Yet Another Study Shows the Real Dangers of Raw Diets for Dogs

I have covered the raw diet issues since the very start of this blog, which is about nine years now. My articles on the subject are collected here. Very little has changed in my assessment of the evidence over this time. The bottom line is clear:

There is evidence of risk in feeding raw, including infectious disease, parasites, and injury from raw bones. There is no scientific evidence, only anecdote and dubious theories, to demonstrate any benefits from feeding raw.

A new study has recently been published which adds to the already considerable evidence of risk from infectious disease.

Martinez-Anton, L., Marenda, M., Firestone, S.M., Bushell, R.N., Child, G., Hamilton, A.I., Long, S.N. and Le Chevoir, M.A.R. (2018), Investigation of the Role of Campylobacter Infection in Suspected Acute Polyradiculoneuritis in Dogs. J Vet Intern Med, 32: 352–360.

This was a case control study conducted in Australia and designed to look for associations between the occurrence of a serious neurologic disease, Acute Polyradiculoneuritis (APN) and infection with the bacterium Campylobacter sp. This bacterium has been identified as a common trigger for the analogous disease in humans, Guillain-Barré Syndrome. Because exposure to raw chicken is a common source of Campylobacter infection in humans, the feeding of raw chicken, and other raw meats, was one of the variables evaluated in this study.

The results were quite clear. Dogs with APN were far more likely to be have Campylobacter than healthy dogs, and dogs with APN were also much more likely to have been fed raw chicken and other raw foods.

This type of study only shows an association, not a definitive cause-effect relationship. A prospective randomized controlled trial would be needed to prove feeding raw chicken can cause Campylobacter infection which can then cause APN. However, such studies are not always necessary or appropriate to guide us in reducing our risk of disease. Case-control studies are the main source of evidence showing smoking increases the risk of lung cancer, and certainly a randomized trial in which some people are made to smoke for years and others are not to definitively prove this relationship would be unnecessary and unethical.

We are more often willing to inflict harm on animals in order to investigate the causes of disease, so it is possible someone will do such a study in dogs even though we would not do it in humans. However, it is clear that this study, in the context of the existing evidence in veterinary and human medicine, supports the clear health risks eating raw meat.

Proponents of raw diets will certainly argue that the risk is small compared to the benefits. Unfortunately, no scientific evidence yet exists to show any benefits, and personal anecdotes or theories about the natural history of dogs are not sufficient reason to ignore the robust scientific evidence of the harm that raw diets can cause. Unless some reliable research evidence emerges to show meaningful health benefits from raw feeding, there is no good reason for pet owners to participate in this dangerous fad.

 

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34 Responses to Yet Another Study Shows the Real Dangers of Raw Diets for Dogs

  1. evelyn macrae says:

    I do agree feeding raw bones to small dog is dangerous.The latest theory which I fell for was feeding a raw lamb bone which because of the relative softness of the bone should be perfectly safe.I had been giving my terrier a lamb bone under careful supervision to gnaw for about 20mins.every few days for about a month.His teeth were sparkling and removed a lot of tarter which was the reason for using a bone However he crunched of a bit of bone and appeared to be having difficulty getting it down.After a few heartstopping moments all was well although he was sort of making chewing movements as if uncomfortable.A call to the vet who thought he may have a piece of flesh stuck at the back of his teeth put mind mind at rest and have vowed never to give him a bone again.
    The brigade for raw bones I dont take into account small dogs in their” wild dog “theory,only wolves. With terriers and todays smaller breed dogs it is too dangerous to feed bones however soft and crunchy in my opinion.Their gullets are very small and it is not worth the risk.

  2. zyrcona says:

    Dogs evolved alongside Man and village dogs are the thought to be (by genetic studies) the direct ancestors of modern dogs. Most village dogs eat copious amounts of human excrement as a natural part of their diet. I look forward to the revolution in dog food modelled on this natural food chain.

  3. Frances says:

    Evelyn – Seems to me there is a balance to be found. If a soft raw bone is keeping teeth and gums healthy, and thus avoiding all the risks associated with gum disease and a GA for dental work, then the possible small additional risk of a very rare, non-fatal complication linked to many viruses, not just campylobacter, is probably worth it. Mine have coughed and choked on kibble and “safe” processed chews much more than on chicken wings and lamb riblets (pure anecodote, not data!).

