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I got a question about an old post on this topic, so I decided to add a bit of information and re-post it. Not much has changed since it was written in 2018, apart from more reports of people and pets getting sick from raw pet food and raw treats.

“Is freeze-dried raw pet food any different than fresh or frozen raw diets, from a microbiological standpoint?”

We don’t have much pet food-specific research, but there’s little reason to believe there would be much difference between these types of diets when it comes to the microbes we’re concerned about. When I want to preserve bacteria, I freeze them or freeze-dry them – those are actually the preferred methods for long-term storage of bacteria. Freezing or freeze-drying is a pretty hospitable process and state for most bacteria. Some, such as Campylobacter, don’t tolerate freezing (or especially fresh-thaw cycles) as well as others, so freezing or freeze-drying might have some impact on those specific bugs. For the higher profile pathogens like Salmonella, E. coli and Listeria, it probably doesn’t have much of an effect. I can see there being some reduction in bacterial numbers but probably nothing substantial, and certainly not enough that I’d consider it when deciding whether it’s an appropriate diet for a particular pet and household.

The story is quite different for some parasites. Many parasites and parasite eggs don’t tolerate freezing – that’s why fish for sushi is typically frozen at some point before it is served. Some are hardier than others, though. Toxoplasma, a potentially important foodborne parasite, is susceptible to freezing, but only if the temperature is low enough and the time is long enough (e.g. -12C for 3 days will kill most Toxoplasma cysts.  To put that into context, typical household freezers run around -20C).

So, the take home message is that for of the microbes that we’re worried about with raw meat,  freezing or freeze-drying is NOT a food safety practice. It’s food preservation, not bacterial control.

Another point to add… advertizing around pet diets is variable and sometimes quite dodgy. I just checked two websites selling freeze-dried raw diet. One had good info. The other… well… not so much.  Don’t let company advertizing be your infection control guidance.

More information on raw diets and toxoplamsosis are available on the Worms & Germs Resources – Pets page.

While it feels like “all COVID all the time,” other infectious disease issues still carry on beyond the current pandemic. They’re not as big, but they’re still relevant (and a break from writing about COVID-19 is nice).

The FDA has announced a voluntary recall of whole capelin fish treats from IcelandicPlus LLC, because of concerns about botulism. Here, as with most botulism recalls, the concern is the potential for botulism, not identification of the bacterial toxin in the treats or reports of disease. Most often, the risk is limited, but with such as serious disease, there’s little risk tolerance.

Botulism is a paralytic disease caused by toxins produced by the bacterium Clostridium botulinum. This bacterium can be found widely in the environment in some regions. If we ingest a few of these bacteria, it’s not usually a problem. If a person or a pet ingests a minute amount of the toxin, it can cause botulism.

The risk of botulism is primarily a concern in two situations. One is infants that may ingest the bacteria themselves. An infant’s intestinal bacterial population is poorly developed and this can allow the bacteria to grow in the gut (when they likely wouldn’t in an adult).  As the bacteria multiply they produce toxin, which then causes botulism.  That’s one reason we’re not supposed to give honey to infants too, because it sometimes contains C. botulinum spores.

The bigger issue is ingestion of toxin that’s already in something that’s being eaten.  The bacterium grows in specific conditions when there’s no oxygen, such as in decaying matter. When it grows, it produces toxin, and when the toxin is ingested (whether the bacteria are still there or not), botulism ensues. That’s where concerns come into play with this recall.

The recalled pet treats are whole, dried, un-eviscerated fish. That’s allowed, but there are rules about the size of the fish that can be sold like this. With larger fish, there’s more potential for conditions amenable to C. botulinum growth to occur in the fish’s gut during drying. FDA guidelines limit these small dried whole fish to 5 inches in length.  Larger cured fish have been linked to a few outbreaks of botulism in people. Since the company (IcelandicPlus LLC) has been selling fish in excess of this size, they’re being recalled.

The company has also stated that they will be changing their supplier to ensure fish are consistently less than 5 inches and that fish greater than this size will be eviscerated. That’s good, but I’d hope the company would have their own quality control program to check this, and not just blame and change the supplier.

I think I’ve covered this before (probably a few times), but the question keeps coming up so it can’t hurt to talk about it again:

“Is freeze-dried raw pet food any different than fresh or frozen raw diets, from a microbiological standpoint?”

