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A Veterinarian Takes a Stand Against a Common Pet Food Supplement

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  1. june lay

    What is not mentioned is the amount of copper that was in his dog supplement? I just checked the supplent I add to my home cooked food, an
    d it has.303mg, about a third of 1 mg.

    I would like to know whst his dog’s daily intake was.

    1. Susan Thixton Author

      I’ll see if I can find out. But…I doubt he would know. This was the supplement in the pet food he gave his dog – so it could vary with each batch of pet food.

    2. Marcha

      Dr. VanVranken (my vet) was using a commercial dog food. I do not know what brand, but probably a higher end and most definitely a brand that was following AAFCO recommendations.
      If you are feeding raw and feeding liver, please note that copper sulfate was added by AAFCO to ALL single stomach animal feed recommendations. Copper is stored in the liver. Your chicken and beef liver may have elevated levels of copper if the source animals was being fed a feed that was following AAFCO recommendations.

      1. Andrea Davis

        Probably a food they sell in their practice which are all the crap foods. They also hand out Greenie’s & sell them on the counter.

        1. Kelly

          yeah probably hills diet. all vets push that sh*t. i know ppl whose dogs got sick on hills. anyway,a few yrs ago,i gave my dog a greenie(before i knew better) and he threw up for days.

    3. saralynn1113

      That is not good. Dogs do NOT need any copper at all, which is clearly stated in that article. If your current supplement has copper in it, change supplements.

      1. JDJD

        They do need copper – it is in some foods a carnivore would eat if eating in nature. I think the question should be is there too much being added to the manufactured food and is it in a form that is o.k. for the dogs to be eating.

    4. saralynn1113

      That is not good. Copper is NOT needed by dog’s at all, a fact clearly stated in that article. If your supplement has copper in it, change supplements.

  2. Joan

    My dog also died of liver disease from too much copper in foods. Copper should NEVER be added by the manufacturers. It occurs naturally in foods. It sgould never be over 10 mg, (the less the better) and most pet foods are over this. It accumulates in the liver, and over time you end up with a sick dog.And it is a horrible way to die.

  3. Diane

    Does this apply to cat food?

    1. Susan Thixton Author

      Sorry – I don’t know. But I am going to do more research on this and try to learn more. Once I read more on this I will share with everyone.

      1. Dawn

        Please do. I run a rescue and hear many stories of cats and dogs with liver issues related to copper accumulation

    2. Marcha

      Yes. Any food that is fed single stomach animals that are using AAFCO recommendations.

  4. timothy mcmahon

    This article specifically addresses copper sulfate. The food I’m giving my cat (First Mate salmon) contains copper proteinate. Is there a difference?

    1. Susan Thixton Author

      I don’t know. The veterinarian that is leading this campaign told me on the phone he feels any copper supplement is not needed in pet food. But – it is going to be in all that are considered a dog food or cat food (as opposed to supplemental feeding foods) because it is a required nutrient established by AAFCO.

      1. Sage

        My terrier currently eats ORIJEN ADULT DOG FOOD (in addition to home made Raw) and there is NO COPPER listed as an ingredient in her ORIJEN. My cats eat a homemade Raw chicken formula as well as a small amount of ORIJEN CAT and KITTEN which DOES list COPPER PROTEINATE as an ingredient. AAFCO must not require the addition of copper if there is enough in the whole food ingredients, or it would be added and listed in the Orijen Dog food. Copper PROTEINATE as I understand it is a safer form of Copper AND if Orijen can use the Proteinate form of Copper in its CAT food, than all the other pet food manufacturers should be able to use Copper Proteinate as well.

        Maybe price is the issue and once again a dangerous cheaper ingredient received AAFCO approval (at the behest of Big Pet Food) and the cumulative effect over time is killing pets by causing liver failure. AAFCO should be forced to re-evaluate and remove any copper requirement if it isn’t needed, as stated by Dr. VanVranken, OR they should rescind approval of copper sulfate in favor of copper proteinate.

