I get a lot of emails about vet clinic access from a wide spectrum of individuals. This includes:

  • Owners who are upset they aren’t allowed in the clinic with their pet
  • Owners who are worried that their vet clinic isn’t doing enough to prevent transmission of COVID-19
  • Vets who want to know how to increase owner access to clinics safely
  • Vets who want to keep people out of the clinic as much as possible for safety
  • (And still some that just yell at me regardless what I say)

There’s no “one-size-fits-all” approach to veterinary medicine in the COVID-19 era. I‘ve written about different approaches before but since I get so many questions, here are some more thoughts.

Why can’t someone just say “here’s what all vet clinics should do”?

There’s too much variation between clinics. This includes things like the degree of COVID-19 activity in the region, local rules, staff and management risk tolerance, clinic size, waiting room and overall clinic layout, exam room numbers and size, and ventilation, among others.

What are the basic concepts of COVID-19 prevention in a clinic?

  1. Restrict access as much as possible
  2. Choreograph movements in the clinic
  3. Restrict close contact situations, especially in small rooms
  4. Use appropriate PPE

1. Restrict access

I’ve said to keep owners out “as much as possible” in the past. This has led to issues since “as much as possible” is very subjective, but I can’t really say more. There’s a cost-benefit consideration. Every time someone new comes into a clinic, there’s some risk. The more that happens, the more the risk. The better our other control measures are, the lower the risk (i.e. we can get away with more people in the clinic by doing everything else right).

We can limit access but still allow some people into clinics, with some preventive measures. There may be logistical reasons to let people in (e.g. owner walks to the clinic and would have to wait outside in -20C weather) or patient care reasons (e.g. something needs to be shown to the owner that can’t be done well remotely, euthanasia, patient for which curbside transfer might be risky) that are worth the limited increase in risk. There are many other situations where it’s not worth the risk. We can still do a lot with telemedicine, curbside drop offs and hybrid appointments (e.g. telemedicine appointment followed by a drop off for a quick in-clinic procedure like vaccination or blood sampling) where the owner doesn’t need to be present.

2. Choreograph movements

I was in a clinic the other day looking at traffic flow, and it’s a good exercise to try. It’s not usually too hard to come up with a logical flow system that creates one way traffic and avoids mixing of people… if numbers are limited. Minimizing the number of people who come into the clinic helps us optimize other preventive measures in the clinic. In combination with some floor markings, furniture re-arranging, designated direction of movement and designated entry/exit points, we can significantly limit contacts and decrease the risk of virus transmission.

3. Restrict close contact situations

Close contact. Closed spaces with poor ventilation. Droplet generating procedures like talking. Those are the high-risk situations for COVID-19 transmission, and they also happen to describe a vet clinic exam room. Time plays a big role in the amount of risk. Fifteen minutes isn’t a magical number, but it’s the one typically used to indicate the time that risk goes up. The smaller the space and the worse the ventilation, the higher the risk and the less time you should spend in it.

All those factors together show how the normal exam room visit needs to be rethought. To me, exam rooms are now “owner waiting spaces.” If the owner needs to accompany the animal into the clinic, they check in and are admitted directly to an exam room (again, the number of people in the clinic needs to be limited to some degree for this to work). Vet personnel come in and retrieve the animal, keeping chatting to a minimum, distance to a maximum, and everyone’s masked. A little conversation is fine and is good for patient care and the vet/owner relationship, but it should be distanced and short. The pet is then taken to a treatment area for examination and whatever needs to be done. Vet personnel can pop into the exam room or connect electronically to ask more questions or talk about things. The owner and pet are re-united in the exam room, and a short conversation can be had to explain or demonstrate things. If a demo is needed that requires restraint of the animal, someone from the clinic joins in so the owner does not have to help out, and can maintain distance from staff. (That’s still a potential issue because of the reflexive nature of owners jumping in to help hold, but that just needs some communication to head it off.)

