Search results for: influenza

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Canine influenza has been identified in a dog in Calgary, Alberta. It is suspected to have been acquired from dogs that participated in a dog show in the US near the end of September. As expected, H3N2 canine flu is the cause (not H5N1 avian influenza, which has been detected in a number of poultry flocks in Alberta since September). Unfortunately, the dog died. It was a higher-risk dog for more serious disease or complications because it was a brachycephalic breed (i.e. smush-nosed breed).

The canine H3N2 influenza A strain has been present in the US since 2015, but is not known to be circulating in Canada. We had a couple of outbreaks of canine H3N2 influenza in Ontario in 2018, but we were fortunately able to eradicate it, in large part because of intensive testing and good owner compliance regarding isolating affected and exposed dogs, and likely some plain old good luck.

This virus is highly transmissible in the Canadian dog population as almost no dogs have any immunity, since most have never been exposed to the virus before and very few are vaccinated against canine flu. So, it can spread very quickly. As you’d expect, places where dogs congregate, including kennels and dog parks, are higher risk for transmission. We are getting reports of other dogs with flu-like disease in Calgary and other Alberta cities. The problem is, there are many other causes of respiratory disease in dogs, and they all can look similar to flu. So, without testing, we don’t know if we are seeing an outbreak of canine flu or just normal background canine respiratory disease activity.

How severe is influenza in dogs?

It’s like influenza in people: Most dogs have a self-limiting “flu-like illness” with fever, cough, decreased appetite and general malaise. Most will recover on their own with some TLC. Some will develop secondary bacterial pneumonia. A small percentage (1-2%) will die, with the greatest risk of death being in older dogs and brachycephalics.

Can dogs be vaccinated against canine flu?

Yes and no. Yes, there are flu vaccines for dogs. However, they have been hard to get because of production issues, and there is currently no supply available in Canada. But flu vaccines are not going to stop an outbreak regardless. It takes 2 doses and a few weeks for a dog to develop protection from a vaccine, and vaccines are not great for stopping transmission – they’re designed to reduce the severity of disease. That’s useful, especially in high risk dogs, but they’re not a good control tool for this virus.

What should people do?

Step 1: Don’t panic.

Step 2: Think about your dog’s social network. The more dogs it encounters, the higher the risk it could come in contact with the virus.

Step 3: Try to reduce your dog’s canine contacts. If I was in an area where flu was present, I’d avoid dog parks and other places where dogs can meet, until the issue is sorted out. Sometimes we have to mix dogs for specific reasons, but the more we can reduce that, the better.

Step 3b: If your dog is sick, keep it away from other dogs. Dogs with flu can be infectious for a day or so before they get sick, so we can’t rely completely on this, but any dog with potential flu (or that has been exposed to a dog with flu) should be isolated from other dogs. We’ve seen dogs that are PCR-positive for over 3 weeks after infection, so isolating them for a month is ideal. However, realistically, the risk of transmission is probably limited after 10 days. So, it becomes a matter of practicality. The longer the isolation, the better, but I’d definitely isolate for at least 10 days, as an absolute minimum.

Who should be tested?

Testing dogs is often is more useful from a population standpoint. I want to know where flu is to understand transmission and risk. It can also help with isolation recommendations. However, it rarely impacts the individual dog because rarely would be do something specific for influenza. Testing is never a bad idea, but if the dog has known contact with a dog with flu and has flu-like disease, we can be pretty confident is has the flu.

If testing is done, it needs to be done in a manner that prevents more transmission. For our outbreaks, dogs were sampled in homes and parking lots as much as possible, to limit dogs going into veterinary clinics. Clinics can handle flu cases and minimize the risk of transmission to other patients (if they know there’s a potential risk), but keeping dogs out of clinics is ideal unless they need medical care or there’s a clear need for testing (and swabbing a dog for testing can still be done outside, even at a clinic).

What’s the risk to people?