      2. Kelly

        but what does one do? homemade is better but copper sulfate is still unavoidable thanks to the 1993 decision to remove cupric and add copper sulfate. So any animals with one stomach who eats a diet with copper sulfate will have high cop sulf levels when they are slaughtered and consumed?

  5. Laura

    What about copper proteinate?

    1. Susan Thixton Author

      Hi Laura – I’m going to see if I can learn more. At this point – I don’t know.

  6. Neal

    The designation of dogs as Omnivores was also primarily based on studies done with pigs and some molecular science that showed some dogs could tolerate high levels of carbohydrates. Not all but some.

  7. Sage

    Since pet food manufacturers are always eyeing profits and don’t want to spend an extra penny that they don’t have to spend, why are they adding an unnecessary ingredient? However small the cost, it’s still a cost. Makes me wonder if AAFCO is requiring / recommending? it in which case fingers should be pointing at AAFCO. I suspect what they purchase and add is a supplement blend formulated to meet AAFCO specifications, not individual vitamins and minerals. If so, the blend they use already contains this form of copper so it’s not so easy to leave it out until their supplement suppliers take it out.

  8. Beth Marousek

    Here is a copy of a letter I’ve sent to Halo and Wellness. I will keep you posted as to responses.

    Halo, Purely for Pets
    12400 Race Track Road
    Tampa, FL 33626

    Attn: Consumer Relations
    Re: copper sulfate

    Dear Sir or Madam,

    Attached you will find the content of an article that was brought to my attention. The article raises concern about toxic levels of copper found in the livers of dogs and cats, possibly the result of a copper supplement in their commercial pet food. The mineral in question is copper sulfate, and this mineral can be found in some of your foods.

    I would very much appreciate your response to the content of the article, and I will share your information with other concerned pet owners.

    In the event that the attachment containing the article becomes separated from this letter, you can find it at .

    I purchase your products because I believe you truly want to provide a healthier processed food for dogs and cats. If you are not familiar with the issue regarding copper sulfate, it is my hope that you will conduct your own investigation.

    Thank you for your time and consideration.

    1. Susan Thixton Author

      Thank you Beth! Yes – please let us know their response.

  9. Connie Schwarz

    There is something going on with Kirkland/Diamond dog food. My pet owners have started seeing dogs stop eating….some vomited…some got diarrhea. I searched consumer and read many reports in Nov. 2014 and December 2014 posted by people reporting the same thing. The people that switched to another food, their dogs live. Some continued to mask the food to get their dogs to eat…they died. One Diamond user…the vet diagnosed his death as Salmonella. I called Diamond….total denial. As soon as I started posting things on my Facebook page, Texas T’s Toy Schnauzers, I got an email from customer service Nature’s Domain/Kirkland/Diamond. She basically said, “We see you are talking about us…we don’t have a problem”. I gave her more details about our personal experience, and I closed by saying, “Maybe you DON’T have a problem, but I feel more comfortable recommending a food grade dog food, and I’m switching to Eagle Pack. She emailed me back and asked me for the link to the customer complaints I referenced from consumer affairs. She’s not smart enough to google Kirkland customer complaints? I don’t know what’s going on…but I’ve had MULTIPLE people report that there puppy/dog had the same symptoms. Many of them only emailed me after I started posting it on Facebook 3 days ago. All of them experienced problems in December, and were smart enough to switch on their own. On the consumer affairs website you can read recent complaints from people using Diamond products and Kirkland products. There are even some on the Canidae website. I feel really stupid (and guilty) because I had no idea that Diamond made 17 different brands…at least 17 is the number that I found. Is there anything else I can do? I do plan to start emailing Costco. I’m encouraging people to take the food back to the store…most of them had already thrown it away. We have at least 8 bags we are returning. Thanks for all you do, Connie

    1. Susan Thixton Author

      If you take the food back to the store – the evidence is gone. First – please – try reporting all of these incidents to FDA (each pet owner reporting). You can do that on this link:

      If there is something wrong with the pet food and it sounds like there is, by just returning the food no one is going to investigate. Reporting it to FDA might cause an investigation and possibly save lives is the problem is serious.

