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I’m on my way back from Copenhagen where we had a very productive meeting to update the ISCAID pyelonephritis antimicrobial treatment guidelines for dogs and cats. As the process for developing guidelines like these has matured, it’s no longer about simply getting some very smart people in a room and agreeing on recommendations; it’s now a much more structured, evidence-based process. As part of that, we think about more than just “would this drug work?” We also think about factors like adverse effects, cost, acceptability, feasibility, equity and others. One of the newer consideration is now “planetary health,” which is applicable to a lot of things, including antimicrobial use guidelines.

Antimicrobial production, distribution and use have carbon footprints and require other resources that impact more than the individual who gets treated with the drug. (And yes, I fully recognize the irony of talking about carbon footprints while flying across the Atlantic in a plane, but sometimes in-person meetings are important too.) While we’re not going to dramatically alter our guidelines based on a drug’s carbon footprint, it’s something we need to at least think about for awareness. A side benefit of good antimicrobial stewardship resulting in less antimicrobial use is smaller footprints of this sort. But, are those footprints really relevant? It’s always hard to figure out what the contribution of something like a drug (or a flight) is to the big picture, and individual events have near negligible impacts. But, when we do something over and over and over again, the cumulative impact starts to become more relevant.

What do we know about the ecological impacts of antimicrobials? I’m far from an expert in this, but it’s interesting, so I’ll just toss out a few points – food for thought.

That’s a random collection of studies on the topic, and ultimately we don’t really know the full downstream effects of antimicrobial use, but it’s fair to say that these drugs have a big carbon footprint, and we can reduce it through antimicrobial stewardship: using fewer antibiotics, using them better when necessary, and, most importantly, optimizing health so we don’t have sick people or animals to treat in the first place.

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It’s nice to finally be able to talk about H5N1 influenza without discussing ostriches, but unfortunately, we still have things to talk about.

1) Peacocks. Specifically peacocks that don’t have influenza and aren’t going to be culled.

Last month I posted about an animal sanctuary in BC (Critteraid) that was dealing with an outbreak of H5N1 influenza in poultry on the property. The outbreak lead to investigation of the risk to other animals on the same premises, including their peacocks. My understanding is the peacocks were physically well removed from the infected birds, so there was clear rationale to try to avoid culling them. It was a great example of how to respond to H5N1. Critteraid was transparent, worked with CFIA and followed their guidance, and took appropriate measures to contain the infection and decontaminate the affected areas. As a result, CFIA was able to assess the situation through their established processes, the peacocks were tested and were negative for the virus, and they were therefore able to avoid culling them.

2) More sick cats with the flu. This story doesn’t have such a good ending. We know cats are susceptible to H5N1 flu and often develop fatal neurological disease. Recently a lot of attention has been paid to exposure of pet cats to the virus via raw diets and raw milk, but cats can also get infected through contact with infected birds. A recent cluster of fatal H5N1 infections in a group of kittens in the Netherlands reminds us of that risk:

  • On November 19, a kitten from a dairy goat farm was found dead and tested positive for H5N1 flu. Samples were collected from other animals on the property the next day as part of the investigation. Three adult cats (including the kitten’s mother) were tested, as were the goats (the goats probably being the main concern, given the issue with H5N1 in dairy cattle in the US). All of the animals were healthy at the time, and all tested negative.
  • However, the other 7 kittens from the litter weren’t on the farm anymore as they had all been adopted. Further investigation revealed that they had all died; none of them were tested, but it’s quite likely they all could have had H5N1 flu as well.
  • The source of the virus in this case couldn’t be identified, but the mother cat was seen with a dead bird October 27, and it would be logical to assume that the kittens may have eaten part of the bird or been exposed to it it some way. The timing doesn’t quite fit though, as that was 23 days prior to the one kitten being found dead on the farm, which is a very long timeline for flu. I’d have to wonder if there might have been exposure from another dead bird, since the mother cat likely caught birds on more than one day, or she may have been infected by the bird caught on October 27, and then the kittens were subsequently infected by her.

This case is a good reminder of the potentially devastating impact of this virus on cats and one of the reasons why we’d prefer to keep cats away from wild birds. If cats have outdoor access, flu must be a consideration in any cat that develops acute neurological disease or dies suddenly.

We don’t know what’s the risk is to people from infected cats. I think we have to assume there’s some degree of risk since there is evidence to support that cat-to-cat transmission can happen. Fortunately the risk to people seems to be low, given the lack of identified cat-to-human transmission. However, we can’t rely on that to say there’s no risk, both in the present and in particular in the future, as this virus continues to evolve.

It’s World Antimicrobial Resistance Awareness Week. Did you know that? Probably not. Antimicrobial resistance (AMR) is a huge global health threat with an unfortunately crappy marketing plan.

I’m on my way back from the BC One Health and Zoonoses Symposium where I was talking about AMR. It’s a complex issue and there are a lot of things we need to do to address the problem. One is development of clinical guidelines for antimicrobial use (including when not to use them), but a major challenge with guideline development in veterinary medicine is a profound lack of high-quality evidence to guide us.  We have few clinical trials, and even fewer that are properly designed and executed. That doesn’t mean we can’t create guidelines, after all we have to start somewhere, but it limits the certainty we have in the evidence that underpins our recommendations.

Fortunately, we are making progress in this field. Slowly. Trials are difficult to do and can be expensive, and it’s often very hard to find funding for this type of work, but progress is being made.

Peri-operative antibiotics are commonly used (and overused) in veterinary medicine to prevent surgical site infections. Sometimes they are needed, but often they aren’t. Continuing antibiotics post-operatively is still common too for some procedures, but there’s likely little to no reason to do so. We want antibiotics on board during the “period of risk” when contamination of tissues related to surgery is most likely: that starts with the surgical incision and ends soon after the surgical wound is closed. So we want antibiotics in the tissues at good levels during surgery, and potentially for up to 24 hours after, but that’s it. Once the period of risk is over, the benefit of antibiotics plummets and the costs (e.g. adverse events, selection for resistance) outweigh the risks.

