Vitamin K3 (menadione) in Pet Food: Is It Safe?

One of the most popular fallacies that arises in discussions of pet health is the appeal to nature or naturalistic fallacy. Simply put, this is the notion that what is labeled “natural” is inherently safe, beneficial, or otherwise good, and what is labeled “artificial” is inherently unsafe, harmful, or bad. This argument fails on many levels. For one thing, the distinction between natural and artificial is often quite arbitrary and based on ideology rather than any rational criteria. How could any food crop, which consists of huge, bizarrely
mutated plants that could never survive without cultivation, be natural? For
that matter, how could most breeds of dog be considered natural when they have
been so dramatically altered in form and function by thousands of years of controlled breeding? Is wearing clothes, washing our hands with soap, cooking our food, or really any of the basic health and safety practices we follow routinely natural if we are the only species who employs them?

The appeal to nature fallacy also fails on the simple basis of being demonstrably untrue. Arguably natural things like Salmonella, hookworm, bubonic plague, and uranium are clearly dangerous. And clearly artificial things like vaccines, antibiotics, and modern sewage and water treatment systems are the only reason the majority of human beings gets to live past childhood these days. So whenever the only basis for declaring something
good or bad for your pets appears to be the idea that it is natural or artificial, it is wise to be very skeptical of such claims and look for more reliable evidence.

A perennial example easily found on the Internet is Vitamin K3 (menadione) in pet foods. Vitamin K is an essential nutrient needed in very low levels by dogs and cats. It is required for producing the substances that allow blood to clot and prevent us from bleeding to death from every little scratch. Most rat poisons consist of chemicals that interfere with Vitamin K, and these common and very dangerous poisons frequently lead to dogs coming into the veterinarian’s office with severe, uncontrollable bleeding. Fortunately, in
most cases these patients can be saved, and the cornerstone of their treatment
is Vitamin K replacement.

Most of the Vitamin K dogs and cats need is manufactured by bacteria in the gastrointestinal system and absorbed from there, so dietary requirements are miniscule. The one known exception is that cats fed diets with a high proportion of fish oil in them have developed Vitamin K deficiency and bleeding problems. Since fish as a protein source and fish oil as a supplement are becoming more widespread, it is possible that this problem could be seen more frequently. In general, however, the amount of dietary Vitamin K required by dogs and cats is still very, very small.

Plant and animal sources of Vitamin K include two types, Vitamin K1 and Vitamin K2. Vitamin K3, or menadione, is a synthetic form of Vitamin K. By itself, it has little biological activity, but it can be converted to a more active form by bacteria in the gut and other pathways. It is useful as a Vitamin K supplement in pet foods because it is more stable and tolerates heating better than the other forms of Vitamin K. Advocates of
“natural” medicine and nutrition often claim, however, that unlike these other forms, Vitamin K3 is toxic to dogs and cats. So what is the basis for this?

Of course, the first foundation “natural” medicine advocates use for claiming menadione is harmful and should be replaced with Vitamins K1 or K2 is the appeal to nature fallacy. As I’ve already pointed out, this is a meaningless claim which tells us nothing about the safety of any food or supplement. So what about other, more meaningful forms of evidence?

Well, to begin with, no case of toxic effects from menadione in commercial dog or cat food has ever been substantiated. Millions of pets have been consuming this vitamin for
decades, so if the supplement were to have any significant potential risk, one
would expect many documented cases of harm. This is, at least, the basis
“natural” medicine advocates use to claim that the herbal products and dietary supplements they recommend are safe. Unfortunately, without any systematic effort to monitor for such events the best we can say is that there does not appear to be a large or common risk, though we cannot rule out the possibility of some negative effects in some individuals solely on the basis that such cases have not been reported.

There is some laboratory research and pre-clinical animal studies that look at the safety of menadione. These have found that toxic effects can be seen on isolated cells, rats, and other animal models in the laboratory, but at levels tremendously higher than could ever be achieved by eating foods supplemented with Vitamin K3. This points out another common fallacy employed by so-called “holistic” medicine practitioners, the
notion that chemical compounds are inherently either toxic or safe. The reality
is that toxic effects are a function of the dose or amount of a substance one
is exposed to, the route of exposure, the individual’s susceptibility, and many other factors. Water and oxygen are toxic at high enough doses and under the right circumstances. And deadly natural poisons such as curare and other animal toxins can have beneficial medical uses if handled and dosed appropriately. So it is meaningless to simply label something as
“toxic” and ignore the devil in the details.

It turns out that doses of menadione needed to cause health problems are more than 1000 times greater than could be gotten through food supplementation, and the studies showing toxic effects usually involve injecting the vitamin into animals at high doses, not providing it in food in miniscule amounts. It is true that Vitamin K3 supplements for human use have been banned by the Food and Drug Administration (FDA), however this is because
of the potential for very large exposures when humans irrationally choose to take extreme quantities of dietary supplements. The FDA does permit the use of menadione in animal feeds because the consumers, our pets, are unlikely to make similar mistakes. When the toxic dose is more than can be found in an entire bag of food, the risk of accidental exposure to harmful levels is negligible.

Bottom Line
Under normal circumstances, dogs and cats need extremely small amounts of dietary Vitamin K. At the low levels of supplementation in commercial foods, menadione is a safe source of this Vitamin K. Toxic effects can be seen when enormous quantities are given to an animal or when menadione is used injectably, but there are no documented cases of any harmful effects from dietary supplementation of menadione in commercial pet foods. The three veterinary nutritionists and one veterinary toxicologist I consulted on this
issue all agreed that there is no evidence of any significant risk from menadione in commercial pet foods. The concerns about this supplement seem to stem almost entirely from the appeal to nature fallacy and from the mistaken belief that substances are inherently either safe or toxic regardless of dose or route of exposure.


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57 Responses to Vitamin K3 (menadione) in Pet Food: Is It Safe?