Very limited. There’s no evidence that the canine H3N2 strain of influenza can infect people. We never say never, but it’s not something we are currently concerned about. The main risk is simply from having one more influenza strain in circulation in the community, because we are most concerned about mixing of strains, where an individual gets infected with more than one flu strain at the same time, and those flu strains recombine to make a new strain. If that strain can infect people but is different enough from our seasonal human influenza viruses, then we create the risk of a new, highly transmissible human flu to which no one has any immunity. Since we are at the start of human flu season, and we are expecting a fall surge in H5N1 avian flu in wild birds, and we have endemic flu in pigs (and horses), we don’t want to add yet another flu strain to the mix. If a dog got H3N2 canine flu and also got infected with human flu (as we know they sometimes do), then the dog becomes a potential “mixing vessel.” The odds of that happening are very low, but they’re not zero, so we need to take reasonable precautions to decrease the risk.

As usual, this is a fluid situation and we’re trying to get more information. Hopefully I’ll have more updates here and on twitter/X (@weese_scott) soon.

More info about canine flu can be found in the Worms & Germs Blog infosheet on H3N2 Canine Influenza and in some of our previous Worms & Germs Blog posts on influenza.

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

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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.

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.

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This can be filed under “concerning but not surprising,” but H5N1 avian influenza has been identified in a dog in Ontario. 

It’s concerning because any spillover into mammals raises concerns about continued adaptation of this virus to spread outside birds, and because spillover infections in mammals can be severe. 

It’s not surprising because when you have millions of infected birds internationally, it’s inevitable that domestic and wild mammals will be exposed. Even if transmission is rare, when there’s a lot of exposure, transmission becomes more likely to occur and to be detected.

The case at hand is a dog from Oshawa, Ontario that died several days after being found scavenging a dead goose. Both the dog and goose were tested for H5N1 highly pathogenic avian influenza (HPAI) virus, and both were positive. Sequencing of the virus at the National Centre for Foreign Animal Diseases was performed and the virus from both the dog and goose were the same, and were consistent with the H5N1 strain that’s circulating in wild birds and domestic poultry. Further testing is being performed to confirm the cause of death in the dog. Given what we know about spillover infections into related species like foxes, it’s certainly possible that avian flu could have contributed to the dog’s death.

What should people in Ontario (or anywhere else avian flu is circulating) do?

  • Relax. That’s the first thing. This is concerning but not a doomsday scenario. We know that spillover into various mammals is happening and it will continue to happen. Also, this was a pretty high-exposure scenario where a dog had a lot of direct contact with a bird that had died of avian flu. It’s a reminder of why we’ve been emphasizing the need to try to better understand this virus since the outbreak was first identified, and to try to prevent more spillover infections from wild birds.

The next step is to just take (or continue to use) some basic common sense measures to reduce the risk of exposure.

What can be done?

  • The big thing is keeping dogs (and other domestic animals) away from wild birds.  It’s a good general rule to keep dogs away from wildlife anyway (alive or dead). That’s particularly true when there’s avian flu activity in an area.

Can dogs be vaccinated against this flu virus?

  • No, at least not at this point. Canine flu vaccines target different flu strains (canine H3N2 and H3N8) and there’s not likely any relevant cross protection. 

What’s the risk to people from infected dogs?

  • It’s probably very low but this is an unknown. Spillover infections into other species are often “dead end,” where the infected individual can’t/doesn’t infect anyone else. However, there have been some wild mammal outbreaks where limited mammal-to-mammal transmission has been a concern. When litters of wild canids have been infected, it’s hard to say if they were all exposed to the same infected birds or whether there was mammal-to-mammal spread.
  • So, it’s a big unknown. With that, it’s reasonable to take precautions to reduce contact with potentially infected mammals. However, the risk is probably quite low.

Should sick dogs be tested?

  • Testing would be considered in situations where there’s a plausible concern about H5N1 flu, based on likely exposure and the signs of illness in the dog. Lots of dogs have respiratory disease from various viral and bacterial causes and there’s no use testing every coughing dog (especially since a mildly ill coughing dog isn’t going to be a classical presentation for this viral infection). Testing for H5N1 influenza can be done through veterinarians, typically by PCR testing of oro-pharyngeal (throat), nasal and/or rectal swabs. 

