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.

This may be my last update on this topic in the short term (unless things change, of course).

The good news:

The bad news:

  • Well, it’s not really bad news, but we still don’t know what actually happened. That’s far from surprising, because with waxing and waning endemic disease conditions like CIRDC, we rarely have a clear picture of what happened and why.
  • Everything for me continues to point to a gradual increase in the rate of infectious respiratory disease in dogs over the past couple of years, with the usual intermittent local and regional peaks and valleys. This year’s issues were probably somewhat higher peaks overlaid on a higher baseline, making the issue more obvious and drawing more attention.

What was the cause of the increased cases of CIRDC?

I’m sticking to “the usual suspects, doing their usual thing, just at higher rates.” There’s been a lot of investigation looking for new pathogens and, as far as I know, nothing convincing has come to light. Given the number and quality of the research groups that have been looking, it’s pretty convincing that we don’t have a specific new pathogen that’s caused an outbreak of disease in dogs across North America.

What do we do now?

As with any outbreak, we try to learn some things from the experience:

1. Surveillance

This situation was a reminder that we don’t have a good surveillance system in place for CIRDC (or most other companion animal diseases). There’s no easy fix for that, especially with no money, so we need to continue to try to leverage the information that is available to better understand disease patterns. We need to do that on an ongoing basis, not just when there’s concern about increased cases, because when we’re concerned about an outbreak, we need to know the normal rates of disease to put things into context.

2. Vaccination

While we only have vaccines for a few of the important causes of CIRDC (Bordatella, parainfluenza, influenza), they are good vaccines, and we need to optimize their use in dogs that have a reasonable risk of exposure and/or a higher risk for severe disease.

3. Thinking about severe disease

The risk of severe disease in some dogs during outbreaks doesn’t get as much attention as it should; hopefully we’re changing that. In most dogs, CIRDC is a short term, self-limiting problem that’s fairly mild, just like upper respiratory infections in people. However, some dogs get really sick, and some even die. We can’t predict every dog that will have a severe outcome, but we know that there are groups that are at higher risk, particularly older dogs, dogs with pre-existing heart or lung disease, and brachycephalic dogs (i.e. flat-faced breeds). We need to think about minimizing exposure and maximizing vaccine coverage in these groups.

We also need to get people thinking about function over appearance in dogs they are breeding and buying. There is currently a disturbingly high number of anatomically disastrous dogs out there, because people have bred reasonably-functional brachycephalic breeds into extremely flat-faced dysfunctional dogs that have myriad respiratory issues, even without infectious diseases to complicate the situation (see the pictures below). As the French bulldog has shot to the top of the list of the most common breeds in the US, we’re going to see more dogs die from respiratory disease. Not all Frenchies are a mess, but there are enough of them that we see infectious and non-infectious complications in them all the time.

The recent situation with CIRDC also might get people thinking more about their dogs’ social networks and risks, and how to minimize those while having limited impacts on important or enjoyable aspects of dog ownership. We’ll be doing some work on dog social networks later this year, so stay tuned.

Image from: https://pedigreedogsexposed.blogspot.com/2017/08/the-frenchies-that-win-by-nose.html


I’ll take a break from writing about widespread canine infectious respiratory disease complex (CIRDC) in North America to talk about a single case of a rare disease in a dog. Wageningen Veterinary Research has reported a case of Bluetongue infection in a dog in the Netherlands, a disease of significant consequence to livestock that’s recently been found again in the country.

Bluetongue is a viral disease caused by the unoriginally named bluetongue virus (BTV), which is endemic in many parts of the world, especially tropical and subtropical countries. However, a lot of countries put in significant effort to control this virus and maintain disease-free status, because it has major impacts on food animals. The infection often kills sheep, and while it doesn’t usually kill cattle, infection can cause a major drop in milk production. A single case of bluetongue in a previously disease-free country can result major livestock export restrictions. The Netherlands managed to control bluetongue since their last outbreak in 2007, but it was found again in the country earlier this year; based on the strain, it’s suspected the virus may have been imported from Italy.  