We don’t have much pet food-specific research, but there’s little reason to believe there would be much difference when it comes to the things we’re concerned about. When I want to preserve bacteria, I freeze them or freeze-dry them. Those are actually the preferred methods for long-term storage. Freezing or freeze-drying is a pretty hospitable process and state for most bacteria. Some, such as Campylobacter, don’t tolerate freezing (or especially fresh-thaw cycles) as well as others, so freezing or freeze-drying might have some impact on those specific bugs. For the higher profile pathogens like Salmonella and Listeria, it probably doesn’t make a difference.

The story is quite different for some parasites. Many parasites and parasite eggs don’t tolerate freezing (that’s why fish for sushi is typically frozen at some point). Some are hardier than others, though. Toxoplasma, a potentially important foodborne parasite, is susceptible to freezing, but only if the temperature is low enough and the time is long enough (e.g. -12C for 3 days will kill most Toxoplasma cysts).

So, the take home message is that for of the microbes that we’re worried about with raw meat,  freezing or freeze-drying is NOT a food safety practice. It’s food preservation, not bacterial control.

Last month, the Public Health Agency of Canada (PHAC) issued a somewhat vague notice about an ongoing outbreak investigation of Salmonella infections linked to dog food and treats. At the time they were still unable to identify a specific brand or manufacturer to which the outbreak had been linked.

This week PHAC posted an update on the outbreak investigation, which has linked some (but not all) outbreak cases to Puppy World and Puppy Love brand dog treats. So far, the outbreak strain of Salmonella Oranienburg has been identified in Puppy World Lamb Lung Treats, Puppy Love Chicken Wing Tip Treats, Chicken Breast Treats, Beef Chew Treats and “Twisty Jr” Beef Treats.

People often forget that many dog treats are in fact raw animal-based products. Even if they are freeze dried or dehydrated, they are still raw and therefore associated with increased risk of contamination with Salmonella and other pathogens (including H5N1 influenza virus, as has been seen in the US). Salmonella-contaminated dog treats may pose more risk to people than contaminated dog food as people tend to have more contact with treats. I’d guess (or at least hope) that most people feeding raw diets would handle the food carefully and use basic hygiene practices to prevent cross-contamination of surfaces, hands and human food. But when treats don’t look or feel overtly “raw,” it’s easy to see people skipping those basic measures (like hand hygiene).

The number of human infections in the current outbreak is now up to 31 (including a second case in Ontario). That means the true number is probably in the hundreds, as it’s been estimated that 26 people are infected for every reported case of salmonellosis (which would be up to 806 cases for this outbreak). The other cases are still mostly from BC and Alberta, and one case from the Northwest Territories, showing the widespread exposure and highlighting the challenges of such an investigation, even when tied to a fairly small manufacturer. This outbreak has been slowly burning along from February to September, and is potentially still ongoing. Other sources of the outbreak strain may still be identified as well.

Seven people have been hospitalized, with still no deaths to date. Hospitalized cases are unlikely to be missed, as patients in hospital are much more likely to be tested so the outbreak Salmonella strain would be less likely to go undetected compared to a less severe case in the community. The age range of cases remains unchanged (0-87 years), but is another important reminder about the risk of indirect spread and the need for basic hygiene – an infant is unlikely to be feeding a dog treats (although people do strange things), so cross-contamination of surfaces (including the floor) or peoples’ hands would be the likely source of exposure (or possibly picking up a dog treat left behind by the dog).

There’s been no recall of the implicated treats. The company does not put expiry dates on their products, so that complicates tracking and messaging. There’s no mention in the Public Health Notice about specific lots, just the product names. To be safe, for now I would assume that any bags of those products, and realistically anything from that company, is contaminated.

As is unfortunately typical with websites of raw food companies are implicated in disease outbreaks, there’s currently no mention of this risk or the investigation anywhere I can find on the manufacturer’s website. I will give them credit for at least mentioning Salmonella and the need for hygiene when handling their products; the information isn’t very comprehensive and some is a bit questionable, but it’s a start, and it’s better than other companies that ignore or blatantly misrepresent the risks from their raw products.

Treat image from Puppy Love Pet Products.

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There are a couple of new voluntary recalls because of Salmonella contamination of pet diets or treats. Both are US products, and the recalls were posted on the FDA website just before (Canadian) Thanksgiving.