    Skeptvet – I am far from evangelical about feeding raw – I mostly cook for my animals as I find it easier to manage, and only give them raw occasionally – but having read this study with great attention I suspect that had similar methodologies and sample sizes been used to demonstrate the benefits of raw feeding, or homeopathy, or feeding from red bowls instead of blue, your response might have been rather different. Are you absolutely sure you are not giving way to confirmation bias?

  4. skeptvet says:

    ” a soft raw bone is keeping teeth and gums healthy, and thus avoiding all the risks associated with gum disease and a GA for dental work, then the possible small additional risk of a very rare, non-fatal complication linked to many viruses, not just campylobacter, is probably worth it.”

    Yes, but the key word there is “if.” As I’ve said many times, until there is good evidence, not just anecdote, to show such benefits are real, the proven risks aren’t worth taking.

    As for cherry-picking and bias, I have no doubt I am susceptible to this just as anyone else is. However, this is not “just one study.” It is one of a consistent series of studies and other kinds of evidence all of which support the quite uncontroversial claim I am making, that eating raw meat increases the risks of parasites and infectious disease. The disagreement we have, I think, is that I don’t believe this is a risk worth taking unless there is equally good evidence to support the claimed benefits of raw feeding, and so far there is nothing like that. Defenders of raw feeding, reasonable or extreme, are all still basing their claims on anecdotes and guesswork, not research evidence, so it’s not even possible to compare the evidence for risks and benefits because the only evidence so far is for risks.

  5. Sharla Foster says:

    I love this blog. You have no idea how much. I’m a retired pharmacist and I like my medicine evidence based and my science peer reviewed. You are a rare voice in the blogosphere these days but a badly needed one. I am constantly getting in heated discussions over woo. I recently saw someone suggest a person nebulize their sick puppy with colloidal silver. I nearly swallowed my tongue but I could not keep quiet in the face of such insane ideas. I often think we are totally losing the battle for common sense and good judgement. I would be even more depressed if not for your blog.

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  7. Phil S. says:

    A raw foods advocacy group/commercial enterprise wrote a rebuttal to this study here: https://www.dogsfirst.ie/raw-chicken-does-not-cause-paralysis-in-dogs/

    Their rebuttal is unimpressive, but I thought I should give you a heads-up.

  8. skeptvet says:

    Thanks! It means a lot to hear from folks who find the work I do here useful.

  9. Sue says:

    I thought the rebuttal was very impressive and written by a vet who identified himself. Do they feed carnivores in zoos rancid kibble???

  10. Brian Cullen says:

    Are there any online /youtube videos of debates on raw feeding ?

  11. skeptvet says:

    “Rancid” is polemic nonsense.

    Dr. Brady is not a vet. He has PhD in animal behavior and has studied nutrition during his graduate work, but he also sells pet food and is a vehement believer in alternative diets, so his point of view is no better informed and no less biased than anyone you would likely disagree with in this discussion.

    Dogs are omnivores, not carnivores, and they have been intensively selected for significant anatomic and physiologic characteristics that differ from wild canids. As I have pointed out many times, dogs are not wolves. Besides that, canids in the wild eat what they can get, not some magically perfect food, and many suffer from infectious diseases, parasitism, broken teeth, and other diet-related sources of suffering and death that we can prevent in our companion animals.

    My identity is not secret, and you can find my CV on the blog. That said, what does it matter? No matter who I am, haven’t you already made up your mind? Will you really listen to any arguments or evidence to the contrary no matter who makes them?

    Lastly, the “rebuttal” is a sloppy piece of work that desperately tries to dismiss evidence which conflicts with Dr. Brady’s beliefs. I am working on a detailed response to it which you should get to see soon.

  12. Sandee says:

    How do you feel about the new Primal brand freeze dried raw foods?