4. Use appropriate PPE

As much as they are annoying, masks are critical. Masks need to be worn for any close contact situation, by owners and clinic personnel alike.

 

Lots of questions remain, I know. I’ll touch on a couple of them here but I’m sure there will be more to follow.

What do we do with the exam room after the owner leaves?

The room is ideally minimally stocked with easy to disinfect surfaces. Routine disinfection, focusing on owner contact surfaces (vs our previous focus on things like the examination table) is straightforward. A sign on the door indicating the room has been disinfected is useful and is good for clients to see.

What about the airspace in the exam room? Can the next person go right in?

That’s a tough one. We focus on droplet transmission and direct contact when it comes to SARS-CoV-2, but there is likely some risk from accumulated aerosols in closed spaces with poor ventilation (like an exam room). It’s probably limited in time and degree of risk, but we just don’t know. Most aerosols settle quickly out of the air so they’ll be taken care of with surface disinfection. However, should we leave 1 minute, 2 minutes, 5 minutes, or more between owners? Who knows. There are no recommendations for this kind of precaution in similar human healthcare situations, and I haven’t seen any real evidence of risk. A few minutes between occupancies, with disinfection performed after this brief waiting period, is probably reasonable, based on what we know (especially with good mask compliance, as masks reduce aerosol release).

How important is ventilation in the exam room?

More is better. Looking at how much airflow can be achieved in the clinic is useful, as better ventilation disperses and dilutes any aerosols that may be present. Ventilation rates of less than 3 L/s per person have been suggested as being high risk, and 8-10 L/s per person as being low risk. If you don’t know what your ventilation rate is and can’t figure it out, go with the “more is better'” approach.

Just some quick thoughts that I’m sure I’ll add to soon (and get more questions about).

A colleague asked me about scent detection dogs the other day. My response was that I hadn’t heard much after all the initial buzz, which might suggest things weren’t going well. However, as opposed to the horrible pre-print about COVID-19-sniffing dogs I wrote about previously, a paper in BMC Infectious Diseases (Jendry et al. 2020) provides some more robust and interesting information. It’s a pilot study, so it’s small, preliminary and underpowered, but it shows potential. Whether that’s “potential for dogs to be able to detect SARS-CoV-2 under certain circumstances” or “potential for dogs to be an effective detection tool” isn’t clear, but that’s the big question.

Here’s a breakdown of the study and some commentary:

The researchers collected saliva samples and respiratory secretions from hospitalized COVID-19 patients, and healthy people who were PCR-negative for the SARS-CoV-2 virus.

  • This may not be ideal, depending on the goal. My vision is using these dogs in the community to rapidly detect infectious people in high risk situations (e.g entrance to transit stations, public buildings, schools). In that case, people who are hospitalized with severe COVID-19 are likely not the best test population. A dog isn’t going to replace a PCR machine in the hospital.  It’s simply not practical in most cases to collect a sample from a patient, take it to a dog as a quick screening test, and then submit the sample for definitive testing.  We want dogs that can detect a mild case in the community, long before the patient needs to be hospitalized.
  • They didn’t test samples for other human coronaviruses, like those that cause the common cold. It’s a potential limitation, but I don’t think it’s a big deal in this case.
  • They also don’t explain where they got their negative samples. A clear description of the study populations is critical and it’s somewhat lacking here.  We want to be sure the dogs were detecting SARS-CoV-2 and not something else unique to the positive sample population, like a smell associated with being from a hospital.

Because of the potential susceptibility of dogs to the SARS-CoV-2 virus, samples were inactivated prior to exposing them to the dog.

  • That’s a reasonable step, but raises more issues of practicality and how the dogs could ultimately be used (e.g. can the dogs only be used to screen specimens collected from high risk patients, or can they be used to detect infection in someone walking by).

Eight dogs were trained using standard methods. They had a 2-week habituation process for the training system, then had 5 days of training until their rate of detection was greater than what would be expected by chance alone. They then started the study

  • The sample size was small, but reasonable for a proof-of-principle study.

