If we know one thing about influenza A, it’s that there will always be something new with this virus.


A recent study out of China (Meng et al. 2023) describes what seems to be a new canine flu strain. Is it a concern? It’s hard to say at this point, but having more flu strains in a species with which we have close contact is never a good thing.

This was a surveillance study of dogs in an area of China where there’s a massive amount of pet dog breeding and trading. Our familiar H3N2 canine influenza is endemic there, and avian flu strains circulate in wild birds, creating the potential for spillover of avian flu viruses into dogs and/or emergence of new strains from virus reassortment.

Researchers tested dogs from November 2018 to April 2019, and identified influenza virus in 60 of 534 dogs (11%) by PCR. Follow up testing resulted in isolation of live influenza virus from 12 dogs. Isolation of live virus requires culture techniques. We expect to get less recovery with culture compared to PCR, since PCR will detect lower viral loads and does not require the virus to still be viable by the time of testing.

Five of the flu viruses that were isolated were H3N2.

  • That’s not surprising, since H3N2 is a well established canine flu strain in China.

Interestingly, seven of the viruses were H3N6.

  • Looking at the genetic makeup of the virus, it appears to be a mix of H3N2 canine flu and an H5N6 avian flu strain that was circulating in birds in China in 2017 and 2018.
  • It was hypothesized that this was a result of a dog being co-infected with H3N2 canine flu and H5N6 avian flu, resulting in creation of this new H5N6 strain.

Does this mean there’s a new canine flu strain circulating in China?

That’s unclear. Positive samples were from dogs in one shelter at one time point, which could happen for a few reasons:

They found the first dog with this strain, and picked up transmission in the shelter that burned out, making this a one-off event.

  • It’s very unlikely they would have gotten that lucky and captured the very first emergence of this virus. Some of the in vitro characteristics of this virus suggest it should be well adapted to mammals, so full containment is probably unlikely. There’s also some genetic variation in the H3N6 isolates, which we wouldn’t expect with a single point-source exposure.

This virus is rare in dogs and there was cluster in that shelter at that time.

  • Possible, but odds are low that researchers would pick up a rare event like that. As above, the genetic variation in strains suggests that this was more likely from multiple introductions of the virus into the shelter.

H3N6 is circulating in dogs and this study detected a strain that’s been present in the region for a while.

  • This seems most likely.

The lack of clear sampling information is a big limitation in terms of interpreting the study results (e.g. were the dogs sampled on admission to the shelter? Were the positive dogs housed together? Were they sick?).  That’s very basic information that needs to be in a paper like this, but that weak journals may let slip or don’t think to query.

The main things I take away from this report are:

  • We need more surveillance to see if this strain is still present and where it is distributed. H3N6 is probably a relevant new-kid-on-the-block. It’s probably established given it was found in an area like this with massive dog breeding.
  • Changes in importation rules will reduce the risk of this virus hitting North America, but there are enough loopholes that there is still a very reasonable likelihood that it will be introduced here at some point.
  • We need to continue to watch for influenza A infection in various animal species. That includes dogs, which often fall between the cracks because it’s usually VERY hard to get support for disease surveillance in companion animals (compared to food animal). Lots of agencies want to know the results, but rarely do they want to foot the bill. It’s a significant gap in One Health surveillance.

What will we see if H3N6 flu hits Canada (or another country)?

Assuming it causes disease similar to other flu strains, we’ll see large numbers of dogs with typical flu-like disease (which will be lumped together with routine occurrences of “kennel cough”). The number of cases will be the dramatic thing, not the severity; however, with lots of cases, we’ll see more severe cases just based on percentages.

Since dogs will presumably have no existing immunity to this strain, the main thing I’m looking out for is big outbreaks. We see “kennel cough” outbreaks all the time, caused by our usual suspects like canine parainfluenza virus, Bordetella bronchiseptica and canine respiratory coronavirus. However, if/when a new flu virus hits, it will likely be much more and obvious. Rather than an outbreak that affects a lot of dogs in a group (e.g. kennel, shelter), it will affect almost all of them. Rather than a single outbreak in a town, there will be many. I suspect it will be pretty obvious pretty quickly if this virus makes it here.

