I’ve written before about COVID-19 scent-detection dogs. I get lots of questions about them, and there are now several groups working in this area. There’s been a mix of information to date, ranging from encouraging to some pretty bad preliminary studies released on pre-print websites and other places. A dog’s nose is a wonderful thing (except when my dog sticks his in places I don’t want it to go), and dogs have been shown to be able to detect a wide range of different scents with great sensitivity.

The first question is: Will dogs be able to detect people with COVID-19?

If the answer is yes, then the bigger question is, will it be a practical way to detect people with COVID-19?

We may get more answers now that dogs are being used in a Finnish airport to sniff out COVID-19.  Ten dogs have been trained to detect people with COVID-19 based on smelling wipes collected from individuals. News reports include claims of close to 100% accuracy… I’d love to see good data on that, as I suspect it’s not 100% effective in the field. However, even if the dogs are moderately effective, they could be a useful tool when combined with other measures (e.g. rapid confirmatory testing of people that dogs flag as potentially infected).

My big questions at this point is, how effective is it really?

  • We need to consider both sensitivity (how good dogs are at detecting infected people) and specificity (how good they are at only detecting infected people).
  • For a screening test, we want a test that is highly sensitive, meaning it detects most infected people, even if it has some false positives (i.e. people who are mistakenly identified as positive but aren’t actually infected). That works if the false positive rate isn’t massive and if there is a convenient way to follow up to confirm who’s really positive. If we have a quick follow up test of another kind, the initial false positives are a bit of a hassle but not a big deal and easy enough to weed out, so we could tolerate some loss of specificity.
  • False negatives on the other hand (i.e. people who are infected but go undetected by the test) are a bigger concern.
  • So, knowing the sensitivity and specificity of these COVID019 detection dogs in a field situation (where there are lots of people of different types, with different stages of infection and with different smells) is key. Hopefully that’s being studied well.

Another question I have is, what’s the management plan for dogs that stick their noses in wipes from people with COVID-19?

  • Dogs have limited susceptibility to SARS-CoV-2, but limited and zero aren’t the same.
  • Will the dogs be screened in case they get infected in the process?
  • And (an oddball question perhaps) if a dog gets infected, does it lose the ability to detect infection in people? would the dog then smell the scent associated with the virus all the time?

There will be more to come, I assume.

The UCLA Fielding School of Public Health, Department of Epidemiology, is seeking volunteers to participate in their Veterinary and Zoonotic Surveillance for SARS-CoV-2 (COVID-19) and Other Coronaviruses Study.  Their goals are to assess potential exposures to SARS-CoV-2 and other zoonotic pathogens among veterinary and animal healthcare workers, as well as clinical symptoms, mental health, and attitudes and practices associated with the pandemic response. To be eligible to participate, you must work with or around animals, for example: in a veterinary clinic/hospital, with a mobile veterinary clinic, at an animal shelter, animal rehabilitation facility, animal control facility, zoo or aquarium, in an animal research lab, or animal husbandry operation.

Click here for more information and to enroll in the study.

As things continue to gradually open up (more gradually in some areas than others), myriad questions of “can we do…” or “how do we do…” come up. One that I’m getting increasingly is about pet visitation or pet therapy programs. These programs can be very valuable to patients in hospitals and residents in long-term care homes and other settings; however, they always come with some degree of risk from interaction with the animal, and the handler.

Currently, most places have these kinds of visits on hold, which is reasonable in this phase of the COVID-19 pandemic. Fewer people coming in means fewer potential sources of infection. However, some programs are restarting, so thought needs to go into doing this safely.

What are the risks?

While we often try to get people to think about the various pathogens that pets (particular dogs in this case) can leave behind or pick up in these settings, right now the main risk with pet visitation programs is SARS-CoV-2 from the human handlers. This virus likes people a lot better than dogs – the COVID-19 pandemic is being propagated almost exclusively through human-to-human transmission. While there is some potential for dogs to be infected or for them to act as fomites (i.e. tracking virus around on their haircoats), the far greater susceptibility of people means that dogs are probably the lower-risk component of visitation teams.

Routine prevention measures:

  • Standard pet therapy program measures, as outlined in the 2015 SHEA guidelines on animals in healthcare facilities, are still key, with particular emphasis on making sure:
  • Handlers self-screen and are healthy before entering a facility.
  • Everyone involved pays close attention to hand hygiene. Patients should use hand sanitizer before and after animal contact. Handlers should use hand sanitizer before and after every visitation, regardless of whether they touched the person or any part of the person’s environment.