What about cats?

  • Basically, replace everything above with “cat” instead of “dog.” The risks and preventive measures are pretty similar. Keeping cats indoors (when possible) to reduce their exposure to wild birds, is the main measure. That will help protect both them and their human contacts.

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As the current (and unprecedented) H5N1 avian flu outbreak continues, there’s the ongoing threat of transmission to other species. The extent of spread to mammals is hard to say since it’s hard to know how many wild mammals have been infected. However, we know that an impressive range of species has been infected. Spread to mammals is a concern because the more widely this virus spreads, the greater the chance for recombination with other flu viruses to create a “new” strain that could cause serious problems in humans or other species.

A recent news report and the corresponding WOAH report are light on details but describe H5N1 infection in a domestic cat in France from late 2022.

The cat lived on a duck farm and was euthanized after developing severe neurological disease. That’s a clinical presentation that’s not been uncommon in mammals that have been infected with H5N1 influenza during this outbreak. That doesn’t mean this virus usually causes neurological disease. It might be a matter of animals with neurological disease simply being more likely to be noticed and/or tested. H5N1 avian influenza infection was confirmed, and the virus recovered from the cat had “genetic characteristics of adaptation to mammals.”

The good news is that cats (as far as we know) don’t have their own flu virus in circulation (unlike dogs, horses, and pigs). That makes it unlikely that a cat would be infected with avian flu and another flu strain simultaneously, which would increase the potential for viral recombination. However, it’s still a concern since cats can (rarely) be infected with flu strains from other species, including human flu viruses.

Overall, the relevance here is mainly to the cat. The odds of this signalling a new problem are low, but it highlights the concerns we have about how far this virus continues to spread. It’s playing with fire.

The other consideration is the potential for cats to act as a bridge from wildlife to humans. Cats that get infected through exposure to wild birds can bring the virus into closer contact with people. It’s another good reason to keep cats indoors whenever possible, particularly if avian flu is circulating.

The ongoing H5N1 avian influenza outbreak is an unprecedented event in its size, scope and duration (but it’s not getting much press anymore these days). As infections continue to occur is birds in large numbers over a vast geographic range, we worry about spillover events into other species.

There have now been many reports of H5N1 influenza infection in a variety of wild mammals, including foxes, skunks, raccoons and most recently bears. Sporadic transmission into wild mammals that live fairly solitary lives and probably aren’t (currently) great hosts for the virus raises concern, but the broader risks are probably limited because of the low odds that rare infections would result in a relevant change in the virus or recombination with another flu virus. However, more infections create more risk, and infections of species with more animal-to-animal contact, and animal-to-human contact amplify that risk.

That’s why the recent report of H5N1 avian flu on a mink farm in Spain raises some alarm bells. Infection of a farm with tens of thousands of mink is a whole lot different than infection of the odd free-roaming fox or raccoon.

Mink in cages. Source: https://www.bbc.com/news/business-37679652

The good news is that even though the report just came out, the outbreak occurred in October, and there’s no evidence I’ve seen that this resulted in a broader issue. The bad news is that it shows what can potentially happen (and surveillance is far from good enough to say that this hasn’t caused an issue).

The report is about an outbreak on a farm in Spain that housed over 50 000 mink. Concerns were raised when the mink mortality rate increased in October, suggesting something was going on. It seemed like a pretty classic infectious disease problem, as it started in one barn and was characterized by “multiple ‘hot  spots’ within the affected barns consisting of 2–4 pens where all the animals died within a period of 1–2 days.” Mortality rates then increased in neighbouring barns, then eventually across the whole farm. Infection with SARS-CoV-2 was initially the main concern, as has been seen on mink farms in many countries now, but tests for that were negative. Eventually they confirmed H5N1 flu as the cause of illness in the mink, and sequencing of the virus showed it was the same clade (2.3.4.4b) that’s been circulating in birds in Europe.

The decision was made to cull the mink, and over the course of about a month, all of the mink were euthanized and their remains disposed.