Raccoon dog (Nyctereutes procyonoides), Finland.
Photo credit: Jukka A. Lang

I would have hoped that the issues with SARS-CoV-2 in mink would have been (yet another) wake up call, but I guess not. Some changes have been made in some areas, but it’s status quo in most places. Given our pretty crappy baseline, status quo is not a good state to be in.

The latest issue, as per the latest WOAH report, is H5N1 influenza on multiple fur farms in Finland, raising Arctic foxes and raccoon dogs (yeah… because nothing bad has ever been associated with farming raccoon dogs!).

The response? Apparently, basically nothing:

Currently no control measures are applied as HPAI is not “listed disease” in fur animals.”

What could possibly go wrong with some 1500 raccoon dogs and 3500 foxes in close quarters on a farm with H5N1 and a response that seems to be mainly surveillance? Don’t get me wrong, surveillance is important. However, surveillance is not a mitigation tool. It provides clarity on what’s happening and helps guide further response. Great surveillance without mitigation is akin to filming a sinking boat in 4K but not bothering to send in any lifeboats. We get great video of the disaster but don’t save any lives.

Large groups of susceptible species create risk for virus transmission and mutation. That’s sometimes unavoidable. There’s a cost-benefit side to consider, and we can’t eliminate all animals or all human-animal interactions.

However, we can look at situations that create more risk (e.g. susceptible species, dense housing, poor management) and have limited benefit. There’s really no societal benefit of fur farming. Fur production is not essential, the benefits of fur farming are for a miniscule percentage of the population, yet the risks are borne by all of us, are real and could be substantial.

Another wake up call. Will we actually respond?

My own animals provide frequent fodder for this blog, both good and bad. Rumple’s been featured a few times before, and his latest escapade is a great antimicrobial stewardship case.

Rumple’s an indoor-outdoor cat that we adopted years ago through Guelph Humane Society’s working cat program. He was deemed unsuitable for a household, so we got him as a barn cat, but he migrated from the barn to the deck to the garage to being a part time indoor cat afterall (as I write this, he’s stretched out sleeping on my bed). He’s a big suck who spends a lot of time inside, but wouldn’t tolerate being inside 24/7. That creates some risks.

A week or so ago, we noticed a scab on Rumple’s ear and one on his neck. We figured he’d tangled with something outside (we occasionally see other cats around here, as well as the usual wildlife). No big deal. However, a few days ago, I felt a soft fluctuant swelling on his neck, just past his head. It wasn’t overly painful, there was no inflammation around the site and he seemed perfectly normal otherwise, all of which is consistent with a localized abscess.

Antimicrobials? Nope.

Antimicrobials don’t work well for an abscess. The drugs don’t penetrate the abscess well, and the environment inside the abscess can hinder them from working.

More importantly, we have a much more effective treatment: incision and drainage, as illustrated below.

Clipping around a cat bite abscess in preparation for incision and drainage.
Draining cat bite abscess.

Since he was systemically healthy and there was no evidence of a tissue infection beyond the abscess, incision and drainage was all he needed. There was a soft spot under a scab that I opened up with a hemostat and we got big gush of pus. (Abscesses can be really rewarding to treat when they drain like that!) I flushed it out quickly (he’d had enough of me at that point), and that was it. It stopped draining quickly so he didn’t need any more wound care. A few days later, the site has a bit of a scab but is otherwise normal (see last picture below).

If I’d given Rumple antimicrobials when I drained the abscess, one might have thought “wow, look how well the antibiotics worked – it cleared up right away,” but this shows that they weren’t needed. However, as clinicians, we often feel a need to “do something,” even though that “something” may not be required. We also tend to be quick to ascribe good responses to what we did, vs what was going to happen anyway.

What percentage of cats in Rumple’s situation would have been treated unnecessarily with an antimicrobial?

  • Probably a very high percentage.

Why is that? There are lots of potential reasons:

  • Risk aversion
  • Habit
  • Lack of education on abscess management
  • Lack of confidence treating without antimicrobials.
  • Veterinarians thinking the client expects it.
  • Owners asking for antimicrobials.
  • More fear of someone complaining that the veterinarian didn’t use antimicrobials if things don’t go well, than concern about adverse effects of antimicrobials (in the individual or the population).
  • It’s easier and quicker to give an antibiotic than to explain to an owner why it’s not being given.

Sometimes, animals do need antimicrobials if they have an abscess, such as when they have concurrent active tissue infection or systemic disease. (Rumple had a soft tissue infection a few years ago, likely also from a bite, but that time he needed antimicrobials.) In most cases, though, cat bite abscesses are discrete abscesses that just need incision and drainage.