  1. Pingback: Ten Worst Ingredients in Commercial Dog Food - Page 2

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  3. Alexander Balaban says:

    PURINA and other Pet Food Companies are putting profits in front of pet health as their first priority. Why does Vitamin K at all appear in pet food to begin with. If the animal has no deficiency then a particular vitamin supplement is not even needed. Why aren’t the Veterinary Schools speaking out on this as well?

  4. skeptvet says:

    VItamin K is an essential nutrient. You are correct that it need not be supplemented above needed levels, but it has to be in a diet at an appropriate level in order to prevent a deficiency.

  5. v.t. says:

    There are overseas manufacturers who add perhaps questionable amounts of menadione to their pet foods due to the excessive amounts of fish in the products. Part of the problem with that is due to little to no regulation and oversight before it makes it’s way to the US. Cats for example, cannot tolerate a fish-only diet (potential for developing pansteatitis, not to mention vitamin/mineral deficiencies), thus the inclusion of menadione.

  6. There are no studies that provide proof that VItamin K3 ( synethic as in most all pet foods that contain it) is safe for pet food, let along humans ( fda bans it from human food, so why would I/you consider any amount of it safe for my/our loved companions ).

    ” Pet Food Industry Claim:
    “Menadione has not be shown to create any detrimental effects at levels within 10x of recommended levels. (toxicity reports being utilized by this latest group of “activist” are not only disputed but at mega dose levels with no relevance to actual practice)”

    My take on it:
    I don’t know which “activists” make such claims, but I’d like to point out that I do not support the use of any amount of menadione. It has never been researched or specifically approved for long term use, such as in pet food, and the detrimental effects are not just simply related to high levels, but also to long-term exposure to low levels. Again I have to point out we aren’t looking at livestock or lab animals just being exposed for a relatively short period of time, but what this substance can do to pets, especially their immune systems, over a period of 10-15 years or longer. ”

    This is from:

    You are free to contact Sabine and ask her to remove that page as being ‘provocative’ and misleading people, but what she says makes sense from a practical point of view, given there is no humane reason not to use ‘natural’ VitK which admittedly is a bit more expensive but obviously contains no amount of toxity .

    Then there is this website from (not a vmd ) a doctoral dental surgeon , chemist,biologist and dedicated informant for dog food safety ( feel welcome to check his credits) :

    I would professionally expect you would speak to both of these individuals, and if you can convince them with facts and studies, to remove their warnings about Menadione, I would then consider noting this on our webpage for pet food safety as well. Objectivity must be maintained.

    I do not take my animal companions life lightly which means I do my research with great vigilance, and I hope you take this response as such. I look forward to your reply, but please also reply to my email so I know you have don so , as I most likely will not keep this tab open indefinitely.

    Gaillard Lee Johnson

  7. My loved dog Roc died , and in the end no autopsy was done so who knows…but he did die of liver toxicity and as we both know can be caused by various things ,, in the end, the VET should have told us about menadione ( she knew because I told her what food roc was being fed so to me , there is no excuse for laziness, period, and she was the ‘doctor’ not us ) being in the Purina food roc was eating, and let US make the decisions based on one supposed fact vs another. The choice was taken away from us ,and that’s just sloppy and unprofessional, and why I do what I do today.

    If menadione was so needed in dog food, then why don’t all dog food companies place it there ? The AAFCO stamp on all such products is very misleading as well, as they are not a regulated company and they don’t even verify the contents of said food or if its safe for consumption, and most definitely no ‘questionable’ items, where again as the Vet’s office should have, given the final choice up to the consumer and assume nothing.

    The foods found in many vet stores are science diet by HILLS as here:
    , which as shown contains no form of Vitamin K synthetic in any notation I’m aware of, which begs the question; if the vet’s office I went to whose own food they offer does not contain Menadione , why would they not actively try to make sure no client feeds that nutrient to their pets ? I find it hard to believe that lacking ingredient ws an accident, and that the vet’s office wasn’t aware of that ?

    That choice ,- empowering us as parents and guardians was taken away from us and that’s a life no one can get back. Matters of such grave importance to me anyway and our organization, are far too important to be relegated to chance given the complete lacking proof positive on this matter.

    We are not the only ones who would rather not let this seeming low chance to others dictate our concerns for our loved companion animals: < user: kmes, writes:

    " Again this isn't a risk I choose to make, no matter how silly it may seem " . So it seems others find the risk unacceptable, yet again and due trainging defeciencies/laziness, we were not given that choice.

    How full of self worth ( and how dare somehow doubt that ?) does one need to be to audaciously tell someone that their concerns just weren't important enough to log in a file. The height of narcissism and arrogance apparently knows no bounds, even knowing death has occurred.

    To some, and no one is purposely sought out here, the death of one dog may be inconsequential in the end, but to those that loved the particular canine and considered him part of their family, the unwillingness to be cautious at the very least, especially with no long terms studies to back them up in addition to bans from human food of said chemicals, leaves a great void in at least one families life and the other void is where do no harm seemingly meant not enough when those involved thought they knew all.

    Do no harm indeed. When did that become a dirty word ?

    Gaillard Lee Johnson

  8. skeptvet says:

    I am sorry that your pet died, but there is no evidence to suggest that this had anything to do with menadione. The problem I have with the claims that this substance is harmful is

    1. They are almost always made by individuals with a firm pre-existing belief that some things are “natural” and others are not and that “natural” things are safer or healthier, which is demonstrably untrue.

    2. They are generally supported by lab studies on isolated cells or injection of enormous quantities of menadione into lab animals, which isn’t anything like the supplementation of appropriate amounts in pet food.

    You say there aren’t any long-term safety studies, and I agree. The short-term and lab studies suggest it is not harmful until the dose is MUCH higher than could possibly be gotten from pet food, but there is not absolute proof of the safety of long-term feeding. This absence of evidence means we can’t be sure, though so far there is no reason to believe there is a risk here.