Farm workers were tested at one point, and all 11 were negative. That was good news, but single point-in-time testing of people exposed to an infected mink farm over the course of weeks doesn’t rule out transmission. (Though it’s worth noting employees were already required to use enhanced precautions, like wearing masks, because of the concerns over SARS-CoV-2 transmission to (and from) the mink, which may have also helped limit transmission of flu.) One of the workers later developed flu-like signs but tested negative for flu virus. Because of the disease transmission concerns, a “semi-quarantine” of the people was performed to limit contact with other people for 10 days after their last contact with the farm.

The source of the outbreak isn’t known. It’s possible that it was introduced by poultry products fed to the mink, but there’s no evidence that any supply farms were infected. It’s much more likely that wild birds were the source, and infected wild birds had already been found in the area at the time of the outbreak. This highlights concerns about mink farms as a wildlife/domestic animal/human interface. It’s hard to keep wildlife away from a mink farm, which creates risk for transmission both from and to wildlife. If wild birds can infect mink, it’s equally likely that wild birds (and other wildlife) could be infected from mink, through contact with the mink farm environment. A virus that spreads to the mink can then spread to human farm workers, domestic animals on the farm, or other “visiting” wildlife. That’s not a comforting scenario.

The report concludes by stating that the mink sector is still important economically and “it is necessary to strengthen the culture of biosafety and biosecurity in this farming system and promote the implementation of ad hoc surveillance programs for influenza A viruses and other zoonotic pathogens at a global level”. I agree with the second part of this statement, but as for the first part, we need to think and risk versus reward. Are the benefits of mink farming worth the risks that come with raising large numbers of animals that are susceptible to various human viruses, in close proximity and with ongoing contact with people and wildlife? The broader societal benefits of mink farming are (to me) negligible, and the risks may be low, but they are not zero and not adequately understood.

Image from https://www.bbc.com/news/business-37679652

It’s been a busy fall for canine flu.   We’ve started tracking canine influenza cases to have a better idea of its spread and to help with risk assessment and vaccination decisions (although canine flu vaccine shortages have also been an issue).

We’ve created an interactive map of our preliminary canine flu surveillance to date.  A screen shot of the current map is shown below.

More data are hopefully coming, so the map should be more detailed in the near future. Veterinarians can use this link to quickly submit additional case information (just number of cases and location).

Our definition of a confirmed canine influenza case for the map is:

  • Laboratory-confirmed diagnosis of canine influenza OR
  • Acute respiratory disease in a dog that has had direct contact with a laboratory-confirmed case of canine influenza

More frequent map updates will likely be provided on Twitter: weese_scott

As canine flu causes another (and particularly impressive) round of outbreaks in the US, a lot of questions arise. A big one involves vaccination.

I won’t go over the whole “what is canine flu?” spiel in this post, but I’ll give a quick overview of why we care about it. It’s a highly transmissible virus that acts… well… like flu does in people. It can cause disease in dogs ranging from mild to fatal. The mortality rate is hard to estimate but it’s probably 1-2%. It was ~2% in our Canadian outbreak of canine influenza in 2018 and we had really intensive surveillance, so it’s probably a pretty accurate number. Deaths are most often reported in older dogs. Dogs with underlying heart or lung disease are presumably at higher risk for mortality too. The same might apply to brachycephalic breeds (squishy faced breeds like bulldogs) since they are more prone to respiratory complications. Like human flu, deaths in otherwise healthy, younger individuals are rare but can occur.

Flu outbreaks are a big problem, and that can be a bigger issue in dogs than people, because we don’t have the same degree of seasonal flu every year in dogs. In humans, there’s a lot more population immunity because of repeated exposure and vaccination. Most dogs in North America have neither been exposed nor infected, so they’re ripe-for-the-picking immunologically.

Obviously there’s a canine flu vaccine, since that the topic du jour…

Yes, we have a couple of canine flu vaccines. They can be for the H3N2 strain alone, or H3N2 and H3N8. H3N2 is the currently circulating canine flu strain. It’s an avian-origin strain that has become adapted to dogs and entered the US from Asia in 2015 (and repeatedly thereafter). H3N8 canine flu emerged in the early 2000s, but as far as we can tell, it hasn’t been around for a while. So, H3N2 vaccination is the key.

