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My daughter’s kindergarten class is having a gingerbread cookie decorating event tomorrow. They’re supposed to bring a guest (in Amy’s case, me) and some items (e.g. candy sprinkles, gummies) to put on the cookies. I was surprised (but impressed) to see a statement asking people to avoid bringing items from bulk bins because of the potential for cross contamination. The concern is that bulk bin items could be contaminated with items such as nuts, which are banned from schools because of allergies.

Cross contamination can also involve bacteria, and can extend into the realm of pet treats. Salmonella contamination of rawhide treats is a problem, and rawhides and other raw pet treats have been the cause of multiple outbreaks of salmonellosis in people. Salmonella (and E. coli, and other bacteria) contamination is a concern with any raw animal-origin product, and while there have been improvements in some areas in manufacturing practices, some risk will always be present. That’s why rawhides, pigs’ ears and similar treats shouldn’t be present in households with young children, elderly individuals or people with compromised immune systems, and why good attention to hand hygiene is needed when these products are handled. Buying individually-packaged rawhides (instead of bulk bin items) is also recommended. Bulk bins may offer some cost savings, but you are at the mercy of cross-contamination and potential accumulation of Salmonella and other bacteria. If one rawhide is contaminated, it can cross-contaminate all the other rawhides in the bin. If bins are just topped up as they get low, this can lead to contamination of a large number of rawhides. There’s also the risk of exposure when you reach into the bin and grab one (and it’s unlikely that you’d wash your hands afterwards).

Hartz Mountain Corporation has voluntarily recalled one lot of its chicken-basted rawhide chews for dogs because of potential contamination with Salmonella. 

Rawhide treats, as the name suggests, are raw treats that  are literally made from the hide of typically cattle or pigs. The finding of Salmonella in rawhide treats is not particularly surprising, since Salmonella is commonly found in raw meat products, especially chicken.  In this case it is not known exactly how the product may have become contaminated. High rates of contamination of raw pet treats have been reported, although a recent study reported improvement in products in Canada.  This has likely occured because of action from the industry in response to outbreaks of disease in people that originated with treats. It’s important to remember that any raw animal-based product that has not been treated (e.g. irradiated) to get rid of bacteria could contain harmful pathogens like Salmonella. They are best avoided, especially if high risk individuals (e.g. very young children, elderly persons or anyone with a weakened immune system) might come in contact with the treats or the pet to which the treats are fed. If you do decide to feed your pet raw animal-derived treats, care should be taken to reduce the risks of transmitting pathogens like Salmonella, as is recommended with raw meat diets. More information about raw meat feeding and Salmonella in pets can be found on the Worms & Germs Resources page.

rawBecause of the significantly higher rates of shedding of certain potentially harmful bacteria by dogs that are fed raw meat, I think raw meat diets are a bad choice – especially in households with young children, elderly individuals or people with compromised immune systems. However, if you are going to feed raw meat to your pet, you should take some basic precautions.

  • Only use meat that is suitable for human consumption. Don’t buy ‘adulterated’ meat or meat labeled unfit for human consumption.
  • Keep raw meat frozen until you need it. Only thaw out the portion that is need for the next feeding, and thaw the meat in a sealed container on the bottom shelf of a refrigerator.
  • Handle raw meat with care. Do not allow it to contaminate kitchen surfaces or items that may come in contact with other food. Clean and disinfect any items that come into contact with raw meat.
  • Wash your hands thoroughly after handing raw meat or anything that has touched raw meat (e.g. your dog’s food bowl).
  • If your pet does not finish all the meat fed right away, discard any uneaten raw meat promptly. Do not allow raw meat to sit in a bowl at room temperature. Some dangerous bacteria can multiply rapidly under these conditions.
  • Regularly clean and disinfect your pet’s food bowl, but bear in mind that  a recent study showed that it is very hard to eliminate Salmonella from raw meat in food bowls.
  • Make sure your veterinarian knows that you feed raw meat. This is particularly important if your dog develops vomiting or diarrhea.
  • It is very important to make sure that your pet’s diet is well balanced, which can sometimes be difficult to do when feeding non-commercial or raw diets.  Read about raw meat feeding, and try to find good sources of information (which is not always easy) to reduce the risk of problems caused by feeding an unbalanced diet.
  • Never feed raw meat to sick dogs, puppies or pregnant dogs.

