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.

Since we’re entering kitten season, there will be lots of animals in shelters needing homes. I’ve done a couple of virtual talks for shelter groups this week, with a focus on implementing physical distancing and other preventive measures, while maintaining as much of a semblance of normal shelter operations as possible.

I’ve also had quite a few questions from people asking about any risks that might be associated with adopting an animal from a shelter at this time. In all those discussions, I’ve emphasized the need for some basic practices, similar to what you see in grocery stores right now. If a shelter uses good preventative practices, I’d have no hesitation adopting a new pet.

It’s always useful to put a personal spin on discussions like that, and that’s easier since we adopted a new kitten today ourselves.

Was I worried about COVID-19?  No.

  • The shelter confirmed the health status of the fostering family before bringing the cat back to the shelter, and transfer of the critter was contactless.
  • The odds of the kitten being infected or his haircoat being contaminated with SARS-CoV-2 aren’t zero, but they’re exceptionally low. The drive to and from the shelter was likely the greater health risk.

There will always be infectious disease risks when adopting new animals, even without SARS-CoV-2. However, with some common sense practices, the risk of transmission of SARS-CoV-2 is negligible. We’re much more likely to get infected with our typical new-pet-associated pathogens like Campylobacter, but some basic hygiene measures (e.g. hand hygiene) can minimize those risks as well.

Here’s the yet-to-be-renamed kitten. (He actually currently has about 20 names, many of which are hockey players). My personal health risks will probably be greater navigating the family name debate than anything else.

 

 

Nothing too remarkable to report, but here are a few recent developments.

Dogs

Details about the first two SARS-CoV-2-positive dogs in Hong Kong have been published in Nature. We’ve previously heard most of the information before, but here’s a quick summary:

  • Two out of 15 dogs were identified as positive for SARS-CoV-2, after being in contact with COVID-19-infected owners.
  • The first dog was a 17-year-old Pomeranian. SARS-CoV-2 was isolated from nasal and oral swabs shortly after it arrived in quarantine, and it had positive nasal swab results multiple times over 13 days. It also produced antibodies against the virus (seroconverted). The repeated isolation of the virus and seroconversion are convincing evidence that the dog was infected. However, it did not have any apparent signs of illness from SARS-CoV-2. It died shortly after its quarantine ended but that was attributed to its old age and other issues, not the virus (see figure below for timeline info).
  • The 2nd dog was a 2.5-year-old German Shepherd, one of two dogs in the household of another COVID-19-infected person. The virus was detected from sets of oral and nasal swabs collected on arrival and the next day, but further samples were negative shortly thereafter. Rectal swabs were also collected at the second sampling time and were positive. This dog also seroconverted and remained healthy.
  • Unsurprisingly, when they looked at the genetic sequence of viruses from the dogs and their respective owners, viral sequences from the dogs were identical to those from their owners (and sequences from the two households were different). This supports the assumption that the dogs were infected by their owners.

Cats

Another couple of infected cats have been identified, one from Germany and one from France.

The German cat’s owner was in a retirement home with an ongoing outbreak, and had died of COVID-19. The cat was infected, while two other cats at the facility were negative. The cat was healthy, as seems to be fairly common with infected cats.

The other cat was the 2nd reported positive cat from France. This cat had respiratory disease that was non-responsive to antibiotics and anti-inflammatories, and it’s quite possible those signs were the result of COVID-19, but we can’t rule out other underlying causes based on the available information.

Mink

There are now four mink farms in the Netherlands with confirmed outbreaks of SARS-CoV-2 in the animals. There’s still limited public information about the number of infected mink or information about transmission patterns on these farms. With thousands of animals on each premisis, there is certainly concern about the potential for widespread transmission, as well as ancillary issues such as what to do with all of the potentially contaminated manure. There’s not much mention of illness in the mink, but it’s apparent that at least some have developed respiratory disease, including fatal infections, with pregnant mink seemingly predisposed to illness.

Cats are susceptible to SARS-CoV-2. That’s been shown experimentally and in a limited number of documented natural infections. However, there’s still a lot we need to know to better understand the feline and human health implications of this virus. While limitations of experimental studies always have to be considered (since they’re based on an artificial situation), they can answer some questions a lot quicker than field studies.

A new correspondence in the New England Journal of Medicine (Halfmann et al. 2020) provides a bit more information about this virus in cats, largely supporting what’s been reported before . I found it pretty surprising to see this report in a prominent human medical journal, since it only involves cats.  I also found it surprising how superficial the information was. I guess they were trying to squeeze everything into a letter to the editor, but they sacrificed providing good information for publication in a high profile journal. They did provide more details are in the supplementary appendix file, but there are still lots of gaps.

The study looked at experimental infection with SARS-CoV-2 in three cats:

  • The day after the three cats were inoculated with the virus, another cat was co-housed with each of them.
    • There is no mention of what, if anything, they did to make sure there was no viable virus on the haircoat of the infected cats after experimental inoculation.
  • Nasal and rectal swabs were collected daily to test for the virus.
  • By day 3, virus was recovered from all inoculated cats.
    • There is no mention if the virus was found on the nasal swabs, rectal swabs or both.
    • It appears that the infected cats were healthy, although how they were monitored isn’t clear beyond saying they didn’t lose weight or have abnormal body temperatures.  However, their graph shows 2 of 3 infected cats had a 1C temperature jump by 24 hours post-infection, and one of the co-housed cats seemed to spike a fever on day 7.
  • Virus was ultimately detected in all three cats co-housed with the inoculated cats.
  • Virus was detectable for several days in all cats (see graph below).
  • All cats developed antibodies to the virus, further confirming they were truly infected.

My take home messages from this study aren’t really anything we didn’t know before, but it’s still useful confirmation:

  • Cats can be infected with SARS-CoV-2.
  • Infected cats don’t necessarily get sick.
  • Cats can spread the virus to other cats.

Since cats can spread the virus to other cats, the logical question is whether they can spread it to people. It’s logical to assume that they could, so it makes sense to take some basic precautions around exposed cats (like we’ve been saying for months). This is nothing new or scary, just a reminder to keep using some common sense preventive measures.

As the authors state, earlier reports, “coupled with our data showing the ease of transmission between domestic cats, [show] there is a public health need to recognize and further investigate the potential chain of human–cat–human transmission.”

Well said.