    On the other hand, there are also no long-term feeding studies showing it is harmful, yet despite this evidence you assume it is and blame it for killing pets. There is no evidence this is true, but you believe it and so you don’t feel evidence is needed. This is not a rational or useful way to approach questions about nutrition safety. As I pointed out in the article, oxygen and water can be poisonous in sufficient quantity, but we don’t try to avoid these substances or blame them for every unexplained death.
    According to one veterinary nutrition specialist:

    “Vitamin K1 (phylloquinone or 2-methyl-3-phytyl-1,4-napthoquinone) is the naturally occuring vitamin K found in plants. Vitamin K2 (menaquinone-7) was first found in putrefied fish meal. The parent compound is vitamin K3 (menadione or 2-methyl-1,4-naphoquinone). It does not have the same biologic activity as Vitamin K1 until a side chain is added. This can be done my microbes in the GIT or in the body once absorbed. The toxic level of menadione in the diet of dogs or cats is >1000 times the dietary requirement according to the NRC (1987). It can be toxic if given parenterally. I was unable to find anything about toxicity of any vitamin K compound in dogs and cats when searching PubMed.”

    And according to a veterinary toxicologist:
    ” ‘Dogs given 15-40 mg/kg of menadione IV for 15 days developed methemoglobinemia and anemia, but no mortality occurred.’ As such, it is unlikely to be a problem.”

    These are people with extensive advanced training in veterinary nutrition and toxicology. In the absence of the definitive studies we would both like to see, I find their interpretation of the existing evidence more convincing than that of random people on the internet who believe all commercial pet foods, especially those with “unnatural” ingredients, are harmful.

  9. I don’t recall saying ‘roc was killed’ by menadione, as I have no absolute proof , as I clearly indicated, so IF I said that anywhere, it certainly was not my direct intention. I thought I made all that quite clear. But I certainly did mean to infer that I felt there was a possible link to it , and given there was no autopsy , I can’t help but wonder for many different reasons, all which I have cleanly and directly pointed out.

    I clearly said, that I feel there is enough evidence, based on common sense things like the FDA not allowing Menadione in human food, and its liver killing capacity and that it can remain in fat cells in the body ( if true, but that’s only another indicator and on its own not necessarily enough to be smoking gun & Im not a vet so Im not sure ‘yet’ its accurate!) that I personally feel there is no reason to take ‘chances’ with it. Why would I, went pet food DOES exist, you must admit skeptvet, that does not contain Menadione. Does that give you no pause ? HOw long would it have taken to add to a vet office’s ‘database’ of what pet foods specifically have menadione ? I doubt very long. And seconds to let me know about it, and let US decide to use it, or not to. Done.

    I am insulted, as is my depared dog ( that is not hyperbole,that is heart felt fact to you doctor) that you would label my references as ‘random people on the internet’. You sound like a spokesperson for the industry, just as any one single entity I called refused to comment on the menadione supplement . People in the industry and vets alike seem to tippy toe over this issue , when clearer heads should and will, someday, prevail. I just do not comprehend where ‘choice’ became such a horrible dirty word.

    Arrogance and belittlement has no place in professional circles and you skeptpet should be ashamed of yourself. Again that is not hyperbole, that is how I feel based on your own words. You could have been far more eloquent and empathic. My vet’s office was equally lacking in those abilities, so I guess it just runs in random cirlces ?

    I’m sorry I wasted my time trying to explain to you why I felt the risk was unacceptable, why I felt it ironic and inconsistent that the vets office who sells science diet which does NOT contain menadione, yet refused to note the dog food I fed roc which clearly had Menadione in it, yet my dogs safety apparently didn’t mean enough to them to bother giving ME the information, and letting me decide ‘which dog food’ I felt better with .

    I specifically am not concerned that you may think Menadione lunatics exist or do not, the only important thing we need to know, is ‘do no harm’, and you and others like you by insisting ‘random people’ are giving bad information, suggests I don’t have the right based on any of that, to conduct myself in ways that I FEEL are important to the dignity , safety and well being of my/our specific companion animal.

    Your tone and your answers, reflect the industry you apparently, serve to protect. I shouldn’t have been surprised, but there it is right in front of us. What else could possibly indicate your total disregard for my willingness to be given a valid choice instead of being ignored as a crackpot for some ideological stance on what’s in my dogs food. To reiterate, science diet which my vet sold, does not contain this chemical. I hope the irony here is being understood, and abundantly clear to you doctor.

    I’m surprised, you left several of my questions unanswered, but again choice offered you that position. I’m glad you had that choice, as ours was arrogantly taken away from us.

    I am sadened by your willingness to selectively respond, and will take that into account as I weight the totality of your response.

    Thank you for response at least.

    Gaillard Lee Johnson
    Health matters as does ‘choice’.

  10. skeptvet says:

    I don’t recall saying ‘roc was killed’ by menadione, as I have no absolute proof , as I clearly indicated, so IF I said that anywhere, it certainly was not my direct intention. I thought I made all that quite clear. But I certainly did mean to infer that I felt there was a possible link to it

    I understood that, I simply don’t agree that there is much chance of there being a link. And given how strongly you appear to feel that people should avoid this ingredient, I think you have gone beyond merely suggesting a possible risk and are now suggesting that the substance is very likely unsafe, which I do not believe is supported by the evidence.

    the FDA not allowing Menadione in human food, and its liver killing capacity and that it can remain in fat cells in the body

    The problem here is that
    1. the FDA rule relates to the risk of menadione supplements due to human behaviors, such as taking megadoses of vitamins or overdosing on them, which are not risks that are relevant to the use of this supplement at low doses in pet food. There simply is no logical link between the FDA guidelines and the risk you seem to believe exists for pets.

    2. Yes, given intravenously or put in a petri dish with liver cells, menadione can be harmful. As I’ve already pointed out, so can water and oxygen. This is not a reason to suggest it is intrinsically harmful or not safe when used for an appropriate purpose at an appropriate dose. If we avoided everything that could possibly be shown under any circumstances to cause harm, we couldn’t eat or drink or breathe anything.