The bluetongue-affected dog in this report was a 3.5-year-old pregnant dog from a Dutch dairy farm. The dog had severe signs of illness, including shortness of breath, pulmonary edema, severe emaciation and lethargy. It’s interesting that someone considered bluetongue and tested the dog, especially since the disease wasn’t known to be present in cattle on the farm, though it was subsequently identified in two cattle after the dog’s diagnosis. Thanks to an astute vet and access to testing, a diagnosis of bluetongue was made through detection of BTV by PCR. Not surprisingly, it was the same strain of BTV that’s been circulating in sheep and cattle in the Netherlands.

There’s no mention of whether the dog survived and/or if it was treated. For something like this, we’d be focusing on supportive care and treating the consequences of the infection, while the dog hopefully fought off the virus itself, since we don’t have a specific antiviral treatment for BTV (or at least not one that we know is safe and effective in a dog).

This isn’t the first case of bluetongue in a dog, but it’s a very rare diagnosis. Interestingly, most of the reported canine cases have been in pregnant dogs. We don’t know why that is, but it could be for a number of potential reasons, or a combination thereof, including:

  • Just a coincidence
  • Greater likelihood of testing a sick pregnant dog
  • Increased susceptibility of dogs to infection during pregnancy

How was the dog infected with BTV?

Livestock-to-livestock transmission of BTV is mainly by biting midges (little insects), so the virus can move with infected sheep and cattle, infected midges (blown off course by storms or hitching a ride in a vehicle), or contaminated raw food items that somehow end up being fed to livestock (e.g. food scraps).

How this dog was infected isn’t clear. Contact with or ingestion of colostrum, fetal fluids or fetal membranes, raw meat or blood from an infected ruminant are considered the most likely routes of transmission. However, spread by infected midges can’t be ruled out. This dog lived on a dairy farm, had direct contact with cattle and their environment, and may have had access to high-risk tissues like placentas, so there were a variety of potential sources of exposure.

Does/did this dog pose a risk to other animals?

Presumably not. It’s assumed that dogs are “dead end hosts” for BTV. Dead end hosts can have serious disease but usually don’t produce or excrete enough virus to pass infection on to others. But that is an assumption here, and especially with a rare infection like BTV in a dog, we can’t have complete confidence in assumptions.

Does this case change anything in the big picture?

Probably not much. It’s a reminder of the unpredictability of infectious diseases, the need to consider the whole human/animal/environment ecosystem (versus having tunnel vision about certain species), and that spillover of infections from the main host to others probably occurs a lot more than we recognize for a wide range of infectious diseases.

As concerns about an outbreak of canine infectious respiratory disease in the US continue, we’re still at a point where media hype massively outweighs any true data. Not much new has been reported recently. If anything, I’d say we’re hearing more about things being stable in different areas, that investigations haven’t turned up anything beyond the usual suspects, and the typical messaging to use common sense but relax.

One thing that is getting some press is a suggestion that a rather bizarre little bacterium might be involved in some of the current canine illnesses. “Might” is the key word though. At the risk of having to eat my words later, I’d guess this bug is probably not going to pan out to be a driver of widespread disease – it’s possible, but there’s a long way to go before we can say that with any confidence. In the meantime, let’s recap what we know:


In the spring of 2023, the New Hampshire Veterinary Diagnostic Lab reported they were investigating a potentially novel organism as a cause of respiratory disease in dogs. I remember reading about it in a taxi on my way to the airport in DC; I thought it was interesting, but in my experience, the vast majority of “new pathogens” end up being commensal organisms (i.e. also present in lots of healthy dogs) or otherwise not panning out to being relevant. But, I never totally discount the possibility, and was glad to see it investigated. The initial (and I think only) report involved a pretty small number of dogs. They found snippets of DNA that were similar to IOLA KY405 in 21/31 samples. Their latest update is here.

