As reports of animals testing positive for SARS-CoV-2 continue to trickle in (as expected), it’s clear that some domestic animal species are susceptible (at least to some degree) to this virus. A recent article in National Geographic about “Buddy,” the first dog in the US to test positive for SARS-CoV-2 back in May, has flooded my inbox with emails about the story and the broader question about whether we need more testing of pets. Here’s my take:
- Yes. We know little about human-to-pet transmission , pet-to-pet transmission and the clinical implications for animals or people. More testing – along with good data collection about clinical signs, contacts, timelines etc. – could provide important information.
- Not really. At this point we know pets can be infected, and there are some risks (e.g. to clinic staff) when it comes to testing of potentially actively infected animals. Whether 10, 20 or 200 pets have been diagnosed, it doesn’t tell us more unless we know the context, i.e. we have accurate information about the cases, including other clinical data to help figure out whether the test result means the animal was actually infected with +/- sick from SARS-CoV-2, and we have accurate information about the animals that test negative as well.
From a clinical standpoint, I think of three questions when it comes to testing pets:
- Is there a realistic chance that the pet was exposed to the virus?
- Does the pet have clinical signs that could realistically be due to infection with SARS-CoV-2?
- What would I do with the result? More specifically, would I do anything differently if the result is positive vs negative?
- The answer to the third question is almost always “no.” The hassles and risks involved with taking a pet to a clinic for testing only make sense if we are going to learn something useful from the the result. That’s rarely going to be the case now.
We do need more research testing to answer questions about prevalence, clinical implications and transmission, as we can’t answer those by piecing together clinical testing results from haphazardly tested pets. Getting a data dump from a lab that says “this many” cats tested positive tells us a lot less than a research study that looks at positives and negatives, and can put the story together about things like how often human-to-pet transmission seems to occur, how often infected pets get sick, what risk factors increase the odds of transmission or illness, how long infected pets shed the virus and, ideally, help us determine the risk of subsequent transmission from an infected pet to other animals or people.