  13. skeptvet says:

    Commercial raw diets which meet AAFCO minimum nutritional standards are less likely to be deficient in micronutrients than homemade diets. Freeze-drying can still allow infectious disease exposure, so like most raw diets there is some risk, though exactly how high compared to other forms of raw diet isn’t clear. In any case, still no evidence of benefits to make taking this risk worthwhile.

  14. skeptvet says:

    As promised, here is my evaluation of the rebuttal you mentioned. Not compelling nor convincing.

  15. Kristy McTaggart says:

    My reason for feeding raw to my four adult rough collies for the past two and a half years (with stellar results) was mainly because of the alternative. Kibble diets are risky, and no one can convince me they aren’t. Recalls are scary, because it usually means a significant number of dogs or cats died or contracted some horrible condition because of their food, before it comes to public attention. Sourcing is scary too. Even if all the “meat products” come from the good old USA, a lot of the vitamin and mineral supplementation that has to be done to bring kibble up to AAFCO standards are materials that are manufactured in India and China, where standards are – well – different.

    Collies are MDR-1 mutant, generally, and putting a collie under anesthesia to clean their teeth annually just isn’t good management practice for them. They are big enough to handle raw bones and eat one every morning. Sparkly teeth with absolutely no brushing required.

    And finally, we have a smallish fenced yard. Before I started making raw dog food, the poop was impossible to keep up with. Flies, odor, and a lot of dead grass. Now the poops are so small and odorless that that I don’t even pick up anymore; they just turn to white powder and blow away.

    I breed show dogs and conditioning is vital to compete. My dogs have gorgeous coat health, good muscle tone and don’t tend to overweight. Yes I spend a good amount of time balancing and prepping their meals, but it is SO worth it.

  16. skeptvet says:

    “Kibble diets are risky, and no one can convince me they aren’t”
    The fact that you are rigidly committed to a belief that is not true makes the rest of the discussion somewhat pointless, but you have to at least try to understand that not everyone accepts this claim or finds it convincing.

    “Recalls are scary, because it usually means a significant number of dogs or cats died or contracted some horrible condition because of their food, before it comes to public attention.”
    1. Not true. Most recalls are precautionary and no evidence of actual harm is found
    2. Plenty of raw diets are recalled, and there are several confirmed cases of serious illness in pets and humans from raw diets, so this argument applies to those as much or more than to kibble.

    “Collies are MDR-1 mutant, generally, and putting a collie under anesthesia to clean their teeth annually just isn’t good management practice for them.”
    Some are and some are not, and there is a test for this now. Even for homozygous mutant individuals, anesthesia is safe if the drugs are selected and dosed properly. And finally, there is no evidence that bones prevent periodontal disease relaibly, and they can cause fractured teeth, which then require anesthesia to remove. None of this is a good argument for raw diets.

  17. skeptvet says:

    Here are two recalls just this month for raw diets, both of which traced illness in people or animals to the foods. How is this safer than cooked food?

    FDA Investigates Pattern of Contamination in Certain Raw Pet Foods Made by Arrow Reliance Inc., Including Darwin’s Natural Pet Products and ZooLogics Pet Food

    The Minnesota Department of Health reports that two children in a single household were exposed to contaminated Raws for Paws product, which was used to feed the family dog. One child’s illness resulted in septicemia (blood infection) and osteomyelitis, a painful and serious bone infection.

    Testing performed by the Minnesota Department of Health and the Minnesota Department of Agriculture demonstrated that the same strain of S. Reading found in the ill children was also found in four samples of Raws for Paws Ground Turkey Food for Pets that was used to feed the family pet.

  18. Kristy says:

    Any commercial food is at risk of recalls. The reasons I feel safer making my own raw diets are these:
    1. I use all human grade ingredients from the grocer. While thats no guarantee of absolute safety, at least it is the most stringently regulated. Pet food is far less likely to have been inspected.
    2. Because I am making the meals, I have a chance to see everything and notice if anything looks “off”.
    3. I know everything my dogs are ingesting. Commercial foods, not so much. I can vary their protein sources and remove something that seems to be not agreeing with one of them, in real time. In fact thats why I started homemade raw. I had a girl with skin problems and my vet suggested a food trial, which would have taken months. As soon as we converted to raw, her rashes and hot spots stopped and healed up.