    2. Leannan

      Sorry, but I think you should keep looking [past Eagle Pack] for a new dog food. Eagle Pack is part of WellPetLLC. Berwind [an ex coal mining company] now an “investment management company, dedicated to long-term capital appreciation”

      Market position
      Acquisition targets should be leaders within their niche market.

      We measure value at the gross margin level. Berwind only considers companies that consistently deliver high gross margins.

      We insist on 100% ownership. We are a cash buyer.

      Berwind bought WellPetLLC from Catterton Partners. You can Google the whole mess.

      To me, it’s the same as being owned by “Big Pet Food” it’s only for profit.

      I wouldn’t go with Orijen either. If you are feeding dry dog food I like Wysong Epigen. I’m not familiar with their other [newer, revamped] lines.

    3. Michele

      I read something on Consumer Affairs recently about Kirkland and the number of dogs who had gotten sick in recent months. I’ve attached the link here. Kirkland is a Diamond brand and Diamond has had several recalls on their dog food. Since most pet food manufacturers have one facility they produce the food in it stands to reason that if they recall one food others have problems too.

    4. Sharon Norris

      I stopped using anything made by Diamond years ago. They have had so many recalls among their many brands of dog food, cat food and other animal feed. They make some premium brands that my dogs really liked but their recalls were quality control that seemed to go from one plant to another. They don’t seem to be improving at all–they just add a new line.

  10. Cindy

    Is it just copper sulfate that causes problems, and not other forms of copper, like copper proteinate?

    1. Susan Thixton Author

      I don’t know. There is a Cornell University veterinarian named in the article (the Michigan newspaper article) – she might be able to answer that. I am told there are some ‘studies’ on this which I will look for and read (still catching up from going to AAFCO). I’ll try to learn more soon and will share what I learn.

      1. Sharon Norris

        About copper sulfate. I worked in water treatment for almost 30 years. We used copper sulfate to KILL algae in the water before it came into the treatment plant and it doesn’t take very much. Just dissolve some and pour it on the ground–everything around it dies. It is in a lot of weed killers. It is used to clarify swimming pools when the water turns green and takes just a small amount.
        Why would anybody want to put it in food?

  11. Tim

    I’m really glad this has been illuminated.
    I just wanted to mention that years ago I purchased 500 grams of copper sulfate from a well known chemical company.
    As an inventor, my use of this compound was for electroplating experiments and not food.
    It was delivered to my buisness by UPS and there was an additional charge for handling. About $10 in 90’s USD Hazardous Material Charge.

    On the actual container of the chemical was a warning label stating that copper sulfate is an environmental pollutant. Yeah….feed this to pets. I can’t say I’m surprised….

  12. Mare

    I just looked on my bag of TOTW and its there! 🙁 how can we find out what brands DO NOT have it? Or will it be in every kibble?

    1. Laura

      I know Farmina’s Grain-Free Wild Herring for cats doesn’t have it. The salmon and trout cat foods from Hound & Gatos also don’t have it. They all have copper proteinate though, which is why I asked my earlier question.

    2. Sage

      My DOG eats ORIJEN ADULT DOG FOOD which has NO COPPER listed as an ingredient. In addition to a raw chicken formula, my CATS eat ORIJEN CAT AND KITTEN which DOES include COPPER PROTEINATE in the ingredients list. I believe Copper Proteinate is a much safer form of copper.

  13. Bethany Cortale

    What about copper carbonate? I just switched my cat to Primal Pet Foods’ dehydrated raw food and it contains copper carbonate.

    1. Susan Thixton Author

      I just don’t know – sorry. But I promise I will investigate this as much as I can and let everyone know.

      1. Leannan

        Thank You

      2. Michelle

        I was just thinking of switching to Primal for my Collies. Not sure if the copper is in their dog foods and will await the results about the different copper additives.

    2. Leannan

      I just spoke with owner of Primal last week. I will contact the head of Customer Service tomorrow, Monday, and ask her to answer that question.