One recall is for possible Salmonella-health risk associated with a raw frozen beef dog food from Raw Bistro Pet Fare (MN). That’s not very noteworthy, since Salmonella contamination of raw diets is common. Focusing on the odd batch of food with known contamination when we know that a large percentage of these diets at retail are actually contaminated doesn’t really help much (but the recall is still worthwhile). It’s fair to assume that any raw diet that’s not been high pressure pasteurized is harbouring Salmonella, E. coli, Listeria and/or other pathogens. High pressure pasteurized diets are much lower risk, but not zero risk.

The other recall is for possible Salmonella contamination of specific lots of Raw Dog Barkery, BellePepper Cats, and Kanu Pets brand freeze dried treats from Foodynamics (WI). Recalls of pet treats in particular are worth discussing, since raw animal-based treats are commonly contaminated, but people often don’t often think about them as “raw” unless the word is right in the name (which it often isn’t). You can find dried or freeze dried treats made of pretty much any animal part (e.g. liver treats, rawhides, hearts, pig ears, bully sticks) in most pet stores. If there was no cooking step in preparing the treat, it should be considered high risk for contamination with Salmonella and other bacteria (and raw poultry-based treats can also be a risk for contamination with H5N1 influenza virus in some regions theses days).

As opposed to diets, treats are not often marketed as raw or prominently labelled as raw. People may assume that dried treats have been cooked. They may also erroneously assume that freeze drying eliminates bacterial contamination (when in fact freeze drying is an excellent way of preserving bacteria for long term storage). Some of these treats, like liver treats, are even common in veterinary clinics, because even there people may not make the connection with any risk.

I’ll give a shout out to Fooddynamics for the voluntary recall for their freeze-dried treats in this case. Although kudos shouldn’t we warranted, we’ve seen pet food companies other pet food companies ignore and deflect in response to contamination of their products, instead of doing the responsible thing by issuing a recall, so it’s good to this company doing the right thing.

Impressively, the FDA reported that “Foodynamics successfully traced 100% of the product distribution within hours of the recall notice and has contacted all direct customers. No adverse health effects have been reported in pets or humans to date.” Presumably these are pretty small production lots and sales are online so the company can easily trace who bought what. Still, it’s impressive to see that a company willing and able to track down all purchasers.

It’s also nice to see that “Foodynamics has ceased the production and distribution of the product while it works with the FDA to continue its investigation into what caused the problem.” Again, that shouldn’t be surprising or encouraging, but we’ve seen so much “deny and deflect” by other companies that it’s refreshing to see this type of response.

It was also noteworthy that contamination in both cases was detected through routine FDA surveillance, not in response to animals or people getting sick. That means we got lucky to some degree, since only a miniscule percentage of retail products are tested, but it also shows that surveillance can help prevent problems in two ways:

  • They got contaminated food off the market.
  • It led to an investigation that will hopefully reduce the risk of future problems for the company, if the investigation identifies anything that can be improved.

However, with raw diets, there may not be a lot the company can do. The critical control point is cooking, and if they don’t do that by nature of the product being sold raw, then there’s always going to be a risk of contamination of the final product. Good manufacturing practices can help reduce cross contamination and ongoing contamination from equipment, but can’t prevent Salmonella contamination in the ingredients themselves. If Salmonella comes in and products aren’t cooked, it’s going to come out with the final product.

So, there’s a mix of good and bad in this scenario. Ultimately, there’s still the question of risk from treats and how to reduce said risk.

  • Should we avoid treats? No.
  • Should we avoid raw treats? Yes.

Determining whether a treat is raw can be a challenge for the average consumer:

  • If the label says “raw” then it’s obvious.
  • If the product is freeze-dried, there’s unlikely a cooking step involved, so assume it is raw.
  • If the treat looks like a piece of an animal (e.g. pig ear) and it doesn’t say it was cooked, odds are it was just dried; treat these as raw too.
  • If the product looks like a kibble or other non-anatomical shape, they were probably extruded / cooked and are therefore lower risk (though still not zero based on the odd chance contamination occurs after the cooking step).

I’ve had a lot of questions about this week’s somewhat (understandably) vague notice from the Public Health Agency of Canada (PHAC) about an ongoing outbreak investigation of Salmonella infections linked to dog food and treats. The information available is pretty sparse, but there are still some important messages related to what we do know.

From February to August 2025, there have been 27 people infected with Salmonella Oranienburg across Canada, mostly from out west (13 from Alberta, 12 from British Columbia). Six cases were hospitalized, and the outbreak may still be ongoing.