What on earth is IOLA KY405?

It’s hard to say. As far as I know, it’s only previously been reported in two papers from the same lab in Japan, where it was found in samples from humans with respiratory disease. It’s reported to be a bacterium with a very small and bizarre genome.

  • The first study (Fukuda et al. 2014) reported finding gene sequences from IOLA KY405 in a lung fluid sample from one person, then followed up by finding those DNA bits in samples from 6/386 samples from other patients with respiratory disease. Some unique aspects of this bacterium are a very small genome, similar to Mycoplasma  (just over 300K base pairs; for reference, staphylococci have about 2.8 million base pairs), and a very high AT content (about 80%).
  • In the second study (Fukuda et al. 2021), they presented the whole genome sequence of the organism. They also used PCR to look for it in samples from more people with respiratory disease, and got positive results in 2.7% of about 500 samples. Eight of the 11 positive patients had significant underlying disease, and five were being treated with corticosteroids or immunosuppressants. So, these individuals had lots of other excuses to have respiratory disease or to be infected with something that’s minimally pathogenic.

Someone with more background in genomics would need to assess the papers to know how confident we can be in the results. If they are real, then the researchers have found a small bacterium that’s similar to Mycoplasma, which maybe isn’t surprising since some Mycoplasma are able to infect lungs (but more often are present as normal respiratory tract inhabitants.)

What we’re still lacking is 1) actually growing the bug to confirm its existence, and most importantly, 2) context. Finding DNA from this bug in a small percentage of people with respiratory disease is interesting, but could it be just as common in healthy individuals and just part of our normal microbiota? I don’t think we can say either way at this point.

When something’s only reported by one group over a long period of time, it raises the question of why. Is one group just way ahead of the curve, or is this something that other people have tried to find but have been unable to replicate the results (or have looked at and dismissed as not being worth investigating)? Publication bias is a big problem in cases like this. If other groups have put in a good effort to investigate this and found nothing, odds are high we wouldn’t find out because there’s a tendency to not publish “negative” results, even though those data are really important. So, we have no idea if there are only two papers because only one group is looking for it, or whether lots of other people have tried and failed to find anything similar.

Genome-based pathogen discovery is an established and effective method. It looks at all the genetic bits we can find in a sample, then tries to assemble them into something interpretable, and then we try to figure out what it actually all means. It’s challenging because we have a vast population of viruses and bacteria that are normal inhabitants in our bodies and those of animals. Most are harmless. Many are beneficial. Some can cause disease. Sorting out into which category a new organism fits takes a lot of work, and is rarely straightforward.

We’ve been lead down the wrong path many times before by reports of a “new” organism found in sick animals (e.g. the panic about canine circovirus). People freak out, start testing more sick animals, find it, and freak out more. However, when the science catches up with the hype, we often realize that we can find the bug in the same percentage of healthy animals, and it’s just a normal inhabitant that we’ve recently discovered, versus something new that is causing disease. With modern molecular techniques, our ability to find something often surpasses our ability to understand it.

While it sounds like I’m downplaying the relevance of this finding, that’s not my intention. I suspect IOLA KY405 is a real organism, I just need a lot more convincing that it’s relevant to disease (in people or animals). In an ideal world, the New Hampshire lab and others would be investigating this robustly, including field studies in dogs, to deterimine what the real story is. Lack of funding for companion animal infectious disease research usually slows these to a crawl. The report from the New Hampshire lab adds good context:

  • It is important to note that this is a preliminary finding, and under normal circumstances of a study we would not release these findings. The technology and methods used by the HCGS include cutting edge metagenomic sequencing, and multiple bioinformatic pipelines that are uncommonly utilized in veterinary medicine. Additionally this is an uncommonly studied group of bacteria. There are multiple experiments that need to be run in order to clarify correlation vs. causation, and this gives reason for pause in releasing the findings. However, the syndrome is ongoing and there may be an opportunity to benefit animal health as we continue to validate these initial findings. There is a chance that this preliminary data is disproven with further study, but at this point it does appear that the bacteria we have identified is a potential causative agent.”

