The COVID-19 pandemic has affected animals directly and indirectly. SARS-CoV-2, the virus that causes COVID-19, is zoonotic, which likely to have originated from animals such as bats and pangolins. Human impact on wildlife and animal habitats may be causing such spillover events to become much more likely. The largest incident to date was the culling of 14 to 17 million mink in Denmark after it was discovered that they were infected with a mutant strain of the virus.
While research is inconclusive, pet owners reported that their animals contributed to better mental health and lower loneliness during COVID-19 lockdowns. However, contact with humans infected with the virus could have adverse effects on pet animals.
Background
SARS-CoV-2 is believed to have zoonotic origins and has close genetic similarity to bat coronaviruses, suggesting it emerged from a bat-borne virus.
Cases
A small number of pet animals have been infected. There have been several cases of zoo animals testing positive for the virus, and some became sick. The virus has also been detected in wild animals.
Cats, dogs, ferrets, fruit bats, gorillas, pangolins, hamsters, mink, sea otters, pumas, snow leopards, tigers, lions, hyenas, hippos, tree shrews and whitetail deer can be infected with and have tested positive at least once for the virus. According to the US Centers for Disease Control and Prevention, the risk of transmission from animals to humans and vice versa is considerably low but further studies are yet to be conducted. Mice were initially unsusceptible but researchers showed that a type of mutation (called aromatic substitution in position 501 or position 498 but not both) in the SARS-CoV-2 virus spike protein can mouse-adapt the novel Coronavirus. Some animals which were only thought to have been susceptible at low levels were later found to have experienced higher levels of infection than previously realized, either due to viral mutations or improved surveillance technology. Dogs, for instance, showcased low levels of infection or transmission early in the pandemic, but were later found to have experienced potentially elevated levels of asymptomatic infections.
Animal deaths due to the disease are confirmed to have occurred on numerous occasions, with some species, such as mink, being particularly vulnerable and experiencing high mortality rates.
Asiatic lions
The Nehru Zoological Park reported that eight Asiatic lions have contracted the virus. The samples were taken on 24 March 2021, after the lions showed signs of respiratory distress.
Avian crossover
In the summer of 2022, two cases of SARS-CoV-2 infection were reported in swans within China. Raj Rajnarayanan, assistant dean of research at New York Institute of Technology, hypothesized that Omicron variants were better primed to infect poultry such as chicken and turkeys when compared to the Delta variant.
Deer
North American white-tailed deer have evidenced widespread SARS-CoV-2 infection over the course of the pandemic, together with smaller numbers of infections detected within North American mule deer and, outside of the Americas, within European fallow deer.
SARS-CoV-2 or its antibodies has been detected in white-tailed dear across at least 15 US states, and one Canadian province.
In August 2021, the U.S. National Veterinary Services Laboratory confirmed SARS-CoV-2 in wild white-tailed deer in the state of Ohio.
In January 2022, the Canadian Food Inspection Agency's National Centre for Foreign Animal Disease confirmed SARS-CoV-2 in wild white-tailed deer in the province of Ontario.
November 2021
In November 2021, a Pennsylvania State University pre-print report awaiting peer review was reported on by news sources. The researchers tested roadkill and hunter-killed deer in Iowa between April 2020 and January 2021. They said that they found that up to 80% were infected. CNN has reported that SARS-CoV-2 antibodies were detected in deer Illinois, Michigan, New York and Pennsylvania.
Canada's Environment and Climate Change Department announced that SARS-CoV-2 was detected in wild white-tailed deer in Quebec.
A study published on 23 November 2021 indicates that large proportions of the wild deer population in the U.S. have been infected with SARS-CoV-2. The test results showed one "mismatch" in 2019, low inhibition values in 2020 and 152 positive samples (40% having antibodies) in 2021.
It has been pointed out that such reverse zoonosis spillovers may cause reservoirs for mutating variants that could spill back to humans – a possible alternative source for variants of concern in addition to immunocompromised people.