Not using antimicrobials is easier on the cat (no need for pilling or injections), easier on the owner (no need to pill the cat, cheaper), and means there are no risks of adverse drug reactions or promoting antimicrobial resistance.

Another question that will come up about this case: Did I culture Rumple’s abscess?

No. There are a few reasons I chose not to do a bacterial culture, but the biggest one is that it doesn’t really matter what bug is present – I’m going to treat it the same regardless with incision and drainage. A culture is more useful if I am going to use a systemic antimicrobial, but since I wasn’t going to, it wouldn’t add any value (apart from satisfying my curiosity). Culture is a really valuable tool that’s underused overall, but it’s also overused in some situations, providing information that’s not needed or that can even be misleading. For your typical abscess that’s easily managed with incision and drainage, it’s pretty low yield.


The H5N1 avian flu outbreak in cats in Poland seems to be slowing down but the cause is still under investigation. While outbreaks often die out on their own (sometimes because of what we do, sometimes despite what we do), it’s still important to figure out what happened, to help understand the disease and ideally prevent future problems.

It seems like the number of confirmed cases has stayed at 16 and I’ve received fewer anecdotal reports from people in Poland about new sick cats. Clear information is still fairly sparse (and my lack of Polish fluency doesn’t help) but there have been reports implicating food as the source of H5N1 infection in these cats. I mused about possible sources of the virus in this outbreak last week, and a food link was on the list, but I assumed it was #2 or #3 on the depth chart).

A few pertinent things have been reported from different sources:

The same or very similar H5N1 strain was found in multiple cats from different areas.

  • That would be consistent with a point source exposure such as food, but could also be because there’s a single dominant strain of the virus that different cats were exposed to through other routes over a short period of time.

H5N1 was found in 1 of 5 samples of raw poultry diets from affected households

  • That’s a critical finding. Most importantly, they found more than just viral RNA (which could be dead virus) – they were able to isolate the whole virus, meaning it was in a viable state in the diet.
  • This adds a lot of weight to the food-source hypothesis, but since it’s retrospective and so far just 1 food sample tested positive, it’s not definitive.

For me, a key question remains: Did all of the cats receive the same diet?

That’s a very basic component of the epidemiological investigation that should be easy to sort out, but unfortunately laboratory components of outbreak investigations often move faster than boots-on-the-ground epi / info collection. If all the cats got the same diet and contamination of at least some samples of that diet can be demonstrated, that’s a pretty solid presumptive link, especially for the affected indoor cats. It’s a bit trickier in outdoor cats because of other potential sources (e.g. birds), and more details about the genomics of the locally circulating virus strains is needed to help sort that out. Ultimately, we’re often left with “most likely” cause, versus “Eureka! We’ve nailed the diagnosis!

So, hopefully we’ll get more details soon but we have to move food up to the top of the list for potential sources in this outbreak for the moment. That raises a few more obvious questions:

Should cats be fed raw poultry?

There are various issues with raw diets and this just adds another dynamic. Without knowing more about the food that’s been implicated here, it’s hard to say too much.

The risks from typical commercial diets prepared from poultry that’s deemed safe for human consumption (the poultry, not the pet food) is very low. Since H5N1 infections on poultry farms are usually pretty obvious (lots of sick and dead birds very quickly), it’s unlikely that infected poultry from commercial operations would make it into pet food manufactured by a reputable company.

If there are pet food diets that do not use typical “human-grade” poultry, the risks could be higher. If poultry from infected farms is (presumably illegally) being diverted to dodgy pet food companies, risks from those would be even higher.

If people are making their own raw diets, the origin of the birds/meat is the key. Poultry purchased at grocery stores should be exceptionally low risk. Other sources (e.g. live birds or meat from small outdoor operations) could pose much greater risks. The less scrutiny and transparency about the poultry sources, the greater the concerns.

The safest way to avoid food safety concerns from raw diets is to avoid them, cook them, or use a product that’s at least high pressure pasteurized (there’s no guarantee the HPP process eliminates all pathogens in the food, but it should at least greatly reduce pathogen levels).