 

Meat QuestionFeeding raw meat diets to dogs is a very controversial issue. Some proponents passionately advocate these diets (e.g. the BARF diet) based on vague and unproven recommendations. Opponents cite various studies showing that pets fed raw meat (not surprisingly) have high carriage rates of potentially harmful bacteria such as Salmonella, and reports of diarrhea or nutritional imbalances in these animals. However, there have been only a few good studies looking at the true health benefits and risks of feeding these diets to dogs.

A recent study in the journal Zoonoses and Public Health described the risks of therapy dogs shedding Salmonella and other potentially harmful bacteria. The authors tested 200 dogs over a 1 year period, 20% of which were fed raw meat as part of their normal diet. Dogs fed raw meat were 23 times more likely to shed Salmonella compared to other dogs. They were also 17 times as likely to be shedding extended spectrum beta-lactamase (ESBL) Escherichia coli (a highly drug-resistant form of E. coli).

The study concluded that, because of the risk of Salmonella shedding and the high-risk nature of the patients and other people that therapy dogs interact with, dogs that are involved with hospital/patient visitation programs should not be fed raw meat.

What does this tell us about feeding raw meat to pets?

Although this study doesn’t answer all of the questions about the risks of raw meat diets, it reinforces the fact that pets fed raw meat have significantly higher rates of shedding of potentially harmful bacterial such as Salmonella and antibiotic-resistant E. coli. Eating pig ear treats has also been associated with Salmonella shedding. However, there was no association between a dog being fed raw meat and the animal itself developing diarrhea. In fact, raw-fed dogs had a lower incidence of extra-intestinal infections (combination of eye, ear, skin and urinary tract infections).

In general, raw meat diets should be avoided. While adverse health effects were not reported in this study, disease (including deaths) from Salmonella has been reported in dogs in other studies. While the overall risk may be low, feeding raw meat is an avoidable risk. However, it would be inappropriate to completely ignore the finding that raw-fed dogs had lower rates of certain infections. It is possible that there can be health benefits from feeding raw meat in certain dogs, but the potential benefits must be weighed against the potential risks to the animals and people with which the has contact. Raw meat diets should never be fed to pets that have contact with immunocompromised people (in the household or as part of visitation program), infants or the elderly.

If you are going to feed raw meat to your pet, make sure you take precautions to reduce the risk of infecting yourself or someone else. We’ll post more on that aspect soon.

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The Colorado Department of Public Health and Environment recently released information about 6 cats in the state diagnosed with H5N1 influenza. Some aspects of these cases are totally unsurprising, others raise a lot of questions.

Colorado has been hit hard by H5N1 in dairy cattle, with over 50 herds affected since the spring, but they’ve also taken a more proactive response than many areas. This report covers the 6 cats that have been identified (so far) in 2024.

Let’s start with the totally unsurprising.

One cat was from an infected dairy farm.

  • Duh. That one’s easy to explain.

Three were “known indoor/outdoor cats that hunted mice and/or small birds as prey and also spent time indoors with their owners.”

  • These aren’t too surprising either. When the virus is circulating in birds, species that prey on birds are likely to get exposed.
  • Genomic evaluation of the virus will help tell us if the strains in these cats are consistent with those circulating in local birds (as they should be), versus the slightly different strains circulating in cattle (hopefully not).

Now to the unexpected cases. These are the most interesting and important cases, and they illustrate some major gaps in our understanding and approach to this virus.

Two cats were indoor cats with no known exposure to H5N1.

  • These cats didn’t have contact with birds or dairy cattle.
  • Presumably they also didn’t have contact with any person known to have had H5N1 (as there are still few enough of those cases) or contact with high risk people like dairy or poultry farm workers, but that’s not explicitly stated.
  • I also presume the authorities took a good enough history to make sure “indoor” really meant “indoor,” since “indoor” is sometimes an aspiration for cats, not a lifestyle. (Veterinarians are all too familiar with “indoor” cats that have been hit by a car or gotten into a fight with some kind of wildlife.)

So how did two “indoor” cats get exposed to the H5N1 virus?

A few potential, but still unlikely, possibilities come to mind:

  • Close contact with aerosols from infected birds or bird feces through window screens?
  • Close contact with aerosols from infected mammals (e.g. other cats) through window screens?
  • Birds that snuck into the house?
  • Unidentified infected humans?
  • Contaminated material from outside tracked in on someone’s shoes or clothes?
  • Raw food? (Including possibly raw milk?)