Those disclaimers are key, but unfortunately are usually left out of the media reports.

This is an important but very preliminary finding that needs to be studied. However, we also have to realize that most findings like this don’t turn out to be anything big (or anything at all). We can’t dismiss the potential and it’s great to see the work being done, but we need to make sure that we don’t jump from a preliminary finding of some unusual DNA sequences to “here’s the answer!” which is what human nature wants us to do.

The US CDC is reporting an outbreak of salmonellosis linked to dry dog food. It’s a small outbreak in terms of the number of diagnosed infections (7) but, as always, the diagnosed infections are presumably just the tip of the iceberg, especially since they have been found in seven different US states (see map below).

  • The outbreak strain is a strain of Salmonella Kiambu
  • Cases to date were identified between January 14 and August 19, 2023.
  • Six of the seven infected people were infants.
  • One patient was hospitalized, none died.

Five household investigations occurred and dogs were present in all households. Three reported feeding their dog a specific brand of dry dog food, Victor HiPro Plus.

The outbreak strain of Salmonella Kiambu was also found in a sample of this same dog food that was collected at a retail source in South Carolina. It sounds like that sample might have been part of a separate routine surveillance program, since no human cases were reported in that state. No food from affected households was available for testing because by the time the problem was identified, the offending food was long gone (as is often the case).

Regardless, there was a strong link to a specific lot of of that dog food, since CDC didn’t hedge the wording: “a specific lot of Victor brand Hi-Pro Plus dry dog food is contaminated with Salmonella and has made people sick.”

The implicated dog food, as well as other brands of dog and cat food produced at the same facility, has been recalled by the manufacturer. However, it took some time to trigger the recall. On September 3, they recalled one specific lot of the dog food. Then on October 30, they recalled some other lots. Finally, on November 9, they recalled all brands made at the facility. Presumably they identified issues with ongoing contamination or other significant deficiencies at the plant, so they expanded the recall.

Raw diets for pets get most of the attention with respect to Salmonella risks. That’s fair because they are much higher risk for contamination, and there have been numerous cases and outbreaks linked to them (including one currently under investigation in Canada). However, dry diets also pose some risk; contamination in these cases is usually linked to poor manufacturing practices. While we rarely have contamination issues with dry diets, given the volume of dry food that can be produced by a facility, when contamination does happen it can be a big (and very widespread) problem.

I’m not sure we’ll get much more information about how this happened, but we’ll see if more information comes out after the outbreak investigation is wrapped up. There may be new cases that have not yet been identified or infections that will develop from recalled food that’s still in households. Since there was such a delay in the final recall, presumably there’s a lot of this pet food in households in the US. Hopefully it was more of an “abundance of caution” recall of everything versus evidence of ongoing contamination of all that pet food, because if it was the latter, more infections are likely to happen.

I’ve held off writing about this unusual outbreak of cat deaths on the island of Cyprus for a few reasons, a big one being a lack of clear information, but the situation has drawn a lot of attention.

In general, when we have reports of strange disease events, there are a few scenarios to consider:

  1. It’s a completely new disease
  2. Something has change regarding an known disease
  3. It’s a known disease doing what it normally does, but circumstances have led to a unique local, short term situation
  4. It’s a known disease doing what it normally does, but with more attention being paid to it

All of these happen. I’d say that numbers 3 and 4 are most common, with number 4 being particularly common due to amplification of routine disease situations by social media.

What’s going on in Cyprus?

Clear details have been pretty sparse, so I think it could still be any of these scenarios.

How many cats have been affected?

