Frozen mice recall: Salmonella
MiceDirect, a company that sells frozen mice, rats and chicks as reptile feed, has issued a recall because of Salmonella contamination of their product. Contaminated critters have been sold across the US (except Hawaii) through mail order and pet stores, and recalled product codes can be found in the FDA recall notice. Contamination isn't a big deal for the reptiles, since carriage rates for Salmonella are already high and they are usually healthy carriers. The concern is for people who handle the frozen rodents/chicks (or who can be exposed indirectly from contaminated surfaces in the home). There have been previous outbreaks of human Salmonella infections associated with contaminated frozen rodents.
Unlike many other recalls where the product is recalled because of contamination but without evidence of human illness, human illnesses suspected to be linked to contaminated reptile food have been identified in 17 states. In reality, reported cases may be the tip of the iceberg, and I suspect that if cases in 17 states are confirmed, there will be (or may already be) many more. Other details regarding these cases and the recall, such as the strain of Salmonella involved, haven't been released.
In response to this problem, the FDA report and the company website indicate that products from MiceDirect will be irradiated. It's not clear if this will be a standard protocol from now on, or whether it's a short-term response to the contamination problem. Considering the repeated outbreaks associated with frozen reptile food, irradiation sounds like a good standard practice. Perhaps the best way to help make (or keep) it a standard practice industry-wide is for consumers to vote with their wallets: ask for irradiated or otherwise treated (e.g. high pressure pasteurization (although I'm not sure what that would do to a mouse)) feeds to reduce the risks of contamination.
Because of recurrent problems with contaminated frozen reptile feed, if people are not buying products that are treated to eliminate contamination, they should assume that all such feed is contaminated and handle it accordingly. That means using basic practices such as:
- keeping frozen reptile feed away from human food
- if defrosting it in the refrigerator, keep the reptile feed in a sealed container that is not used for human food and that is disinfected afterward
- washing hands after handling the feed
- disinfecting any potentially contaminated surfaces that come in contact with the feed
- discarding uneaten food promptly, since Salmonella can multiply as uneaten food sits in the open, especially in a nice, warm reptile terrarium
A link to more information about MiceDirect is available through a post on Barfblog.
Salmonella recalls
A couple of more Salmonella recalls have occurred recently. Feline's Pride Natural Chicken Formula, a raw chicken diet, has been recalled, as has Natural Balance Sweet Potato and Chicken, a kibble diet.
Finding Salmonella in commercial raw diets is expected and I'm surprised about the recalls that have happened. If you buy raw meat, you need to assume that it's contaminated with Salmonella and various other potential pathogens. Salmonella in kibble diets is more surprising, and is a concern because people do not tend to handle kibble as potentially contaminated.
These recalls highlight a few points to me:
- Always assume you have Salmonella and other nasties in raw meat. Careful attention to handling of raw meat and personal hygiene (e.g. handwashing) is critical.
- While lower risk, kibble is not innocuous, so wash your hands and prevent cross-contamination of kibble with human foods.
- "Natural," along with "organic," "super premium" and other marketing catch-words tell you nothing about the quality and safety of a product. There's no evidence that any products marketed as organic, natural, or anything else along that line are at all superior to diets produced by reputable companies, particularly diets that have undergone proper development and testing, including AAFCO feeding trials.
Raw Q and A
While I hate to initiate another round of emails from raw diet supporters, here are a few of the more common questions that I get about these diets and some answers:
I use frozen raw food. Doesn't freezing kill harmful microorganisms?
- No. Freezing is an effective way to eliminate most parasites (with an adequately low temperature and adequate time, which varies between parasites). Campylobacter also does not survive freezing well. However, other bacteria, including Salmonella, tolerate freezing quite well. Studies of previously frozen raw diets have found high rates of bacteria like Salmonella.
My dog doesn't defecate in the hospital, so why are we paying attention to intestinal bacteria?
- Inadvertent exposure to fecal bacteria is common. Most gastrointestinal infections in people are from ingestion of bacteria and viruses from feces (e.g. Salmonella, Clostridium difficile, norovirus). We don't knowingly ingest feces, but we get exposed to these organisms nonetheless. Fecal bacteria can end up on pets' haircoats, people's hands and many surfaces in the general environment, and then wind up in the intestinal tract of a susceptible person.
Is there any way to eliminate Salmonella and other harmful bugs from raw meat?