The latter, in the form of raw diets, has been shown to be a risk factor in a few outbreaks in cats, so we can’t dismiss it. However, the odds of a raw diet containing meat from an infected bird in Colorado are really low. So, I think potential causes are still wide open at this point. Genomic analysis should help determine if the virus from these cats is most consistent with the strain in dairy cattle or circulating avian strains.

These cases also highlight something else: surveillance bias. If you don’t test, you don’t find. If testing is focused (or restricted to) cats with known high risk contacts, we can get into a self-fulfilling prophecy of “cats only get infected if they have risk factor X.” The two unexpected cases in indoor cats show that we might need to throw a wider surveillance net, both to find more infected cats and to understand how this virus is being spread.

The disease presentation is also important. Five of the six cats had “an initial complaint of lethargy and inappetence, followed by progressive respiratory signs in some and fairly consistent progressive neurologic signs in most.” It’s not clear how disease progressed in the sixth cat, or if it was perhaps found dead. Consider that if testing focuses on cats with neurological disease, we’ll bias ourselves to thinking that this virus always causes neurological disease. I’m not sure at this point whether H5N1 infection usually causes serious neurological disease or whether the cats with serious neurological disease are just the small subset that we test for H5N1. If those are the only cats we test (perhaps as a secondary test when the cat was a rabies suspect and has tested negative for that virus first), then we’re not going to understand the true picture.

We need better and broader surveillance. I get worried when the focus of testing is on a narrow population. Yes, it’s lower yield to test outside those known high risk groups, but when we have lots of knowledge gaps, we sometimes have to go on fishing expeditions.

What does this tell us?

  • If H5N1 is in birds or cattle, cats can get exposed.
  • H5N1 can cause serious neurological disease in cats. Maybe that occurs in a minority of infected cats, or maybe it occurs in most. We just don’t know yet.
  • Not all cats with H5N1 will have known exposure to infected dairy cattle or birds. We need to do more testing to figure out what’s happening.
  • Infections in cats seem to be rare, but can be fatal, so we need to pay attention.

The risk posed by cats to people and other animals is completely unclear at this time. Some earlier data suggested that cats could have pretty high viral loads in respiratory secretions, so I think we have to assume that infected cats pose some transmission risk. That doesn’t mean we should panic or not try to treat them, but we should make sure we use good infection control practices around suspected and confirmed cases.

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We know a lot more about the situation with H5N1 influenza in dairy cattle than we did a couple of weeks ago, thanks to ongoing research and (more importantly) better disclosure of information that has been held pretty tight up until now.

Current situation with infected dairy herds in the US

Rather than focus on numbers, I’d rather just say it’s on lots of dairy farms in lots of US states. As discussed below, this is likely much more widespread than the official numbers suggest, so those numbers aren’t very useful.

When/where the outbreak of H5N1 flu in dairy cattle likely started

Genomic data suggest that the current H5N1 spillover into cattle likely occurred much earlier than was known. It was unlikely that we’d caught the first (or at least one of the first) affected dairy herds in March. Rather, it looks like the spillover into cattle in the US likely occurred in December 2023 (but maybe as early as October 2023). That was presumably from a single bird-to-cow spillover, with an associated mutation of the virus that made it better able to infect cattle. Where did this happen? Somewhere in the US is all I’d say at this point.

After that first bird-to-cow transmission, subsequent transmission is thought to have been from cow-to-cow, with spread on farms through contaminated milk, and spread between farms and states through movement of cattle. Given the limited evidence of virus in respiratory samples from cattle and the large viral load in milk, spread on farm is probably through human-associated milking practices, based on the high likelihood of tracking milk between cows during milking.

There has been subsequent spillover of this H5N1 strain from cattle into cats and poultry flocks. Some farm cats have had severe disease (and even died) from the virus; farm cats could possibly be good sentinels in this situation (i.e. if you see dead cats (more than usual) on the farm, consider looking for influenza in the cattle). Spillback into wild birds is also a concern, since if this strain goes back into wild birds, the situation becomes even harder to control: We can much more effectively monitor and control cow-to-cow transmission than an ongoing risk of exposure from wild birds (that also don’t respect political borders).

What do we know about potential for human infections with H5N1 flu from cattle?

The human case of H5N1 flu associated with contact with dairy cattle in Texas raises concern. Although it is the only one identified so far, testing of exposed people (e.g. farm workers) has been limited. There are lots of anecdotal reports of farm personnel in the US avoiding testing and not telling anyone when they are sick. That’s in part because a lot of dairy farm workers in the US may be undocumented and therefore have concerns about getting on the radar of anything related to government.