  • Reported Salmonella cases are always the distinct minority. For every case that gets reported, someone has to get sick, THEN go to the doctor, who THEN has to order the test, and THEN the person has to actually submit the fecal sample, and the lab THEN has to isolate Salmonella and THEN report it. That’s a lot of steps where things can get derailed for one reason or another. It’s been estimated that there are likely as many as 26 cases Salmonella in people for every case that gets reported to public health.
  • Hospitalization are probably less underestimated since testing is more common in sicker people. Regardless, six hospitalization highlights how serious these infections can be.

The link to pet foods is presumably based on interviews of infected people. When a cluster of infections caused by a specific (and uncommon) strain of Salmonella like this occurs, investigators try to find common exposures among the cases to help narrow down potential sources for further investigation. Sometimes finding the source is straightforward, such as when everyone reports eating the same kind of food from the same source around the same time. With outbreaks that are more spread out over months and across the countryidentifying the source is tougher.

“Many” (unclear how many) cases in this outbreak reported handling dog kibble, dehydrated pet diets and freeze-dried treats prior to getting sick, but no common supplier was evident. The fact that not everyone reported that type of contact doesn’t rule out pet food/treats as the source, since no one’s recall is perfect (especially if they were interviewed weeks or months after the were ill). Some people could have had indirect exposure through environmental contamination or from a dog that was infected by eating contaminated food/treats, or through visiting someone with a dog, without realizing they could have been exposed. It’s also possible there’s some other risk factor that just couldn’t be identified, or that the pet food/treats is a proxy for some other exposure (but I don’t have a good idea what that could be).

The fact that kibble, dehydrated pet diets and freeze dried treats are all mentioned shows there’s no clear direction towards what might be the source. If I had to rank the probable risk from these products, I’d put dehydrated diets first, treats next and kibble last.

  • Dehydrated diets are raw diets. Raw animal-based products are high risk for Salmonella and other pathogens. Dehydration is not a pathogen elimination tool. It will have an effect on some bacteria, but not all.
  • Freeze-dried treats are also primarily raw animal-based products, and are therefore also high risk for Salmonella and other pathogens. Freeze drying is likewise not a pathogen control tool, in fact it’s a pathogen storage tool – if we want to preserve a bacterium for a long time in the lab, we can freeze dry it so it’s shelf-stable. Myriad raw animal based treats are available too. Go into any pet store and you’ll likely find bins and bags of dried animal bits of various sources (e.g. liver, pig ears, rawhides, bully sticks and much, much, more). Bulk bins of these pose even greater risk because one contaminated item can cross-contaminate the whole bin.
  • Kibble is initially cooked and extruded, which should kill any pathogenic bacteria in the raw ingredients. However, it’s still a plausible source of Salmonella as there have been infections linked to kibble. This may occur from post-extrusion contamination (e.g. contaminated flavour enhancers that are sprayed on the kibble after), or through contaminated machinery. The risk is really low, particularly compared to raw diets, but it’s not zero. Kibble is also probably a less likely source in this outbreak because a specific product would likely be more easily identified during the interviews. However, if contamination occurred because of an ingredient that was sourced by different companies, or if different companies’ food was produced in the same plant (which does happen), then the link would be harder to identify.

Hopefully we’ll get more details as the investigation continues. If the outbreak is ongoing, there will be more data that could help identify the source, and now that public health personnel are aware of the potential dog food/treat link, there might be more detailed questions and quicker testing of products.

  • Testing of dog food and treats to confirm the source requires rapid identification of the issue so that the source food/treat is still possibly available to test. The longer it takes, the less likely that is.
  • It’s unclear if any testing of products has been done so far in this outbreak. At this point, with no clear source, testing of food and treats in affected peoples’ houses would be a fairly low yield fishing expedition, especially given time delays. It would be easier to pick up in kibble, since there could be more bags of the lot around to test, if an entire lot was implicated. Dehydrated diets and treats are usually made in smaller batches, so by the time an issue is identified, there may be none left to test.

It’s hard to say if we will get a final answer as to what caused this outbreak, but in the meantime, it’s a good reminder of some basic infection control practices. PHAC’s advice is pretty basic but like a lot of things in infection control, basic practices are the core prevention methods:

  • “To prevent illness, individuals are advised to practice good hand hygiene and frequent handwashing after contact with dogs, their food and treats.”