- Yes. Besides the obvious (cooking), there are a couple options. One is irradition, which is a safe and highly effective way to eliminate bacteria. The main problems are cost and consumer fears of irradiation (which is actually harmless). Another approach is high pressure pasteurization. This process uses high pressure (with a slight increase in temperature) to kill harmful organisms. The effectiveness of this for raw meat hasn't been clearly determined, but it's an option, and one company is now doing this for all of their diets.
Why don't you just go into hospitals, ask nurses whether animals visit and compare infection rates, so you can see if there is a true health risk?
- It would be nice if it was that easy. Firstly, asking nursing staff doesn't give enough information. You need to know if animals visit, but also if they visited particular patients, and whether they visited before those patients developed infection. Just comparing infection rates between hospitals or wards that allow dogs to visit, and knowing the dietary status of the dogs, is useless. A proper study would require clear documentation of which animals visited which patients (something that is rarely recorded) and whether patients subsequently developed any infections that were not present before visitation (which is not easy to document), while concurrently investigating other possible sources of infection (similarly challenging). Ideally, bacteria causing human infections would be compared to those found in animals to provide stronger evidence of a link. Because the incidence of infections is relatively low, a large number of people would need to be enrolled. There are significant logistical issues, research ethics board issues, problems with the quality and availability of medical records and other things that make this very, very difficult. It needs to be done but it's not as simple as many people think. If it was easy, it would have been done by now.
Dogs have a short and acidic intestinal tract and are not susceptible to Salmonella.
- This statement appears thousands of times on the internet and there's absolutely no evidence supporting it. Dogs can and do get salmonellosis. For every email I've had talking about how a raw diet has made a big difference in someone's dog's health, I get at least one email from an owner or vet whose dog got salmonellosis while eating raw meat (and sometimes people in the house also got sick). A dog that eats Salmonella can shed it in its feces. The bacterium can clearly survive passage through the intestinal tract. Most dogs that ingest Salmonella do not get sick. Some do. Sometimes their owners do as well.
Wild dogs eat raw meat. That's what they've evolved to do.
- Wild dogs also have a much, much shorter lifespan than domestic dogs. It's obviously not all related to diet, but I don't want my dog to have the lifespan of a "natural" dog, I want her to have the longer and healthier lifespan of a modern pet dog. Take a look at older cemeteries and see the number of headstones of very young children. Raw milk played a big role in many of those.
- Regardless, the question isn't about the health of dogs fed raw meat. That's a completely separate issue. The issue is the risk that raw-fed dogs might pose to the highly compromised people that are found in healthcare facilities. People need to think about the health of those susceptible individuals when they get involved in this debate.
More raw debate
Since my post about Delta Society and raw diets, I've had multiple questions or comments about the research behind it.
Here's one question:
"Please site the research that "clearly show..." that raw-fed animals shed bacteria at a higher rate."
Here's the answer:
Lefebvre et al, Journal of the American Veterinary Medical Association, 2009
- Study following therapy dogs over the course of a year. Diet history was recorded. Raw-fed dogs were 17 times as likely to be shedding multidrug-resistant E. coli compared to non-raw-fed dogs, and more likely to be shedding Salmonella.
Leonard et al, Zoonoses and Public Health, 2010
- Study of healthy dogs in households. Dogs fed a commercial or homemade raw diet were greater than 5 times as likely to be shedding Salmonella than other dogs.
Lefebvre et al, Zoonoses and Public Health, 2008
- Study investigating therapy dogs in Ontario and Alberta. Raw-fed dogs were 23 times as likely to be shedding Salmonella and 17 times as likely to be shedding multidrug resistant E. coli.
Lenz et al, Canadian Veterinary Journal, 2009
- Campylobacter jejuni was found in the feces on 2.6% of raw-fed dogs and Salmonella was found in 14% of raw-fed dogs. Neither was found in any dogs not fed raw meat.
That's pretty clear to me.
Raw diets banned by Delta Society
Delta Society has recently announced a policy prohibiting animals fed raw meat or raw animal products from participating in their Pet Partners program. This policy was established because of research indicating dogs fed raw meat are much more likely to be shedding harmful bacteria like Salmonella and drug resistant E. coli in their feces compared to dogs fed commercial or home cooked diets, and the fact that these dogs come into close and frequent contact with people that are more susceptible to infections and at increased risk having severe infections.