  19. skeptvet says:

    Commercial diets are formulated and inspected by veterinarians, nutritionists, and others with extensive training in food safety, nutrition, and other relevant disciplines, and they are regulated. Homemade diets are formulated and “inspected” by amateurs with training that comes from reading articles on the internet or a few books for the lay public on pet food. While I understand that making the food gives you the illusion of greater control over its safety, the reality is that it makes no sense to imagine that we as individuals are better equipped to provide safe and balanced nutrition than experts who do so professionally.

  20. v.t. says:

    Kristy, read the recall links that skeptvet just posted – read them carefully, and note how easy it is for people NOT to recognize the risks, signs/symptoms until it’s too late – this applies to humans and pets alike. Read where pets have DIED with these contaminated raw foods and this is not the first time! You can find various raw food pet products recalled on the FDA website – since the 2007 melamine crisis with manufacturers getting serious about their products and sourcing, there seems a trend in recent years that appears more raw foods are being recalled than commercial. Educate yourself on the various infections that can AND DO live in raw meats and other foods. Just because you don’t think yourself, your kids or your pets have acquired these infections, doesn’t mean they haven’t at some point in time, or won’t in some point in time.

  21. RVN says:

    The raw/commercial argument is a really hot topic at the moment. Thank you for providing many valid points here and equally for raw feeders contributing their thoughts. I have had many discussions on this topic, with raw feeders that fiercely follow suite because someone at a dog show told them it was the way forward. Many absolutely swear it makes a difference to animals with chronic skin conditions but thats not to say a hypoallergenic commercial feed would not have had the same impact.

  22. Erich J says:

    My 16 year old cat went from being on death’s door at 4 lbs to gaining back 5 lbs and living 5 more years when we switched to raw. My now 14 year old 180 lb Mastiff is also still more energetic and mobile today than he was 6 years ago. I fully believe in meat based and preferably raw nutrition but am also highly concerned about the safety. I’ve got young kids that are more susceptible to food borne illnesses. Many of these articles seem to paint a picture that you either feed dry kibble foods to your pets or you’re putting them at a unacceptable risk of pathogens. There are commercially available raw diets that have a kill step (HPP) recognized by the FDA & USDA plus test & hold procedures to help ensure no contaminated product gets released. If safety is your main concern, just know there are options. Stella & Chewy’s is the one I use (I like I can see the test results on their website) and there are a few others. There are, however, still a lot of commercial raw foods out there (most of them actually, including the ones posted above) who still don’t use a kill step, so check first.

  23. Judy Graves says:

    I really appreciate this blog. I have a Springer spaniel who has struggled all her 8 years now with skin issues. Boil like spots that scab over and constantly itch and flake. I have tried just about everything recommended by highly qualified vets and am now for the first time trying k9Naturals raw lamb. I am so confused because I see recalls on Dog foods constantly-both kibble, canned and raw. I want to do the best for my girl and at the moment after having her on raw for 5 weeks it is the best her skin has been since a puppy. She does take a Benadryl or Zyrtec daily but has done this for years so I can only assume the food change is making a difference. These posts are very concerning however and I feel paralyzed as to what I should do to solve the skin issues but to also not have her be at risk. Any comment is welcome.

  24. skeptvet says:

    Though there are no studies specifically on raw pet foods, HPP does reduce the viability of infectious organisms in raw meat, so while I am not convinced of the claimed benefits for raw, choosing an HPP treated food seems a reasonable step to reduce this risk.

  25. skeptvet says:

    There is no reason to believe a raw diet per se will have any effect on allergies. Changing to a limited and new protein source can help for dogs with food allergies, but there is no extra benefit to using a raw protein source. I understand the desperation that comes from dealing with chronic skin issues, but again there just isn’t any reasonable basis to think a raw diet will make a difference. Have you worked with a board-certified veterinary dermatologist yet?