There are some interesting aspects of that one human case, too. The person was a dairy farm worker so there’s obviously a link to cattle, but surprisingly there was no testing of cattle on that particular farm. The strain that caused the human infection is genomically a bit different from the main strain circulating in dairy cattle, which supports concerns that there might be more widespread and ongoing transmission than we’ve realized. With more time and transmission, the the virus gradually accumulates genomic changes. The strain from the person had one of the more common mutations (PB2:E627K) that helps the virus adapt to humans; that raises a bit more concern, but it’s still a long way from being a “human-adapted” virus. Odds are that strain died out in that person, but it shows how there could be cow-to-human transmission and that there can be continued concerning mutation of the virus when this happens.

The risk of H5N1 flu (or lack thereof) in pasteurized milk

An earlier report that described finding H5N1 virus material in commercial milk samples caused a stir, since about 20% of samples were positive. Most of us were pretty unconcerned since the test used (PCR) also detects dead virus, and we’ve been confident that pasteurization will kill flu. Subsequent testing confirmed that live H5N1 virus was not present in those commercial milk samples, which is good news. The most important aspect of the report was that it supported the thought that this virus must be MUCH more widely established in US dairy herds than current testing suggests.

Concerns about raw milk remain, but there are lots of other infectious diseases risks from raw milk regardless (so just don’t drink raw milk).

Is there a risk of H5N1 flu in beef?

There’s not much reason to think that contamination of commercial beef with H5N1 flu would be common or high level, but a small initial study didn’t find evidence of the virus in beef samples.

What is the risk of H5N1 flu in cattle in Canada?

We don’t know. Since the virus was probably flying under the radar in US dairy cattle for months, we have to be careful thinking “we haven’t found it in Canada, so we’re good”. It might not be here. It might be here and we don’t know. That’s why we have to look.

If H5N1 flu has not ye gotten into the Canadian dairy herd, can we prevent this from happening? Maybe.

  • If the virus is only moving via cow-to-cow spread in lactating cattle, we can contain that.
  • If spread is via cow-to-cow transmission beyond lactating cattle, that makes control harder, because that’s more cattle and recent restriction on importation of cattle into Canada are focused on lactating cattle…
  • If this strain of the virus spills back into wild birds, then we’re in trouble. Wild birds don’t respect borders so it would probably just be a matter of time before it found its way onto a Canadian dairy farm and into a Canadian cow.
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Dairy cows produce a lot of milk. That’s great when you’re producing it for sale. It’s not great when you have to get rid of it.

It’s clear that this H5N1 flu virus has an affinity for the udder, and a lot of virus is shed in the milk of infected dairy cattle. It appears that it’s often obvious when a cow’s udder is affected: milk production drops and the milk looks abnormal. Abnormal-looking milk is disposed, so it doesn’t go into the human food chain. With the odd sick cow on a farm, diverting this amount of milk isn’t hard. With a lot of sick cows on a farm, it becomes more problematic – it can be a lot of milk.

There’s also the issue of the clinically healthy cattle on farms with H5N1 infected cows. At this point, we don’t understand enough about the virus in cattle to know if exposed cows could be shedding the virus in their milk before they look sick. With influenza infections in other species, we know that virus shedding in respiratory secretions is common prior to the onset of illness. This “pre-clinical” period is a big problem when it comes to infection control, because individuals can be infectious before anyone has any clue they’re infected.

  • We don’t know yet if this pre-clinical / sub-clinical virus shedding happens in cattle.
  • We might be lucky if when virus is shed in milk, it’s always identifiable by visible changes in the milk.
  • We might not be lucky if virus can also be shed in milk that looks normal (and our luck when it comes to infectious diseases hasn’t really been great in the 2020s).

If cattle have a period where they are shedding virus in milk without any outward signs of illness, we have to consider what that means. We’re pretty confident that pasteurization is highly effective against this virus (the other day @SafeFoodCanuck and I wrote a commentary on why the risk of H5N1 flu from pasteurized milk is likely still low in The Conversation). However, raw milk still poses a risk, and we also need to think about exposure of people who handle milk before it’s pasteurized. That raises the question about whether all milk from infected herds should simply be dumped. That’s a lot more milk. I can argue both ways at this point.