Not surprisingly, internet chat sites are abuzz, and there's much condemnation and consternation from some. Some of the more vocal minority are stating that they'll just lie and say that they're not feeding raw. I guess such dishonest actions would be based on a combination of ignorance and arrogance - feeding raw is your own decision, but blatantly flouting a policy that was put in place to reduce risks to those most susceptible is stupid and irresponsible.
One of the problems with peoples' reactions is the fact that they are confusing two separate issues. One debate is whether raw feeding is more healthy or more harmful to the pet. That's a controversial area, but this policy has nothing to do with that. This policy deals with the increased likelihood that raw-fed pets are shedding harmful bacteria. That's been very well proven in scientific studies. Do raw-fed pets cause disease in people in hospitals? We don't know. However, we have enough evidence to indicate there is the potential for increased risk to patients, and that added risk can be eliminated by not feeding raw meat products.
Hopefully, people will realize that this policy has been put in place for a good reason, and that it's focused on protection of people at high risk of serious illness. It's not a broad condemnation of raw diets, it's just a statement that it is not considered appropriate for dogs that will have contact with high risk populations - a recommendation that's far from new.
Details about this policy can be found here.
Disclosure: I'm a member of Delta Society's Medical Advisory Board. However, the opinions expressed here are mine and do not necessarily reflect the views of Delta Society.
Raw diet "research"
PetProductNews.com reports that Nature's Variety, a raw pet food company, has unveiled results of a recent "research study" on their products. Whenever you see "research," especially on the web, you need to consider whether it's really valid scientific information or a marketing ploy. This particular case certainly doesn't seem like anything approaching real research.
Apparently the study, commissioned by Nature's Variety, involved the feeding of six adult dogs variations of different diets over a 4.5 month period. They looked at stool quality, volume and odor, blood chemistry, quality of their skin and coat and body weight.
- In research, we worry about sample size. You need to have enough animals to detect any real differences. With 6 dogs, 4.5 months of feeding and different diets, you don't have much of a chance to detect a problem (or a benefit, usually). You could have a diet that kills 10% of the dogs that eat it every year and not detect it in study of that size!
- The number of dogs and time don't even fulfill AAFCO feeding trial requirements, so this doesn't provide any information that would be accepted using standard requirements.
Nature's Variety director of research stated “It’s kind of a sigh of relief.”
- It's pretty concerning that the head of research would be relieved that there were no obvious health problems in such a small study. If they don't have real confidence in the quality of the food, why are they selling it? If you have confidence in your diet, you say "Of course, as expected, our diet was shown to be nutritious and safe..." not "Wow, we're really happy no dogs died!" Research to indicate safety and nutritional value should be done before you sell, not well after.
Duclos said she expects the study to be published in a peer-reviewed journal in about one year.
- Not likely. For one thing, from what they are releasing, it's very weak and not defensible scientifically. For another, they've already released the results. It's inappropriate for people to release results before they've undergone peer review, and releasing data in a press release will probably prevent any reasonable journal from even considering the study.
It's good that Nature's Variety is trying to do some research. It's also good that they're addressing Salmonella contamination following their recent recall. The fact that they are doing something progressive is an encouraging sign. However, they need to do proper research, and make sure it undergoes appropriate scrutiny, instead of using small and relatively useless studies to generate press releases.
Raw feeding has inherent risks of exposure for people and pets to potentially harmful bacteria like Salmonella. Raw feeding can probably be done safely for both the pet and people in some, but not all, situations. More information about raw meat feeding can be found on the Worms & Germs Resources page.
Raw food recall expanded
Nature's Variety has expanded their recall based on more concerns about Salmonella contamination of their products. In a lot of ways, this makes no sense to me since you have to assume that raw meat is contaminated with Salmonella, E. coli, Campylobacter and various other pathogens. That's been clearly shown in studies of raw meat for humans and animals, and that's why we cook meat intended for human consumption and emphasize good food handling practices. It's also why there are concerns about feeding raw meat to pets, and the explanation for various studies showing pets fed raw meat have much higher rates of shedding potentially harmful bacteria like Salmonella. You have to assume that a reasonable percentage of Nature's Variety's food has been contaminated with Salmonella, not that this is an uncommon and preventable event.