Unfortunately, it can be difficult to convince people to stop giving antibiotics post-operatively, because it’s what many have gotten used to doing, and people are resistant to change. Post-op antibiotics is more psychotherapy for the veterinarian or owner…. it make us feel better if the animal gets an antibiotic, but it doesn’t make the animal feel any better (and may in fact do more harm than good).

A new study published just a couple of months ago (Vlhäinen et al. 2025) provides some good new evidence regarding the use of antimicrobials to prevent infectious complications following pyometra surgery in dogs. Good data like these can help convince people to change their habits and helps support our guidelines. Pyometra is an infection of the uterus that is not uncommon in unspayed dogs. In these cases, the uterus basically becomes a big pus-filled bag, and the most effective treatment is removing it (hysterectomy).

In this well-designed randomized controlled trial, 152 dogs undergoing pyometra surgery were enrolled and received an intravenous antibiotic (trimethoprim-sulfadoxine) pre-operatively. Then, they were randomized to either receive 5 days of oral trimethoprim-sulfadiazine (TMS) or a placebo. It was a non-inferiority study, so all they were aiming to do was to determine if no treatment was no worse than antibiotic treatment.

  • Surgical site infections developed in 7.8% of dogs that got post-operative antibiotics and 2.7% of those that didn’t, so not giving post-op antibiotics was definitely no worse than giving them.
  • Post-operative urinary tract infections developed in 2.7% of the treated dogs and none of the untreated dogs, so antibiotics didn’t help prevent these infections either.

In another interesting component, they looked at bacteriuria (bacteria in the urine without infection) of a subset of 43 dogs that were known to have been bacteriuric pre-operatively. They found 14/20 (70%) in the placebo group and 2/23 (8.7%) in the treatment group were still bacteriuric post-operatively.

  • That’s not too surprising, since TMS is a great urinary drug, and 5 days of post-op treatment would be more effective for clearing bacteria from the lower urinary tract than a single dose (single dose treatment for urinary infections works for some drugs but not something I’d have a lot of confidence in for TMS). But remember that only 2 of those dogs had signs of cystitis, and both of them were dogs in the treatment group.  None of the dogs that had pre-operative and then post-operative bacteriuria had any clinical signs of infection. This supports the notion (and our guideline recommendations) that bacteriuria in the absence of disease (subclinical bacteriuria) doesn’t need to be treated.

This study provides some nice evidence supporting the lack of need for post-operative antibiotics in pyometra surgery, which is something we can also likely extrapolate to a range of other “clean-contaminated” procedures.

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The mention of fur farming can evoke some pretty strong reactions from some people, but this industry largely flies under the radar most of the time. The industry itself is dying out in much of the world, as people turn away from raising animals solely for their coats, but large numbers of animals are still farmed in some countries.

Recently, the Federation of Veterinarians of Europe (FVE),  Federation of European Companion Animal Veterinary Associations (FECAVA) and World Small Animal Veterinary Association (WSAVA) released a joint position statement on fur farming. It’s pretty straightforward, and consistent with various other statements, but further highlights concerns about fur farming and pressure from professional groups for countries to take action. The statement calls for:

  • A legally-enacted complete phase-out of fur farming globally in the next decade.
  • A phase-out of farmed animal fur and products containing such fur being placed on the market.
  • A ban on importing farmed animal fur and products containing such fur from countries that have not phased it out.

The position statement supports its call for a ban on fur farming by highlighting the inability of confinement rearing to meet the complex behavioural and physiological needs of species commonly farmed for fur (e.g. species like mink and fox, which naturally range over wide areas and don’t live in large groups), health and welfare problems from common rearing conditions (e.g. wire-floored cages), concerns about euthanasia methods commonly used for these species, the impact of escaped non-native animals on local ecosystems and native species, and zoonotic disease risks.

Some people will point to arguments like “If we ban fur farming, then we should ban all animal farming,” for two different reasons. Some will say it because they want all animal farming stopped. Others will say it to argue that we shouldn’t restrict one type of farming if we aren’t going to restrict others, and to let consumers decide which industries should survive.  

Like most things, there’s a middle ground. The cost:benefit also comes into play, but it can be tough to calculate for multifaceted issues like this where the costs and benefits are not easy to quantify (especially animal welfare) and where a component of the “cost” involves the potential for future infectious disease outbreaks. The societal component is also part of the consideration.

  • The societal benefit of fur farming is likely negligible. Yes, some people make a living from it, and some people like the products, but that’s a very small group. There are less than 100 known fur farms in Canada.  Given the small number, it could be more practical to fund transition plans for fur farms to close or move into other types of agricultural activities, if the main concern is those who rely on the industry for their livelihood.
  • The societal risk from fur farming could be substantial (though it’s hard to predict) since some farmed species are potential reservoirs of a variety of infectious diseases, including some that can infect wildlife or even people. Mink, in particular, are good hosts for a few concerning viruses, like influenza and SARS-CoV-2. Mink farming was eliminated in some countries during the COVID-19 pandemic when it was recognized that mink were getting infected, and the farms had potential to act as viral reservoirs and increase the risk of viral mutations. While the odds a problem developing are really low, the implications if it happens could be really high. The position statement adds “Despite biosecurity measures, fur farms remain a persistent potential reservoir of zoonotic risk, requiring disproportionate disease surveillance, culling, and resource investments.”

So, we have little to no broader societal benefit but the potential for serious infectious disease risks, on top of the substantial animal health and welfare concerns when it comes to fur farming, which is why this statement ultimately calls for a ban. We’ll see if more veterinary associations follow suit with similar statements.  

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Canada recently lost its measles-free status, in large part because of a slip in our overall vaccination rate. A lot of that has been driven by vaccine hesitancy. The resurgence of measles in people shows what can happen when we aren’t using one of our best control methods (vaccination) optimally.

