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Raw diets have been in the news a lot lately because of Salmonella contamination. It’s not surprising at all since bacteria like Salmonella, E. coli, Campylobacter and Listeria are expected to be found in raw meat (that’s why we cook it). We know that dogs and cats fed raw meat are at increased risk of shedding bacteria like Salmonella, sometimes with serious consequences to the animals or their owners.

Reducing the risk is a challenge when you know there’s a reasonable chance the food is contaminated, and when the preferred method of control (cooking) isn’t used. Irradiation is an alternative approach, but not something in which a lot of raw feeders are probably interested. High pressure pasteurization (HPP) is therefore increasingly being used to help control bacterial contamination of these products. HPP, as the name suggests, uses high pressure (with minimal increases in temperature) to reduce bacterial loads.

Notice I said reduce, not eliminate.  That’s the problem.

A while ago, I used to go on the assumption that raw food products that underwent HPP were similar in risk to commercial cooked diets, with the disclaimer that we don’t really know for sure. We still don’t know a lot, but what we know now isn’t encouraging, so I’ve had to change that assumption.

I’ve talked to a few people who have done limited investigations of foods treated with HPP, and the results were disappointing. Unfortunately the studies were small and remain unpublished.

A 2016 research abstract gives us a bit more substance (although a proper research paper would be preferred). In that study (Hasty et al. 2016, Reciprocal Meat Conference – Meat and Poultry Safety), raw beef pet food was spiked with E. coli. (A harmless strain of E coli was used in place of a disease-causing strain or other bacteria like Salmonella, presumably because of biosafety concerns.) They used a HPP process that subjected the meat to a standard pressure (600 mpa) for 480 seconds. Then they checked to see if any viable bacteria were left in the meat.

The good news: There was a definite reduction in viable bacteria.

The bad news: It didn’t kill them all.

This doesn’t mean HPP is ineffective. It’s a matter of being aware of what it can do, and what it can’t. It can reduce the number of viable bacteria in the food, and that probably reduces the risk of disease in people and pets. But it does not eliminate all the bacteria, so it can’t eliminate the risk (only proper cooking and handling will do that).

If someone is going to feed a raw diet, I’d still recommend using a HPP-treated diet versus one that has bot been treated. However, people have to realize it’s not a panacea and that they still have to assume the food is contaminated.

Here’s a quick reminder of some basic take-home messages for raw meat feeding:

  • There’s always some risk of bacterial contamination. We can reduce, but not eliminate, that risk.
  • Careful handling is required to prevent cross-contamination of human foods, surfaces and environments. A little common sense when it comes to food handling can go a long way (but it’s amazing how uncommon “common sense” can be… check out Barfblog.com for annals of food safety stupidity).
  • Raw meat diets should not be fed to dogs and cats at increased risk of serious disease (e.g. very young, elderly, pregnant, immunocompromised) or in households where people (or pets) fitting those categories are present.
  • People who feed raw diets should make sure their veterinarian knows this, should their pet get sick. The same applies on the other side of the One Health spectrum – if someone is feeding raw meat to their pet and a person in the household has gastrointestinal disease, exposure to raw meat needs to be mentioned to the physician involved.

More information about raw meat feeding and basic safety practices is available on the Worms & Germs Resources – Pets page.

The Minnesota Department of Agriculture has recalled some lots of raw pet food from Woody’s Pet Food Deli, after linking them to a human infection. The link isn’t definite, but was obviously enough to prompt a recall.

The situation involves a person who developed salmonellosis and, as is typical, an investigation of possible sources ensued. Salmonella Reading was isolated from the person. This strain has been previously found in raw turkey-based pet food, and the affected person had handled just such a product that was fed to the patient’s dog. A fecal sample from the dog was tested and Salmonella was isolated. It wasn’t Salmonella Reading, but isolation of Salmonella from the dog was enough to cause concern, particularly given the previous linkage of this Salmonella strain to raw pet food-associated infections. If no other potential sources were identified, it’s reasonable to assume the pet food was the source.