Because of the problem or consumer concerns, Nature's Variety has announced that they will be treating all of their diets using high pressure pasteurization. Basically, this process uses very high pressures (with only a slight increase in temperature) to reduce bacterial levels. I can't find any scientific literature about the effectiveness of this method on Salmonella contamination of raw meat (it's mainly used with milk and cheese) but it should be able to greatly reduce bacterial levels in meat. That's a good thing, as long as it works. What's important to know, however, is whether it is really highly effective in this situation and whether all potentially harmful bacterial will be eliminated every time.
I'm concerned that if people think this food is "sterile" and it's not, they might not take the necessary food handling precautions. If this method usually, but not always, kills all of the bad bacteria, or if it reduces levels greatly but not completely, then there could still be the risk of infection of people and pets. This information is critical. In the absence of clear scientific data, I think we need to assume that some level of contamination could still be present (although probably much less often and at a much lower level), and make sure that proper food handling practices are used.
It's good to see this company taking measures to reduce the risks associated with raw meat feeding. Let's hope that some objective research is made available to indicate what risks might remain.
Image source: www.defendingfoodsafety.com
Risks of Raw - More evidence
A study by Erin Leonard of the University of Guelph and others, that has just been published in the journal Zoonoses and Public Health, once again points to the increased risk of Salmonella shedding associated with feeding raw diets to dogs. The study looked at 138 dogs from 84 households in Ontario. One-quarter of households (21/84, 25%) had at least one dog (32/138, 23.2%) that was shedding Salmonella at one time, which is considerably higher than the 1-4% of pet dogs that are typically expected to be shedding this zoonotic pathogen. Only 4 of the 32 positive dogs had any history of diarrhea in the last month, so the vast majority of these dogs had no signs that they were shedding Salmonella. Here were the study's main findings:
1. Consuming a commercial or homemade raw diet, a homemade cooked diet, or raw meat and eggs, increases a pet dog’s risk of carrying Salmonella.
Raw is raw, and by now we're hoping that people are getting the message that raw is contaminated, whether we're talking about a commercial or homemade raw diet, or feeding any raw animal products (e.g. meat, eggs). The fact that homemade cooked diets also made the list could be explained by the fact that in order to make such a diet, owners still need to start with the raw ingredients. Handling and cooking raw meat and animal products for your pet should be done with the same precautions as handling and cooking raw meat for yourself or your family. If these homemade diets were not cooked as thoroughly as they should have been, or if there was contamination of the dog's dishes with raw product, that could explain the association with Salmonella shedding. Although traditional commercial diets can also be contaminated with pathogens (usually after processing), the risk with these is much lower.
2. Testing multiple consecutive whole fecal samples greatly improves Salmonella recovery in dogs.
This is no great surprise either. Dogs (and many other species) shed Salmonella intermittently, so not every fecal sample from a Salmonella-positive dog is going to yield Salmonella on culture. The authors tested five daily fecal samples from each dog. Based on this study, the sensitivity of testing a single fecal sample in a dog (i.e. the likelihood that a Salmonella-positive dog will test positive on one fecal sample) was only 35.5%. That means almost two-thirds of positive dogs will be missed if they're only tested once. The take-home message on this point is that in order to find Salmonella in a healthy pet dog, multiple samples should be tested.
3. Having multiple dogs in a household, using probiotics and contact with livestock are important potential risk factors that need to be investigated further.
These were factors that were flagged by the authors for future investigation, because at first they seemed to be associated with Salmonella shedding in the dogs, but when the feeding of raw diets was taken into account the associations were no longer significant. A larger study, or one using a different design, will be needed to help tease apart the potential effects of these factors from feeding practices.
The bottom line: Feeding raw is risky business. Some people swear by the benefits of raw diets, but the objective evidence is lacking. There is clear evidence of the risks. In my mind, the potential up-side simply cannot outweigh the well-established down-side of feeding raw diets to pets.
Raw food recall: Salmonella
Nature's Variety has recalled chicken-based raw meat products because of Salmonella contamination. After a customer complaint about "digestive problems," they tested the food and found Salmonella, prompting the recall. (For more details about the recall, click here.) In some ways, this doesn't make a lot of sense to me. If you think Salmonella contamination should be an uncommon event and a problem, you should test routinely, not wait until animals get sick. If you think that Salmonella contamination of raw meat is expected (which it is), then why test or recall? Just assume that every raw meat sample is positive for Salmonella (and Campylobacter, and E. coli). Recalling raw meat for Salmonella isn't logical. Presumably, a large percentage of the raw meat that they have sold and which they will sell in the future is contaminated, based on various studies of commercial raw meat. Handling and feeding raw meat carries an inherent risk of human and animal infections with Salmonella, Campylobacter, E. coli and other bacteria. People that feed raw meat need to understand that risk, and consider whether it's a reasonable risk for their pets and the people in the household. I don't think feeding raw meat is a good idea, but in some situations it's a particularly bad idea (e.g. when there are infants, elderly persons or immunocompromised people in the household, when the pet is very old or very young, when the pet visits high risk people).