How good is the canine flu vaccine?

Well, it’s a flu vaccine. They’re not known for being incredibly effective, but are useful to reduce the incidence and severity of disease. I’m most motivated to have higher risk dogs (e.g. old dogs, dogs with other health problems) vaccinated to reduce the risk of them getting severe disease. It’s going to be less effective as a population control measure since it isn’t great for protection against viral shedding, but it should help some.

What dogs should be routinely vaccinated against flu?

That’s a tough call since it’s a really sporadic disease. You might not have flu within 100 km of your dog for its entire life, or you might run into an infected dog tomorrow.

My main considerations are risk of exposure and risk of severe disease.

  • Risk of exposure depends on whether the virus is in the area, how likely it is that it will be brought into the area (e.g. outbreaks nearby), how likely it is for the dog to be exposed somewhere else (e.g. the dog travels with its owner or goes to dog shows), how likely it is for the dog to be exposed to a high risk dog from somewhere else (e.g. contact with dogs imported from Asia, or dogs from other areas where flu is active) and how many dog contacts it has (the more contacts, the greater the risk, particularly if there are contacts with dogs of unknown health and travel status).
  • Risk of severe disease is the other consideration, as described above.  I’m quicker to recommend any respiratory disease vaccine in seniors, dogs with other illnesses and brachycephalics.

Thinking about those two components helps assess how useful the vaccine might be.

If flu is active in your area, vaccination is definitely worth talking about with your veterinarian.

How is canine flu vaccine given, and how often?

It’s an injectable vaccine.  It requires an initial dose and then a booster 2-4 weeks later. That booster is important and shouldn’t be missed. We don’t do that in people, but dogs need it since most don’t have pre-existing immunity from earlier exposure and vaccination. After that initial series, it’s boosted once a year.

Another potential issue is vaccine availability. It’s been a niche vaccine, but with the large number of outbreaks in the US at the moment, demand has outpaced supply. Shortages are currently an issue in many areas.

While not related to the vaccination theme of today’s post, the question of whether canine influenza poses a risk to people often comes up too.

As far as we know, currently circulating canine flu strains do not infect people. That doesn’t mean it’s impossible (the current H3N2 changed from a bird to canine flu virus) but there’s no evidence it’s a concern right now. The main concern is the potential for a recombination, where different flu viruses (e.g. human, avian, swine, canine) infect the same host and the same time, and then reassort and create a new flu virus. We don’t have evidence of this happening but it’s always a concern with flu viruses, and it’s why we try to limit the number of different flu viruses in circulation (in any species).

What am I doing about canine flu?

At this point, we don’t have any evidence of canine flu in Canada. It might occur any time, and who knows where it will pop up, but at this point, the risk of infected dogs in my area is low.

Beyond that, Ozzie and Merlin don’t’ have particularly busy social calendars. We live in the country and they don’t see other dogs here. They see a small number of family members’ dogs sporadically, but their overall dog contacts are limited.

Ozzie (pictured here) is young and probably at limited risk of severe disease.

Merlin’s 11 and has chronic lymphoid leukemia that we’ve been managing for a year. He’s pretty healthy, but presumably at higher risk of a complication.

If flu was in the area, I might vaccinate them, but their risk of exposure is still pretty low so I’m not sure I would. If they had more contacts, I’d vaccinate Merlin for sure, and probably Ozzie too. With no flu in the area and limited dog contacts, I’m not motivated to vaccinate them at the moment. For some dogs, though, vaccination is definitely worth considering.

And from a non-canine standpoint… get your own flu shot. It won’t protect you or your dog from canine flu, but it’s been a nasty human flu season, and it can definitely help with that.

As H5N1 avian flu ramps up again across Canada with the fall wild bird migration, we’re likely going to see more situations where more unique populations of captive birds are affected, beyond the usual large or small poultry flocks. The CFIA’s standard response to highly pathogenic avian flu (like the current H5N1 strain) is “All infected flocks are humanely destroyed, and carcasses are disposed of in an environmentally acceptable fashion.”