So, at this point, I’d avoid feeding raw poultry to pets if there’s not complete confidence in the source, especially in areas where H5N1 is active in birds. I’d stick with products from companies with strict (and transparent and adhered to) rules about their sources, that use commercially reared poultry and that have a proper food safety program.

Are there related food safety concerns for people?

More information about poultry sources that are linked to this outbreak is critical. If food was a source, was it the same poultry that’s eaten by people, or was it from some other pathway? That’s a big question.

That said, fortunately people don’t tend to (deliberately) eat raw poultry. Cooking will eliminate any influenza virus (and a lot of other pathogens) in the meat. However, there’s always some risk of exposure to foodborne pathogens from improper handling and cooking (that’s how we get things like Salmonella) and H5N1 can survive on meat for at least a few days. So, we can’t ignore the risk entirely.

The risks would be lowest (and approaching negligible) from poultry sold in grocery stores. The risks would be highest from live market-sourced birds where there’s no information about the health status of the flock. There are gradations in between, but overall, the less the confidence in the health status of the flock, the greater the risk of contamination of the birds and the products made from them.

Cooking poultry properly, prevention of cross contamination and good kitchen hygiene (including hand washing) would greatly reduce any risks, even in the unlikely event contaminated poultry was present.

Information continues to trickle in about the situation with H5N1 avian influenza in cats in Poland. It’s mainly been updating the number of confirmed infected cats, with 16 cats in 3 cities being the latest number I’ve seen. It’s also now reported that some of the cats are primarily indoor (house) cats.

Numbers are part of the story, but the bigger question is how the virus was acquired by the cats, and if it’s spreading between cats. I still haven’t seen a good description of the epidemiology, investigation of infected households and clear information about pathways. Presumably (hopefully) that part of the investigation is well underway.

An OFFLU report about the situation with the infected cats in Poland reads “Early reports indicated that not all suspect cases had outdoor access suggesting that a direct role from infected wild birds is unlikely as a common source. The wide geographical distribution of suspected cases suggests that the primary mode of spread in these cases is not cat-to-cat transmission.

That raises the question, “If the virus isn’t coming from birds and it isn’t coming from cats, where is it coming from?

  • I haven’t seen lab leak, 5G, aliens or Tony Fauci implicated yet on social media, but that may come.

Unlike most spillover events, the situation here is still pretty cloudy at the moment. I don’t have any inside knowledge, so it’s easy to arm-chair quarterback and be completely wrong, but I’d wonder whether there’s enough data to actually rule out those two sources.

At this point, there are three main possible sources for discussion:


 I’ve seen suggestions that food (that is, what the cats are eating) could be the source of the virus. I wouldn’t rule it out, but it’s a stretch. It would have to be from raw diets made from infected birds, obviously. I assume it’s unlikely that infected commercial poultry would be put into any food chain, even for pet food. When poultry are infected, it’s pretty obvious since there’s widespread illness, so it would almost certainly have to be someone making a diet from birds that were known to be sick. People do dodgy things, but that’s unlikely.

H5N1 virus making it into a cat’s diet is one thing. Actually causing an infection is another. Flu viruses don’t persist well outside the host. I haven’t seen any H5N1 data, but a study of H7N9 showed survival of the virus for up to a week at refrigeration temperatures. So, while it’s possible, “up to a week” means that’s the upper limit that was found, and I’d assume that there was a pretty steady decrease in virus viability (and therefore risk) over that time. We should assume there’s some potential IF a diet is made from infected birds AND it’s not cooked AND it gets to the cat within a few days (and even then, there has to be exposure to a minimum infectious dose).

Overall, I wouldn’t completely discount food as a source, but I think it’s unlikely. To start, I’d want to know whether these cats were all fed the same diet (and same lot of that diet). A diet history is a pretty easy way to see whether this even deserves investigation.

Cat-to-cat transmission

This is pretty easy to rule out since cats were from multiple cities with disease onset around the same time. Given the way cats do (and don’t) move, a common contact pathway is exceedingly unlikely, so let’s toss this one out for now.

Repeated wild bird-to-cat transmission

This is still my #1 guess. The kicker is that some cats were indoor cats. A question about this is whether the cats were “indoor”, or actually indoor. Not uncommonly, people say their cats are indoor, but they get outside (e.g. sneak out, are allowed outside on a deck, taken out on a leash). It’s far from rare vet clinics to see an “indoor” cat that’s been hit by a car or tangled with a wild animal.