More information about raw meat feeding can be found on the Worms & Germs Resources page.
New York Times and Pet Health Advice: Bad Combination
I used the think the New York Times was a reputable newspaper and source of reasonable information. However, considering some of the articles I've seen, I no longer have a good opinion of this newspaper. One example from a few years ago came across my desk recently. The article is basically an infomercial for an unqualified person that sells pet health products. The person in question is an industrial designer by training - you'd think a reasonable news source would look for someone with training in veterinary medicine, nutrition or pharmacology when discussing pet health. (Given the level of expertise they require, I guess I'm qualified to comment in the New York Times about how to solve conflict in the Middle East or fix the economy). Among some of the gems in this article are:
- People "have to include raw and whole foods in their pets' diets..." and "[Pets] don't get E. coli or Salmonella." Tell that to the dogs and cats that get sick and die from Salmonella. I can't believe people that sell raw foods continue to falsely claim that pets can't get Salmonella. Outbreaks of salmonellosis associated with raw foods have been reported. Dogs have even been sickened in the recent peanut butter Salmonella outbreak.
- The big problem with the pet food industry is that people treat pets like televisions and get a new one if they're sick. Apart from the last part being ludicrous, what does that have to do with the pet food industry?
- The alley dogs this guy grew up with in the Bronx lived a long time. Now, a dog is considered old if it lives past 7 years. Show me any evidence that feral dogs live longer than household pets. Not a chance.
- Pets are dying younger because of low grade nutrition and pharmaceuticals. Again, show me evidence that pets are living shorter lives. I'm certain it's the exact opposite.
People need to make sure that they critically assess things that they read about pet health and diseases. Just because something is written in a high profile newspaper doesn't mean it's necessarily correct. In the internet era, volume overload and differentiating good sources from bad sources can be difficult. Here are some tips:
- Look for advice from qualified individuals. That's not a guarantee, but I'd rather have my car fixed by a mechanic than a gardener.
- Beware of advice from people that are in a conflict of interest, such as people selling a product. For most reputable companies, representatives can be sources of good information, but unfortunately it's not always true.
- Ask your veterinarian about questions relating to animal health and nutrition.
- Use common sense. If something seems too good to be true, it probably isn't. Something that claims to cure all that ails you probably cures nothing.
Organic meat is not sterile!
I frequently get e-mails from people who are proponents of feeding raw meat to pets. The e-mails often start by calling me an idiot, and they generally go downhill from there. Some, however, go into detail about why they think there are no health concerns for themselves or their pets associated with feeding raw meat. Recently, one argument I've heard repeatedly is that using only organic meat lowers the health risks. While there are certainly merits to the organic food movement, there is absolutely no evidence that organic meat is any less likely to be contaminated with bacteria than non-organic meat, nor is there any reason to even suspect that this would be the case. Bacterial contamination occurs during slaughter and processing, and organic raising of animals has no impact on that.
More discussion about the health concerns associated with raw meat diets can be found in our raw meat archives and elsewhere. I do not recommend that people feed raw meat, particularly in certain situations such as when there are young children or people with weakened immune systems in the house. If you are considering feeding a raw meat diet to your pet, learn as much about this practice as possible so you can make an informed decision. More information about raw meat feeding and things you can do to reduce the risks that come with it can be found on the Worms & Germs Resources page.
Remember: Using organic meat is NOT an infection control measure.
Nontraditional Pets and Children: Beware
A report about the health risks in children associated with nontraditional pets was recently published in Pediatrics, the official journal of the American Academy of Pediatrics. The report also discusses diseases associated with animals in public settings such as petting zoos and pet stores. Although contact with pets and animals can be beneficial to growth and development in children, it is very important to be aware of the risks associated with certain kinds of animals. Physicians, veterinarians and public health personnel can help parents select appropriate pets in order to maximize the benefits while minimizing the risks to children.