Good basic hand hygiene, preventing cross contamination of pet food and human food, keeping higher risk people (especially young children) away from pet food and food bowls, avoiding raw diets and raw animal-based treats (which are abundant, and people don’t often realize are raw) and good hygiene when handling pet feces are all easy, reasonable and critical core prevention practices, especially until (and even if) the true source of this outbreak is identified.

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A recent opinion article in the Washington Post about how to protect cats from H5N1 influenza includes some good considerations, but alongside some bad information. It’s prompted me to write a bit about pet food preparation and how it does (and does not) affect the presence of infectious pathogens (but please keep in mind while reading this that I’m an infectious disease veterinarian and not a food safety specialist!).

In the article, there’s a statement from a professor at a school of public health who said they were avoiding canned pet food “…largely because the pet food industry is not as closely regulated as the human food industry,” …Coleman has not been giving her cats canned food, as it might contain unpasteurized milk. Kibble, on the other hand, is heated at very high temperatures, which, like pasteurization, would kill H5N1.”

However, canned pet food is actually likely the lowest-risk form of pet food when it comes to pathogens. Processing conditions are very different for different forms of pet food, and the processing significantly impacts pathogen survival:

Canned pet food

These diets are heated to high temperatures (235F/115C or above), akin to sterilization. If it wasn’t, cans would spoil quickly and often explode because canned food is otherwise a great culture medium for bacteria. Canning will absolutely kill H5N1, full stop. No question, no concerns. Move on please.

Kibble / dry pet food

These diets are also thoroughly cooked prior to being made into kibble. The temperatures used are not standardized, but are well above the recommended temperature for cooking poultry (165F/74C). Heat is also generated during extrusion process (forming the food into kibble) and desiccation (being dry food) will also decrease pathogen survival. The food isn’t sterile, but as long as the finished product is kept away from raw ingredients (a pretty standard food safety step), I have no concerns about flu contamination in dry kibble.

Lightly or gently cooked diets

These diets are in the grey zone. They’re marketed as diets that are cooked but are not to the same extent as kibble. Killing pathogens in food is a function of temperature and time. If they reach the recommended cooking temperature for poultry (165F/74C), any flu virus in the product should be long gone. At lower temperatures, there’s more variability and more need for a longer cooking time (e.g. 60C/140F for 30 minutes). A challenge with these diets is the lack of information about the “gentle” cooking parameters (temperature and time). I suspect they likely all hit a high enough temperature to at least kill flu viruses (which are easier to kill than some food borne bacteria) but that’s a bit of a guess. I’d consider them low risk overall, but if I was going to feed a diet like this I’d ask the company how they cook the food, to be sure.

High pressure pasteurized raw diets

High pressure pasteurization (HPP) uses pressure (instead of heat) to inactivate microorganisms. However, the effectiveness is dependent on the amount of pressure and how long it’s maintained, as well as the food matrix itself, and volume of food undergoing HPP. If the method is validated and performed properly, the risk of flu virus surviving the process should be really low. However, we’ve seen at least one report of fatal H5N1 influenza in a cat that was eating a HPP-treated diet. Recalls of HPP treated diets for Salmonella contamination are also far from rare (and if the process doesn’t kill Salmonella in a certain product, we’d be concerned it might not effectively kill flu virus either). I consider HPP a risk reduction method, not a risk elimination method. If a company can show that their method kills flu (or a proxy virus), then I’d be more confident the diet is safe (at least from a flu standpoint). 

Raw diets with “natural preservatives”

Preservatives are used to reduce spoilage. That means they reduce growth of bacteria that are already in the food. They are not designed to kill pathogens (bacteria or viruses) in the food. So, whether or not there are preservatives (and whether or not they are considered “natural”) likely has no impact on survival of and risk of contamination with H5N1 flu in the diet.

Freeze-dried pet food

These diets are frozen, and then the water is removed under vacuum. Freeze drying is actually great method for preserving viruses for long-term storage in laboratories. I’m not aware of any evidence of any impact of freeze drying on survival of flu viruses, so until then I would assume that freeze dried diets are the same risk as fresh diets.

Raw (fresh) poultry

If H5N1 flu is present in a bird, it will be present in the meat from that bird. If there are no steps to kill it, flu virus can persist for a while in that nice moist environment, even after the bird has been slaughtered or died. Refrigeration probably helps with survival of the virus. Freezing probably has a bit of impact, since freeze-thaw cycles can impact viral viability, but I have no confidence in simply freezing the meat to significantly reduce viral contamination, and would not consider frozen raw diets to be any different than fresh in terms of risk. Untreated raw poultry is undoubtedly the highest risk pet food when it comes to H5N1 flu (not to mention a lot of other pathogens as well).

