As the SARS-CoV-2 Omicron variant rages across the globe, we realized we had not heard anything recently about the virus – that causes COVID-19 in humans – infecting companion cats and dogs. So, what is the latest? The good news is the story remains the same at this point in time.
According to the American Veterinary Medical Association (AVMA):
“Under natural conditions – meaning, when the virus is transmitted via close contact with a COVID-19-positive person – the primary domestic animals that have been diagnosed with SARS-CoV-2 are dogs and cats. It should be noted that these species are not easily infected under natural conditions, and there is no evidence that infected cats or dogs spread the virus to other animals or to people.”
Now, the Centers for Disease Control and Prevention (CDC) states:
“Based on the available information to date, the risk of animals spreading COVID-19 to people is considered to be low. At this time, there is no evidence that animals play a significant role in spreading SARS-CoV-2, the virus that causes COVID-19, to people. More studies are needed to understand if and how different animals could be affected by SARS-CoV-2.”
Now, these two statements may seem contradictory to you. So, let’s break this down:
#1. The AVMA refers to transmission from cats and dogs to humans or other animals. We do not have any evidence of this occurring in natural conditions (i.e. the home environment).
#2. The CDC speaks of ALL animals. The agency’s primary concern at this time is mink-to-human spread, which has been reported in other countries and it may have occurred in the United States. However, the agency still considers the risk of spread from animals to humans as low (actually very low).
So, why are minks in particular more susceptible?
Besides the fact that we have evidence of mink-to-human spread, we have to remember how this coronavirus works.
Many animals have ACE2 receptors on the surface of their cells. By the way, ACE2 is short for angiotensin-converting enzyme 2. ACE2 receptors in humans help to stabilize blood pressure. So, they do serve a valuable health purpose.
Putting aside the cell for the moment, we need to talk about the word “corona”, which is Latin for “crown”. Coronaviruses have spike proteins on their surfaces that reminded the research discovery teams of monarchical crowns.
Now, we need to put the two together. Think of the SARS-CoV-2 spike protein as a key and the ACE2 receptor as its lock. The SARS-CoV-2 spike protein locks on – or binds to – the ACE2 receptor very well in humans.
So, why does it bind to the ACE2 receptor in humans and not all animals with ACE2 receptors?
ACE2 receptors have different configurations in different species. Think of it this way, your house key won’t work on your car door.
ACE2 receptors in cats, minks, Syrian hamsters and ferrets are very similar to those in humans, but ACE2 receptors in dogs are structurally different. Thus, making cats, minks, ferrets and Syrian hamsters more susceptible to coronavirus infections.
Of course, the virus structure and function is more complicated than its receptor surface binding. Importantly, after a spike protein binds onto an ACE2 receptor and gains entry into a cell, it needs to replicate efficiently to survive.
Plus, remember that minks that are farmed are kept in close quarters, so transmission rates are higher.
Let’s discuss the latest with companion cats and dogs.
The Animal and Plant Health Inspection Services (APHIS) National Veterinary Services Laboratories (NVSL) are overseen by the United States Department of Agriculture (USDA). As of March 15, 2021, NVSL performs confirmatory SARS-CoV-2 testing on all animals except companion cats and dogs in states, territories or tribal nations that have previously had a confirmed case in cats and dogs. Before then, confirmatory testing was required for those companion cats and dogs.
According to the laboratory:
“While NVSL confirmation of previously confirmed companion animal species (household cats and dogs) from states that have already had a confirmed case will no longer be required, NVSL stands ready to support states and laboratories for confirmatory testing as needed. After conducting confirmatory testing and investigation of over 130 confirmed cases, we know the vast majority of household/companion animal cases are associated with confirmed COVID-19 positive human(s).”
This shift in testing protocol demonstrates that the risk of companion dog or cat transmitting the virus to humans and other animals is considered very low at this time.
But, cats and dogs can still “catch” the virus in the circumstances explained above.
True. However, the symptoms they have are usually mild or none. If they become positive, it probably came from you or someone else in your household. The best thing to do would be to test your household first (do not test your companion pets with the at-home COVID-19 tests), with a CDC or WHO SARS-CoV-2 approved test, and then contact your veterinarian and give the clinic a copy of the household’s results. Veterinarians have always been advised to rule out other possible and more common causes in domestic pets such as the feline upper respiratory viruses (calicivirus, rhinotracheitis/herpes virus), canine Kennel Cough, Bordetella and canine Influenza infections.
The AVMA has published a flyer on how to care for a companion pet that has a confirmed case of SARS-CoV-2.
The AVMA is more concerned about how you and your family will care for your companion pet, if you become ill.
The AVMA has a flyer about this too! It definitely reads like an emergency preparedness guide. So, whether a pandemic or a natural disaster, you need to ensure the care of your companion pets and make back-up plans if you are unable to care for them. Please see: COVID-19: Protect animals by planning their care.