The source of the Salmonella found in the dog was likely also the food, since Salmonella shedding by dogs is rare. Samples of raw food from the manufacturer were tested and Salmonella (not S. Reading) was isolated, which prompted the recall. An issue that comes up in investigation of raw pet food-associated outbreaks is the small production batches and the variability of contamination. By the time someone gets exposed to Salmonella from pet food, gets sick, goes to the doctor, gets tested, the result is reported and public health investigates, the batch of product that was originally fed to the dog is typically long gone. So, other batches have to be tested and even if the food was the source, subsequent batches may not be contaminated or, as is the suspicion here, might be contaminated with different Salmonella.

Finding Salmonella in raw meat is expected, and human (and animal) illnesses occur sporadically. They’re underreported and we don’t really understand the full scope of the problem. However, these infection are preventable.

I’m long past the stage where I think I can convince people not to feed raw diets to their pets. That’s a personal decision, and while I think it creates unnecessary risk and hassles, it’s going to be done by some. However, there are some households where raw diets should NOT be fed. These include households where high risk people or animals are present, i.e. individuals who are more likely to get sick and/or more likely to develop serious illness. Households with young kids, elderly individuals, immunocompromised individuals or pregnant women are high risk. The same applies to animals, so households with old, very young, immunocompromised or pregnant dogs/cats should avoid raw feeding too. I’m also wary of it in growing animals, since there are lots of cases of nutritional deficiencies when the diet being fed isn’t properly balanced for such an animal (which is tricky to do).

For people who choose to feed a raw diet, the key is using some simple precautions to reduce (though they will not eliminate) the risk. We have a fact sheet outlining these practices on the Worms & Germs Resources – Pets page.

We’ve known for some time that there are human health risks from feeding pets raw meat-based diets. Most of the evidence of this has been anecdotal, as published reports have been sparse. A few better documented reports have started to appear, including the fatal E. coli O157 infection I wrote about recently.

A few days ago, the CDC released a report about an outbreak of Salmonella Infantis infections in the US. It involved 92 people from 29 US starts and was linked to raw chicken products. Raw chicken-based pet food was among the raw chicken products from which the outbreak strain was isolated, and one person got sick after their pets ate chicken-based raw food.

This isn’t particularly surprising since Salmonella contamination is an inherent risk with raw poultry. Human disease can occur when people ingest Salmonella from undercooked meat or from contamination of their hands or environmental surfaces (e.g. in the kitchen). When it comes to raw pet food, people can be exposed from handling the food, cross contamination of food or surfaces, contamination of the food bowl or exposure to Salmonella in in feces of the pet.

CDC’s recommendation is pretty straightforward: “CDC does not recommend feeding raw diets to pets. Germs like Salmonella in raw pet food can make your pets sick. Your family also can get sick by handling the raw food or by taking care of your pet”.

I have the same recommendation, but am realistic enough to know that it’s still going to be done by some people. It definitely shouldn’t be done in households with very young, very old, pregnant or immunocompromised people or animals.

If you are going to feed raw diets to your pet, do it wisely. More information about this is available on the Worms & Germs Resources – Pets page.

Human health risks from raw pet food (either from exposure to pathogens in the food or in the feces of pets eating the food) are known to exist but they’re not well characterized. We know that dogs fed raw meat-based diets clearly have increased risk of shedding various pathogens, particularly Salmonella and multidrug resistant E. coli. We know this results in some degree of disease risk in animals and in humans, but the scope of the problem is poorly understood. A recent report from Public Health England provides some more information about the risks associated with feeding raw pet food.

The report is about four people who were infected with E coli O157, a particularly nasty strain of E. coli that can cause serious disease in people.

  • One person developed hemolytic uremic syndrome (HUS), a particularly severe consequence of infection, and died.
  • The four cases involved the same strain of E. coli O157. Three individuals had been exposed to dogs fed a raw meat diet. Tripe was the specific ingredient that was implicated.
  • Samples of raw pet food were collected for testing. All samples from one raw pet food producer were positive for STEC (shiga toxigenic E. coli, the group to which E. coli O157 belongs). A positive test was also obtained from the freezer of one of the affected individuals, and from one sample of raw tripe. It strain isolated from the tripe was a different from the outbreak strain but supported the notion that tripe might have been the cause. It’s not surprising that they couldn’t isolate the outbreak strain from the food, given the lag from the time of exposure of people to the time of sampling of pet food. Contamination is probably sporadic, with different strains contaminating different batches.