If the cats were truly only indoor, that limits the transmission pathways a lot and largely (but not completely) rules out direct transmission from a bird.

A mix of these

This might be an explanation for some of the “indoor” cat infections. For example, if there’s a cluster of infections in outdoor cats that’s predominantly or solely bird-to-cat transmission, with maybe some cat-to-cat transmission. But how, if a cat is truly indoor only? Well, it’s maybe a stretch but the picture below of cats facing off through a window is one I put on Twitter the other day, as a reminder that indoor cats need to be vaccinated since they can still have close encounters with outdoor cats. For affected indoor cats, if food is largely ruled out, I’d query the household situation, such as are there screened windows or some other way to have close contact with any outdoor cats (or other cats in the household that do go outside).

Hopefully the investigation will generate some more information. It’s important for us to know more about transmission pathways and risks, both for cat health and to assess risks to other species (including humans).

Milo, the indoor cat and Rumple, the outdoor cat, have an encounter through a window screen.

Yesterday, I discussed a situation where avian flu was suspected in the deaths of a reasonably large number of cats in Poland. “We need more information” was a big part of that, and as of today a few new pieces of the puzzle have come to light.

It’s now reported that H5N1 was detected in 9 of 11 samples from cats. Positive samples were from three different cities, which is a very important finding. A reasonably large number of cats affected (and this likely being the tip of the iceberg) from multiple different cities definitely raises concern, since this wasn’t just one group of cats exposed to the same infected bird or group of birds. Bird-to-cat jumps must have happened multiple times in multiple locations, and that’s not good.

Why might there be a large number of affected cats in this case?

The most logical explanation to me is that there’s a big outbreak of avian flu in the types of birds with which cats have more contact. Birds that live in cities and are more likely to be caught and eaten by cats. In parallel, there could be greater awareness of the risk of transmission of H5N1 to cats, so people are looking for and testing sick cats.

Regardless, this shows us we need to keep investigating. “Dozens” of potentially affected cats is still a pretty small number in the grand scheme of things, but it’s a lot for an infection that has been assumed to be a rare event, particularly considering we likely detect only a small minority of spillover events into animals. Every spillover to a mammal creates more opportunity for the virus to adapt to mammals (including humans), and when the virus infects domestic animals or animals with which people or domestic animals have more contact, spillovers increase the risk of human exposure. We’ve been fortunate that the serious impacts on mammals have, so far, avoided people. However, it’s a dynamic situation and we need to be vigilant (but not paranoid).

  • We need continued research to figure out what’s happening.
  • We need to use basic preventive measures to reduce spillover into domestic animals.
  • We need to prioritize vaccine development for humans and domestic animals in case it’s  needed.

A couple of days ago, there was a ProMed request for information following a report of a large number of dead cats in Poland. The cats were reported to have had respiratory and neurological disease, so my thought process went to “that fits with avian flu spillover,” then “but that large of a number would be really surprising.” However, it had to be on the radar given the clinical signs, limited other diseases that would cause that type of clinical presentation in otherwise healthy adult cats, and the dynamic nature of this massive international H5N1 avian flu pandemic.

Details are still pretty sparse, but there are now various reports that “flu” or “avian flu” were identified in at least some of the dozens of dead cats. That obviously raises concern and highlights a need for more detailed information.

It also gets me thinking about a few big questions:

  • Were these actually H5N1 avian flu infections?
  • Was this one transmission event (e.g. a bunch of cats exposed to the same source of virus) or multiple spillover events?
  • Was this likely all bird-to-cat or was cat-to-cat transmission also involved?
  • Have there been less severe infections in cats in the same area?

The last question is a big one. Right now, we know very little about the range of clinical signs in infected cats (and other species). The risk calculus is a lot different if this virus always causes severe/fatal disease versus if it causes a range of disease. We are more likely to find severe disease, especially in wildlife and feral animals, because we don’t notice mild illness as well in those species. Very sick or dead animal are much more likely to be caught and tested.

  • If there was group of 10 dead cats, odds are pretty high that would be recognized and at least some of the cats would be tested.
  • If there was a group of 10 cats with transient fever, cough and lethargy, that’s much less likely to be noticed (and the cats are less likely to be caught and tested).

That second group might be really important though. From a population standpoint, a virus that kills consistently and quickly is generally less likely to spread compared to one that causes more mild, prolonged illness, especially if the animal is still moving around and interacting with other animals.