  26. Judy says:

    Yes, I have seen 2 board certified vets that specialize in dermatology. She has been on antibiotics a few times when they do skin scrapes. Both have diagnosed that it is a recurrent staff infection which is a pretty stubborn infection. I bathe her once a week with medicated shampoo and anti-itch sprained have had her on single protein foods for awhile (duck, lamb) Always grain free – I have stayed away from fowl and seafood as her skin definitely does get worse with those. I used to make her dog food but felt she wasn’t getting all the correct balanced nutrients. It does seem like she needs something that will boost her immune system to fight this?

  27. skeptvet says:

    The problem with the concept of “boosting” the immune system is that allergies are actually an excessive and inappropriate immune system reaction. That’s why most of the medications that help actually reduce inflammation and other immune system activities. Recurrent secondary infections are typically overgrowth of normal skin flora caused by damage to the normal defenses on the skin caused by inflammation, scratching, and other symtpoms of the underlying allergy. One of the most effective treatments is often desensitizing the immune system with immunotherapy (aka “allergy shots”). But hopefully this has been explained by the dermatologists. Have you seen the guidelines from the international canine allergy group of treatments for environmental allergies in dogs?

    Evidence-Based Canine Allergy Treatment

    Evidence Update- Evidence-based Canine Allergy Treatment

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  29. Meggie Moo says:

    I’ve been pondering on this research since it was published as we currently have three dogs who are raw fed (of nine) and reading around too.
    So I thought right lets try switching the raw fed to commercial cooked food again like the others have (high protein, excellent quality food I might add).
    Fail! My old lad refused to eat and so of course got even skinnier, my not quite so old hound flared up again with his yeast infections even though it was a protein source he can eat raw that we went for (rabbit), my young hairy thing started going bald again.
    So despite my best efforts we appear to be back on the raw. Although we’ve cut all poultry out to hopefully reduce the risk and all other meat is sourced from commercial suppliers who have good standards and regularly test their foods (got to love those EU rules).
    Anyway… this was a more balanced article on the study by a pro raw feeding group which you might be interested in.

  30. Robert says:

    I started to read the rebuttal since I like both sides of a story and understand that everyone is able to be biased. I was able to comfortably stop at the line “First off, who has even heard of APN? None of YOUR dogs have it right?”. I say comfortably because if he’s opening his argument with a statement of diminished importance, it’s reasonable to assume the rest of his arguments are equally vapid.

    I don’t know who you are. Never read the CV. But I will say I’ve stumbled onto a blog that may not always say what one wishes to hear, but so far seems to be providing an objective view on things, and I dig it.

  31. Robert says:

    Should we point out that the “stringently regulated” raw foods you’re using probably all clearly advise that raw foods carries a greater risk of bacteria and infection that cooked foods?

    Feed them natural and unprocessed all you want but for Pete’s sake, JUST COOK THE DAMN FOOD!

  32. Kate says:

    My evidence is pretty much entirely based on my experience with the animals in my care over the past 10 years or so. I am not a veterinarian nor have any background in medicine of any sort save a few tidbits thrown my way from my RN mother.

    The first occurrence is with Ms Kittily. I met her when she was a mature cat (I moved in to the house where she had already decided to live). She had a long history of vomitting and regurgitation (2 different things). When I began living with her, I also noticed that she had these sort of choking/hacking episodes prior to either of the other 2 events. I took her to the vet.

    He listened to me and examined her and prescribed a diet that had no chicken protein. She got worse. I googled. I found raw diet. I purchased all the necessaries to produce and followed the given recipe. Transitioned her over 4 days. She improved immediately and lived for 3 more years. When she died, it became much more evident (by the *way* she died) that what the real problem had been was her heart. NOW I understand what the choking/hacking was. At the time, I don’t think that my description of the sound was adequate for the vet to look further than diet. My bad.

    Next: Ba Ba (pronounced bah bah). We didn’t know at the time that he was Ms Kittily’s child—we thought that they had been either litter mates or were cousins. His problem was obesity. Again, I googled and found raw was the solution to that, too. Rather convenient except that it took me 4 months to convert him completely. He had to have kibble sprinkles to be convinced. So I fed him this diet and played “stick” (a game that I am not going to explain) with him until he got down to optimal weight.