      1. Angeline

        I am the primary Customer Service Rep at Primal, and the owner and myself just wanted to step in for a quick minute with our two cents on the subject of copper carbonate:
        Primal uses a natural supplement that is mined from an ancient mineral deposit in the USA that contains a broad spectrum of over 70 minerals and trace elements. Due to AAFCO protocols, Primal was instructed to list the naturally occurring copper as Copper Carbonate on our current packaging.

        If you’re at all concerned what this means for the food and your pet’s health, we make the copper contents of each of our foods (which we test for) available in the Products section of our website, the first page for which of the Raw Frozen Canine Formulas can be found online at

  14. Debi Cohen

    Found this on a science page difference between copper Proteinate and copper sulfate.



    Canadian Journal of Animal Science, 1990, 70(3): 895-904, 10.4141/cjas90-108

    Copper (Cu) depleted steers were used to compare copper sulfate and copper proteinate as Cu sources for cattle consuming high molybdenum diets. Two experiments utilizing corn silage and barley concentrate diets with 10 mg added Mo kg−1 DM were undertaken. Experiment A was a 105-d study in which an 83:17 ratio of silage to concentrate was fed, whereas, experiment B was an 84-d study comparing the same Cu treatments for cattle fed a 26:74 (Low) or a 64:36 (High) ratio of silage to concentrate. Cu treatments for both experiments were: no supplemental Cu (0Cu); a dietary supplement of 10 mg Cu kg−1 DM added as copper sulfate (CuSO); and a dietary supplement of 10 mg Cu kg−1 DM added as copper proteinate (CuPro). Both Cu supplements improved (P < 0.05) concentrations of Cu in plasma for both experiments and improved (P < 0.05) concentration of Cu in liver for experiment B. Copper supplementation (P < 0.05) reduced plasma Mo concentrations in experiment A relative to animals receiving no supplemental Cu. Both Cu sources resulted in reduced rumen fluid soluble Mo concentrations. Steers in experiment A had lower initial liver and plasma Cu concentrations than was observed for experiment B. Average daily gains for steers consuming CuPro were 16.8% greater (P < 0.05) than for 0Cu with CuSO being intermediate for experiment A. Results indicate that the bioavailability of Cu from Cu proteinate is similar to that of copper sulfate in-Cu depleted steers consuming diets containing excess Mo. Key words: Cattle, copper sulfate, copper proteinate, copper, molybdenum

    Cited by

    View all 16 citing articles

    1. Sage

      I hope AAFCO isn’t using cattle FEED studies to determine ingredients for cat and dog FOODS. Wish cat and dog food ingredients could be overseen by an entity other than AAFCO – a new organization that is not connected to or overseeing animal FEED requirements.

  15. Abouknight

    Here we are with yet more deaths and illnesses due to commercial pet food. Wake up, it’s a for profit business with little oversite, of course they will cut every corner. I stopped feeding ANY commercial dog food treat or food and my two are happier for it. You can feed a healthy prey- model raw food right at home for only slightly more than a “premium” kibble. I found a yahoo group/ Facebook group for support and to ask questions of. I feed a 60 and a 40 lb dog. 80% meat, 10% edible bone and 10% organ half of which is liver. They are happy, their fur is soft and full, all itch issues are gone (dog food ingredients cause that),their teeth are pearly white with no brushing, their poop is small and MUCH less smelly. Mostly they are happy and energized and not needing to visit the vet constantly. My last dog was on PREMIUM kibble and died of liver disease. He had so many health issues. When I got another dog after his death I started seeing the same issues with her. I switched to raw and all that stopped. I will never feed kibble again. I’m done.