One of the most important pathogens discussed in the report is Salmonella. Although Salmonella can be transmitted by many animal species, including traditional pets like dogs and cats, it is a particularly high risk with certain other kinds of pets, including reptiles, amphibians and baby poultry (chicks and ducklings). It has been estimated that direct or indirect contact with reptiles or amphibians is responsible for 6% of all sporadic Salmonella infections in the US, and 11% of cases among people younger than 21 years. There is also a relatively high risk of Salmonella transmission associated with animal-derived pet treats, such as pig ears, and raw meat.
The report makes several recommendations about how to reduce the risk of infection, injury and allergies from nontraditional pets, many of which you may have seen before on the Worms & Germs website. Just a few of these are:
- Always wash your hands after contact with animals, animal products or their environment, and after contact with animal-derived pet treats.
- Supervise hand washing for children less than five years old
Children less than five years of age and individuals with weakened immune systems should avoid contact with reptiles, amphibians, rodents, ferrets and baby poultry. These animals:
- Should not be kept as pets in households where children less than five years of age or individuals with a weakened immune system live.
- Should not be brought to childcare centres.
- Should not be allowed to roam freely in ANY house or living area.
- Should not be permitted in kitchens or anywhere food is prepared.
More information about Salmonella in pets and the risks associated with feeding raw meat and animal-derived treats to pets can now be found on the Worms & Germs Resources page.
Rawhide treat recall: Salmonella
Hartz Mountain Corporation has voluntarily recalled one lot of its chicken-basted rawhide chews for dogs because of potential contamination with Salmonella.
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Rawhide treats, as the name suggests, are raw treats that are literally made from the hide of typically cattle or pigs. The finding of Salmonella in rawhide treats is not particularly surprising, since Salmonella is commonly found in raw meat products, especially chicken. In this case it is not known exactly how the product may have become contaminated. High rates of contamination of raw pet treats have been reported, although a recent study reported improvement in products in Canada. This has likely occured because of action from the industry in response to outbreaks of disease in people that originated with treats. It's important to remember that any raw animal-based product that has not been treated (e.g. irradiated) to get rid of bacteria could contain harmful pathogens like Salmonella. They are best avoided, especially if high risk individuals (e.g. very young children, elderly persons or anyone with a weakened immune system) might come in contact with the treats or the pet to which the treats are fed. If you do decide to feed your pet raw animal-derived treats, care should be taken to reduce the risks of transmitting pathogens like Salmonella, as is recommended with raw meat diets. More information about raw meat feeding and Salmonella in pets can be found on the Worms & Germs Resources page.
Raw meat feeding revisted, part II: So you want to feed raw meat to your pet...
In a recent post, I discussed a study about the health effects of feeding raw meat diets to pets. Because 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.
Raw meat feeding revisited: what are the risks and benefits of raw diets for dogs?
Feeding 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.
Echinococcus and hydatid disease - not your average tapeworm
A previous Worms & Germs post talked about the (very low) zoonotic risk of the tapeworm most commonly found in dogs and cats, Dipylidium caninum. Dogs can also carry other species of tapeworm, such as Taenia pisiformis, which cannot be naturally transmitted to people. But dogs can also carry tapeworms from the genus Echinococcus, the most common of which is E. granulosus. Echinococcus multilocularis is much less common in North America, and can also be carried by cats.
In Canada, dogs tend to be exposed to E. granulosus when they eat certain animals, particularly wild herbivores like moose and caribou. In other parts of the world, eating sheep organs is the most common way dogs are exposed. The immature form of the worm is found in the animal’s lungs, liver and other tissues. After being eaten by the dog, the worm matures in the intestine, and tapeworm eggs can soon be found in the dog’s stool. Tapeworm segments, as seen with Dipylidium infection, are usually not seen in the stool with Echinococcus. Under a microscope, it is possible to tell Dipylidium eggs from Echinococcus eggs, but it is not possible to tell Echinococcus eggs from Taenia eggs.
If a moose, caribou, sheep or another suitable “intermediate host” swallows the eggs from the dog stool, the parasite migrates through the animal’s body and forms cysts in various tissues which contain the immature form of the worm. If the animal dies or is killed, and a dog (or a wolf or coyote or related species) eats the cysts, the cycle begins again.