    He died just over 3 years ago at age 13. Not very impressive for a raw diet. He had become thirsty in a way that he could never satisfy and had troubles keeping his food down. Oh-oh. Off to the vet. He was given the sub-Q fluids for dehydration (of course) and then examined by x-ray. The doctor showed me the problems while discussing things found in the blood and urine samples: tumour on pancreas, suspected beginnings of diabetes, oddly shaped /squished stomach (guessed at perhaps another tumour squishing it from somewhere not shown on x-ray), severe constipation/compaction from the dehydratioin and . . . some pain. Prognosis—it will only get worse. I had him put down.

    When Ba Ba was 8 and a few months before Ms Kittily died, I rescued a kitten that had been “left” at a farm on which I was working. Enter Dumpling. He got raw from his introduction to our household. Two years later he showed extreme diarrhea and didn’t eat for a day and then later only very little. He was drinking lots. He was taken to the vet every few months with the same symptoms. Four years ago, a vet happened to mention that he thought it might be colitis. It was never followed up by any other vets.

    Colitis? Not very impressive for raw.

    In addition to this raw diet, ALL of the above cats ate mice, sage voles, squirrels, the very young rabbits (slow enough for cats to catch, you see), wrens, starlings, a snake attempt, bugs, spiders, one bat attempt, etc., etc. Only Dumpling gets colitis symptoms. When the colitis symptoms show up, he goes to the vet to be tested for worms and other bugs (test are always negative) and then we feed him a canned food with rice in it for 5-7 days and switch him back to the raw.

    This time, he was having nothing to do with it. So, for the last 5 weeks he has been eating a canned cat food. Since I have manufactured my own food for more than 10 years, I know what the ingredients are for. Other than the food colouring (please don’t say this is a problem in the food—just read the actual studies) and the modified corn starch (I use a tablespoon of gelatin instead for a 13-pound batch), the ingredients are the same. Their food is cooked, mine is raw. The recipe for producing the cooked variety differs only in the cooking instead of dipping in boiling water to kill the clostridium perfringens.

    My point is that you can’t always believe (a) what you read from people who have only good experiences with raw diet, (b) what you learn from people who have treated specific problems in their animal with a raw diet. It seemed to work for Ms Kittily—except that maybe all it did for her was remove one difficulty as the heart problem was clearly the bigger deal with her. It seemed to work for Ba Ba because he got down to a good weight but, apparently his personal genetics had other ideas. Raw does not prevent diabetes as I had been led to believe.

    At the moment, it seems to be making absolutely no difference for Dumpling. Oh, and the other thing about teeth: chewing the hearts / chunked up chicken breast has made NO difference to his dental health. What a load of bologne!

    Thank you, SkeptVet, even though you usually talk about dogs. I, too, shall be bookmarking your blog. 🙂

  33. skeptvet says:

    Well, I wouldn’t call it a “balanced” article. It is an attempt to discredit the Australian study in order to defend raw diets, and while it makes some legitimate points, it is not a convincing rebuttal at all. I have actually responded in detail to the article you mention here.

  34. Megan says:

    Thank you so much for this article and the associated comments. I have ferrets and have been prompted to do some research into ferret diet after seeing many posts from vocal and enthusiastic raw diet advocates on the ferret forums. Many ferret owners strongly advocate against any kibbles, but especially the most common brands, like Marshall’s, found in pet stores. The argument is basically the same as raw for dogs… ferrets are the domesticated form of the European polecat, so shouldn’t they eat the same diet as their wild counterparts? My skepticism of this argument centers around 2 points: 1) ferrets have been domesticated for 2000 years… surely their dietary requirements have followed a somewhat different evolutionary path in the course of thousands of generations of selective breeding? This is certainly true of dogs vs wolves. And 2) As is addressed in this article, raw seems unnecessarily risky. I worry about bacterial or parasitic contamination and choking hazards. I’ve done some Pubmed searches that have turned up very minimal results (beyond demonstrating that ferrets are obligate carnivores and do require a higher protein/lower carbohydrate diet than even cats – commercial ferret kibbles provide this). The ferret forums contain plenty of anecdotes and the same circulated diet recommendation tables, but I can find little actual evidence to support any of it. I, like most pet owners, just want what is best for my critters. I think many would welcome this evidence-based perspective.

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