  16. Michelle

    I am so glad for this information and all the articles from Truth about pet food ——and very guilty that we have been feeding Blue Buffalo to our four Collies. We add some supplements ordered by our holistic vet and some meat and veggies so they get less kibble. We had not had problems and my Collie girl had excellent complete blood work results a couple months ago after her senior exam and the others declared healthy at their vet visits. However, recently all of them have loose, tan stools. Blue Buf must have changed something (and made the food worse) as nothing else has changed. We started probiotics, but the issue remains. I have the approved food list and found a store close by that has some of them. Time to pick one and change immediately. I feel like a fool not deciding sooner.

  17. Connie Schwarz

    This is the best article I have found to explain the difference between Copper Sulphate (an inorganic compound) and Copper Proteinate (organic compound). To summarize, copper is an important trace elements for animals. The copper sulphate is poorly absorbed from the stomach and not as easily metabolized. The copper proteinate is copper that is attached to an organic substance…like amino acids or polysaccharides. It is better absorbed, but more easily metabolized. There are so many variables….who established the levels for dogs…should there be variations of the levels within the different breeds, whose testing the levels after they are added…how are they added and by who, etc.

  18. Ian

    susan, would you consider doing an article about raw feeding? I did a google search once to learn about it and was discouraged by the resources I ran across. many posters here say they have found helpful online resources. I would like to learn more about it. if you did an article then readers could chime in their suggestions in the comments? I know you’re busy right now but maybe “someday”…? thanks.

    1. Michelle

      I would like that as well, Ian. I joined a raw feeding group on Facebook hoping to learn ,but after so many posts there showed whole, dead animals thrown on the floor or in the yard for the dogs to tear apart and eat, I am hoping for a better way. Also, the posts that did give some good information were so contradictory, everything someone posted as good raw feeding was challenged, so I was not able to feel comfortable with the information.

      1. Martina

        I joined raw paws at Yahho groups many years ago and they are a great source for info on raw feeding. The moderator has decades of experience when it comes to raw food. The members ( many of which have been with the group for years) are also very good about helping out with questions and concerns.

        1. Michelle

          Thank you, Martina! I will try that group.

  19. Connie Schwarz

    I’m a retired pharmacist/breeder, and trace minerals in SMALL amounts are critical to humans and animal health. While humans get a variety of foods…fruits and vegetables with copper in them…dogs don’t..

    “In an article by Monica Reinagel, M.S., L.D./N, she poses the question, “Are Fruits and Vegetables Getting Less Nutritious”, and tries to separate theory from fact. She points to a study in England that found “calcium content of modern vegetables was about one-fifth lower than what was measured in the 1960s and average copper content declined almost 80%.” A comparative study in the US “found that amounts for a few nutrients like vitamin C, iron, and riboflavin declined somewhat, several were the same, and a few actually increased.”

    I think there needs to be more research to establish SAFE levels of copper proteinate. I wonder if there was initially sound scientific research to establish the current levels of copper. I think copper sulphate should be banned from dog foods, and only Copper Proteinate allowed. Research needs to be done to make sure that the current levels of copper proteinate are safe.

    Sadly the fruits and vegetables that we are eating today are far less nutritious than the ones in the 50’s and 60’s. These critical trace elements are disappearing from our soil. Magnesium is all but non-existent. Here is another good article:

  20. Sasha Fayek

    It is sad to see that companies put profits before morality. Instead of trying to provide nutritious pet food to sustain our beloved animals, they try to get get away with providing sub par food “enriched” with supplements.

    Those things are called trace elements because, well, there should be a trace of it in the food!

    That is why I emphasize supplementing your pets diet by including regular, whole food “supplements” (like liver for example) in your pet’s diet. This prevents nutrient deficiencies and at the same time makes you less dependent on the whims and greed of the pet food manufacturers.

  21. Leannan

    The head of customer service at Primal forwarded my question to the owner and she will respond when she has the information I/we requested. She also thanked us for making them aware of our ‘conversation’.

  22. Leannan

    Primal has posted a comment/reply to an earlier question, and I didn’t want it to get overlooked. Here is the content. Scroll up for the original post/comment.