Regardless, with influenza circulating in dairy cattle, we’re going to have to dump milk. Maybe a lot of it. An unfortunate waste to be sure, but dumping that much milk is also not as simple as it sounds.

Dairy farms aren’t plumbed into municipal wastewater systems, and don’t have their own septic systems to handle waste. You can’t just flush hundreds of litres (or more) of milk down a drain. It usually goes into manure pits or lagoons, then is eventually spread on fields. That’s fine for the relatively small volumes of milk that typically are dumped from sick cows, but when we have large amounts of milk potentially contaminated with a concerning virus like H5N1 flu, what do we do with it all? There are a few options, but none are great:

  1. Dump it in the manure pit / manure lagoon as usual.
    • That’s the easiest and most practical means of disposal. However, at this point we don’t know how long the virus would survive in a manure pit / lagoon, or on a field after the manure is spread. So this could result in exposure of lots of wildlife, including more mammals (bad for continued mammalian transmission and adaptation) and wild birds (bad for spillback into birds and subsequent transmission over wide areas).
  2. Pasteurize the waste milk before it’s dumped into the pit / lagoon.
    • Some farms have small pasteurizers on site for milk that’s used to feed to calves. Probably no farms have pasteurizers that could handle their full production capacity, so this isn’t a realistic option if all the milk has to be dumped.
  3. Send the waste milk away for disposal.
    • Sure, farms could conceivably contract someone to come pick up the waste milk and dispose of it another way (perhaps into a wastewater treatment plant?). But, that’s not cheap or easy, and might open up a whole new can of worms.
  4. Cull the affected cows (so they’re not producing milk that needs to be dumped).
    • Not a viable option for many reasons.
    • Animal welfare is one reason. Killing an animal that has a short-term, usually mild, infection is extremely hard to justify.
    • Economics is another reason. Individual dairy cows are valuable animals; dairy cows don’t start milking until they’ve had their first calf, which is usually around 2 years of age, so each one represents a significant investment of time and resources. Some can also have very high genetic value. You can’t just clear out a herd of dairy cattle and repopulate the farm next week and be up and running, like you can with poultry.
    • In addition to the animal welfare issues and economic costs, if the cows were culled then farmers would also need to figure out what to do with hundreds or thousands of dead animals.
    • Last but not least, if a dairy farm was depopulated but the virus is still circulating nearby or present in the environment, any new cattle brought to the farm could be re-infected at any time, and it would all be for nothing.

There might be other options, but none jump to mind as practical to me. For example, there might be some other potential on farm virus inactivation approaches, but the cost, logistics and timeframe would likely not make sense in this scenario.

So, we’re most likely left with the option of dumping the contaminated milk into manure pits, going on the assumption (hope) that the virus will die quickly (since it’s not very tough) and it won’t be a source of further spread. It’s not an unreasonable approach, and is probably the least-bad way, but isn’t ideal.

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In case you need a break from all the discussion about H5N1 influenza and the multitude of species it now seems to be able to infect, there’s nothing like a good zoonotic parasite story to make your skin (or pants in this case) crawl. (I promise that this will be a normal-length blog post… ahem.)

There was a recent research letter in Emerging Infectious Diseases (Hobbs et al. 2024) that caught my eye – particularly because it includes a picture/video which you should definitely check out.  The letter was about the finding of a sizable – and motile – adult roundworm in the diaper of a 2-year-old girl in Mississippi (now that’s got to be uncomfortable…).  The worm was identified from the video taken by the child’s mother (before she disposed of both worm and diaper – can’t say I blame her) as Ascaris lumbricoides.  That may not sound terribly noteworthy, as A. lumbricoides is the primary species involved in human roundworm infections globally, but it is usually spread by ingestion of eggs from human feces in areas where the is very poor sanitary infrastructure (e.g.  where human feces are more likely to be found in the general environment due to “promiscuous defection”) – but not in a region like northern rural Mississippi, on a farm with two flush toilets.  However, pigs have a very closely related roundworm that was previously known as Ascaris suum, that was more recently determined to actually be the same species as the human roundworm, A. lumbricoides.  Ascariasis is not uncommon in some farmed pigs even in the US, particularly those raised outdoors. In this case, no one in the family had traveled outside the US, and there was no reason to suspect there was human fecal contamination in the environment, but there were pigs on the property.  The two young kids were also reported to occasionally eat dirt from house plants, which has to make one wonder if they may have eaten other “dirt” on the farm as well (along with some pig feces and the parasite eggs therein).  Unfortunately by the time the Department of Health conducted their field visit, the family’s pigs had all been sent to slaughter, so it was not possible to confirm that the pigs were carrying the same parasite, but the story all fits together (admittedly it would have been nice to have some more definitive proof).