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Issues with raw diets and H5N1 influenza risk in cats (and dogs) have gotten a lot of attention in the last week or two. Like most emerging disease situations, it’s still fluid, and we’re learning more as time goes on, but we know enough at this point to at least make some basic assessments and recommendations. Here’s my current take on it.

What are the concerns with H5N1 influenza and raw diets for pets?

The unprecedented pandemic of H5N1 highly pathogenic avian influenza (HPAI) has ongoing for more than 2 years. Massive numbers of wild birds have been affected around the world. Spillover into domestic animals is an ever-present risk where this virus is circulating in wild birds, with domestic poultry being the most severely affected. Millions of domestic poultry have died or been depopulated due to infection, and spillover infections have also occurred in mammals, including many cats and at least one dog.

Recently, H5N1 influenza infection has been linked to consumption of contaminated raw meat diets in at least two cats. It’s been well established for some time that ingestion of infected birds can lead to H5N1 influenza infection in cats, based on earlier studies and field observations. It is therefore unsurprising that infections could occur if infected poultry makes its way into raw diets fed to cats, and unfortunately the infection in cats is often fatal.  The risk to dogs is less clear, but infection was reported in one dog that died shortly after close contact (chewing on) an infected bird. Dogs may be less susceptible to H5N1 influenza than cats, but they are still susceptible and infection can have dire consequences, so the same concepts apply to both species.

What types of raw diets for pets pose a risk of H5N1 influenza infection?

Poultry-based diets are the main concern, including chicken, turkey and duck, as all poultry are highly susceptible to H5N1 influenza. However, the virus is now also widespread in dairy cattle in the US, particularly in certain states (like California at the moment). Work done by the Food Safety and Inspection Service (FSIS) in the US has found no evidence of virus in retail beef samples and only very low levels of virus in samples from 1 of 185 cull dairy cows tested (the positive cow did not enter the food chain). More investigation is needed, but it is likely that viral loads in muscle of infected cattle are far less than those in poultry. Risks from beef are presumably low, but the potential for the virus to be present in meat from infected dairy cattle cannot be dismissed.

Does use of “human grade” meat in raw diets eliminate the risk?

Human grade meat does not mean pathogen-free – it only means that the meat would have been allowed for sale for human consumption based on more rigourous requirements for the animals, facilities, processing and handling. These presumably reduce, but do not eliminate,  the risk of H5N1 infected animals entering the pet food chain.  

Does high-pressure pasteurization of raw diets eliminate H5N1 influenza virus?

High pressure pasteurization (HPP) of food products uses high pressure (rather than high heat, as in cooking) to reduce contamination with bacteria and viruses. Many commercial raw diets for pets are high pressure pasteurized (which is good). The pressures achieved during this process should inactivate influenza virus, but there are no standard methods for HPP. The effectiveness of HPP depends on the pressure, temperature, and composition of the food matrix. It is unclear whether manufacturers have developed and validated the method for their wide range of diets and pathogen risks. Recalls of high-pressure pasteurized raw diets because of Salmonella contamination have been regular occurrences, and a recent infection in a cat was linked to such a diet. High pressure pasteurization should be considered a risk reduction step, not a risk elimination step.

Are frozen or freeze-dried raw diets lower risk for H5N1 influenza?

Freezing and freeze drying are effective preservation methods for viruses, so its unlikely that these methods substantially reduce the risk of viral contamination in raw diets. Ultralow freezing is used for longterm preservation of viruses, but shorter-term survival is also possible at temperatures achieved using normal freezers (-20C). A study of the survivability of H7N9 influenza on raw chicken meat (Dai et al. Lancet 2022) reported that viral infectivity was maintained for 9 days at -20C, 4 days at 4C and 4 days at 25C. This was a rather small study, so it is possible that somewhat longer survival could occur in some situations. In nature, long term (e.g. overwintering) survival of influenza virus in ice has been suspected.

While the survival kinetics of this virus with freezing are not clear, it should be assumed that the virus could survive frozen for at least a week, and possibly much longer. Freezing should not be assumed to be a risk mitigation measure for viral contamination of raw diets.