    3. All fat soluble vitamins (Vitamins A, D, E, and K) can accumulate in fat and be toxic at excessive levels. Vitamin A posioning is probably the most common example of this. However, this has nothing to do with whether these vitamins are inherently safe. All of them are necessary for life AND potentially toxic. The issue is the dose, not the inherent quality of the substance. Once again, if you avoid anything which can accumulate in fat, you will eventually die of a deficiency.

    I am insulted, as is my depared dog ( that is not hyperbole,that is heart felt fact to you doctor) that you would label my references as ‘random people on the internet’. You sound like a spokesperson for the industry, just as any one single entity I called refused to comment on the menadione supplement . People in the industry and vets alike seem to tippy toe over this issue , when clearer heads should and will, someday, prevail. I just do not comprehend where ‘choice’ became such a horrible dirty word.

    Well, this is simply ridiculous. You cited web pages by people who do not have any qualifications in veterinary nutrition or veterinary toxicology. Someone with a degree in dentistry and GreatDaneMOM on the dogforum web site seem the definition of “random people on the internet.” They are entitled to their opinions, but they aren’t entitled to any special credence since they have no relevant expertise in veterinary medicine, nutrition, or toxicology, and they do not present any compelling evidence to support their claims. I cannot see any reason why openly stating this should be offensive to anyone.

    Similarly, how incredibly arrogant and “belittling” is it of you to suggest that the only reason I disagree with you is because I have some presumably financial interest in the pet food industry? That is a poor excuse for an argument. I disagree with you about the risk of menadione based on the available evidence and the interpretation of this evidence by experts with appropriate training and knowledge. I have on connection with the pet food industry, and whether menadione continues to be used or disappears tomorrow has no impact on my career or my income. You are, of course, free to disagree with me, but it is not productive, and frankly it is silly, to use imaginary motives instead of evidence to dismiss my arguments.

    As for not answering your questions, I’m not sure what you mean. Your first comment contains no questions. The second asks:

    1. If menadione is necessary in dog food why don’t all companies use it? The likely answer is that there are several possible Vitamin K sources available with different pros and cons and some companies probably choose a source other then manadione for marketing reasons (they want to claim they are more “natural”) or others. If you mean to imply that since some companies don’t use it none should, that makes no sense.

    Apart from that there are just a couple of rhetorical questions intended to make a point about how angry you are about what happened to your dog.

    In any case, you don’t seem at all interested in exchanging ideas and evidence, since you’ve made up your mind and you automatically demonize anyone with the temerity to say you’re wrong and your sources aren’t convincing. I’ve made an honest effort to explain my position and why I disagree with you, but this seems unlikely to be avery productive discussion now that you’ve resorted to self-righteous outrage and ad hominem insinuations.

  11. ” I understood that, I simply don’t agree that there is much chance of there being a link. And given how strongly you appear to feel that people should avoid this ingredient, I think you have gone beyond merely suggesting a possible risk and are now suggesting that the substance is very likely unsafe, which I do not believe is supported by the evidence. ”

    Much chance..if you can’t categorically state there is no chance, then my and other trained and professionally trained individauls would seem to indicate there is a chance. That’s why this is so relevant. If there is even a 1% or so risk of this being a problem, why would I take it , if my companion animal means anything at all to me ? I sincerely doubt many parents would take that risk of their child, so I refuse to ,and I would most would, to take that risk with a mere animal ? No thanks.

    I emailed the author of dogfoodadvsior, and he stands by his website on menadione and you are free to contact him, and publish the results on your blog; I have no problem with that, and I’d be happy to update my website with those same results; if you care enough to follow through on that, yourself as a ‘trained vmd’ , and if you have the time to dedicate to it, feel free. You can trust us that we will follow up.

    You may think we are ‘angry’ over losing our prior canine companion and of course as a human being with applicable emotions, you wouldn’t be correct, but that itself does not somehow bar me from having a valid opinion on the subject, after having contact at least 2 professionals on the subject. You may not agree with their credentials, but it doesn’t excuse you from playing loose with their findings because you disagree. The majority opinion doesn’t always hold up to the scrutiny of time, so I think its wize for us all to consider what goes in our companions food as carefully as our own. If I see a risk in the world, I most certainly will not take it and find alternative foods that do NOT contain it, and I most certainly will apply that to companion food without fail. That is called due diligence, not hyperbole or angst of anykind.

    I am not sure I presented this URL, but if I did not it’s available and relevant: < and as noted near bottom of page, other 'scientists' are certainly concerned about this issue as seen by:

    " Conclusion:

    In my opinion, Michael von Lüttwitz and Herbert Schulz worded it best in their article "Vitamin K3: eine Geissel im Gesundheitssektor?" [Vitamin K3: a scourge in the health sector?], published in the May 2003 issue of "Der Deutsche Schäferhund" (the professional journal of the Swiss German Shepherd Club):

    "When food contains menadione, every owner and breeder has to make the decision for himself whether he can take responsibility for giving his dog a substance that is not permitted in the [human] food sector and led to permanent damage and deaths in humans."

    I agree 100% and after presenting the information, as always, I leave the decision up to you. "

    Hoffmann-La Roche Corporate Health Protection 10/03/2000
    The better is always the enemy of the good. Or here: Vitamin K1 is undisputedly better than Vitamin K3.

    Prof. Dr. Wolfram, Technische Universität Munich 12/14/2000
    Menadione (vitamin K3) is 'cheaper' because it does not occur naturally. It is also burdened with considerable side effects. It is unsuitable for use in humans.

    Why is it added to pet food?
    Menadione is added as an inexpensive vitamin K supplement in commercial foods. The common statement as to why it is added is "to help with blood clotting", yet it is scientifically proven that the effectivity of menadione on blood clotting is inferior. Even veterinarians will administer vitamin K1 as an antidote to dogs who have for example ingested rat poison, which causes internal bleeding.