Said another way, a big question is whether severely ill cats are the norm for H5N1 spillovers or whether they are just the tip of the iceberg. If the latter, then we have a much greater need to figure out what the risk of spread from them is. We haven’t really been able to explore this well yet here in Ontario because of logistical challenges, but the situation in Poland may help shed some light on the matter if more testing of live cats is done as part of the investigation.

(TL:DR… check out the TikTok version at the bottom)

When I was a newly graduated veterinarian in general practice, I gave puppies and kittens their first rabies vaccine at 16 weeks of age. That was the standard at the clinic and a common practice elsewhere. Now, if I ask audiences of veterinarians when they vaccinated against rabies, I’d say a majority still say 16 weeks.

But is waiting until 16 weeks to vaccinate against rabies a good approach?

When we vaccinate young animals, we’re aiming for the sweet spot of vaccinating them as young as possible, but at a time when we’re confident the vaccine will work. Antibodies that animals get from their mothers can interfere with vaccines, but those antibodies wane over time. We give a series of “core” vaccines (e.g. parvovirus and distemper virus in dogs) starting at a young age, knowing that they may not respond initially but eventually will, as maternal antibody interference disappears.

For core vaccines, we want to give at least one dose at 16+ weeks of age. However, rabies vaccine can be given earlier. Rabies vaccines in Canada are licensed for use at 12 weeks of age. In Ontario, the legal requirement is vaccination of all dogs and cats (and ferrets) against rabies at 3 months (12 weeks) of age.

So, why are puppies and kittens commonly vaccinated for rabies at 16 weeks?

The main reason is probably habit – “that’s what we’ve always done so that’s what we do.” Another reason is a focus on getting puppies and kittens back for that critical 16 week core vaccine. There’s concern that if people are fixated on the need for rabies vaccination for their pet, if they get it at 12 weeks, they may not be motivated to come back at 16 weeks, and therefore might put their pet at high risk of getting other serious disease like parvovirus or distemper.

12 weeks vs 16 weeks… what difference does 4 weeks make?

Most of the time, nothing, but sometimes, it’s life-and-death. Earlier vaccination means earlier protection from rabies. However, probably as importantly, earlier vaccination reduces the risk of significant isolation requirements if the animal is exposed to a potentially rabid animal.

For example, let’s say a 16 week old puppy was outside in the yard and night, and fought with an abnormal-acting raccoon. The puppy has some bite wounds, but the raccoon ran off and can’t be tested for rabies. This would typically be considered a potential rabies exposure.

Scenario 1: Puppy was vaccinated at 12 weeks of age. It’s been more than 28 days since the vaccine, so we’re quite confident it’s protected. In Ontario, that means we would give a booster vaccine within 7 days, and they there would be a 45 day observation period. That’s pretty minor and mainly means minimizing the animal’s contacts outside the household and keeping it on a leash when off the property.

Scenario 2: Puppy hasn’t yet been vaccinated (or was vaccinated so recently that it’s not considered protected). There are major implications here. If the puppy gets a rabies vaccine within 7 days, it gets a 3 month “precautionary confinement period” (basically, quarantine, but there are legal connotations to that word so government guidance avoids it). If a post-exposure vaccine isn’t given, the confinement period is extended to 6 months. This is a much bigger deal than Scenario 1 because it requires keeping the puppy at home at all times (unless medical attention is required), limiting contact to one age-appropriate caretaker, preventing contact with other people or animals, only going outside on a leash and in a fenced area (double barrier to escape) and keeping the puppy in a secure indoor area that allows the caretaker to observe the animal before direct contact and prevents accidental escape when indoors (for example, double door entry).  That’s tough to do with a puppy and sometimes, euthanasia is elected instead. Even if owners chose to proceed with confining the puppy, it can have a major impact on the puppy’s socialization and increase the risk of behavioural issues later in life.

So, from my standpoint (plus the legal requirement here), we want to vaccinate puppies and kittens as close to 12 weeks as possible. It’s rare that a 4 week delay would cause a problem, but when it does it can be major. We also want to make sure that doesn’t result in puppies and kittens failing to come back for that critical 16 week core vaccine, but we can educate owners about the need for that.


What age should puppies and kittens be vaccinated against rabies?