Vaccine hesitancy is an issue in veterinary medicine too, and it’s probably increasing. There are known overlaps between vaccine hesitancy in humans and animals; people who are wary of or opposed to human vaccination often have similar approaches to vaccination of animals. It’s a complex issue, though, with many causes, and unfortunately pretty limited data.

  • One study of people in the US (Motta et al. 2023) showed that 53% of respondents reported at least one component of hesitancy, i.e. expressing concern that veterinary vaccines may be unsafe (37%), ineffective (22%), or unnecessary (30%). We don’t have comparative data for Canada; my guess is it’s less prominent here, but still a significant issue.

Vaccines are highly effective disease control tools, in both human healthcare and veterinary medicine. They aren’t perfect, but they are critically important. They can range from useful aids to critical tools to essentially the only line of protection, depending on the vaccine and the disease. Without vaccines, pet life expectancy would be shorter: we’d lose a lot of young animals to preventable diseases. Veterinary care costs would also be higher. We’d probably have fewer people with pets because of these challenges, especially in urban areas where a lot of pets and pet contacts would mean a lot of disease transmission.

Why are people vaccine hesitant?

It’s critical to understand the reasons behind vaccine hesitancy to try to mitigate the problem.

  • Some people have completely understandable and valid concerns.
  • Some people fundamentally do not believe vaccines are safe or effective, and they will not trust anyone or anything that says otherwise.
  • Some people may not really know why they are hesitant – they’re simply unsure.
  • Internal conflicts can be part of the problem too, such as a person who is really worried about the cost of vaccines, but doesn’t want to admit it (openly or to themselves), and might therefore convince themselves that it’s safer not to vaccinate, to avoid feeling like they are compromising their pet’s health by not vaccinating.

Various other complex scenarios occur too. The bottom line is it’s complicated, and often unclear. That makes addressing vaccine hesitancy challenging.  

  • If someone has trust issues, we can educate them all we want about vaccine efficacy and safety. It won’t matter.
  • If they’re terrified that their dog is going to die from the vaccine because of something they read online, that’s a completely different scenario that requires a different approach.
  • If cost is driving concerns, that’s harder to address.

There’s a lot more to discuss about reasons for vaccine hesitancy, but I’ll hold off on that for now. My focus today is on the implications of vaccine hesitancy.

Potential impacts of moderate decreases in vaccine coverage

Less vaccination means more disease at the individual level. It can also increase the risk of outbreaks, increase the risk of well-controlled diseases becoming uncontrolled, and allow for re-introduction of diseases that were previously successfully contained.

For humans, we want really high measles vaccination rates (>95%) to prevent spread, as well as to protect individuals from disease. That way if someone happens to have measles, the risk of spread is low because so many people are already protected. We need a really high percentage of vaccinated people in the population for this to work for a highly transmissible virus like measles, but we were previously able to do that in Canada – until recently. As vaccine rates slip, when there is an introduction of measles virus into a population, there is a higher risk of sustained transmission among unprotected people, sometimes with devastating results.

It’s a bit different for dogs and cats. We don’t have the same level of baseline vaccine coverage for most of the diseases against which we vaccinate pets, and for some diseases, we also have feral and wildlife reservoirs.

Individual animal risk is straightforward, but population risks in pets are harder to understand. Those risks can’t be ignored, but they also shouldn’t be overstated, since we need to be transparent and clear in our communication with pet owners in order to maintain trust. Let’s use vaccination of dogs as an example:

Distemper

Canine distemper virus (a relative of measles virus) is one of our big concerns in dogs. Disease can be really severe, but vaccines are highly effective. However, we’re nowhere close to eradication because we still have a fairly large pool of unvaccinated dogs, and canine distemper virus is also endemic in wildlife in many areas (especially in raccoons). Reduced vaccination in dogs won’t lead to re-emergence of the disease, since it’s already endemic. Reduced vaccination will mean more disease in general.

So, the risks of less vaccination are mainly to the unvaccinated dogs. However, there is a spillover risk. Just like in humans, where we focus on vaccinating as many people as possible to protect those who can’t be vaccinated, the same principle applies in dogs, since some dogs cannot be vaccinated or cannot respond well to a vaccine. An unvaccinated dog that gets distemper poses a risk to those dogs. The more unvaccinated dogs, the greater the risk to puppies especially, and for a potentially devastating outbreak.

Parvovirus

Issues with parvo are pretty similar to those with distemper. It’s a potentially life-threatening disease in unvaccinated dogs. There’s low level but continual circulation of parvo in the dog population because there are enough unvaccinated dogs (domestic and stray) to maintain it. The risks of decreased vaccination are mainly to the unvaccinated animals. However, as with distemper, when there are more infected dogs, there’s more risk of transmission to other dogs, including puppies that are still to young to be vaccinated.

Leptospirosis

This is an important vaccine in many areas. Leptospirosis is a bacterial disease caused by the spread of Leptospira from wildlife reservoirs (e.g. raccoons, rats). We can’t eliminate lepto from wildlife, so reduced vaccination doesn’t change the overall risk of exposure, but it increases the risk to the unvaccinated dog.

However, there are some secondary risks here too. Dog-to-dog and dog-to-human transmission of lepto seem to be rare, but can happen. If a dog is unvaccinated, it’s at risk of severe disease, and that risk extends (at a low but non-zero level) to its canine and human contacts.

Rabies

There are a lot of interesting aspects to rabies when it comes to dogs. In North America, we don’t have the strain of rabies virus (canine variant) that circulates in dog populations in other countries. Dogs can still get rabies from wildlife reservoirs, such as bats, raccoons and skunks, but we don’t expect strains from those species to result in ongoing transmission of rabies within the dog population. However, canine variant rabies is highly prevalent in some parts of the world, where it causes most of the ~60,000 global human rabies deaths annually. We are at some risk of importing dogs carrying canine rabies. Despite the controls we have in place to prevent it, at least two rabid dogs have been imported into Ontario since 2021, and there’s ever-present risk of it happening again.