    Manufacturers who use menadione in their products also like to claim that it is "more stable" than natural vitamin K and has "more nutritional value". Not a single one of them has acknowledged the scientifically proven side effects of this substance.

    It is simple to come to a conclusion about the truth in these statements when you consider that

    not all pet food companies add menadione to their foods and dogs have eaten these products for years without developing deficiencies
    the National Research Council was not able to demonstrate a dietary requirement for vitamin K in dogs during tests when natural ingredients were fed and
    fish meals, liver and green plant supplements (e.g. alfalfa, kelp and other seaweed, nettle leaf, blue-green algae, spirulina) are rich sources of natural vitamin K.

    Here is a list of negative effects of menadione on the body.

    causes cytotoxicity in liver cells
    causes formation of radicals from enzymes of leucocytes, with the consequence of cytotoxic reactions
    considerably weakens the immune system
    possible mutagenic effects
    damages the natural vitamin K cycle
    has no effect on coumarin derivatives, which are often present in commercial food due to mold contamination (toxic when ingested)
    causes hemolytic anemia and hyperbilirubinemia, not just linked to large doses
    disturbs the level of calcium ions (Ca2+) in the body, which is an important factor fibrinolysis
    is directly toxic in high doses (vomiting, albuminuria), unlike natural vitamin K
    builds up in tissue and has been detected in eggs, meat and milk of animals supplemented with menadione derivatives
    causes irritation of skin and mucous membranes
    causes allergic reactions and eczema

    Bässler, K.-H. et al. (1997): Vitamin-Lexikon für Ärzte, Apotheker und Ernährungswissenschaftler. ISBN: 3437211404
    DGE (2000): Referenzwerte für die Nährstoffzufuhr. ISBN: 3829571143
    Elstner, E. F. (1990): Der Sauerstoff. ISBN: 3411140011
    Friedrich, W. (1987): Handbuch der Vitamine. ISBN: 3541120118
    Hoehne, Dr. med. vet. Eberhard (1985): Vitamine. ISBN: 3873470284

    So it's not as if we awoke one morning from a dream and decided to take on this cause, it was after much research, pro and con and deciding the risk wasn't worth it, when 'dog food that does not contain Menadone' exists. That is the choice we referred to earlier and why we felt the vets leaving this important point about our lifestyle choices ( dog food choice) out of the decision making process for our dogs health, oddly troubling, and why today we refuse to take any risk ( given all the above facts) with Menadione.

    We called hills diet pet food company, and they do not ship Menadoine ( consumer affairs dept.)as they are not convinced of the need for VItamin K in pet food by all available science on the topic. They therefore include only ( and as asked for by consumers ) natural fruits & vegetables,and as noted earlier, the efficacy of Vitamin K for blood clotting is inferior, and therefore as a 'additive' in the form of Meadione ( synthetic Vitamin K3) is unneeded and therefore any possible risk inherant in it is made sterile.

    For further verification on this topic, you can view which verifies why Hills does not ship Menadione ( and why consumers ask for it):
    Daily Recommendations
    The Food and Nutrition Board, which is a subgroup of the Institute of Medicine, has set recommendations for daily intake of vitamin K. If you follow these recommendations, your body will have enough vitamin K to allow normal blood clotting. Adult men should aim to consume at least 120 mcg of vitamin K daily, whereas adult women should consume 90 mcg of vitamin K per day. The best sources of vitamin K include vegetable oils and green vegetables such as broccoli, kale, spinach, lettuce, Swiss chard, watercress and parsley, according to the Linus Pauling Institute.

    Read more:

    We all deserve choices ( free from dissection), and no one has the right to take those away, and inactuality, when those choices present alternatives that carry zero risk themselves, to hold back said choice seems the ultimate in hypocrisy and arrogance.

  12. skeptvet says:

    I have no idea why you think I or anyone is attempting to take away your choice. You can choose to feed a food with or without menadione absolutely freely. Now if you think veterinarians should specifically tell all their that a small number of people consider this substance dangerous without any good evidence and that vets should inform their clients that they can choose not to feed it, well that makes no sense. I am not going to “warn” people about something and suggest they can avoid it when I don’t believe it is a true hazard. This is not about “rights” and “choice,” it is a debate about the evidence and its interpretation. We disagree, and that’s fine, but nobody is taking away any of your rights or freedoms by not agreeing with you and not doing what you think they should do.

  13. sam says:

    my friend’s cat died of Menodione poisoning. in fact she sued the company that made that brand of food and won the case. it is not safe

  14. skeptvet says:

    I’m sorry your friend’s cat died. How do you know the menadione was the cause?

  15. terry says:

    Many thanks for this..makes perfect sense..I will be feeding Purina One afterall–thanks for clearing this up…

  16. Pingback: Food question, I know I know, Merrick/Pro Plan/Dog Chow - Page 2

  17. Erica says:

    Thanks for the facts. I trust a well argued appeal to reason and peer-reviewed evidence over the numerous emotional online sources decrying the substance. My dog food is grain free but doesn’t have any leafy greens, and my dogs would turn up their noses at a bowl of salad, so I’m glad this (safe in moderation) supplement is included in my dog’s food.

    Thanks for explaining the facts and nothing but the facts!!

  18. Pingback: Switching from Royal Canin to Acana -has gas - Page 5

  19. Thanks for the great information. Now I think that Vitamin K is also an essential nutrient needed in very low levels by dogs and cats.

