Knowledge of the effects of SARS-CoV-2 on animals continues to emerge, albeit slowly. We already knew that the virus probably originated from bats, and may have passed on through an intermediary animal, perhaps the pangolin.
We now also now that SARS-CoV-2 can infect pet cats and dogs and cause illness, very probably from contracting the disease from humans. Domestic cats, ferrets, and Syrian hamsters appear to be more seriously affected by the virus than are dogs.
Large cats have also been affected. Lions and a tiger at a New York zoo developed respiratory signs and tested positive to novel coronavirus. They subsequently recovered from the illness. Again, the large cats probably were infected via a human being at the zoo.
Mink on farms in the Netherlands have been affected with respiratory and gastrointestinal signs. The disease appears to have led to mink deaths. Domestic cats on these farms were found to have antibodies to SARS-Cov-2 but did not get seriously ill or die.
SARS-CoV-2 is regarded as an “emerging disease”, meaning that cases of it causing infection and illness should be reported to the World Organisation for Animal Health (OIE).
So far, it looks like certain species do not get infected. Mice, pigs, chickens, and ducks seem not to get ill when experimentally infected.
It appears from what we know that, with respect to the virus and illness itself, animals are generally more at risk from human beings than vice versa. The CDC says that animals may potentially experience fever, coughing, dyspnoea, lethargy, sneezing, nasal/ocular discharge, vomiting and diarrhoea. It advises that we should take precautions with our pets as we would with human family members. This includes limiting pet dogs’ contact with people at dog parks and grooming establishments.
Various bodies also recommend that we take other steps to protect our own animals from COVID-19. For example, if a human family member has COVID, we are told to avoid close contact with our pets, such as snuggling up with them, sharing food with them, or having them sleep on the bed. Pet owners who might have COVID-19 have also been advised to wear a mask and wash their hands before interacting with the animals.
However, some of the biggest risks to animals from COVID-19 are likely to come not from the disease itself but from how humans respond to it. The World Organisation for Animal Health (OIE) notes that “SARS-CoV-2 may have implications for animal and human health, animal welfare, for wildlife conservation, and for biomedical research.” The OIE issued a warning to tread carefully in responding to COVID-19. Kneejerk responses might unnecessarily harm animals. It says:
“There is no justification in taking measures directed at companion animals which may compromise their welfare…It is important that COVID-19 does not lead to inappropriate measures being directed at domestic or wild animals which might compromise their welfare and health or have a negative impact on biodiversity.”
Fortunately, there is no evidence that animals on the whole are significant spreaders of SARS-CoV-2. Of course, this situation could change. But for now, the evidence is that the most animal species don’t pose a major risk. Hence, there is no good reason to enact policies that might harm them in order to protect humans. This includes wild species of animals. In the US, for example, the CDC cautions against taking harmful action against bats:
“Bats are an important part of natural ecosystems, and their populations are already declining in the United States. Bat populations could be further threatened by the disease itself or by harm inflicted on bats resulting from a misconception that bats are spreading COVID-19.”
Another impact on animals is from research into SARS-CoV-2. For example, because ferrets and cats can contract a disease from the virus they may serve as subjects for medical research into COVID-19. Primates like macaques can also be infected and may be used in research.
One of the largest impacts on animals, however, has been the response to the infection of mink on fur farms in the Netherlands. Tens of thousands of young mink were gassed to death with carbon monoxide in order to reduce the risk of SARS-CoV-2 spreading back into human beings.
In this case, unlike in others, there appears to be some evidence that mink can infect human beings with SARS-CoV-2. Still, the example shows how vulnerable animals are once there is any suggestion that they may pose a risk to people.
Moreover, animals, like the mink, are particularly vulnerable when they are used in commercial production. The twist to this story is that the Dutch have passed a law to ban mink farming by 2024 on animal ethics and welfare grounds. Meanwhile, mink will be at risk of being gassed in that country, and in other countries where mink is farmed.
What are your thoughts on this topic? Do you have something you’d like Simon to consider in the next issue? Email us and let us know.