If a dog is not vaccinated against rabies, the main risk is to itself. If it tangles with a bat and is exposed to the virus, it’s more likely to develop rabies (which is essentially always fatal). There are other risks, though. When a dog has rabies, there is a short but important window of time when it can transmit the virus through its saliva to any human, domestic mammal or wild mammal contact. There can also be substantial healthcare costs for investigation of human exposures and treatment of exposed individuals. Unvaccinated dogs and cats that are potentially exposed to the virus can be at risk of developing rabies for months, necessitating long confinement periods to prevent exposure of even more people and animals (and sometimes pet are even euthanized because of the risk if they can’t be safely and effectively confined).

The broader population risk from decreased rabies vaccination is much lower. We have eradicated canine rabies in Canada and really don’t want it back. For that to happen, we’d have to import a dog with rabies, it would have to infect other dogs or wild canids, and they would have to keep infecting enough new dogs/canids to keep the disease cycle going. That’s not realistic in a controlled pet dog population, but is a concern with feral dogs (which we don’t have many of in most regions) and wild canids (which are very common in some areas).

The odds of canine rabies virus coming into the country, making it into wild canids and establishing itself anew are really, really low, but they are not zero. While the risk of an unvaccinated pet dog contributing to re-establishment of canine rabies in Canada are likewise exceptionally low, the implications were it to happen, both in terms of health (human and animal) and the costs for control are substantial. So it should not be ignored. Still, the main risks from a dog that is not vaccinated for rabies are to the unvaccinated dog itself and its close contacts.

“Kennel cough” (canine infectious respiratory disease complex, CIRDC)

When it comes to CIRDC, we mainly vaccinate dogs against Bordetella bronchiseptica and canine parainfluenza, with a smattering of vaccination against canine flu. These vaccines are meant to help reduce the risk of infection and reduce severity of illness when it occurs. They’re useful, but they’re mainly for individual health, not reducing transmission or containing the disease. These vaccines are also not as widely used as others, so overall vaccine coverage is pretty low. A moderate reduction in vaccination would not do too much to impact the broader epidemiology of this complex. It would mean that more dogs would get sick, or get sicker than they would have with vaccination.

Do I worry about vaccine hesitancy?

Yes. I hate to see animals dying of vaccine preventable diseases. We can’t prevent all disease, but by optimizing vaccination, we can maximize the benefits to vaccinated animals, and to some degree, other animals and people around them.

How do we address vaccine hesitancy?

That’s way more complex that I can cover in a few paragraphs, but I’ll highlight a few key aspects for addressing vaccine hesitancy (hard core anti-vaxxers and people who spread misinformation are a separate topic):

Communicate communicate communicate

  • We have to listen to why people are hesitant.
  • We have to acknowledge their concerns, even if we disagree.
  • Sometimes we can educate.
  • Sometimes we can work to provide more confidence in veterinary care or vaccines.
  • Sometimes we can allay fears.
  • Sometimes we can just have a good conversation, agree to disagree, and still work to care for the animal.
  • …and unfortunately sometimes it falls apart, or views are so polarized that there’s no moving forward. We just hope those are the minority of cases.

We don’t have the exact same issues in veterinary medicine as human medicine, and approaches to vaccine hesitancy aren’t necessarily going to be identical, but vaccine hesitancy among animal owners is definitely a concern. We need to develop a better understanding of how common it is (and more importantly, the reasons for it), look at ways to address it (including how it’s done in human medicine), have open and honest discussions, and try to optimize vaccination. There’s no one-size-fits-all approach to vaccination and there’s no one-size-fits-all approach to a vaccine-hesitant owner.

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When I was in general practice, we gave puppies and kittens their first rabies vaccine at 16 weeks of age. I didn’t ask why, it’s just what the clinic did, so as a new grad, that’s what I did. This practice is (unfortunately) still common in a lot of clinics; however, all rabies vaccines approved for use in dogs and cats in Canada are labelled for use in puppies and kittens starting at 12 weeks of age. In Ontario, it is legally required for all cats and dogs (and ferrets) to be vaccinated for rabies as of 3 months of age.

This begs two questions:

  • Why is rabies vaccination still often not done until 16 weeks of age (even in Ontario)?
  • Does it really matter if dogs and cats are vaccinated at 12 weeks vs 16 weeks?

The answer to the first question isn’t really clear, but there are a few possibilities:

  • Habit. That’s what was done before, so that’s what we do now.
  • The desire to make sure owners bring their pet back for the other core vaccines at 16 weeks of age. We need to give at least one dose of core vaccines (i.e. DAPP for dogs, FVRCP for cats) dose at 16 weeks of age or older, because antibodies from the animal’s dam can sometimes block response to those vaccines before a certain age (known as maternal antibody interference). Owners often focus on getting their pet an initial rabies vaccine (if they’re getting vaccines), so there’s some concern if they get it at 12 weeks, they might not come back for the critical 16 week dose of the core vaccines.
  • Concern about adverse events. Some people want to avoid the extra vaccine at 12 weeks of age when the animal is younger, and smaller (even though we don’t know that actually helps).

Overall, we don’t have great reasons to wait to vaccinate pets until 16 weeks of age, but we have at least one very good reason (i.e. protection against a universally fatal viral disease) to vaccinate them as early as possible.

Does 12 weeks versus 16 weeks of age really matter? Sometimes yes.  

I’ve been involved in a few situations where a puppy or kitten (usually a puppy) tangles with a wild animal (often a bat) and is considered at risk for exposure to rabies. The most unfortunate cases are the ones where the dog was old enough to have been vaccinated before the exposure happened, but vaccination was delayed. In Ontario, the difference in post-exposure management for a vaccinated versus unvaccinated puppy is huge (and the same is true in many other jurisdictions as well).

