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.


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.


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.


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.

We’ve spent a lot of timing working on various recommendations for managing COVID-19 risks in veterinary practice. They’re mainly focused on the most biohazardous species with which veterinary personnel work on a daily basis: humans. While we’re still sorting through animal-related issues, the main emphasis is reducing exposure risk from people, and a recent assessment from the UK’s Office of National Statistics shows why. They have an interesting interactive map that characterizes the risk for a range of occupations, based on the frequency and closeness of contact they have with other people in general, and the potential exposure to infected people specifically.


  • Not surprisingly, healthcare practitioners top the list, particularly dental nurses.
  • Where veterinarians and veterinary technicians rank might surprise some (take a guess then check out the link to the interactive map here).  This shows why we’re working so hard on this, and why some short- and long-term changes in behaviours and veterinary practice are needed to help protect everyone’s health.
  • It’s designed as an assessment of generic disease exposure, not just COVID-19, so the vets and vet techs get higher on the ranking than they would be on a strictly COVID-19 exposure risk assessment, but it highlights the amount of close contact that vets have with a large number of people on a daily basis. More contacts means more risk. Reducing those contacts reduces the risk

Pretty soon, I’ll stop writing about single reports of cats identified as infected with SARS-CoV-2. These cases aren’t surprising,  and sporadic case reports don’t provide much new information. However, I’ll give a quick rundown of the latest case of an infected cat from Spain. It’s only reported in news articles, as far as I can find, so we have to be a bit wary of the info.

As expected, the cat lived in a household with COVID-19-infected people. The cat developed respiratory difficulties, and was ultimately euthanized. Low levels of SARS-CoV-2 were found in its nasal passages and an abdominal lymph node. But the cat also had hypertrophic cardiomyopathy, a potentially serious heart disease that can cause death.

This case raises concern about a severe SARS-CoV-2 infection in the cat, which would be different from the milder cases that have been previously reported. However, the cat’s underlying health issues could have accounted for its death, so it’s more likely that the cat had an incidental infection rather than a fatal SARS-CoV-2 infection.

Regardless, my assumption has been that we’re bound to see the odd case of serious disease in cats. I get some calls about suspicious cases, but we haven’t been able to test too many of them. Most infected cats probably don’t get sick at all or develop mild signs of illness (like people), but it’s reasonable to expect that a subset of infected cats (especially those with underlying health problems) could get more serious disease, but that’s likely rare. However, most cats exposed to infected people likely don’t even get infected.

As per all my other discussions, the key here is that if you social distance pets (as we do people), then the risk that a pet would bring this virus into the household is very low.

We’re nowhere near the end of this pandemic, and one concern we have is opening things up too quickly and losing the benefits of all the sacrifices that have been made to “flatten the curve.” As restrictions get lifted, we’re not going straight from “now” to “normal.”  We’ll have to continue with good physical distancing practices for the foreseeable future.

With that in mind, a new document has been released, in collaboration with the OVMA, outlining preparation for veterinary medicine when the “urgent care only” directive in Ontario gets lifted. It’s meant to help us be prepared for the next phase, so that we can provide more veterinary services while still minimizing the risk of COVID-19 transmission.

That’s a difficult balance to find.

The document is written for the Ontario context, but the overall concepts would likely apply pretty much anywhere. We’re going to have to change how we practice for a while, and some changes may be permanent. The better we can be prepared, the more responsible and effective we can be.

As always, guidance may change based on how the pandemic evolves, government guidance, experiences and new ideas, but this is a good place to start.

You can find the Guide to reopening veterinary medicine in Ontario as well as many of the other resources we’ve posted since March on the Worms & Germs COVID-19 Veterinary Resources page.

A few quick updates and comments.

Are pugs a high risk breed for SARS-CoV-2?

This question has come up a few times since the report of an infected pug in North Carolina. It has been suggested by some people in news articles that pugs are higher risk for getting infected. Like other brachycephalic (squishy faced) breeds, some pugs are at increased risk of respiratory disease in general. They are also at increased risk of complications if they get a respiratory infection of any kind. But they should otherwise not be at increased risk of getting infected with this particular virus compared to any other similarly exposed dog.

So, pug owners should relax (some have apparently already asked about getting rid of their dogs). If you own a pug, it is probably at increased risk of complications if it gets infected with SARS-CoV-2 (or any other respiratory virus), but it should not be at increased risk of getting infected in the first place, and the odds of any dog getting infected are very low.

Update on two positive cats in New York

Antibodies to SARS-CoV2 were detected in the blood of both cats from New York that tested positive by PCR in late April . This is not unexpected, but it is one more indication that they were truly infected.

Infected cat in France

In a study of cats owned by people with COVID-19 in France, one cat was identified as positive by PCR.  There’s no mention of how many cats were tested (yet). The positive cat had mild respiratory and gastrointestinal disease, and only its rectal swab (not the throat swab) was positive.

This result isn’t surprising either, as it’s likely that a reasonably large number of human-cat infections have occurred. As has been typical so far, the cat had mild disease. I’ve had some anecdotal reports that suggest some cats can get more serious disease but we need to properly investigate those. This report is just one more piece of evidence indicating that human-animal transmission of this virus is occurring. Human and animal health implications of this are probably limited but it’s an area we need to keep studying.