Unfortunately, humans can also be an “intermediate host” for these tapeworms. If a person ingests Echinococcus eggs from dog stool, the parasite can form cysts (called hydatid cysts) in many tissues and organs, including the liver, lungs, brain and heart. If the cysts are small and there are only a few, they may not cause any problems for years, and the person may never know they’re there. But as the cysts grow, they can get very large and start to interfere with the function of organs, or their size alone may be a problem, depending on where they are located. Treatment can be difficult – drugs are frequently not effective, and large problematic cysts may need to be surgically removed, if the surgery can be done safely. If a cyst bursts it can cause anaphylactic shock, which is very dangerous.
In Canada, Echinococcus infection and hydatid disease are most common in the western provinces. Nonetheless, everyone can take a few simple steps to help prevent exposure of people to Echinococcus:
- Always wash your hands after handling dog stool, even if you use a plastic bag or a scoop to pick it up.
- Your dog should have a fecal examination for intestinal parasites at least once per year, or more frequently if your dog is at increased risk of exposure to Echinococcus. If tapeworm eggs are identified, your veterinarian can prescribe medication to treat the infection.
- Monthly heartworm preventatives that are effective against other intestinal worms are not effective against tapeworms!
- Do not let your dog eat uncooked meat, especially the organs of sheep or wild game such as moose and caribou.
More information on Echinococcus and hydatid disease is available on the CDC’s Echinococcosis webpage.
Salmonella-contaminated pet food
The CDC has released the findings of an investigation of a prolonged multistate outbreak of salmonellosis that was linked to dry dog food in 2006-2007. This outbreak implicated two different dog food brands, both made by the same manufacturer in the same plant in Pennsylvania, as the source of a particular strain of Salmonella Schwarzengrund. The strain infected numerous people, and was also found in some dry dog food samples and stool samples of dogs that were fed the food, with which the affected people had had contact. No illness was reported in the pets. It is unclear whether people were infected from contact with the food or contact with the pets' stool.
This is the first report of salmonellosis associated with dry pet food. Previous outbreaks have been associated with contact with raw pet treats such as pig's ears. Overall, the risk from contact with dry pet food is quite low, although this outbreak clearly demonstrates that some risk exists. Handwashing after contact with pet food should greatly reduce the already low risk.
This report is certainly not a reason not to feed your dog or cat a commercial pet food. One concern that I have is that this report will (and already seems to) be used by proponents of raw meat diets as support for this feeding practice. Feeding of raw meat has been clearly shown to increase the rates of shedding of potentially dangerous bacteria such as Salmonella. Illness and death from these bacteria have been identified in dogs fed raw meat. The high rates of Salmonella shedding in raw-fed dogs are a significant public health concern, and these concerns have been previously reviewed. Outbreaks of human salmonellosis have not been reported in association with raw meat feeding. This could indicate minimal risk, but could equally be due to lack of identification of sporadic cases that would be more likely with raw food than large-batch commercial contamination or better hand hygiene practices associated with raw meat handling.
- The risk of Salmonella exposure is still much lower with good quality commercial pet food compared to raw meat.
- Wash your hands after handling pet food (of any variety), as well as food and water bowls.
- Care should be taken when handling animal stool to avoid any direct contact with it. Wash your hands after picking/cleaning up any type of stool, even if you use a plastic bag or a designated scoop to do so.
Information Sheets for Pet Owners
INFORMATION SHEETS specifically for KIDS, for VETERINARIANS, for PHYSICIANS and for PUBLIC HEALTH PERSONNEL are also available on the Worms & Germs RESOURCES page!
Click on the highlighted topics below for information sheets. Topics that are not highlighted are in development and coming soon. Sheets for other animal species and diseases are also under development and will be added when they are available.
| Animals | Diseases | Other |
| Dogs | Rabies | Litter Boxes |
| Cats | Giardia | Sandboxes |
| Turtles | Toxoplasma | Cat Bites |
| Hamsters | Leptospira | Raw Meat |
| Rabbits | Clostridium difficile | Petting Zoos |
| Pet Birds | Cryptosporidium | Needlestick Injuries |
| Reptiles | MRSA | |
| MRSP | ||
| Salmonella | ||
| Ringworm | ||
| Campylobacter | ||
| Bartonella henselae | ||
Please Remember:
- Your veterinarian and physician are your ultimate resource for information about the health of your pets or your family.
- Information provided here is accurate to the best of our knowledge, but infectious diseases can be unpredictable and these sheets are for general information purposes only.
- There can be great variation in disease risks in different geographic areas. The information provided was developed for Ontario, Canada, but most of the information is relevant for other regions as well.