Added COVID-19 measures:

  • Ensure the patient has no signs of COVID-19 and is not being isolated. (Yes, that sounds like common sense, but you’d be amazed how often things like that get missed.)
  • Ensure the handler and animal have not had exposure to an infected person in the past 14 days.
  • Have everyone involved (that is to say the people, not the dogs) wear a mask.
  • Remember the 3 C’s to avoid: closed spaces, crowded spaces, close contact. (I also talk about a fourth C, “continuous,” with regard to time.)
  • Limit person-to-person contact. Handlers should stay as far back from patients as possible.
  • Have the visit outside in an open space, when possible.
  • Keep the visits relatively short – 15 minutes is typically used as the time when risk goes up.
  • Have handlers use a tracking app, like Canada’s COVID Alert app. Anyone involved with pet therapy in a region with an app like this should use it. It might help pick up exposure in a facility, but more importantly, it helps identify other community exposures, so exposed people know when they’ve been exposed and can suspend their visitation activities.
  • Stick to one facility. Some visitation teams typically visit multiple facilities. That’s probably best avoided, especially now. Teams should focus on one facility, to reduce the risk of cross-transmission.
  • Consider limiting visits to one person per team per day, especially as programs restart and while there’s less risk tolerance. Limiting a visit to a single patient each time reduces the risk of encountering or spreading the virus between patients.

How to respond to an outbreak or exposure

  • The key here is being able to identify exposed individuals quickly and easily. One recommendation we’ve had since our very first guidelines on pet therapy is keeping track of who gets visited when, and by whom. This has been very hard to get implemented, but it’s especially critical now. Tracking can be as simple as having handlers write down the date and the rooms/patients they visited, and leave the log with the facility as they depart.
  • An additional component of this tracking should be recording the duration of the visit, since the time spent with the infected person plays a role in determining whether exposure was likely.  With basic practices like hand hygiene, mask use, and distancing, it’s unlikely a handler would be considered exposed if they visited an infected patient for a short time. However, some visits could end up stretching beyond that typical 15 minute limit, and some could end up involving direct contact between the handler and patient. If the handler fits the criteria for exposure, the response would depend on the local public health directives for exposed people (e.g. self-monitoring vs isolation). However, given the severe implications of COVID-19 in most populations where pet therapy is used, handlers with any plausible degree of exposure should suspend visitation for 14 days. If a dog had direct contact with an infected person, then I’d isolate the dog for 14 days as well, to be safe.
  • Handlers also need to have an established means of communication with the facility and must be able to report illness. If a handler develops COVID-19 (probably acquired in the community, not during visitation), the person needs to be able to contact the facility as soon as possible, so they can then determine if any of the patients/residents might have been exposed, based on the timing of illness and visitation.

None of this is rocket science, or expensive. It’s use of basic infection control practices and good communication. Unfortunately, those are often lacking.

The risk from a well-run pet visitation program following these precautions is low, but not zero. There’s never going to be risk-free pet visitation. The key is limiting the risk as much as possible, while maximizing the benefits. The implications of tracking SARS-CoV-2 to, within or between facilities (especially long-term care homes) can be huge, so serious thought needs to go into when and how to restart these programs.

I’ve been away and need to catch up on some posts.  I was planning a nice non-COVID post, until a few seconds ago when I saw the CNN headline “Chinese officials say chicken wings imported from Brazil tested positive for COVID-19.”

My response… oh crap.

Not because I fear a wave of foodborne COVID-19. Rather, I fear a wave a paranoia about foodborne COVID-19 (and an overstuffed email inbox today).

According to the report, testing identified SARS-CoV-2 in a sample of chicken wings from Brazil. We have to realize that it’s most likely the testing was done by PCR, which is a very sensitive method that detects the nucleic acid building blocks of the virus (the RNA). That means it can detect live OR dead virus.  This virus does not live long outside its host, so it’s almost certain the virus (or more specifically pieces of virus) detected in the chicken wings wasn’t infectious.

How did the virus get there?

  • Likely from people handling the food. While research is still limited, this virus has not been identified in poultry, so a human origin is almost certain. That would fit with other recent reports from China of detection of SARS-CoV-2 on packaging of imported food. Infected people contaminate surfaces they touch.

Is there any risk?

  • Presumably no. Small amounts of this virus are probably common of surfaces in areas where the virus is circulating. The more infected people, the more contamination is likely. Yet, transmission risk still seems to be mainly from droplets and direct contact. The presence of viral “bits” on surfaces does not mean the presence of risk.
  • The risk from handling chicken wings is mainly from our run-of-the-mill foodborne bugs like Salmonella.

What should people do?

  • Pay attention to measures that we use to reduce the risk from our run-of-the-mill foodborne bugs like Salmonella, such as handwashing after handling raw meat, and cooking meat properly, and avoiding cross-contamination of food and surfaces in the kitchen. (If you want an extra level of protection, avoid sticking raw chicken wings up your nose.)”

There are a lot of things regarding SARS-CoV-2 to be concerned about. This isn’t one of them.

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.