Freeze drying is a highly effective virus preservation method. Survival of virus in freeze dried food has not been assessed, but in the absence of specific evidence, it is reasonable to assume that influenza virus would survive for long periods of time in such diets.

My cat is doing well on a raw diet and I don’t want to change. What can I do?

Raw diets can be cooked so that the cat receives a diet with the same ingredients but without the risk from H5N1 influenza (and other pathogens). There is no evidence that cooking reduces the health benefits of a diet. Cooking the food to an internal temperature of 165F/74C will inactivate influenza virus and other pathogens such as Salmonella.  

My cat has eaten a raw diet that’s been recalled diet. What should I do?

You should observe your cat closely and contact your veterinarian in you are concerned or your cat develops any signs of illness. Antiviral prophylaxis could be considered in particularly high-risk situations where it is likely that the cat has eaten contaminated food. This may not be the case for all recalled diets and would depend on the nature of the recall. Early signs of H5N1 influenza in cats are not well established, but often seem to be vague signs such as lethargy, malaise and decreased appetite. Rapid progression to severe disease can occur so veterinary care should be sought as soon as possible.

My cat has eaten a raw diet that’s not been recalled. What should I do?

Unless there is evidence that the diet has been implicated in disease, the odds of a problem developing are low. However, it would still be ideal to transition the cat to a cooked diet, whether that’s a commercial wet or dry diet, a home-cooked diet or cooking the cat’s current raw diet. Monitoring of your cat for illness, as above, is still indicated, as always.

What are risks to people from contact with contaminated raw diets?

The risk to people from H5N1 influenza from handling contaminated raw diets is likely quite low but not zero. Exposure could happen from inadvertent ingestion of the virus from contaminated surfaces (e.g. food prep surfaces, refrigerator, food bowls). That would likely be low level exposure, but the infectious dose of the virus is not known so it could still be relevant. There are similar risks with these diets from pathogens such as Salmonella, so good food handling practices are always warranted. These include avoiding cross-contamination with human foods and kitchen surfaces, careful cleaning and disinfection of in contact surfaces, dishes and utensils, and thorough handwashing (or use of an alcohol-based hand sanitizer) after contact with the raw diet or food bowls.

The greatest risk to people would be from exposure to a cat (or less likely a dog) infected with H5N1 influenza. An infected animal might be shedding enough virus to infect people, although the risk of this is still unclear. Any cat or dog with suspected influenza should be handled sparingly, and with use of good infection control measures, including a mask (ideally an N95 respirator) and eye protection.  

Closing thoughts

My opinions on raw diets have been pretty clear all along. I don’t think there’s any evidence that raw diets have any health benefits over an appropriate cooked diet, but raw diets come with numerous infectious disease risks. I’ve seen enough dogs and cats (and sometimes owners) sickened from raw diets to be confident in that. At the same time, I’m a realist and know that some people will continue to feed pets raw diets regardless. That’s why we have a infosheet about raw diets that includes ways to reduce the infectious disease risks for those who choose to feed them to their pets.

The current situation doesn’t really change anything for me. I’m still opposed to raw diets for pets, and this simply adds yet another layer of risk to pets and people that consume/feed them.

If someone is adamant that they are going to feed their pet a raw diet, here’s what I currently recommend:

  • Avoid diets that contain poultry (including duck)
  • Use a diet treated with high pressure pasteurization (realizing it reduces risk, but does not eliminate it)
  • Take care to avoid cross contamination of human food, and use good food handling and hygiene practices (always)
  • If your pet has been fed raw meat and gets sick, make sure your veterinarian knows about the diet so they can consider whether that might be relevant
  • Pay attention to the news and recalls so that you can stop feeding a diet if there are any known issues (but realize that we don’t typically know about any issues until one or more animals gets really sick or dies from the diet)

The multi-state outbreak of salmonellosis linked to pig ear treats continues in the US. In the latest CDC report on the outbreak, 48 new infections have been added to the investigation since July 3, and 3 new Salmonella types are now involved (Salmonella Infantis, London and Newport). This brings them to a total of 93 cases of infection with the outbreak strains… or, I should say, reported infections. As always, reported cases are likely just the tip of the iceberg, since people who get sick have to go to a doctor, submit a fecal sample, Salmonella has be identified and it has to be linked to the outbreak. Most cases presumably are never diagnosed.

Of the 93 infections, 20 required hospitalization. Fortunately, no one has died.