Feeding raw meat-based diets is popular, but associated with risks to pets and people (have we said that enough times yet?). My preference is for it not to be done, but I’m realistic enough to know that people are going to do it anyway. So, I focus on two things:

  1. Who should definitely NOT feed raw meat to their pets?
    • Households where pets or people are at increased risk of severe disease, including those where young, old, pregnant or immunocompromised individuals (human or animal) are present.
  2. If raw meat is to be fed, how can the risk be reduced?

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.

A recent report from the Netherlands in Emerging Infectious Diseases (van Dijk et al 2018) describes a new twist on raw feeding concerns, Brucella suis infection.  Here’s the short version of the story:

A dog in the Netherlands developed fever, ascites (fluid free in the abdomen) and inflammation of the testicles.  After failing to respond to antibiotics, it was taken to surgery to be neutered.  In the process, culture samples were collected from the epididymis (tissue adjacent to the testicle) and from the abdominal fluid. Brucella suis was identified in both samples, which presumably caused a bit stir in the lab and the clinic since this bacterium is a rarely identified, can also infect people and is federally notifiable in the Netherlands (i.e. the government has to be contacted when it’s found). Ultimately, the dog was euthanized after failing to respond to further treatment.

Because this is a notifiable disease, there was an investigation. The dog did not have any of the typical exposures that would increase the risk of Brucella infection, such as contact with wildlife or livestock, breeding, or travel to brucellosis-endemic areas.  The dog’s raw, rabbit-based diet that was imported from Argentina therefore became the leading suspected source. Brucella suis was ultimately identified in samples from a 30,000 kg batch of raw rabbit imported from Argentina, a country where B. suis is present.

It’s a single case report so we can’t get too worked up about it, but it’s noteworthy for a couple reasons:

  • Reason 1 is the disease – brucellosis is a nasty. It can be hard to treat, is potentially zoonotic, and sometimes results in public health-mandated euthanasia of the dog.
  • Reason 2 is the importation aspect. The dog wasn’t imported but the bacterium was, via food. We’re trying to increase awareness of the need to query travel and importation history in pets, as it can significantly impact disease risks. Querying diet origins is even tougher.  While most people know where their dog has been in the past few weeks, they may not know much about where their dog’s diet has been. With commercial processed food, it’s not a big deal, but with higher-risk food like raw meat, importing food can be similar to the dog visiting the country of origin, from a disease standpoint. With raw meat, knowing where the meat came from and the disease risks in those areas may be important, but often not easy to find out.

The incidence of disease in dogs and cats associated with raw meat feeding isn’t clear, and is probably low. Nevertheless, I recommend avoiding raw meat feeding, especially in  high risk households (e.g. with elderly individuals, kids less than 5 years of age, pregnant women or immunocompromised individuals). However, if raw meat is to be fed, some basic precautions can used to help reduce the risks.  For details, see the raw meat infosheet on the Worms & Germs Resources – Pets page.

I haven’t written much lately about recalls of raw pet food because of Salmonella contamination. In large part that’s because it’s essentially an expected event. There are very good reasons why we cook food – one is to kill things that can make us sick. We assume that raw meat intended for our consumption is contaminated with bacteria like Campylobacter and Salmonella (because it often is). Therefore, we similarly expect raw meat for pet consumption to be frequently contaminated. Various research studies have confirmed that.

Highlighting the issues and risks yet again is a recent recall involving Blue Ridge Beef of Eatontown, Georgia. They are recalling “kitten grind” (an unfortunate name, in my opinion, but that’s a different story) after consumer complaints of deaths of two kittens. One death was confirmed to have been the result of Salmonella. Salmonella and Listeria were identified in the food (although it’s not clear to me whether it was the same strain and the same lot). Regardless, it’s not too surprising. Salmonella contamination of raw meat is common, and while disease in animals is fortunately rare, it can happen, sometimes with fatal consequences.

This should be a reminder that handling and feeding raw meat is a risk for exposure to pathogens such as Salmonella. My main recommendation is “don’t feed raw” plain and simple. That’s particularly true in households where there are high-risk people (e.g. young kids, elderly individuals, pregnant women, immunocompromised individuals) or high-risk animals (same types as for people). If someone’s determined to feed raw, it’s important to reduce the risk as much as possible. More information about that can be found in our raw meat infosheet on the Worms & Germs Resources – Pets page.