  • After a potential rabies exposure, a vaccinated dog/cat that gets a rabies booster within 7 days only needs to be observed at home for 45 days, which is pretty easy to do, and the animal can still be socialized.
  • After a potential rabies exposure, an unvaccinated dog/cat is considered at risk for developing rabies for 3 or 6 months, depending on whether the pet gets that critical post-exposure rabies vaccine within 7 days. This necessitates a much stricter “precautionary confinement period” (PCP), which can be really difficult to do with a puppy (or kitten), and dramatically limits the ability to properly socialize a young animal, which can have life-long consequences. In some situations the owner can’t effectively confine the pet, in which case they may (sadly) choose to euthanize the pet instead.

The general recommendations for an observation period versus a PCP in Ontario are shown below:

Why can we give a single dose of rabies vaccine at 12 weeks, but we can’t be confident in the response to other core vaccines at the same age?

Rabies vaccine is really good at what it does – it stimulates a great immune response. Rabies vaccine is also a killed vaccine, and killed vaccines are not impacted by maternal antibodies to the same degree as modified live or recombinant vaccines. Those vaccines usually contain a small amount of the modified or recombinant virus, which has to either replicate or induce expression of their target proteins to stimulate a protective response from the immune system. Maternal antibodies can neutralize this small amount vaccine virus, which limits or prevents the desired immune response. While there can be some maternal antibody interference with killed vaccines, it’s much less of an issue because of the large amount of antigen in the vaccines, and no need for it to replicate.

As a result, our default should be to vaccinate puppies and kittens (and ferrets) against rabies at 12 weeks of age. There may be rare circumstances where that’s not possible, but that should be the goal. At the same time, we have to do good client education to make sure they bring their pets back for the all-important 16 week core vaccines, because when I see parvovirus or distemper “vaccine failures,” it’s almost always dogs that got some puppy vaccines but stopped too early, before that 16 week dose.

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Hot on the heels of the H5N1 influenza in ostriches debacle in BC comes a reported outbreak of H5N1 influenza at an animal sanctuary in the same province. The sanctuary (Critteraid Animal Sanctuary) is not one I’ve ever heard of before, but based on their website, it looks like a good operation, and their response to this situation elevates them further in my mind. Unfortunately, even the best run facilities can be at risk from H5N1 influenza.

The sanctuary said on Facebook that one of their roosters got sick on Saturday October 25 and died; they sent the body for diagnostic testing (which is great). By Monday October 27, three more chickens had died; they were sent for testing too.  Ultimately testing identified H5N1 influenza as the cause. Overall, 8 of their 10 chickens died, and the other 2 were sick and had to be euthanized (probably both because of the severity of disease and because of the H5N1 flu test result on the other chickens, which would trigger a cull order).

The CFIA confirmed the test result and the farm closed. Five ducks had to be euthanized too. It’s not clear if they were sick (it doesn’t sound like they were sick, at least not yet) but because they’re poultry and there was potential exposure to the virus, they would be included in the cull order. It’s heartbreaking, since these were truly pet ducks that had likely been at the sanctuary for a long time. However, the sanctuary didn’t try to hide the birds or argue with the authorities – they accepted the unfortunate but necessary response to control this high consequence disease. They worked with CFIA and euthanized the birds themselves (versus having CFIA do it), saying “we made the choice that to ensure our policies of compassion were upheld and they deserve that dignity, that we did it ourselves.”

The farm has been working with CFIA and BC Interior Health, and they provided information about human contacts for contact tracing. Twelve people were potentially exposed to the infected birds.  They are all healthy and presumably are being monitored by public health for a couple of weeks to make they don’t develop any signs of influenza.

As per standard policy, the facility is quarantined and is undergoing decontamination to further contain the virus. The other animals on the farm consist of pigs, goats, cows, dogs and cats, which are not subject to culling, as they are not poultry. They will presumably be closely monitored. Ideally we’d test any that had very close contact with the infected birds or their environment, but that would be primarily to gain more knowledge about the inter-species transmission risks, rather than as a control measure on the farm. Testing the other animals is not required, but it would be an opportunity to learn more.

Even though the sanctuary is in the middle of this highly stressful and draining situation, they’re thinking ahead, as they indicate “now more than ever we feel the need to educate ourselves further to ensure we have a safe environment for birds in the future.”

This is the antithesis of the Universal Ostrich Farm.

Sadly, but not surprisingly, what should have been a relatively small local story has blown up, with anti-vax / anti-CFIA / anti-public health activists and influencers making up stories about the CFIA “coming for all the animals” (and more broadly, anyone’s pets). I assume they were hoping to move the convoy to another location to continue to party, protest and ask for money.

The situation also seems to have (again, not surprisingly) led to threats against the facility. On Facebook, they outlined the time frame and their response (see below). As part of that, they address a lot of things that they shouldn’t have to, including that they have nothing to do with a couple of petitions that are just spreading fear, misinformation and mistrust. That’s the last thing with which they should have to deal right now. Clearly the conspiracy fringe is in full motion:

I don’t know why the sanctuary is being threatened. It could be because they’re not being vociferous against CFIA, and thereby making it hard for that crowd to leverage the incident for attention and fundraising.

Regardless, the situation and the facility’s response are worth noting. From all I’ve seen, this is a great example of what should be done. The farm has been transparent, fair and taken responsibility for what needs to be done. It’s not their fault they got H5N1 flu in their birds. Particularly with birds that live outside, a big component of it is just bad luck. How they responded is key, and that seems to be going well.

Rather than sending more donations to grifters, dodgy “reporters” and everything else we saw with the ostrich debacle, donating to this sanctuary that is navigating a very tough situation would be great. I just did.

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As the H5N1 influenza debacle at the Universal Ostrich Farm in British Columbia finally comes to a close, part of me wants to ignore all the crap that’s coming in, but there’s value in recapping this incident in an effort to help move us forward.