  20. Somevetskillpets? says:

    Maybe Dogs aren’t carnivores after all? Vets hand out Samples of Corn Meal Dog food, so it must be safe. Remember your vet knows best! If they give you adrenal shrinking prednisone for an allergy, and suggest lifetime treatment”, maybe its just best to listen, after all, the dog food industry EdUmAhcAtes them. Corn and prednisone a Perfect recipe for an ignorant pet owner,virtually guarantees, your pets suffering your suffering, and keeping their pocketbooks Fat$$$$$. But then again, a doctor wouldn’t put profits above your well being or your pets. Science diet is designed for your vet not your pet. Science Die-t

  21. Somevetskillpets? says:

    Without exception” every vet has had Purina or Science Die-t as a reccomended food for our pets. That’s Not a typo. Every Vet we have been to has suggested Purina or Science die-t. A 1 st grade educator could teach pet owners that these foods are detrimental to canines. There will always be the post that claims their dog has eaten corn based dog food and taken prednisone for 10-20 years and their dog is happy as can be! These billion dollar a year industry’s have no problem selling crap and claiming its The Best” like the vet that warned against me feeding chicken,broccoli, cottage cheese almonds kidney beans carrots,apple,red meat liver,turmeric milkthistle,vitK to stop the bleeding. His kLaiM Their Dog Food is healthy and balanced…insane? Greedy? Ignorant? I will never know, irresponsible? All of the above? I’m not going to let his problems become ours. Their is 1 vet. I like her. She doesn’t argue. She gives the occasional CBC.. She heard me loud and clear, after she raved about the Blood results for a pom with itp. Her body looked like it was hit with a baseball bat head to toe…sniffle. After I weaned the pred. Started vitk (Phylloquinone) and removed the bagged food. I changed the diet. After 2 wks I returned for another CBC. After results came,She left a lengthy vmail, amazed at the results……. At the end of her message she suggested weaning the pred. Over a year. I called her back and let her know, pred was weaned and on diet change. She was speechless. I still take the bear to her, and kid her about opening her own practice and going Holistic. Silence. I’m not against healthcare, I’m against Unhealthy irresponsible ignorant care that harms family’s and their loved ones.

  22. skeptvet says:

    Sarcasm and paranoid conspiracy theories eith no hint of actual evidence. Excellent and compelling arguments indeed.

  23. Somevetskillpets? says:

    P.s.A well know animal hospital. Vca. Here is the list of vaccinations they wanted to give a 10 lb.canine with just discovered itp…This was a list given to me with my CBC bill. Highlighted was” OVERDUE OVERDUE OVERDUE OVERDUE OVERDUE Rabies vaccine,Bortadella vaccine,Leptospirosis vaccine,dental cleaning,flea prevention,Rattlesnake vaccine, I have never seen a rattlesnake here in 20 years! Distemper vaccine,heartworm test,parvo vaccine,heartworm RX refill,Guardia vaccine. I never went back.

  24. skeptvet says:

    Sorry, but there’s nothing but your opinion here, and it doesn’t suddenly become fact just because you feel strongly or claim it’s obvious. You are free to believe what you like, but if all you offer in support of your belief is sarcasm and anecdotes, there’s no reason for anyone else to take you seriously.

  25. andy mcfadden says:

    It is annoying that I have to go spend two hundred dollars a month on cat food now because of hysterical cat mommys who have me me one of them.

  26. Pingback: Menadione: Synthetic Vitamin K Supplement in Pet Food |

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  29. Daniel says:

    Sound sad and complicated , really appreciate thanks for your information ,
    so is there more reference? Vitamin K Toxic effects can be seen when enormous quantities are given to an animal or when ?

  30. Kirk says:

    I bought a Purina One recently because of chicken being its first ingredient listed. But then I saw the menadione present. I’ve heard that it’s not good over long exposure too. I always want the best for my cat and not many better brands are available where I’m from. So should I keep feeding my cat this? If it can cause harm I want to stop from now and count the money spent a loss.

  31. skeptvet says:

    As you can see from this article, there is no good evidence that this compound is harmful despite its use in literally tens of thousands of animals over many years. It’s understandable that you should worry when people claim it is harmful, but hopefully the fact that there is little evidence to support those claims will help you in making your decision.

  32. In reply to Kirk: we had a terrible experience with Purina One. We used to believe their marketing pap and bought right in to it being a high-quality “complete” diet. It made us feel good about ourselves when we dumped it into our six cats’ bowls each day.

    One day, (after using it for several years) I opened a brand new bag and within an hour of putting the new food out, all six healthy adults cats were vomiting violently. My first call was to our vet who told me to immediately pull all food and water. He said to make a bland diet and gave me instructions for the (home-cooked) food preparation. Within a day, no one was vomiting but all were weak and shaky and not acting normal. We were drinking the same water and were not sick, as was our geriatric dog. None of our cats went outside. The sudden onset pointed to acute toxicity. The commonality was the food. I called Purina to see if I could get some answers. The woman I spoke to told me that the “machine that puts the supplements in had malfunctioned” and that it wasn’t “the entire lot, just a few bags that seemed to have too much”. Of course, I guessed that this answer was likely going by anecdotal reports from the handful people who connected the dots – not every cat owner would because owners of single cats might not see the food as a suspect like we did and could potentially assume their kitty had gone outside and eaten a poisoned rodent or something spoiled out of the garbage.

    They (Purina) were very nice and quickly sent me a coupon for a free bag, instructing me to make sure it wasn’t the same lot number. We drove clear across town and bought the new bag from a different store. By the time we’d gotten the coupon, the cats were all pretty much back to normal. As soon as we fed from the new bag, we had vomiting kitties again. At that point, there was no going back. We changed to a better quality (more expensive) food, and had no further problems.

    Then there was our (young) little dog, diagnosed at first with “contact dermatitis”, then “food allergies” after being plagued with a persistent itchy rash for nearly a year. This was the very beginning of my research into what goes into “pet food.” We switched him to a brand that was very high quality and the “allergy” went away. Note that this particular food (Acana) has no menadione.

    Fast-forward over ten years, and we lost our Congo African Grey baby (just three years old) to eating food that was (per the pathologist doing his necropsy, a DVM, MS, Ph.D., Diplomate ACPV – so VERY well-credentialed as well as well-published) “very highly contaminated with aspergillus spores.” Our baby went from a complete yearly physical with avian bloodwork panel showing all results WNL, to being dead – in less than a month. There were no granulomas in his lungs, however the rest of his body was full of them indicating a systemic route of exposure rather than the typical (for African Greys) inhalation route of exposure. What does this have to do with menadione, you may wonder?