The ability of dogs to detect positive samples increased over time. There was some variation between dogs, but all of them were pretty good. The overall sensitivity (percentage of positive samples that the dogs correctly identified as positive) was 83%, ranging from 70-95%. The specificity (percentage of negative samples that the dogs correctly identified as negative) was 96%, ranging from 92-99%.

  • For a screening test, we’d actually want the reverse, that is to say higher sensitivity at the expense of specificity. That would mean the dogs would catch most of the positives. Lower specificity is okay initially if the screening test (i.e. the dog sniffing) can be followed up with a more specific test, and if the implications of an initial false positive aren’t high. If a dog calling a person positive results in that person being sent home to self-isolate for 14 days, then a high false positive rate is a problem. If it just results in the person being pulled aside to have a swab collected for a lab test, that’s not as big of a deal (perhaps a bit of a hassle but maybe not a deal breaker).
  • A low sensitivity and high specificity means you run into fewer hassles with false positives, but the test will miss more positive people. The fact that 17% of prime samples from people hospitalized with active COVID-19 were called negative is a concern in terms of the dogs being able to detect the virus in less severely affected people and from less voluminous and close samples (e.g. detection directly in someone walking by).

I’d file this in the “interesting but preliminary” folder. Anything that can help identify infectious people is useful. If dogs can do it, that’s great, but they also have to be able to do it from a distance, because a handler and a dog getting very close to large numbers of people might cause more problems than they fix.

In my perfect world:

  • A SARS-CoV-2-sniffing dog would be parked at the entrance of schools, office buildings, transit stations, etc.
  • The dog would be able to detect infected people from a short distance away (i.e. without direct contact).
  • The dog would signal its handler when it detected a positive person.
  • That person would then (discretely) be pulled aside for testing, which would (in my perfect world) be done quickly, right there (there is lots of work being done to develop a more rapid test like this that can be done on the spot, but we don’t have one yet).
  • If positive, the person would be told right away and sent home to self-isolate. If negative, the person would be good to go (though maybe wondering why they smell like a coronavirus).

As I’ve said, it’s an interesting and useful preliminary study that shows potential. The key is to follow up preliminary studies with more detailed, rigorous work, which unfortunately often doesn’t get done. Nonetheless, I suspect media headline writers will jump on this and over-interpret the results. It’s also another example of the remarkable things a dog’s nose can do, but the potential practical applications (if any) are still very much up in the air.  I’ll be a bit surprised if this ever becomes a common/useful tool, but I’d love to be wrong about that.

I’ve been slow posting in the past few days, so here are a few quick recaps from the animal/COVID-19 world.

Higher quality debunking of crappy dog-SARS-CoV-2 paper

Back in April, a paper (Xia 2020) was released that suggested dogs could be the source of SARS-CoV-2.  Most of us considered it crap at the time (read more about it in our previous post), and most people moved on pretty quickly, but it still left some fear and poor messaging in its wake. Now, a proper dismissal of this paper (in the same journal) has been published.  I won’t get into the details, but it basically says “Everything that was written in that paper… yeah, not so much.”

More formally, here’s what they concluded: “In summary, the proposition of Xia (2020) that dogs are a likely pre-human host for SARS-CoV-2 is not justified by available evidence. Xia (2020) did not demonstrate that the low CpG frequency in the SARS- CoV-2 genome was driven by a unique selective environment in dog digestive tracts. The SARS-CoV-2 is also less virulent than other human betacoronaviruses (SARS-CoV-1 and MERS-CoV), contradicting his assertion that CpG-deficient viruses are more virulent. Furthermore, closely related betacoronaviruses from bats and pangolins have CpG-deficiencies similar to SARS-CoV-2. Dogs are not more plausible than most other potential host species, and based on current data, far less plausible than bats or pangolins. Still, we are missing ~20-70 years of the recent evolutionary history of the lineage leading to SARS-CoV-2, and we must broadly survey a wide range of wild and domestic species to uncover the origin of SARS-like coronaviruses.