    January 23, 2015 at 2:23 pm
    I am the primary Customer Service Rep at Primal, and the owner and myself just wanted to step in for a quick minute with our two cents on the subject of copper carbonate:
    Primal uses a natural supplement that is mined from an ancient mineral deposit in the USA that contains a broad spectrum of over 70 minerals and trace elements. Due to AAFCO protocols, Primal was instructed to list the naturally occurring copper as Copper Carbonate on our current packaging.

    If you’re at all concerned what this means for the food and your pet’s health, we make the copper contents of each of our foods (which we test for) available in the Products section of our website, the first page for which of the Raw Frozen Canine Formulas can be found online at

  23. Cocker Lady

    Dr. Jean Dodds made this connection many years ago. You may want to contact her.

  24. Christine

    The one kibble that doesn’t use any synthetic vitamins or minerals is Nature’s Logic.
    They also point out, “The problem is that these un-natural element additives are not merely what they appear to be; innocent supplements. Not only do they pose potential toxicity issues addressed in many scientific studies, they contain many undisclosed processing aids, preservatives and other additives. If you are using a pet food with added vitamins, they will most likely contain other things such as BHT and ethoxyquin as preservatives, rice hulls and corncob as carriers, sodium aluminum as an anti-caking agent, and other processing aids such as gelatin, mineral oil, sucrose, and modified starch. Not exactly what you want to be feeding your pet.

    The natural alternative is Nature’s Logic. We do it with 100% natural, whole foods. We have no need to use these chemical vitamin and mineral supplements. Our adequacy comes from formulating with enough wholesome and nutritious whole foods, which supply all needed nutrients for pets without the use synthetic elements using all these other additives and processing aids. Doing it with food as nature designed is the logic behind Nature’s Logic.”
    They also say, “As far as toxicity, one has to use at one’s own risk or at the risk of their pet, products that are supplemented with synthetics. The experts admit they may or may not have determined what the upper safety levels of these elements are. They also admit that it may represent a virtually unexplored area when two or more synthetic mineral elements are present at high levels. There happens to be up to twelve of these synthetic mineral elements added to pet food, not just two.”
    I myself only feed commercially made raw foods with no synthetics, but I often point my customers in the direction of Nature’s Logic due to their commitment to no synthetics or hidden ingredients (like MSG added in the form of hydrolyzation of proteins)

    1. Michelle

      But Nature’s Logic uses chicken MEAL, beef MEAL etc. in the kibble. So much info states not to feed anything with meat MEAL as an ingredient. The rest of their ingredients or lack of the other bad stuff seems good though.

  25. kali

    Besides Nature’s Logic, Carna4 is another “kibble” that does not use synthetic vitamins or minerals. It is also gently oven baked, and uses only fresh meats (no meals).

    1. Michelle

      I went on Nature’s Logic web site and checked the kibble ingredients. They contain Chicken MEAL Beef MEAL etc.

  26. Jude

    My 8-y.o. female Rottweiler has just been diagnosed with liver disease. Her dog food contains copper sulfate. Should I explore this with my vet? I am just sick about this.

    1. Susan Thixton Author

      Yes – and you might want to ask your vet to get in touch with Dr. VanVranken of this article (the original). I’ve spoke with him and he’s a really nice guy trying to do the right thing. He might have some good treatment options for you/your vet.

  27. matt brasket

    My Doberman has CAH. Was prescribed Hills Hepatic food which has 4.5mg copper (compared to 8-22mg in other commerical foods) I’ve been feeding him raw diet which probably has about the same as Hills but cost about the same and I’m sure is better for him than Hills, have you seen the ingredients? It’s crap dog food $100 for 25 odd lbs. I wish there was a high quality commercial food without added copper. has anybody found any?

  28. Christine Hubbard

    Hi all I know this thread is old and I’m not sure if anyone is still following but u wanted to let you know my kitty was diagnosed with copper accumulation recently. I know it’s rare but wanted to point out yes it does happen to cats. Cornell university Dr Sharon Center indicated he has copper accumulation , cholangiigeptits and chronic lymphoplamacytic with ductopemia.

  29. PS Harris

    What happened to the copper sulphate issue

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