    Since that death – that could have been prevented by proper diet – I have been obsessed with what our companions eat. If it’s not human-grade, not one creature eats it. Not dogs, the sole remaining cat, not any of the over 100 parrots that live at our sanctuary. Menadione is banned in human foods. After doing considerable research into this hepatotoxin (cytotoxic to liver cells), we have made the decision that it’s completely banned at our facility.

    Also, with all due respect to Dr. Skepvet, addressing the point that it’s banned for human use because of human behaviours causing them to be tempted to use too much – that’s not exactly the case. Here’s some information (from the National Institute of Health) that presents “human health effects”:

    “Drug Warnings:
    … Probably should not be given to newborn infants or women during last few wk of pregnancy.
    [American Medical Association, Council on Drugs. AMA Drug Evaluations Annual 1994. Chicago, IL: American Medical Association, 1994., p. 795] **PEER REVIEWED**” I am pretty sure newborn infants are not prone to taking more medication than recommended.
    … and…
    “… Menadione is irritating to skin and the respiratory tract. Its solutions have vesicant properties. Menadione and its derivatives have been implicated in producing hemolytic anemia, hyperbilirubinemia, and kernicterus in the newborn, especially in premature infants.
    [Hardman, J.G., L.E. Limbird, P.B., A.G. Gilman. Goodman and Gilman’s The Pharmacological Basis of Therapeutics. 10th ed. New York, NY: McGraw-Hill, 2001., p. 1784] **PEER REVIEWED**”

    Years ago it was given as an injection, to prevent bleeding in newborns, but… “There were reports of hemolytic anemia and hyperbilirubinemia severe enough to cause kernicterus in the mid 1950s with high doses (50mg) of vitamin K2 (menadione). As a result, use of this form of vitamin K was abandoned. ” (from — (please note the K2 is an error or likely a typo, menadione is known as Vitamin K3, not K2). For those without a medical background, kernicterus is a type of brain damage caused by severe jaundice (very high levels of bilirubin). I am pretty sure these outcomes weighed heavily in having it banned for human patient use.

    To me, any chance of benefit is outweighed by the potential health risks. Do I want my birds/dogs/cat eating food with a chemical that is cytotoxic to the their livers? Absolutely not. With dogs and cats, it may be a bit harder to get them to snack on leafy greens, (mine do easily) however parrots will readily eat Vitamin K rich greenery, so we feel there’s no justifiable reason to put this toxin in their food bowls.

    Anecdotally, we had a bird die of liver disease – blamed by most vets on a “seed diet” fed over the course of years. The problem was, this bird never ate a “seed diet”. This bird was not obese and aside from the liver, was in good condition. The bird (budgerigar) had been surrendered by a family that was told by the pet store where they bought him to feed “pellets”, so the bird had eaten nothing but Zupreem (incidentally, made by the same folks who bring you Science Diet). Zupreem contains menadione. The bird was only these pellets before coming to our facility (the family stated they got the bird as a baby almost 2 years prior). The bird was here for just a few months when symptoms developed and the differential diagnoses of “fatty liver” or a liver tumor were suggested by both physical exam and diagnostic imaging. We have birds that were here years longer, who are still with us and are perfectly healthy eating the foods we feed them (not pellets). Why did this little bird develop such severe liver disease and die at less than 4 years of age (we are unsure of exact age but estimated it to be around 3-3.5 years based on information given by previous owners)? I don’t know. But someday, I think we will have solid, evidence based answers and I don’t think it’s going to be positive towards menadione. In the meantime, I will continue to use “an abundance of caution” in feeding our companions as well (and often better) than we feed ourselves.

    In human medicine, a common cause of “fatty liver” is regular consumption of alcoholic beverages. Drinking a certain amount of alcohol can cause fatty liver disease (then hepatitis, then cirrhosis). Alcohol is a liver toxin. If daily exposure to that liver toxin can cause these disease conditions in my human patients, then why is it so hard to believe that daily doses of the hepatotoxin menadione cannot also cause them in non-human patients?

  33. skeptvet says:

    Lots of anecdote here, but not any evidence at all that this vitamin source is harmful to pets in the form and doses used. You can say the words “liver toxin,” but that doesn’t make it so. Reviews of the evidence by food safety experts still do not support the concerns you have about this ingredient:

    Toxicity of menadione or its derivatives is reached at levels exceeding the requirements by a factor of at least 1 000.The use of MSB and MNB in animal nutrition does not pose a risk to the environment. MSB and MNB are regarded as effective sources of vitamin K in animal nutrition.

  34. Paulette Acosta says:

    I’m a strong believer in an ounce of prevention is worth a pound of cure so if there is only a SMALL chance of artificial vitamin k making my dog sick, then I will NOT give it to my dog. Since NO ONE can say this vitamin is safe long term at small doses, I’ll err on the side of caution and not buy dog food that uses it.

  35. Amy Li says:

    Thank you for this site! I’m a bit of a helicopter cat mom and have read so many articles debating certain ingredients in cat foods—namely carrageenan and menadine sodium bisulfate complex. I recently added weruva to my kitty’s rotational diet and kicked myself for feeding him something MSD in it after seeing it on the label until I read this!! Thanks so much for putting my mind at ease.

  36. skeptvet says:

    You’re welcome. Thanks for the feedback!

  37. ron says:

    Wellness canned cat food and merrick backcountry pouches are my choice to feed my cat. 3 hrs before his bedtime i give him a tray of nutro wild frontier. All wet no dry. Dry has way too many carbs and puts weight on. Dont feed raw. Also many problems. Salmonella being one of them.