More SARS-CoV-2 in mink

Mink are really susceptible to this virus, and human-to-mink transmission seems to occur quite easy.  In the Netherlands, SARS-CoV-2 has infected mink on at least 24 farms, with widespread disease in mink and even some plausible mink-to-human transmission. There was a plan to end the mink industry in the Netherlands by 2024, and this crisis appears to be speeding things up as mink on affected farms are culled.

In Denmark, multiple farms have also been affected. They’re taking a different approach there, now choosing not to cull affected mink farms, but putting strict measures in place to control any outbreaks and monitoring closely for more.

In Canada, so far, so good. Since infection with SARS-CoV-2 in mink was first reported, there’s been an emphasis on biosecurity measures to avoid infecting mink, and relatively low disease rates in people in Canada (at the moment) mean the risk is currently fairly low. However, it’s still a concern. An additional worry is mink farms becoming a source the virus that could spread to wildlife. Feral cats have been infected on at least one affected mink farm in the Netherlands. Spread to wild mink (which are present throughout Canada and the US) is an even bigger concern given how susceptible this species is. We don’t want to create a wildlife reservoir of SARS-CoV-2, either through spread from farms to wild animals or from escape of farmed mink.

Human-to-pets transmission is still a thing

Reports of cases of human-to-pet transmission of SARS-CoV-2 continue to trickle in, and probably represent a small fraction of cases that actually occur. I’m sticking to my promise not to report each new case if there’s not really anything new about it. Infections in pets are still uncommonly reported, but a lot of cases are likely not detected because there’s limited testing. The animal and public health risks of these cases are probably very limited regardless, especially in places where there’s rampant human-to-human transmission. But, we’d still like to contain exposed animals to prevent them from playing any relevant role.

Still no signs of infection in livestock

So far, so good on the livestock front. Fortunately, major livestock species do not seem to be overly (or at all) susceptible to SARS-CoV-2. We still need to pay attention to this though, and I think the message “If you might be infected, stay away from animals” remains important, regardless of the species. However, the risk of significant issues from livestock seems pretty limited right now.

Still looking for the animal origin of SARS-CoV-2

This is still a huge question. It seems a little late, but the World Health Organization has sent a team to China to further investigate the animal origin of the virus. Kind of.  They’ve sent two people there to discuss a larger investigation.  It might be a challenge to find the animal source but we still have to try. We need to know if this virus is still lurking somewhere in the wild, and where. We also need to understand how and why this outbreak happened, to help prevent it from happening again (with this virus or one of many other potentially nasty bugs that are no doubt also lurking in the wild).

Things have been relatively quiet on the animal/COVID front for the past week or so (and that’s good).  We’ll likely continue to see sporadic cases in pets that get infected from their owners. Hopefully, all of those cases will stop with the pet and there will be no further transmission to other people or animals (including wildlife and community cats, which would perhaps be the most conerning).

I suspect the next big wave of information regarding SARS-CoV-2 in companion animals will be when serological (antibody) testing starts to give us an idea of how often human-to-pet transmission has occurred over the course of the pandemic. Most of the limited testing to date has focused on testing samples from animals for the virus itself, which lets us know if the subject is actively infected.  Unfortunately, that type of testing is hampered by the fact that we have to identify actively infected households and then find a way to collect samples during the fairly short window when the pet might be infected, so we’re going to underestimate transmission that way. Combining those kinds of studies with antibody testing is important, as serology can be done more easily after-the-fact because the antibodies remain in the bloodstream much longer than the virus itself hangs around in an individual.

