. At this point, over 100 million people have been infected with over 2 million lives lost worldwide((Johns Hopkins Coronavirus Resource Center. “COVID-19 Map.” Accessed January 28, 2021. https://coronavirus.jhu.edu/map.html.)). Multiple other species have also been found to be able to be infected with COVID-19. Most animal infections have been from exposure to infected  humans. Species that have been documented to have caught the virus via human transmission include dogs, cats, ferrets, minks, gorillas, lions, tigers, snow leopards, and pumas. Sample sizes and occurrences for all the animals aside from minks have been relatively small; most only develop observable symptoms seen in other coronaviruses such as mild respiratory disease and fatigue((American Veterinary Medical Association. “In-Depth SARS-CoV-2 Animal Infection Report.” Accessed February 10, 2021. https://www.avma.org/resources-tools/animal-health-and-welfare/covid-19/depth-summary-reports-naturally-acquired-sars-cov-2-infections-domestic-animals-and-farmed-or.)). This goes for household pets and exotic zoo animals alike. Minks on the other hand are the only documented animals to see harsher symptoms and death due to the high spread within the mink farms; farmers noted higher incidences of gastrointestinal and respiratory disease correlated with the higher overall mortality due to COVID-19((American Veterinary Medical Association. “In-Depth SARS-CoV-2 Animal Infection Report.” Accessed February 10, 2021. https://www.avma.org/resources-tools/animal-health-and-welfare/covid-19/depth-summary-reports-naturally-acquired-sars-cov-2-infections-domestic-animals-and-farmed-or.)). Recent experimental research suggests other species can be infected including mice, fruit bats, hamsters, treeshrews, and non-human primates like Rhesus macaques, cynomolgus macaques, grivets, and common marmosets. Researchers also concluded that rabbits, guinea pigs, pigs, chickens, turkeys, and ducks cannot infect or be infected by SARS-CoV-2((CDC. “COVID-19 and Your Health.” Centers for Disease Control and Prevention, February 11, 2020. https://www.cdc.gov/coronavirus/2019-ncov/daily-life-coping/pets.html.))¹.

Minks have become an animal of interest after making headlines in November 2020 when the Danish government announced that they were culling all 17 million minks in their mass rearing facilities((“Mass Culling of Minks to Protect the COVID-19 Vaccines: Is It Rational? | Elsevier Enhanced Reader.” Accessed January 29, 2021. https://doi.org/10.1016/j.nmni.2020.100816.)). Minks are a special and important case because they are also the first significant animal in a livestock setting to be infected. They are also the only animal that has exhibited evidence of horizontal transmission amongst its populations. Minks infected in Denmark and later The Netherlands and The United States initially received SARS-CoV-2 from humans working at the facilities where the virus then spread like wildfire amongst the minks. Due to the rapid spread of the virus amongst the minks, fears of rapid mutation of the virus began. These fears that a mutated virus might interfere with future vaccines of SARS-CoV-2  led to the mass extermination of mink farms numbering in the millions initially in Denmark and then later seen in other mink rearing countries like The Netherlands and The United States((“Mass Culling of Minks to Protect the COVID-19 Vaccines: Is It Rational? | Elsevier Enhanced Reader.” Accessed January 29, 2021. https://doi.org/10.1016/j.nmni.2020.100816.))². As we have seen recently from the COVID mutations from places like The United Kingdom, South Africa, and Brazil, risking another mutation especially one stemming from animals can lead to a very dangerous scenario. These newer variants are already proving to be detrimental towards vaccine effectiveness((CNN, Michael Nedelman. “Why the Coronavirus Variant in South Africa Has Put a Damper on Vaccines — and Why Many Are Still Hopeful.” CNN. Accessed February 10, 2021. https://www.cnn.com/2021/02/09/health/south-africa-variant-vaccine-research/index.html.)). I think that although it is sad to see, the culling of the infected mink farms is probably for the best.

With the sheer number of people testing positive for COVID-19, many people are unsure of what this could mean for in-house animals. Although it is rare, common animals like dogs and cats have been confirmed to be able to be infected with the SARS-CoV-2 virus when come into close contact with infected humans. Figure # shows a study done in the Lombardy region of Italy, an area that was heavily hit with SARS-CoV-2 in early 2020, that illustrates how unlikely it is for dogs and cats to contract COVID-19 even in households with people positive with the disease((Patterson, E.I., Elia, G., Grassi, A. et al. Evidence of exposure to SARS-CoV-2 in cats and dogs from households in Italy. Nat Commun 11, 6231 (2020). https://doi.org/10.1038/s41467-020-20097-0)).

Cats and dogs with COVID-19 have been documented to be both asymptomatic and symptomatic with those with symptoms showing only mild symptoms like those seen in a common cold; none have died((Mayo Clinic. “Can Dogs and Cats Get the COVID-19 Virus?” Accessed February 10, 2021. https://www.mayoclinic.org/diseases-conditions/coronavirus/expert-answers/can-pets-get-coronavirus/faq-20486391.)). According to the Mayo Clinic, even though the  probability of animals spreading COVID-19 to humans is low, people should still take necessary precautions like avoiding dog parks and public places, using leashes, and keeping cats indoors((Mayo Clinic. “Can Dogs and Cats Get the COVID-19 Virus?” Accessed February 10, 2021. https://www.mayoclinic.org/diseases-conditions/coronavirus/expert-answers/can-pets-get-coronavirus/faq-20486391.)). The Mayo Clinic also says that if you or someone you know is sick with COVID-19, you should isolate from your pets when possible, avoid petting, snuggling, sleeping, etc with your pets, and wearing a face mask and practicing proper hand washing when handling your animals and their food, waste, supplies, etc((Mayo Clinic. “Can Dogs and Cats Get the COVID-19 Virus?” Accessed February 10, 2021. https://www.mayoclinic.org/diseases-conditions/coronavirus/expert-answers/can-pets-get-coronavirus/faq-20486391.)).