As would be expected, this response is based primarily on commercial poultry, where if one bird in a flock is infected, you can be pretty sure the virus is widespread in the group. However, other kinds of birds that can still be infected may be housed very differently, and management and infection control measures may affect their risk if an infected bird is found on the property.  Other factors to consider are the ability to contain the risk from potentially exposed birds (which may include financial costs), and the importance of some birds in terms of conservation or genetics.

The standard approach is understandable with poultry that are highly susceptible to the virus and housed in a manner that transmission can be rampant.

However, given how widespread this virus now is in the wild bird population in North America, and the wide variety of captive birds that can be affected, could a one-size-fits-all approach perhaps cause more harm than good in some situations?

  • Maybe.

The main issue relates to non-commercial birds (those not raised primarily for food), particularly pet birds and birds in rehab facilities.

Sometimes, exposure of the entire group is likely and a whole-group response (euthanasia) might be indicated.

  • Risk assessment should play a role in this.
  • If a rehab facility has waterfowl and raptors (and maybe some pet birds in the house), and those groups are kept separate, does it make sense to depopulate all the birds on the property? Maybe not, at least all the time.
  • It comes down to the risk of exposure. Often, there can be pretty good  physical and procedural separation.

We shouldn’t realistically aim for “is there absolutely, positively, no chance that the birds were exposed?”. We can never hit that bar. Rather, we should aim for “are these birds at any greater risk than any other birds in the area, when we know that H5N1 flu is circulating in wild birds?”. That changes things a bit and recognizes that there might be some degree of risk, but it might not be any more than is inherently present with a virus that’s currently fairly widely distributed in nature.

Another major concern I have with any strict policy is driving things underground. If bird owners know a positive test means all their birds will be killed, they’re more likely to try to ride out a problem and not get testing done. That means we lose valuable information, don’t get a chance to respond to help contain the issue, and we can miss the ability to manage disease properly if it’s something other than flu. I can absolutely see non-commercial bird owners avoiding testing if stories of mandatory depopulation of birds like theirs increase. We need to know the extent of the spread of this virus so we can take other steps to control it, and driving things underground doesn’t help.

I fully admit it’s a tough situation. It requires people to change standard approaches, make decisions on the fly and do risk assessments without much information (at a time where CFIA is certainly not overflowing with resources).

We want to contain this virus for both human and animal health reasons. But, we have to realize this is an unprecedented avian flu situation in North America. We’ve never had this degree of sustained and widespread infection of wild birds.

I’m certainly not saying we should surrender and say ‘it’s endemic, we’re done, good luck.” but a more risk-based approach than has previously been considered is warranted, based on the risks to people and animals in the broader context. That’s a challenge, and we absolutely have to prioritize protecting human health.  As we enter human flu season (which is shaping up poorly), we don’t want mixing of avian and human flu viruses. We also need to minimize the risks to commercial poultry operations, which can affect thousands of birds at a time and can have ripple effects on the entire agri-food supply chain.

However, does a one-size-fits-all approach that requires euthanasia in every situation make sense? I don’t think it does.

What are the challenges to a risk based approach?

  • Lack of data to guide risk assessments in more unique situations.
  • Overloaded regulatory personnel (most veterinarians can relate to this right now too).  Case-by-case assessments and tailored responses typically take more time and resources than using the one-size-fits-all approach.
  • Often unclear or unreliable information on premises about what’s done and what the risks might be.
  • Perceived risk and risk aversion (e.g. the safest thing for regulators to do from a risk standpoint is euthanize any potentially exposed birds. Doing something different, even for good reasons, can increase risk to people or other animals, and then regulators may get blamed if things go wrong).

I think it’s time to try to implement some risk assessment-based approaches to control of this virus in some unique collections of captive birds. Often, euthanasia will still be the result if transmission between birds cannot be controlled, and that makes sense. However, there may be some situations where it can be argued that not all groups on a property are at the same risk for exposure.