Recap: A large flock of captive ostriches was found to be infected with H5N1 influenza in December 2024. Contrary to federal legal requirements to report this disease immediately, the farm hid the issue and didn’t do any of the things typically required to respond to a detection of this high-consequence virus. It’s been reported that 69 birds died and 300-400 birds survived (they never could come up with an exact number). When the outbreak was discovered, the Canadian Food Inspection Agency (CFIA) got involved, as is their mandate. As per standard protocols for detection of H5N1 flu in poultry (captive ostriches are considered poultry by international designation), a cull order was issued immediately. However, the farm fought the order by trying to appeal and sue the CFIA, while taking no measures to try to control the spread of the virus – if fact they did the opposite, showing pictures of people posing with the birds without personal protective equipment (PPE), and inviting a convoy of farm supporters onto the grounds. Ultimately, the case made it to the Supreme Court of Canada, which issued one last temporary stay order on the cull in late October, but ultimately declined to hear the last appeal. As a result, CFIA completed the cull of the remaining birds on November 7.

Make no mistake, the ostriches are the victims here. They had bad luck in being exposed to H5N1 flu in the first place, and they had little chance of avoiding a cull because of the mess of a farm on which they lived. But this case moved quickly from being about disease control to being about politics and fundraising, and the birds got caught in the middle.

Why was a cull done?

A cull is a standard approach to controlling H5N1 influenza in poultry because of the risk to animals and people. It’s done to contain the virus and reduce the risk of further transmission to other birds, spillover into mammals (which increases the risk of the virus adapting further to transmission between mammals), infection of people (given this virus has a historically high mortality rate) and, of most concern, recombination with other animal and human flu viruses (which is how all pandemic flu viruses originate).

Were the ostriches infectious in December 2024?

Yes they certainly were, and likely at great risk of infecting wild birds, wild mammals and any people or other domestic animals on the farm. It was subsequently determined that the strain found in the ostriches was a variant that has caused human infection and had some potentially concerning mutations.

Were the ostriches infectious when they were culled in Novemeber 2025?

Probably not. In a group like this, the virus probably burned through the entire population by January or February. Long term shedding of flu virus in infected birds is unlikely, so with a group this size over 10 months, realistically the flock would have had to be reinfected to sustain transmission. Could that have happened? Maybe, but probably not. Unfortunately ” but “probably” isn’t an acceptable threshold for control of this disease. If we don’t know the virus is gone, prudence dictates that we assume it’s still there. That’s the approach that CFIA (understandably) takes with highly pathogenic avian influenza like this.

Was there an alternative to culling the birds?

That’s a big “maybe” with lots of caveats. While culling is the international expectation, countries can take alternative approaches if they can show they’re taking other measures to adequately contain spread of the virus. That’s not expressly defined though, so it’s a grey area for a regulatory agency that doesn’t like to work in the grey zone for a lot of good reasons. It would require reliable isolation of the birds, strict infection control practices, testing, monitoring and documentation. That’s tough to do in general, but t’s really tough with outdoor birds and uncooperative owners.

At the time the outbreak was happening, it was fair to say trying to contain the virus by any other means was not reasonable. The risks were too high with the setup they had. But the ball got dropped, and so there we were ten months after the fact… at that point, testing could have potentially made more sense. That’s no easy feat either, though. Ostriches are big birds that can cause significant injury to people handling them, especially where there are poor (to non-existent) handling facilities. Trying to stick a swab down the throat of a large bird that can split you open with a kick is hard to sell.

In order to make testing work, each bird would have needed to be caught, identified, and tested. If there were zero positives in the group, I’d be pretty confident the group was negative. That’s theoretically possible. However, there would likely have been a need for ongoing monitoring to have confidence in the negative group status. Since the farm hid the disease initially and showed no interest in implementing disease control measures, it would be hard to convince anyone such an approach could have been effective.

Furthermore, even if the World Organization for Animal Health (WOAH) thought such an approach for controlling the virus was adequate in this flock, that doesn’t mean all countries would agree. Any country could then restrict importation of poultry (or other food products) from BC or even all of Canada on the premise that Canada was not protecting its food supply. Even if it’s a dodgy claim, a country with an agenda or that wants leverage for negotiations could play that card, and be successful.

When there’s potential risk to animals, humans and multi-billion dollar industries, the bar for disease control is obviously going to be very high. So was an alternative to culling the birds possible? Yes. Would it have been easy? Certainly not. While easy isn’t a requirement, in this case it wasn’t that it was just a hassle, it was that there was a good chance it might not ultimately be possible.

Did the ostriches have herd immunity to H5N1 flu?

For a group of supporters who were comprised of a large proportion of individuals who were anti-vax (and anti-PCR, and anti-public health and some people who don’t believe viruses exist at all), they put a lot of attention on herd immunity (which we typically try to achieve in a given population of people or animals through vaccination). It’s very unlikely this group was immune to H5N1 flu. the birds that were exposed and fought off the infection would have some immunity, but we know that immunity to influenza after natural infection isn’t great or long-lasting – that’s why people and animals can be repeatedly infected with flu. Some of the birds might have been immune, or at reduced risk of severe disease. Some were probably previously infected but are not immune. Some might not have been exposed and were not immune. As a group, it’s very likely that there would have still been susceptibility to re-infection if there’d been another exposure to the virus, so there was still risk.

What about the “research value” of the ostriches?

The farm talked a lot about how these are no longer meat birds, but rather a “research flock.” However, they were never able to present any information about valid research for which the birds were being used. They didn’t indicate that there was ethics approval for research on the farm (a basic requirement for research involving animals). They didn’t even know exactly how many birds they had, and the birds had no form of identification (tags, microchips); without basic information like that, the farm can’t be a legitimate research operation.

Even though the remaining birds survived H5N1 influenza, that still doesn’t make them inherently useful research animals. We don’t know how many fought off the infection (something we know many birds of some species can do) or weren’t actually exposed. The birds that survived an infection may have antibodies against H5N1, but so would any other animal that survived natural or experimental infection, so there’s no unique value there.

Where do we go from here?