The story started around January 2023, with subsequent reports of “thousands” of cats dying in Cyprus. There appears to be some debate about the scope of the problem. One claim is that 200,000-300,000 cats, or roughly 20-30% of the cat population on the island, have died.

However, that claim has not been substantiated, and it has been suggested that the actual number of deaths is less than 10,000. That’s still a lot of cats, so clearly significant, but some context is needed.

  • How many feral cats normally die every week in Cyprus?
  • Is this mortality rate higher than normal, or are people just paying more attention to it?
    • If the true number of cats that have died is around 10,000, that would be approximately 1% mortality, and a 1% mortality rate over a few months is actually on the low side for what would normally be expected in such a population.

Those are key initial questions that need to be answered to help us determine if we actually have something different happening on the island.

What’s the cause?

The outbreak was quickly attributed to feline infectious peritonitis (FIP). This didn’t make a lot of sense based on what we know about FIP, which is caused by feline coronavirus (FCoV). The disease develops in a small minority of infected cats, when the FCoV mutates to become more virulent. FCoV is very common, especially in large cat populations. If you have more than 10 or so cats in a group (e.g. shelter, colony, feral cats), it’s almost certain that one or more of them are infected. So, finding FCoV in dead cats is not surprising. We’d find lots of it in live cats, too.

FIP outbreaks are uncommon, though. When they occur, they are usually small outbreaks associated with some local factors in the cat population (e.g. age, genetics, health status) that make a small group of cats more likely to develop FIP. A country-wide outbreak, even in a small country, would be pretty surprising.

Diagnosis of FIP involves more than just finding the virus. We have to figure out if it’s actually causing disease. I haven’t seen details about how the diagnosis of FIP has been made in these cases. It could be that a large number of cats have been solidly diagnosed with FIP, a small number of cats amongst a large number of untested dead cats had FIP, or that there wasn’t actually any solid diagnosis of FIP (and someone was just guessing).

The question is whether FCoV is causing disease or it’s just there, and whether any cats with FIP were representative of the outbreak or there were just some cats with FIP alongside something else. That’s what’s unclear to me. I’ve heard that FCoV from some infected cats is being sequenced, which is a great start. This will help determine if there’s something unique about the virus in these cats and if it’s one strain that’s present in the majority of affected cats.

A good epidemiological investigation to define what’s happening is key to sorting out situations like this, but often, that gets neglected (or at least done superficially). With a better understanding of the situation and context regarding how it compares to normal, we’re better able to target the laboratory investigation and figure out what we need to do to contain the outbreak. Hopefully that’s underway.

There was also a recent report that extra COVID-19 drugs are being used in some cats on the island. Details are sparse and it’s hard to see how that will help much in the context of an outbreak. Some COVID-19 drugs (mainly remdesivir) have great promise for treatment of FIP, which is usually a fatal disease in cats. However, while it will help the small number of sick cats that get access to the drug, it won’t help stop the outbreak since it will have no impact on transmission within the population. It’s circulation of the wild-type FCoV that’s the problem, and treatment of a handful of cats with FIP won’t do anything for that. Presumably they’re not treating healthy cats preventatively, since that probably wouldn’t help anyway, would require a massive amount of drug, would be impractical for feral cats (that would be the main reservoir) and, depending on the drug, might just be setting the scene for harmful mutations (especially if molnupiravir is used).

If this is something new, what do we have to do?

The first step is make a diagnosis. We need to know whether this is a new version of FCoV, a new disease or whether it’s just normal viruses doing their normal things. Until we know that, it would make sense to ban importation of cats from Cyprus.  


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

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

A few pertinent things have been reported from different sources:

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

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

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

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

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

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

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

Should cats be fed raw poultry?

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

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

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

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

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

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

Are there related food safety concerns for people?

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

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

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

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

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

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

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

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

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

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

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


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

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

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

Cat-to-cat transmission

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

Repeated wild bird-to-cat transmission

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

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

A mix of these

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

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

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

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

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

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

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

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

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