As if another reason was needed, a recent study from Australia (Martinez-Anton et al. 2018 J Vet Internal Med) found a strong association between dogs that consume raw chicken meat and a serious neurological condition known as acute polyradiculoneuritis (APN).  APN is comparable to Guillain-Barré syndrome (GBS) in humans.  The main objective of the study was to look at the association between APN and Campylobacter spp. infection, but knowing that this bacterium is commonly found in raw chicken, they also looked at consumption of raw chicken as a risk factor.  Owners of dogs with APN were 71 times more likely to report feeding raw chicken to their dogs compared to controls.  Of the 27 dogs in the study with APN, 96% (all but 1) were fed raw chicken, compared to 26% of control dogs.

And of course, anytime we’re talking about feeding a raw diet to a dog, we also need to consider the risk to the people who handle the food as well.  According to the CDC, about 1 in every 1,000 reported Campylobacter illnesses in people leads to GBS, and as many as 40% of GBS cases in the United States are thought to be triggered by Campylobacter infection.

Just one more reason to avoid feeding raw chicken to pets, and some extra motivation to pay close attention to safe food handling practices at home.

When we have discussions about the risks of feeding raw meat to dogs and cats, a frequent refrain is “where are the published reports of people getting sick?” While we know some illnesses occur, they tend not to get investigated to the level that they are published, which is problematic when trying to demonstrate the risks. Often the cases aren’t published because of failure to follow up with food testing, disjointed testing of the food and samples from affected people, or issues coordinating the animal, food and human information (given various barriers, including privacy issues).

However, a recent investigation in the US shows yet again that this is a real concern. Salmonella Reading infection was identified in two kids in a household, and the same Salmonella strain was isolated from four samples of pet food, namely Raws for Paws Ground Turkey Food for Pets (which is now under a FDA recall). One child was hospitalized with septicemia (i.e. bloodstream infection, a potentially fatal disease) and osteomyelitis (bone infection).

Deciding whether to feed raw meat to pets requires consideration of the risks.

My approach is that I don’t think it’s a good idea for anyone, but if you’re considering it:

  • A) think about situations where it should never be done, and,
  • B) take measures to reduce the risk.

Check out our raw meat infosheet on the Worms & Germs Resources – Pets page for more information on how to reduce the risks if you’re going to feed raw.

Situations in which raw feeding should not be done include households with people or animals that are more likely to get sick or suffer serious illness, including those with young children, as was the case here.

Image source: CDC Public Health Image Library 21918

Raw meatAccording to an alert from the College of Veterinarians of British Columbia:

The BC Centre for Disease Control is collaborating with BC health authorities, the Public Health Agency of Canada, and Health Canada to investigate an outbreak of Salmonella infections in British Columbia likely related to raw pet food. Raw pet food is food served to pets that contains raw animal proteins like meat, bones, organs, and eggs.

Four British Columbians who feed their pets raw food diets have become infected with the same strain of Salmonella. The exact source of the Salmonella is unknown but investigations are ongoing. Infections can occur during handling of raw meat, including raw pet food, or from pets shedding the bacteria. Animals can carry Salmonella bacteria but show no signs of illness.

I haven’t seen any other details yet and hopefully contact tracing is narrowing it down to the food type. It would be good to know how widespread exposure might be, since foodborne disease is markedly under-reported and if 4 cases of salmonellosis were confirmed, it’s likely that many more have actually occurred. Diagnosed case numbers tend to be the minority because they miss people that had mild disease and didn’t go to the doctor, situations where fecal testing was not recommended by the physician, or where the requested fecal samples were not collected.

Raw meat feeding inherently poses some risk to pets and households. It’s of particular concern when there are high-risk individuals (old, young, pregnant, immunocompromised) or high risk pets (similar groups) in the household, as members of these groups are more likely to get sick and more likely to have serious illness.

More information about raw meat feeding, including recommendations to reduce the risk for those who still want to do it, is available on the Worms & Germs Resources – Pets page, under the infosheet for raw meat.