Hopefully we can look back on this case and salvage something positive from this mess and the unfortunate ending for the birds. There are a few key components:

The Supreme Court has re-inforced the appropriateness of CFIA’s disease response. This is important since it might reduce the chance of future lower court successes with appeals and stays. It’s fair to criticize CFIA and demand that they have oversight. It’s also fair for CFIA to say “we have to contain this disease for the protection of animals and people, and we need to do it quickly.” No one at CFIA celebrates when they have to cull animals. They do it as an unfortunate but necessary part of their mandate to protect animal health, human health, agriculture and the food supply.  Allowing people with agendas to weaponize the court system creates risk.

There may be valid arguments for approaches other than a cull, in certain situations, as H5N1 flu is now an endemic disease in wild birds. However, this needs to be done carefully, with a lot of transparency, effort, structure and excellent care. In other words, exactly the opposite of what happened here. A mechanism to promptly evaluate a potential alternative, with a clear approach, set criteria to review (what, who, etc.), a very rapid response and no appeal process would be interesting to investigate.

As part of any alternative approach, there would need to be excellent interim containment. If a farm wants to convince CFIA to take a different approach, they need to do absolutely everything possible to contain the disease when an outbreak occurs. If it can be done with minimal risk, it’s potentially viable. If it creates risk in the interim, it’s not. Even if this farm had done the exact opposite of what they did, and diagnosed the issue quickly, reported it, properly disposed of dead birds and enacted strict infection control practices, it’s debatable whether an exemption during the acute disease period would have been viable because of their set up. You can’t contain a few hundred large birds (producing lots of virus-laden snot and feces) outside in an area with abundant wild birds, with no indoor isolation options or handling facilities. Without appropriate facilities and management, it’s not an option. That’s not CFIA’s fault. That’s a choice by the farm about how they operate. Raising birds outdoors isn’t bad, it just create risk that any farm needs to accept. And when it results in disease, there are consequences.

We had a high consequence virus on this farm, they handled it horribly, the virus in question had some mutations that created even more risk, and nothing bad seems to have come of it (that we know of, at least) in terms of disease spread. Does that mean none of this made sense?

  • No – we just got lucky, and you only get lucky so many times with a high consequence infectious disease that has pandemic potential.

It’s really sad how infectious disease control (and beyond) has gotten so politicized. This went from an issue with one group of infected birds to having a convoy on the (quarantined) farm, massive misinformation, dodgy “media” stirring up hate, threats to experts and people doing their jobs, massive fundraising and grift, largely by people who likely don’t care whatsoever about those ostriches. It also cost taxpayers a huge amount of money, and took up time a resources that could have been much more effectively spent elsewhere. The ostriches were political pawns and an excuse to complain, raise money and have a party at the farm. We need to move beyond that component of this issue and come back to the valid disease control questions that can and should be discussed going forward.

New World Screwworm (NSW) is a nasty parasitic infestation (with a very high ick factor) that’s back on the radar in North America, re-emerging after several decades of highly successful control and eradication efforts that had pushed its northern reach back as far as Panama. It has now made to back as far as northern Mexico, within a few hundred kilometers of the US border, and there’s significant concern that it will continue to move north, despite concerted efforts to halt its progression. The primary risk is to livestock, which can be infected when the flies (Cochliomyia hominivorax) lay their eggs in any tiny wound or break in the skin. Importing animals from affected regions, including much of South America and some Caribbean countries, is a huge risk for moving NWS to new area, which is why the US closed its border to livestock from Mexico months ago. But NWS can also infected companion animals, and lots of dogs also get imported to the US and Canada from endemic countries. While the parasite can’t establish itself in the northern US or Canada thanks to our cold winters, it’s still very important for veterinarians here to be on alert for NWS in imported animals.

Treatment of NWS infections involves first and foremost physical removal of the maggots (ick), followed by administration of anti-parasitic drugs to try to kill any deeper maggots we can’t see or remove. Some anti-parasitics can also help to prevent disease by killing developing larvae after the fly eggs hatch, before they start destroying the living tissues of their host.

There isn’t a licensed drug for NWS in Canada or the US, not necessarily because nothing works, but because manufacturers haven’t sought this approval for any existing products, because it’s a very time consuming and expensive process to do so, and the disease has been eradicated from the region for decades.

Fortunately, we do have some off-label options. A few different antiparasitic drugs that we routinely use in dogs and cats can be effective. This would classically focus on ivermectin (shown to have some effect in cattle) and the related drug, moxidectin. There are also a variety of drugs that are authorized for flea and tick prevention / treatment which could be effective.

  • It’s important to note that the label doses of ivermectin and moxidectin that we use for heartworm prevention in dogs are substantially lower than the doses that might be effective for treatment of parasitic infections like NWS, so having a dog on heartworm preventative won’t prevent screwworm infection.

Earlier this year, the US FDA posted information for veterinarians on a few drugs that may be potential options for off-label treatment of NWS, including ivermectin, moxidectin, nitenpyram, afoxolarner, lotilaner, sarolaner, milbemycin and spinosad, mostly based on an assumption that they could work, rather than any hard data showing they do (or don’t) work.

New EUA for Credelio (lotilaner) for NWS in dogs

New this week, the US FDA issued an Emergency Use Authorization (EUA) for Credelio (lotilaner) for the treatment of NWS in dogs and puppies. They concluded that:

  • “Based on the scientific evidence available to the FDA, including data from published scientific literature, it is reasonable to believe that Credelio may be effective for the treatment of infestations caused by NWS larvae (myiasis) in dogs and puppies, as described in this authorization, and when used under the conditions described in this authorization, the known and potential benefits of Credelio outweigh the known and potential risks for dogs of all ages and weights because NWS is potentially fatal in dogs if left untreated, therefore justifying including dogs less than 8 weeks of age or less than 4.4 lbs in this authorization.”

The authorization is based largely on a 2023 study of dogs in Brazil with naturally occurring NWS infection (Vale et al. 2023). It was a very small, single arm, open label study that involved treatment of 11 naturally infected dogs with a single dose of lotilaner, which showed 100% efficacy at expelling and killing larvae after 24 hours. It’s a small study, but still very useful, as such a high success rate provides pretty good confidence in the efficacy of the drug.