What about hold and test?

  • That’s a consideration but it brings in some challenges.
  • Some tests are better than others, but no test is 100%.  It’s not as straightforward as it may first appear. However, with serial tests in a group, I think we can be pretty confident whether flu is or isn’t in a group of birds. That’s what we’re really looking to say. We want to say “are one or more birds in this specific group infected” vs “is this individual bird infected’. We can design logical testing strategies to do that.
  • Testing takes time, and also involves cost and that would be on the facility/owner. Cost concerns might certainly prevent this approach from being viable in some situations, and risks need to be carefully controlled while testing is undertaken.
  • Human exposure risks also need to be considered. If we’re collecting samples from birds, we’re potentially getting exposed to this flu virus. We can do things to reduce the risk, and any testing approach would require people that are properly trained and willing to accept the risk (like we, as veterinarians, do regularly). Fortunately, the current H5N1 seems very low risk for causing disease in people, but flu viruses are notorious for changing and low risk doesn’t mean no risk. We also want to make sure potentially infected birds don’t get exposed to human flu, another reason for careful handling during sampling.

Although the safest (and easiest) way to eliminate an “animal problem” is to eliminate the animal, euthanasia of any captive birds that might possibly be exposed to this virus when a positive is detected may not be the “best” approach in all cases.  It will be interesting to see if and how the CFIA adjusts their approach as they continue to deal with this unprecedented outbreak of avian flu.

As the unprecedented outbreak of H5N1 avian influenza continues in North America, there are numerous concerns about where the outbreak is heading and threats to other species, including domestic and wild mammals, and people (the latter being just another “domestic mammal”).  My inbox is filled with questions about different concerns and scenarios. The one I’ll address today is about risks to veterinary clinics that treat backyard poultry.

Backyard poultry are increasingly common in many areas.  Since they are typically kept outdoors and not managed with anywhere near the same degree of biosecurity as most commercial poultry, they are at high risk of exposure to avian flu when it’s circulating in wild birds in the area, as it is right now.

The good news about the current H5N1 influenza outbreak:

This H5N1 strain is not well adapted to infect humans, or mammals in general. It lacks some of the genetic material that makes other flu virus more transmissible to and between people. Only a couple of human infections with this strain have been reported, including one person infected with H5N1 in the US in whom the only symptom was fatigue. Transmission to other non-avian species is probably rare too, but all we can say is “probably” because of limited testing of wildlife. Spillover has occurred, including the recent cases of H5N1 influenza in fox kits in Ontario. Whether these infections are really rare events or just rarely diagnosed isn’t clear and remains a big question. Still, it’s safe to say that, at this point, spillover risks are limited.

(Some of) the concerning parts about the current H5N1 influenza outbreak:

It’s still a flu virus, and flu viruses change. The circulating strain can evolve and reassort (swap genes with other flu viruses) anytime. We have plenty of other flu viruses circulating in North America, including seasonal human flu and flu in other species such as pigs, horses and (in the US) dogs. There are also other avian flu strains around here and there. The more flu viruses in circulation, the greater risk of them getting together to reassort and make a new strain, potentially with more affinity for people.

So, back to veterinary clinics treating backyard poultry:

Like all domestic animals, backyard poultry sometimes need veterinary care, and this often falls to small animal or mixed animal veterinary clinics, since there are only a small number of specialist poultry veterinarians in Ontario (and many do not treat backyard birds, for several reasons including biosecurity risks). Unlike most livestock, backyard poultry that need veterinary care may be taken to the clinic (in contrast to most livestock where the veterinarian visits the farm). This creates a few concerns that need to be taken into consideration by the clinic when it comes to avian influenza.

Risk of transmission to people

  • Fortunately, as noted above, transmission to people is rare, at least at this point. Rare doesn’t mean it can’t happen, but the odds of clinically significant bird-to-human infection seems to be very low. It’s not likely someone handling an infected bird will get sick, but it’s possible.
  • We also need to think about the potential impact of people who have human flu getting exposed to birds that might have avian flu. If one infects the other (and therefore has an infection with two different flu viruses), that’s the recipe for re-assortment to create a new strain. We might be getting into excessively theoretical issues here (I doubt it, though), but hopefully the “stay home if you’re sick” message is getting across.  Unfortunately we know that’s not always the case, and people who are infected with influenza don’t always have symptoms.