Contact with pig ear treats has been implicated as the source. This isn’t surprising since they’ve been linked to outbreaks in the past. Pig ear treats are just dried pig ears. Pigs can shed Salmonella, leading to contamination of the treats. They can also be contaminated during handling, processing or later, such as through contamination of bulk bins in stores. The latter might be important in this situation, and there was a recall of bulk pig ear products because Salmonella contamination was identified.

Some key points for reducing the risk of Salmonella in people and pets from treats include:

  • Remember that raw animal-based products are prone to contamination with potentially harmful bacteria such as Salmonella, E. coli and Listeria.
  • Check to see if the treats have been processed in a way to kill bacteria, such as cooking. Dehydrating is not the same thing.
  • Avoid buying treats from bulk bins. All it takes is one contaminated treat (or hand) and many other treats can become contaminated.
  • Avoid feeding raw animal-based treats (such as pig ears) when you have a high-risk person in the household. This includes children less than 5 years of age, people over 65 years of age, pregnant women and individuals with compromised immune systems (e.g. due to illness or drug therapy).
  • Avoid feeding raw animal-based treats in households with pets that fit into high-risk groups as well. Also avoid them in dogs that are used for hospital visitation programs, where the dogs will be in contact with a lot of high-risk patients.
  • Wash your hands after handing any pet treat, especially those from raw animal products.

Pet treats are widely used, and for good reason. Treats can be useful training tools, and pets typically like treats (and owners like to make their pets happy). But even something as simple as feeding pets treats carries some risks (and not just to the pet).  Balancing the risks and benefits is the key. For example:

Pathogens

  • I have to start with this one, since Worms & Germs are what we deal with here. Pet treats have been implicated in a few different outbreaks in people. Salmonella-contaminated pig ear treats are historically the main offender, but any animal-based treat that is not processed to kill pathogens (e.g. cooking, pasteurization, irradiation) is a concern.
  • While pig ears used to be the primary culprit when it comes to contaminated treats, now, you can go into some pet stores and get dehydrated "insert almost any body part here" – lung, trachea, liver, ear, etc. Presumably these items carry a similar degree of risk for Salmonella if they are otherwise unprocessed.

Toxins

  • The main concern here is chicken, duck and sweet potato jerky treats from China, which have been implicated in a large number of pet illnesses and deaths, including at least 1000 dead dogs. No reason for the Fanconi-like syndrome associated with these treats has been identified, and therefore there’s no way to test the products to ensure the same problem won’t happen again.

Injuries

  • Hard treats can result in tooth damage or fractures, which can be both painful and expensive to address.
  • Treats with sharp edges (e.g. bone fragments) can cause damage to the intestinal tract as well.

Obstructions

  • Dogs eat stuff they’re not supposed to all the time (at least mine does). Most often, it’s not a problem, but sometimes it is. If a pet swallows a large piece of a poorly digestible treat it can cause an intestinal blockage. Realistically, this is of limited concern for most edible treats, but is a bigger issue with toys and things like rawhides.

Obesity

  • Weight gain and obesity aren’t usually considered when thinking about problems with treats, but a lot of treats are high in calories, and obesity isn’t just a problem with pet owners. As with human snacking, moderation is the key. Also remember that sometimes size does matter, as  demonstrated in a recent study of bully sticks (dried bull penis) in which is was determined that these treats contained 9-22 calories per inch (Freeman et al., Can Vet J 2013).

Before giving it to your pet, think about the treat, how to use it and what problems might occur. Most treats, particularly those that are not raw animal product based (e.g. pig ears), not prone to fragmenting (e.g. bones, especially cooked bones) and not excessively hard (e.g. bones) are okay in moderation.

One question that’s come up recently is whether pig hair in or on treats can be a problem…

For some, pig hair on their dog’s treats has a bit of an "ick" factor (although it’s a little odd to see people freak out about some hair and then feed their dog a chunk of bull penis or the ear of a pig), but is there really a risk?

  • I can’t see there being any realistic concerns.
  • A dog would have to eat a massive amount of hair-laden treats to have any potential concerns about obstruction (and even then the risk would be remote at best).
  • Hair could be contaminated with various bacteria, like other raw animal parts, but if the treat is cooked (or otherwise treated to kill bacteria) that becomes irrelevant. Certainly, it’s fair to ask whether hair is supposed to be there but I wouldn’t get worked up about it. I’d be more concerned about whether the treat is processed to kill pathogens and fed in moderation (to reduce caloric intake more than hair intake).