Fortunately the child was treated promptly by her pediatrician, and did not expel any additional worms, and suffered no further ill effects.  A fecal sample collected within 24 hours was negative for any parasite eggs, so they suspect there was only one adult worm present (I’m sure finding that once in the girl’s diaper was quite enough!). 

One more reason not to eat poop (from any species!) and wash your hands and veggies (or at least do the best you can, if you’re two years old :p).

As with any emerging disease, we have more questions than answers, but we can make some interim assessments based on general principles of infection control, and what we’ve learned over the past couple years about this particular H5N1 influenza A virus that’s been circulating in wild birds all over the world, and spilling over into many different species of mammals (including cats), along the way. The details are likely to change over time as we learn more, but this is where I see things at the moment.

Cats can get infected with this H5N1 influenza strain

We’re known this for a while. There have been infected cats (big and small) in various countries over the past couple of years. It’s a bit cumbersome, but there’s good tracking of avian influenza cases in mammals worldwide on the WOAH (World Organization for Animal Health) website.  As with most infections, we no doubt only diagnose a small subset of infections that actually occur (just the tip of the iceberg).

Infections with H5N1 influenza in cats are rare

Notwithstanding my comment above about underdiagnosis of cases, we need to keep this in context. There have been millions upon millions of infected birds all over the world in the last few years. There are lots of cats in areas where infected birds have been present, and cat-bird contact is far from rare. So, there’s likely been lots of exposure, but disease (at least serious disease) in cats has been rare; that’s a bit of good news.

Although H5N1 infections in cats can be severe, social media claims of “100% mortality” are overblown

As we’ve seen in many other mammals with spillover infections (but fortunately not humans so far), infected cats can have very severe disease, including fatal infections, typically with severe neurological signs. It can be very bad, but it’s presumably nowhere near 100% fatal.

  • We’re missing a lot of context because of testing bias, because we’re mostly only testing cats with severe signs of illness, or cats that are found dead in areas where birds have avian flu.
  • We don’t do enough testing of other cats that have been exposed but are still healthy, or only have very mild disease. We just don’t know enough yet to say what the true morbidity or mortality rates are in cats.
  • For all the hype, getting samples from exposed cats to test is a challenge. I’ve been set up for a while to get samples from cats with wild bird contact, but despite there being lots of outdoor cats and lots of infected birds, I haven’t been able to get any samples. (But when the dairy cow news broke this week, I made sure my PAPR was charged and my sampling kit was ready, in case there’s now more motivation to test.)

We don’t know whether H5N1 infected cats can be infectious to others

With only a small number cats tested, it’s hard to gauge the risk of transmission from cats to other animals (or people). Hopefully we’ll get more information about the cats on infected dairy farms. A challenge with multiple cats being infected in a situation like this is sorting out if they were all exposed to infected birds, all exposed to infected cattle (especially contaminated milk) or whether there may have been some cat-to-cat transmission of the flu virus. There’s very little we can do to sort that out when investigating a single farm at a single point in time. We can infer some things from testing results (particularly from quantitative viral loads in respiratory and fecal samples), but it’s still a bit of a guess without more testing and epidemiological investigation.

What can the average cat owner do?

If possible, keep your cat inside, as it minimizes any risk of exposure to infected wild birds (which are still the main source of H5N1 influenza). That’s not always possible though, since some indoor-outdoor cats simply won’t tolerate being inside 24/7, and some outdoor cats can’t be moved indoors.

Take our three cats as examples:

  • Milo is an indoor only cat. He’s low risk.
  • Rumple was adopted through the Guelph Humane Society’s working cat program as a barn cat since he was deemed unsuitable for indoor living. He’s actually a huge suck and now spends a lot of time inside, but he wouldn’t tolerate it full time (I’m not sure he’s ever used a litter box).
  • Alice is an outdoor cat that Rumple adopted. She was a scrawny, completely feral cat who started living with Rumple in the garage, and on our deck. She’s a sweetie around us now, but only on her terms. She will take a few steps in the house (very warily) and then dart back outside, but when outside she’ll roll around on us and purr her head off. She cannot be moved inside. We can make sure she and Rumple are well fed (they’re both on the chunky side), but can’t guarantee they won’t hunt anyway. So they (especially Rumple) are a risk as a bridge from outside to inside. We know that and accept the risk.