♬ original sound – Scott Weese – Scott Weese

There’s nothing too earth-shattering here, but a few useful changes pertaining to rabies regulations are coming to Ontario as of July 1, 2023.

  1. Medical officers of health (MOHs) will have the ability to require rabies testing of animals that have died or are euthanized during their 10 day observation period after they’ve bitten someone.

When a person is bitten by a dog or cat, it needs to be reported to public health, and the animal undergoes a 10 day observation period. Based on what we know about rabies shedding, if the animal is still alive and neurologically normal on day 10, it could not have transmitted rabies to the person via the bite on day zero. That means the bite victim can relax and doesn’t require rabies post-exposure prophylaxis (PEP).

Previously, if an owner animal died or had to be euthanized during this period, MOHs didn’t actually have the authority to require testing. They could recommend, ask, cajole… but the wording was vague enough that animal owners could refuse to have their animal tested. In the past, owners consented to the testing most of the time, but not always. Now, testing can be mandated, since otherwise, we couldn’t rule out rabies and the person that was bitten might have had to undergo unnecessary PEP.

  1. Rabies vaccination requirements will allow for vaccination outside of Ontario, under certain conditions.

The current wording in Regulation 567 requires all dogs, cats and ferrets over three months of age (and certain horses, cattle and sheep) to be vaccinated for rabies by a veterinarian that’s licensed in Ontario and with a vaccine that’s approved in Canada (I think a lot of veterinarians in Ontario don’t actually realize this). It makes sense to require re-vaccination of many imported dogs, but not all, especially those vaccinated in the US where veterinary training, vaccines and documentation requirements are basically the same.

After July 1, rabies vaccination will be considered adequate if performed by a veterinarian licensed anywhere in Canada or the US, with a vaccine licensed in the same jurisdiction, and accompanied by proper documentation (i.e. a vaccination certificate that meets the requirements listed in the Ontario Regulation 567).

So, the retired person that spends the winter in Florida and gets their dog vaccinated there doesn’t need to get the dog re-vaccinated again upon returning to Ontario (at least until the US vaccination expires). The imported dog from overseas where we may have less confidence in the reliability of the vaccine, documentation or reporting still needs to be re-vaccinated on arrival in Ontario.

The Ministry of Health and College of Veterinarians of Ontario have provided a decision tree to help clarify rabies vaccination requirements in imported animals:

Yes, I’m prone to making typos. No, this title isn’t one of them.

While we’re in the midst of an unprecedented international outbreak of H5N1 avian flu (with ongoing spillover into mammals), there’s a new kid on the block: H5N5 influenza. I think recent reports of H5N5 were glossed over by some who didn’t realize we’re talking about a different strain from the H5N1 we’ve been dealing with the last couple of years. While it’s not necessarily a game-changer, we need to pay attention to new strains like this.

The story starts with the finding of H5N5 flu in birds in Atlantic Canada, which started in January 2023. The genetic makeup of the virus indicates it’s a Eurasian lineage that’s circulating in birds in Europe. It’s suspected that it made it to Canada via migratory birds last fall.

More recently, and more concerningly, this H5N5 strain was identified in two raccoons in Charlottetown, Prince Edward Island. As far as I know, this is the first report of H5N5 in mammals. Presumably the raccoons were infected from eating infected birds, which is how we suspect most mammalian wildlife with H5N1 get infected too.

With reports of “new” diseases, we always have to consider surveillance bias. We’re looking and testing a lot more now because of H5N1, so we’re more likely to find other things (such as other strains, like this) as well. That raises the question of whether this is truly something new or just something we’ve found now because we’re looking harder. Based on the genomics of the virus (being a Eurasian lineage), it’s probably something new for this region.

Regardless, the presence of yet another avian flu strain and more spillover into mammals is a bit disconcerting, to say the least. Recent genetic study of this H5N5 virus has indicated that it’s likely also capable of long-term circulation in birds and recombination with other flu viruses, so this is a virus to watch.

That’s not to say that we’re heading into a massive H5N5 outbreak. It’s one more flu virus in the mix, one more flu virus with the potential to recombine with other (human, avian, swine, equine, canine, etc.) flu viruses, and one more flu virus that can (even in its current state) spillover into mammals. So we need to stay on alert. There are lots of influenza viruses out there: some are nasty, they are prone to changing, and sometimes that can be bad for humans or other species.