  38. Maria says:

    Hello, my dog will start on a homemade cooked diet designed by a vet, which includes 4 tablets (!) of this supplement ( I asked him if that wasn’t too much, given humans should take 1 pill daily (100 mcg) instead of 4, according to the label… He said no, because my dog (20 kg) should consume at least 400 mcg (0.4 mg) of Vitamin K daily, and that’s the amount included in 4 pills. It just seems off to me and now I’m even more worried after reading this post in which you say that dogs need only minuscule amounts of Vitamin K through diet… Can you please tell me what minuscule means in numbers? Thanks!

  39. L says:

    This product is not approved for veterinary use. Isn’t that enough of a red flag for you?

    Let me guess, your vet is a homeopathic vet.

    I would definitely withhold giving this product for now and get another opinion asap.

  40. Joad says:

    I have a cat with CKD and two other cats without, one is a Maine coon and one is a CH kitty. We started on the vet recommended kidney food but because the three cats insist on rotating bowls while they eat, we saw muscle wasting and weakness in the normal cats. After research I started all three on Weruva with a small amount of Instinct as additional protein and they all see to be doing well. Then I came across some scary posts on FB regarding Menadione and thought I was in for another round of hours of research. This is long winded but appreciate the factual listing of what we know and what we don’t. Given my three cats ages (13, 14, and 15) and their issues, I have to take a moderate, what works for all three approach as opposed to catering to just one.

  41. Pingback: Best Cat Food for IBD in 2020 (with Reviews!) - The Halo Pets

  42. Jessica says:

    I think it’s interesting that people are bashing you for “defending the industry” and then stating that they get all their info from a blog that gets kickbacks (via affiliate links) from every food they review. It just so happens that the K3-free food is FAR more expensive and thus, the owner of that blog gets far more money every time someone buys a K3-free food. Hmm, sure sounds like a conflict of interest and a reason to “defend” their position on the ingredient.

    The disclosure on his website even says “Please be advised we are not veterinarians. For this reason, this website was never meant to be used as a substitute for sound professional advice.”

    Skeptvet is a professional and gives sound advice. I 100% trust what is said here but I’m definitely skeptical of blogs that rate foods and link to products with affiliate links. They have a clear conflict of interest but people seem to trust them far more than actual veterinarians. It’s infuriating.

  43. Craig Fleming says:

    If people would take notice that that menadione is close to the very bottom in the list of ingredients in pet food that the amount in it is so minuscule that it would never cause liver toxicity. But people don’t seem to understand is that the amount needed to cause toxicity is 100 or more times the amount that’s in pet food. Any vitamin or mineral for that matter can become toxic if someone consumed a massive amounts of it. Just like when someone takes a multivitamin a multi mineral supplement the amount in it is so small it hardly does any good but is better than taking nothing, but if you took the whole bottle at once of vitamins then it would probably have negative effects. In that case if someone is concerned about themselves or their pets consuming excessive amounts then that is highly unlikely as a pet it’s not going to overdose on menadione since they are not taking massive doses or injecting it in themselves. And someone on here use the argument that if they wouldn’t give it to their kid they shouldn’t give it to their pet, while in that case that means you should never give your kid any medication from a doctor because there’s always a risk of side effects from it or give vaccines since there’s always a risk that someone could have at first reactions to that. If these people think everything synthetic will cause them problems, then you might as well go live in a bubble somewhere instead of the real world. Seems like some people just come on here to hear themselves talk and are looking for an argument. I agree with you skeptvet, that the miniscule amounts of menadione in pet food is nothing to be concerned about as the real problem that lies with menadione toxicity is overdosing in massive amounts in pill form or injectable, not the tiny amounts found in pet food. Also people feed their pets food with corn gluten meal, meat by products and grains which have been shown to be far more problematic and causing health issues then a tiny amount of menadione ever would. But this is a free country in anybody has the right to feed their pet whatever they want so if you don’t want to feed them something with menadione, then don’t it’s that simple, no one is forcing me to do anything.

  44. Craig Fleming says:

    Vets get a commission for carrying Hills science diet and similar products so they are going to push this brand of food. If you read the ingredients in Hills prescription diets in particular, they are full of corn and wheat and other grains pets do not need. I’ve been told by several vets that there are much better foods out there than Hills or Royal canin. Two pet foods I like for cats are, CRAVE pet food brand chicken flavor and Pure Balance pet food brand chicken flavor.

  45. Craig Fleming says:

    Well said.

  46. skeptvet says:

    This is simply not true. The vast majority of the foods my clients feed are not bought through our practice, including Hills and all the other major manufacturers. The few that we do sell are therapeutic diets intended only for specific medical conditions, and for each of these we cary all the competing brands so that clients have choices and options. We also provide referrals for nutritionists consults to have homemade diets formulated for the owners to make and suggest commercial fresh diets if that fits the clients’ needs. The bottom line is that we recommend the diet that best meets the medical needs of the patients and the goals and desires of the owner regardless of any financial incentive, and this sort of “they push crappy food for the money” line is untrue and offensive.

  47. Ron says:

    I do not believe you!

  48. Luna says:

    I wonder, were there any studies for safety of menadione done on cats and dogs? If there are, for how long did the studies lasted? How long was the food containing a certain dose of menadione fed to the test cats and dogs? How many cats and dogs participated in each study? Have there been a long term study, several years long, where a few hundred cats and dogs have been fed food containing menadione, that show no ill effects? If there are I would appreciate links.

    Please note I’m not a native English speaker, sorry for any errors.

  49. skeptvet says:

    Vitamins are not subjected to this kind of lengthy and expensive safety testing because there is no reason to believe they present a meaningful health risk. Do you ask for this kind of data every time you eat a new type of fruit or add a new spice to your food? It would be unreasonable to use resources to run clinical trials on every substance we and our dogs eat without something other than anecdotes and anxiety to suggest a risk. The safety profile of Vitamin K3 is based on scientific understanding of its composition and metabolism as well as pre-clinical research. It has also been fed to millions of animals for decades with no reliable evidence of harm turning up, which is also supportive of its safety.

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