More about mink and SARS-CoV-2

This virus seems to really like mink. In addition to outbreaks of SARS-CoV-2 on multiple Dutch mink farms, SARS-CoV-2 has now been identified on a mink farm in Denmark as well. These outbreaks all appear to start off with mink getting infected by people, but the mink can then spread it amongst themselves and in rare instances even spread the virus back to people. The fact that stray cats on mink farms have been infected as well is concerning, and is yet another reason we want to prevent that initial human-to-animal transmission. We want to keep this a strictly human issue, so that it’s easier to control.

Webinar

It seems like I’ve spent a lot of my time over the last few months doing webinars, which I guess is not surprising since I’ve actually done a large number them. I did one earlier with week for MightyVet alongside Dr. Mike Lappin (a great veterinary infectious  disease veterinarian from Colorado) and Dr. Chris Woods (an MD from Duke who’s a leader in the “human” side of one health).  It’s had 130,000 views so far so hopefully that means it’s useful.  Click the following link to access the webinar on the MightyVet Facebook page: “Ask an Expert: Confronting COVID-19 myths“.

Here’s a bit of an odd-and-ends post covering some common questions I’ve been getting about COVID-19 and infection control in veterinary clinics. As always, answers are based on little or no evidence, but on principles of infection control, and they may change as we learn more and as this pandemic continues to evolve.

Would it be safe to let one client per pet into our building, if they have to wear a mask and use hand sanitizer on entry?  And only letting a client in that has to see a veterinarian.  Not to buy merchandise.

“Safe” is subjective and a moving target. Realistically, we’re looking at gradations of risk. There’s always some, and the closer and more prolonged the contact, the greater the risk. Having a client in the clinic is riskier than having them outside, undoubtedly. If they come into the clinic, the measures described (especially mask use) can help minimize that risk. There’s no way to say how much risk is present because we still have limited data, and where you are would be a major factor, based on the local epidemiology of the virus (which also changes). In some places, community disease activity is very low, so the odds of any single person who comes into your clinic being infected are exceptionally low. That’s not true everywhere, though.

Ultimately, our goal is to keep people out of clinics as the default. If there’s a solid reason for them to come in, then the risk goes up, but that can be mitigated through minimizing the closeness and duration of contact, wearing masks and good hygiene. It comes down to the cost-benefit… how important it is for the client to be in the building vs the risk you (and all the staff) are willing to take (and the ability to make sure preventive measures get done).

That’s a bit of a non-answer but there isn’t really a yes/no response to a question like that, unfortunately.

Some people recommend to use a coffee filter or towel sheet with reusable masks. What do you think about that and if it’s a good idea, is it okay to use in surgery and how many hours does it last?

For surgery, I’d rather use a proper surgical mask, if you have access to them. Their performance is more predictable, and surgery is a higher risk environment. If you’re low on surgical masks, then a cloth mask is a tolerable backup (although I’d be a bit wary of using a cloth mask for a surgical procedure involving an implant). I haven’t seen anything that indicates those extra filters in masks do much. I assume they don’t make anything worse (unless they make it harder to breathe or are so resistant to airflow that they direct more unfiltered air out the sides of the mask), but I don’t recommend them over regular cloth masks.

What should we do about dental procedures on small animals? (I’ve had dozens of variations of this question.)

Cat dentals are the big question, and a lot of the uncertainly relates to a lack of understanding of the prevalence of SARS-CoV-2 in cats, particularly cats from households that are not flagged as high-risk based on querying the owner’s health status. Risk also varies geographically, since the risk from cats directly parallels the risk of people being infected in the same region. In many areas, the odds of a cat from a purportedly healthy household being infected are probably exceptionally low. However, we don’t have enough data to say much more, and as disease activity varies, the risk will vary. We’re trying to answer some of those questions with PCR-based surveillance as well as an upcoming seroprevalence study. In the interim, there’s a realistic “life has to go on” component, since we will be dealing with this virus for a long time.

