Throughout the pandemic, countless decisions have had to be made, often with limited data. As more information becomes available, guidance and recommendation are updated. That sometimes upsets people, but it’s a good thing because it means we know more. If no recommendations had changed since early 2020, it would mean that we were really intuitive or lucky with our first recommendations (not likely), that we haven’t learned anything  in two years, or that we haven’t applied any of our new knowledge (the human factor, which is often the biggest barrier).

A common question I get is, “how long should an animal from a COVID-19-positive household be isolated when it is taken to an animal shelter?”  Answering that is a challenge, in part because we need to balance being proactive and practical. Longer isolation is better from a disease control standpoint, but it’s more expensive, more of a hassle, ties up often limited isolation space, and complicates care or adoption.

So, we try to find a sweet spot in the middle that minimizes risk as much as possible while not being completely disruptive, all based on pretty limited data.

  • We use data from experimental studies and natural infections in animals, information from human isolation guidelines, and then we essentially just pick what we hope is a reasonable number. Not completely scientific, but with scientific underpinning.  It’s the best we can do at this point with the information available.

Our initial guidance for isolation of exposed pets coming into animal shelters erred on the side of caution, and was therefore set at 14 days.

Over time, guidance for isolation of infected and exposed people has changed, and we ended up in a situation where isolation of pets was stricter/longer than in humans (despite humans likely being the most susceptible to SARS-CoV-2). There actually is some sense to that, because the implications of isolation played a big role in changing the guidance for humans, and recent changes have focused more on getting people back to work than high level confidence that they are no longer infectious. We can sometimes take a stricter approach with animals since there isn’t a societal need to spring a cat from isolation a few days earlier.

In many areas, it’s now recommended that people isolate for 5 days after onset of symptoms or a positive test (whichever is first). Those changes are a bit weak since we know a lot of people will still be infectious as of day 5, but the decision was driven a lot by economic concerns, and it’s clear the risk of transmission drops fairly soon after symptom onset. Part of this allowance also depended on strict adherence to some basic practices like masking (which obviously can’t be applied to animals in shelters) and testing (which we don’t routinely do in animals, and we don’t have validated rapid tests for animals either).

So, while 14 days of isolation for an exposed animal seems like overkill at this point, reducing it to 5 days is probably too far a leap in the other direction.  So shall we split the difference?

  • That’s pretty much it, to be honest. I’ve been recommending 7-10 days isolation for COVID-19-exposed pets coming into shelters. Ideally it’s 10 days, especially for cats since they are probably much higher risk than dogs.

That said, I get asked about different scenarios pretty much daily, and I say if there’s a compelling reason to shorten the isolation period, I’m fine dropping it to 7 days, particularly for dogs. It reduces confidence in protection a little bit, but sometimes those 3 days can have a significant impact on logistics or animal welfare, so it’s a cost-benefit decision based on many factors.

Understanding the epidemiology of the pandemic in a given area also is important in these decisions. If there’s rampant community transmission of SARS-CoV-2, and especially if there’s poor masking in the shelter and limited restriction of visitors, the added protection from a few more days of isolation is probably limited given the much greater human-to-human transmission risk.  If a shelter is still predominantly curbside or allowing only limited numbers of visitors by appointment, the relative risk from the animal is presumably higher (since there’s less human-to-human transmission risk), so being a bit stricter about the isolation period makes sense.

Take home message:

  • I think isolation of exposed pets in a shelter (or a clinic) for 7-10 days makes sense. The shorter window is more reasonable for dogs and in situations where there are significant isolation limitations or other needs to open up isolation space.
  • Five days of isolation for pets, as for humans, is a bit dodgy, since we don’t have the data to support it.  While we don’t have a good handle on the risks, a few extra days provides some added security.