Does having this EUA for Credelio (lotilaner) in the US change anything?

Yes and no. Veterinarians have always been able to use the drugs on the FDA list in an extra-label manner in companion animals, so in that sense having the EUA doesn’t change this kind of access. However, it’s an impetus to consider lotilaner first since it’s now authorized and has some supporting data. That provides more confidence and backing when it’s used to treat an infected dog.

It doesn’t necessarily mean that lotilaner works better than the other drugs on the list for treating NWS? It just means the drug has been given an EUA. Presumably that could have happened for other drugs with some efficacy data, such as ivermectin, but since ivermectin is off-patent and available in a variety of products, it’s unlikely a manufacturer would go through the time and effort to get an EUA. Nonetheless, it’s ideal to use authorized drugs whenever we can, so this should lead to preferential use of lotilaner for treatment of NWS in dogs.

Should lotilaner be the tick preventive of choice now, since it also helps treat screwworm?

That’s a tougher question, and presumably will be a big talking point for all companies marketing ectoparasite preventatives. The EUA is for treatment, not prevention of NWS, but the two go hand-in-hand to some extent as treatment of early infection is basically the same as prevention. Since NWS is (hopefully) going to be a very rare occurrence in dogs in the US (and even rarer in Canada since our climate prevents the fly from living here much of the year), it’s to use this as a reason to say lotilaner should be the ectoparasite preventive of choice. However, it would be a fair consideration in areas where the risk of NWS is high (e.g. if it establishes a foothold in southern Texas).

It’s great to have an EUA for a treatment product for dogs, to help guide treatment choices and provide veterinarians with some backing when managing a case, but the EUA isn’t really a game changer. It’s nice that the manufacturer pursued it, even though it might have been driven by marketing advantages more than anything else. Emerging and rare diseases are often neglected and efforts by companies and the FDA to support their management are useful.

Image from https://www.cdc.gov/new-world-screwworm/about/index.html

The other day, I did a half-hearted tick drag while walking Ozzie in our back field (yes, I know that’s strange, but let’s move on…). It was far from a professional job – just me dragging a blanket through the field as we walked, but it did the job. It quickly picked up a tick, that I quickly dropped – by accident (I’ve fortunately moved beyond the point of being freaked out about ticks). However, I had a an more effective tick-dragger with me: Ozzie. When we got back to the house, my towel was clean, but my dog was not – we found not one but three ticks on him (and none on me… I checked). It really didn’t stress him out too much.

Although we’d been walking through a hay field through which I’ve cut a walking path, Ozzie of course trolls through the longer plants and leaf litter along the side of the field, which is classic tick territory, so it’s not overly surprising that he’d pick up some ticks. Not surprising these days at least, but it would have been about 5 years ago. Up until then , I’d never seen a tick on one of my animals (or myself, or my kids). Things have changed a lot in those years.

It’s noteworthy that Ozzie picked up black legged ticks, Ixodes scapularis (first picture below).

That’s the first time I’ve seen that type of tick here, but I’ve been expecting it as it’s been steadily moving into the area. Ixodes scapularis is one of the vectors of Lyme disease and anaplasmosis, diseases that affect both dogs and people. When we first started seeing ticks in this area, they were all American dog ticks, Dermacentor variabilis. The next picture below is one of these ticks which we found on Ozzie earlier in the year. We’ve traditionally considered that tick to be pretty benign in Ontario, but the recent detection of Rocky Mountain Spotted Fever in Long Point, Ontario might change that.

Tick exposure risk definitely varies over the seasons of the year.

Tick exposure risk drops substantially in the winter, because when the temperature is below 4C (or maybe 0C), ticks aren’t looking for hosts (questing). Ticks also tend to stay hidden in protected areas during hot, dry weather, so there is also usually a lull in tick exposures in late summer.

There’s also seasonality to what tick species dogs or people are likely to encounter. Fall is black legged tick season here, with almost none of the American dog ticks we see at other times, but the American dog tick season here may be getting longer as we seem to be finding them later and later in the season lately.

Ozzie’s on tick prevention medication, so any ticks that attach should die within hours. That’s great for preventing Lyme disease and anaplasmosis, as those take at least a day to be transmitted from the tick. It’s a bit less effective for Rocky Mountain Spotted Fever, since ticks can transmit the bacterium that causes that disease (Rickettsia ricksettsii) much quicker, and there’s overlap between the potential transmission time and the time that it takes tick preventatives to work. The preventatives are still very useful, but they aren’t 100% effective at stopping all pathogen transmission. So, other risk reduction measures such as avoiding high risk areas and tick territory (e.g. long grass and leaf litter) and doing regular tick checks are also important. We’re fortunate that Ozzie is a yellow Lab, as it’s not hard to find ticks on a dog with a short light-coloured haircoat. Darker dogs and dogs with long hair are a much bigger challenge. Tick checks are likewise far from 100% effective, but they’re an important part of the toolbox.

There’s also an important dog factor to consider with regard to the risk of human exposure to ticks. The ticks we found on Ozzie after the walk weren’t yet attached to him, they were just wandering around in his hair coat. If left alone, they’d most likely they’d attach to him quickly and subsequently die because of the tick preventative he’s on. However, loose ticks can also fall off a pet or be transferred to people or other animals that weren’t necessarily exposed to the environment where the tick originated. I’ve found the odd tick free in the house that presumably hitched a ride in on Ozzie. Ticks checks on dogs can therefore also help protect people by preventing loose ticks from ending up in the indoor house environment.

Knowing about local ticks and tickborne diseases is important for everyone, dog owner or not. It helps us understand when and where the risks are highest, and informs the types and intensity of prevention measures we need to use.

Public Health Ontario has a relatively new online interactive vector borne disease tool that shows high risk areas for black legged ticks, and provides information about the incidence and distribution of various vector borne diseases (in people). The black legged tick risk map shows our property just within one of the risk zones, which fits with the changes we’re seeing.