For now, a key step is screening the owners for current or recent respiratory disease. It’s not a guarantee, but restricting these procedures to pets from healthy owners should help drop the risk a lot. Beyond that, it’s mainly PPE. Aerosol generation is an inherent issue with dentistry, but exposure can still be minimized with appropriate PPE, cleaning and disinfection and other basic infection control practices. I think we can look to human dentistry here, since they are dealing with even greater risks.  Below is a table from an Ontario guidelines document. In this table, “positive” and “negative” refer to syndromic screening, the same as we would do for owners of animals coming to a veterinary clinic. They recommend N95 respirators for aerosol generating procedures (AGPs), regardless of screening status, presumably based on the risk of asymptomatic shedding in the general population. However, they give the option of surgical masks for lower risk patients and procedures. Our risk as veterinarians is presumably lower than theirs, so the decision of whether to wear an N95 plus eye protection vs a surgical mask plus eye protection may come down to mask availability, understanding of COVID-19 activity in the area, and risk aversion. The key is to wear A mask of some kind, and to wear eye protection as well (the latter in particular is not consistently done in veterinary medicine).

If N95 masks are used, they would only be required for those in close proximity to the AGP.  It’s debatable whether technicians and anethesiologists would need this level of protection (vs a surgical mask), especially when surgical masks are considered tolerable for AGPs in low-risk human patients. People coming in and out of the dental suite (which should be minimized in any case), or who are farther from the patient’s mouth would be much lower risk for exposure.

Cleaning and disinfection of areas potentially contaminated by aerosols is also important.  People generally do a good job on disinfecting tables and countertops, but don’t think about the other areas or surfaces that get contaminated by aerosols, like the anesthetic machine for example. That also highlights the need for a good OR/dental suite environment with limited open storage. We don’t want aerosols contaminating things that people will use for subsequent procedures (e.g. gauze sponges, suture packs), so if an AGP is being performed, it’s best to make sure that the area is as barren as possible.

With some basic practices like that, the risk of SARS-CoV-2 transmission related to doing a cat dental is probably much greater from the transfer of the animal to/from the owner, than from the cat during the procedure itself. That’s why we need to focus on physical distancing from owners as much as possible.

I’ve had countless questions about the potential for scent detection dogs to be useful for COVID-19 surveillance. It’s an interesting idea, but it’s dependent on COVID-19-infected people producing some volatile compound detectable by the dogs than uninfected people do not.  (The virus itself is not likely to have a detectable odour.)

A recent pre-print paper on bioRxiv provides a rambling description of a pilot study about the potential for dogs to sniff out COVID-19 in people based on their armpit sweat.  This one can probably be filed under the “not likely to ever be published in a journal, but an interesting story” category.  (It may also be another paper in the “let’s get something online first, who cares about the depth and editing” category. Sixty-one authors is a bit extreme too, but I digress.) As I’ve said before, pre-prints can be useful, but there has to be at least a modicum of effort…

Anyway, they collected armpit sweat samples from people with COVID-19 and patients without signs of COVID.

They used 18 dogs that had been trained for explosive detection, search and rescue and colon cancer detection, but their table also lists an arson detection dog.  Further, they say that “We did not decide to work with drug detection dogs as there is always a possibility that COVID-19 positive or negative people use prohibited substances that would let catabolites be excreted by the axillary sweat.” And yet, their table lists a drug detection dog.

After training, the dogs were tested to see if they could differentiate sweat samples from COVID-19 patients in scent boxes, from the samples from the non-infected patients.

  • Three of the 18 dogs flunked out of COVID-19 detection school as they were “unable to adapt to an olfactive search on a line of sample”.
  • Eight others were removed because they were “late in their testing period due to this necessary basic “retraining”. I’m not really sure what that means. I guess they weren’t completely kicked out of school but had to repeat the year, and no one wanted to wait to rush out the pre-print.

The authors say that left 8 dogs whose results they used for the analysis; however, my math says that 18-3-8=7, not 8.

Numbers aside, results were interesting, as the remaining dogs seemed to have fairly high detection rates (84-100%).