A comment I made today to someone was “There’s some degree of risk but in the absence of sick birds, the zoonotic risk isn’t likely any greater than that posed by your average new puppy (e.g. Campylobacter).” I think that’s a fair statement, but at the same time, one of my goals in life is not to become a case report describing a rare/new infectious disease, so I still want to take care.

Risk of transmission to mammals

  • The issues with risk to other mammals are similar to humans (in the end we’re just another mammal, afterall). The risk of transmission is low but not zero. I wouldn’t get too concerned about it, but I’d still rather not create the chance for rare bird-to-mammal transmission in the clinic, especially since we can largely prevent it with some basic infection control measures (see below).

Risk of transmission to other birds

  • This is probably my main concern. There could be transmission to other backyard poultry (not too likely, since there usually aren’t multiple backyard chickens at a clinic at the same time) or transmission to other pet birds. Susceptibility amongst different bird species varies, but we’re seeing lots of wild birds dying from this virus. We don’t want to see it spread in a clinic to someone’s pet bird (or worse, to someone’s aviary). That creates risk of illness and death for the bird(s), and more human exposure to the virus.

So, what do we do?  We do what we do every day: We assess and manage risk.

We can never 100% eliminate risk of infectious disease in a clinic setting, especially flu. However, we can use some basic, common sense measures to reduce risk of avian flu transmission.

Risk assessment

Since healthy looking birds can be infected, there’s no way to guarantee that a given bird isn’t shedding avian flu virus. However, we can identify situations where the risk is higher and increase the infection control measures that are used. Higher risk situations include:

  • The bird is sick with signs that are compatible with avian flu infection (including neurological disease)
  • Other birds in the group are sick
  • Other birds in the group have died
  • Avian flu has been found in wildlife in the area, and the bird has outdoor access

Physical separation

If we can keep poultry away from people and animals as much as possible, we greatly reduce the risk of pathogen transmission. That can be done a few ways:

  • Admitting birds directly to isolation or another separate, contained space (versus hanging around in the waiting room)
  • Examining birds outside so they never set foot in the clinic
  • Housing hospitalized birds in isolation or a separate area

Limiting contact

Minimizing the number of people who handle the birds in the clinic to the one or two who might be required for examination and procedures reduces transmission points.

Appointment scheduling

It’s not always possible to have poultry come into the clinic at a time when no other birds are present if there’s a high bird caseload or for emergencies, but it’s something that should be done whenever possible.

PPE and hand hygiene

Routine infection control practices can go a long way, and are used based on the assumption that any patient might be harbouring something infectious.  Things like wearing proper protective outwear (basic lab coat) and hand hygiene help a lot. Protective measures can be increased if there’s more risk (see above) to include a disposable gown, mask and eye protection.

Testing

Accurate rapid tests for avian flu would be very useful and are available in some other jurisdictions. However, we have not had success getting approval to import the tests for screening birds in places like clinics and wildlife rehab facilities. Rapid tests (as we learned from COVID-19) are not perfect and can never rule out flu. However, they could be a useful screening measure, as a positive would indicate a need to use stricter precautions, and to get confirmatory testing done while providing more surveillance info. There was reluctance to use rapid tests for COVID-19 initially, but they ended up being a very useful tool. Currently, the only testing available for avian flu is PCR testing through diagnostic labs, which doesn’t help us from a clinic control standpoint since the turnaround time can be a few days.

The current H5N1 avian flu outbreak is definitely something to be concerned about. It’s having major impacts on domestic and wild birds. We want to control it to reduce the impact on those population and reduce the risk of this developing into something more. However, vet erinary clinics should be able to treat poultry without much risk, if some basic infection control measures are used.

Photo credit: https://www.insauga.com/backyard-chickens-may-come-home-to-roost-in-ajax/