People who have indoor/outdoor cats should assess the risk, the ability to change their cat’s living arrangements, and their risk tolerance.

We can also try to discourage mixing of cats and birds. Removing bird feeders from yards is a simple step that I’d recommend at this point.

What if an indoor/outdoor cat gets sick?

Most of the time, the cat won’t be sick from flu, but it’s a possibility, and the risk would be higher if the cat is a known hunter and if there’s recent flu activity in local wild birds. In that event, I think it’s reasonable for owners to limit close contact with the cat, consider wearing a mask if close contact is required, and talk to their veterinarian about testing (for flu and/or other causes). We can’t freak out every time a cat gets sick, but acute onset of severe respiratory and/or neurological disease in an adult indoor/outdoor cat would raise a lot of concern, since that’s uncommon in otherwise healthy mature cats. (Young kittens are a completely different story – they’re upper respiratory snot factories at the best of times.)

What should veterinarians when presented with a sick cat?

I don’t think we’re at the point of saying respiratory PPE should be worn for handling every sick cat. A risk assessment is always appropriate, and ideally there’s a triage process over the phone prior to any sick cat entering the clinic. If the cat has outdoor exposure, especially known exposure to wild birds, and the cat has an acute onset of respiratory or neurological disease, it makes sense to start off with enhanced PPE (e.g. mask, eye protection, gown, gloves) until the situation is sorted out

Are there any concerns about H5N1 influenza and raw meat diets?

Maybe. There are a variety of reasons why raw diets create disease risks (Salmonella being a big one), but there are some specific concerns about the H5N1 virus in these diets too. Last year, there were reports of outbreaks of H5N1 infection in cats linked to raw diets in Poland and South Korea. However, confirmatory data has been lacking, so it’s unclear how strong the link is. It’s probably also mainly or solely a risk from very fresh diets.

I’d use this as yet another reason to avoid raw diets. If someone wants to feed a raw diet, high pressure pasteurized diets should be considered as that likely eliminates influenza virus.

What am I doing about H5N1 influenza in cats right now?

I’ll keep an eye on Rumple and Alice for any signs of illness. If they get sick, I’ll keep them away from everyone, sample them, and go from there. If they have severe illness, I have a plan to manage that, but that’s more medical than I want to get into here. Beyond that, I’m staying aware of the situation and will act (and adjust) as necessary.

What about the risk of H5N1 influenza in dogs?

Separate species. Separate story. But, we know dogs can be susceptible to H5N1 influenza too (but likely even less commonly than cats). Keeping dogs away from potentially infected birds is important at this point, especially dead birds that are higher risk for having died from infection. (That’s something that’s important for me since we live in the country and own Labradors that consider basically anything (live or dead, organic or not) to be a potential snack.)

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There’s been a lot of concern about the recent identification of H5N1 avian flu in cattle in the US, along with a single human infection in a person working with infected cattle. Some of the concern is warranted, but some is overblown.  We need to balance awareness versus paranoia, and try to better understand the problem and reduce the risk, while avoiding excessive, ineffective or harmful responses. That sweet spot is hard to define early on with emerging diseases. We should liberally apply the precautionary principle, but also ensure we keep re-assessing the risks based on emerging evidence.

Here are some initial thoughts on what we can all do regarding the current situation at this stage:

Cattle farmers

  • Be on the lookout for sick animals. Based on what we’ve seen do far, flu will likely cause mild signs in cattle such as decreased appetite and decreased milk production.
  • Call your veterinarian as soon as possible if you suspect a problem in your herd (good advice at any time!), and allow testing of suspect cases (good to know what’s going on, whether it’s influenza or not).
  • Although it’s tough, try as much as possible to keep wild birds out of barns. Also try to discourage migrating waterfowl in particular from entering cattle housing areas or taking up residence in fields.
  • If you’re sick, stay away from cattle. We don’t want human and animal influenza viruses mixing, and putting an infected person in a barn with potentially infected cattle increases this risk. Farmers are notorious for “sucking it up” and working as long as they’re not fully dead, but we need to encourage a culture shift that limits contact of sick people with animals. If that’s not possible (which is often the case), farm personnel that might have the flu should minimize contact with animals as much as possible, and wear a mask to reduce the risk of spread.
  • If there’s flu activity in wild birds in the area, it’s not unreasonable to wear a mask around cattle, but I realize that’s unlikely to happen.
  • Consider adjusting grazing practices to reduce exposure of cattle to infected birds or their feces, especially if there is flu activity in wild birds in the area, and particularly if dead birds are found in the pasture.
  • If your cattle might have flu, definitely wear a mask and eye protection around and sick animals, and limit close contact. Also, think about high risk items and surfaces that may get contaminated by sick cattle, and take additional measures as appropriate (e.g. increasing routine disinfection, reducing direct contact, wearing appropriate PPE when contact is required). Contamination with respiratory secretions from sick animals were the main initial concern, but recent information suggests that milk could be more important for potential cow-to-cow transmission during milking (e.g. shared milking equipment). Contact with milk and milking equipment might pose a risk for people too, meaning we should take extra precautions with contact with the udder, milk and any in-contact surfaces. I’d also take care around cattle feces until we better understand if cattle can also shed the virus that way (but there are lots of other reasons to avoid contact with cattle feces besides flu too).
  • Keep cattle away from any other species that might carry or acquire an influenza virus, which basically means keep cattle away from all other mammals and birds, but with a particular focus on avoiding higher-risk flu species (i.e. domestic poultry and pigs).
  • If you develop flu-like illness, make sure your physician knows you have contact with cattle. If your cattle are sick at the same time, absolutely make sure your veterinarian, physician and public health know so the situation can be properly investigated.

Veterinarians

  • As for farmers, consider flu in cattle and on beef and dairy farms, and be on the lookout for it.
  • Communicate with farmers, infectious disease specialists, labs and government agencies if you have concerns about flu in a particular herd.
  • Use standard infection control practices to minimize the risk of farm-to-farm spread of flu (and other pathogens). That route of transmission is pretty unlikely for flu, but there is potential for veterinarians to track flu between farms, which can’t be ignored.
  • As for farmers, if you might have the flu, stay away from animals (at least birds and mammals) as much as possible. Yes, that’s tough since that means not working, but we don’t want co-infections of people or animals with different flu viruses.
  • Consider wearing a mask around cattle. I realize that’s not likely to happen routinely, but definitely wear a mask and eye protection if you suspect flu might be present in cattle you’re seeing. Take particular care around handling the udder and with milk sampling.
  • If you develop flu-like illness, do the same as mentioned above for farmers.

Governments

  • Support testing for influenza A in cattle. We don’t know what we don’t know. We need a fairly wide net of testing to understand this issue. That costs money, and it’s hard to expect farmers to cover all the costs of this kind of testing, especially when there’s limited direct benefit to them (because so far flu only causes mild disease in cattle, and there’s no specific treatment).
  • Don’t make it hard to get testing done. Sometimes, we run into barriers when we want to test for emerging diseases. Don’t make veterinarians jump through permission processes to limit testing. We need more information, not push back against getting more information.
  • Support farmers who have suspected or confirmed cases of influenza in cattle. We need to see a balance of measures that are adequately restrictive to contain flu, but not so extreme that they drive the situation underground. If the response is over-the-top, there will be a strong disincentive for anyone to test for flu, and that just makes the situation worse.

Consumers

  • Relax.
  • Don’t drink raw milk (for lots of reasons).
  • Avoid fearmongering Twitter threads.
  • Relax.

Public farm events/petting zoos

  • I really have no idea what to say here. Petting zoos or other similar animal exhibit events can result in large numbers of random people have contact with cattle, with limited hygiene, no health screening  and no contact tracing. There’s a risk, but it’s too early to say how much of a risk. We need to see how the situation evolves.
  • Fortunately, these kinds of events are most common in the summer and early fall, so we have a bit of time. At the moment, if there’s flu activity in wild birds in the area, it’s reasonable to say that we shouldn’t allow random access to cattle, pigs and other flu-susceptible species.
  • If visitor contact is allowed, make sure cattle are assessed daily to confirm none look sick, try to keep sick people away, try to maximize ventilation in animal areas, and facilitate (and encourage) hand hygiene.

As with any emerging disease, guidance will change. People don’t like that, but it’s actually a good sign – it means we’re learning and responding. We shouldn’t be so arrogant to think that what we recommend now will ultimately be the optimal approach. Hopefully we’re pretty close, and we can make good recommendations based on what we know now, but I’d be disappointed if we don’t change them at least a bit (because that would more likely mean we didn’t adapt than we knew it all from the start).