It’s hard to say what this means and whether it’s relevant. I guess it means that there’s potential for some dogs, but you have to find the right dogs, and train them.  The authors make a fair point that they were looking at effective dogs, not whether it worked in the whole dog population.

Is this of any use?

It’s hard to say. They tested samples from people with overt COVID-19 disease, and that’s likely not very relevant. If someone has signs of COVID-19, we want to treat them like they have COVID-19 at least until they are definitely tested, regardless of what the dog thinks. Where this would be more useful is for detecting asymptomatically infected people, in which case the dog might provide an early warning of infection. The downside is that it requires a dog and a person to be in close proximity to the patient being screened. Dogs are low (but not no) risk for picking up SARS-CoV-2, but there’s also reasonable concern about handlers. The practical nature of this is also questionable. The study mentions that armpit sweat is “easy and safe to collect”, but if the “test” relies on people taking samples of their own armpit sweat, it’s no longer a quick, easy detection method. It’s more appealing if the dog can, for example, be used to screen people coming into a building or workplace.

The authors have a few excuses for some of the false negative results, which seem to be a bit of a stretch, or indicate potential issues applying this to a real world situation (e.g. distraction by a “too zealous television team”). Some other discussion points are a bit hard to follow. They attributed false positives to two male dogs and a young woman that “had been sampled during her fertile period”… they’d better sort that problem out since that’s a reasonably common subset of the population.  The paper’s discussion devolves considerably from there: “In Shakespeare’s day, a woman in her fertile period used to hold a peeled apple under her arm until the fruit became saturated with her armpit scent ; then she presented this “love apple” to her lover to inhale in order to provoke his sexual excitation. Pheromones are defined as substances produced by on animal which conveys information to other individuals by olfactory means. And in such a situation androsterone and molecules like benzoate derivates, excreted in axillary sweat, enhance sexual attraction by men toward women near the end of follicular phase of the menstrual cycle when fertility is at highest.”

Overall, it’s an interesting pilot study that shows more study might be warranted. In particular, it’s important to figure out whether dogs can be good detectors of COVID-19 infected people in situations like busy, high risk places in the community.  Criticisms aside, it would be really cool to have a dog hanging out at the entrance of busy places, picking out infected people, to help curb further spread of SARS-CoV-2 in the community.

I said I’d probably stop reporting on individual animal cases if they’re just repeating what we already know. So, I hesitated on this most recent feline case, but there’s an interesting timing component that’s worth discussing.

SARS-CoV-2 was identified in a cat with respiratory disease in Minnesota. The owners were infected first, the cat then got sick and the cat recovered after a few days of illness.

  • That’s not surprising. This seems to be the standard pattern in terms of timing and severity in cats that have tested positive, and we’re probably markedly underdiagnosing infected cats.
  • The cat is being isolated at home for 14 days.

The noteworthy component of this case is the timing. The onset of the cat’s illness was after its owner had recovered. Our messaging has been to keep animals away from others for 14 days after their last chance of exposure. That would be 14 days after the date the owner was believed to have eliminated the infection. This approach means restrictions on animals would go past restrictions on their owners, and a case like this shows why that may be prudent. If the household was considered COVID-free after the person’s illness resolved, SARS-CoV-2 infection (and infectivity) in the cat might not have been considered.

A few quick updates on some recent SARS-CoV-2-related stories.

North Carolina dog: Positive result not confirmed

This case, a pug in North Carolina that had an oral swab that supposedly tested positive for SARS-CoV-2 as part of a Duke University household surveillance study, was reported a few weeks ago.  It was strange that there was no confirmation of the test result since then. Now we know why.  It appears the original test result was actually “inconclusive” (i.e. not strong enough to be truly considered positive). Follow up PCR testing was negative. That in itself doesn’t mean the dog wasn’t infected, since it could have been a short term infection that wasn’t sampled during peak shedding. However, no antibodies were detected in the dog. That indicates the immune system didn’t recognize the presence of the virus. It’s not completely definitive, but supports this not being a true infection.  Perhaps transient contamination of the dog’s mouth with virus from its infected owners could have caused the original inconclusive test result.

Hydroxychloroquine/chloroquine study debate

This topic is a bit outside the animal health-related area, but is still interesting (and relates to some of my recent Twitter ranting about the state of scientific publication). The high profile Lancet paper that reported increased deaths associated with hydoxychloroquine use in COVID-19 patients, and led to WHO suspending that arm of its study, has been challenged because of numerous concerns about data and data availability. It doesn’t mean the results are necessarily wrong, but questions about the data mean that things need to be clarified, which the authors have apparently been reluctant to do so far. An open  letter to the journal outlines various problems with the report and has a large and reputable list of signatories.

Tiger SARS-CoV-2 whole genome sequencing

There’s not really anything notable here in the big picture, but anyone with an inclination towards whole genome sequencing data might be interested in the sequence results from the virus isolated from one of the Bronx Zoo tigers.

SARS-CoV-2 in a cat in Russia

Just one more report of a cat with SARS-CoV-2 infection, presumably from its infected owner. Not surprising.

As described by ProMedMail, the Dutch Agriculture Minister has provided another update on the outbreaks of SARS-CoV-2 that have affected at least 5 mink farms in the Netherlands to date (click here for the original Dutch version of the letter).

Another suspected mink-to-human transmission of SARS-CoV-2 has been identified (with potentially infections in  an additional two mink farm staff). These cases appear to be from a different farm than the first suspected mink-to-human infection. The route of transmission is presumed to be mink-to-human based on the gene sequences (and the illness in the mink preceding infection in the people). The sequence data I saw earlier seem consistent with that, but it’s hard to be 100% certain.

There’s also some more information about barn cats. On mink farms, cats would rarely have direct contact with mink (because mink would try to eat any part of a cat that was within reach), but the cats would have access to mink manure, which typically falls from wire cage flooring to the ground below. They have now identified antibodies against SARS-CoV-2 from 7/24 cats on one farm, indicating the cats were previously infection. The virus itself was also found in the samples from one cat, indicating it likely still had an active infection. Whether all 7 cats got infected from the mink (or mink manure), or whether there was subsequent cat-to-cat transmission will be pretty much impossible to figure out at this point.

While a lot still needs to be determined with these outbreaks, information to date highlights some important themes:

  • SARS-CoV-2 is predominantly a human virus but it can spill into other animals.
  • While most transmission is human-to-human, some infected animals can send the virus back to people, and infect other animals. (That shouldn’t come as a surprise, although sadly the One Health response to this virus has been pretty disappointing.)
  • Keeping infected people away from animals, as well as away from other people, is important. It’s better to prevent human-to-animal infection than to have to figure out how to deal with infected animals and worry about spread into wildlife.
  • Reducing the number and closeness of interactions, be they human-to-human, human-to-animal or animal-to-animal (within reason) and using practical precautions when distancing can’t be maintained (e.g. masks, gloves and other protective equipment when handling animals in high risk situations) are the key control measures for this virus.

The fact that there are multiple affected farms in the Netherlands but no reports elsewhere needs to be considered. It’s unlikely Dutch mink farmers are more likely to be infected or have closer contact with their mink. There’s reluctance in some countries to consider or test for infection with SARS-CoV-2 in animals, so whether this is a uniquely Dutch situation or a more common problem that’s not been diagnosed or reported elsewhere remains a question. Hopefully mink farmers everywhere are paying attention to this situation and implementing some control measures. It’s tough to use really good infection control practices in some of these facilities, considering how mink farms are managed and how many animals may need to be handled on a given day (e.g. when thousands of mink are being vaccinated), but measures to reduce human-mink contact whenever possible, use appropriate PPE, identify problems early and keep wildlife (and cats) away from mink barns are important.