Pet Food Ingredients

Science in Australia Concerning to Pet Owners in the US

Some recent pet food information out of Australia has some concerns for pet foods in the U.S. Sulphite preservatives used in pet foods causing “thiamine deficiency and lead to neurological problems.”


“In this day and age, with the knowledge that pet food manufacturers have, this is an entirely preventable condition,” said Dr Anne Fawcett, companion animal veterinarian at the University of Sydney’s Faculty of Veterinary Science.

“Sulphite preservatives are added to some pet meats, sometimes at very high levels, to mask the signs of putrefaction, giving it a longer shelf life – but long-term consumption endangers the wellbeing of our pets,” Dr Fawcett is lead author of an article on the issue, recently published in the Australian Veterinary Practitioner.

The article highlights a case of thiamine deficiency in a cat treated at the University of Sydney. The cat was exclusively fed a commercial, kangaroo meat pet food purchased from a supermarket. The food was tested and demonstrated high concentrations of sulfur dioxide, a known cause of thiamine deficiency in cats.


“Sulphite preservatives continue to be found in some pet foods at harmful concentrations. We need to ensure that the levels of these preservatives in all pet foods are regulated,” Dr Fawcett said.

“Until there is a change in the way pet meat is regulated, I would only feed my pets human grade meat.”

Questions were sent to FDA regarding sulphite preservatives in U.S. pet foods (based on the Australian findings).  Below is FDA’s response.

Dear Ms. Thixton:

We are responding to your e-mail of May 1, 2014 in which you ask several questions about sulphite (or sulfite) preservatives and their use in pet food products. In our response we will copy each of your questions and then provide the answer to the question.

You asked: “What are the names of various sulphite preservatives?”

The sulfite preservatives permitted in food for animals, including pet foods, are potassium bisulfite, potassium metabisulfite, sodium bisulfite, sodium metabisulfite, sodium sulfite, and sulfur dioxide. The table below lists the regulations for these substances pertinent to animal food that appear in Title 21 of the Code of Federal Regulations (21 CFR).

Name of Preservative Animal Food Regulation in Title 21 Code of Federal Regulations Conditions of use
Potassium bisulfite 582.3616 These substances are generally recognized as safe when used in accordance with good manufacturing or feeding practice, except that they are not to be used in meats or in food recognized as a source of vitamin B1 (thiamine)
Potassium metabisulfite 582.3637
Sodium bisulfite 582.3739
Sodium metabisulfite 582.3766
Sodium sulfite 582.3798
Sulfur dioxide 582.3862

You asked: “[…] what would consumers look for on the label if they wanted to avoid pet foods using sulphite preservatives?” and “Would any of these preservatives be used and not listed on the label?”

When any of these preservatives are used in any animal food, a statement such as “preserved with sulfur dioxide” or “sodium sulfite (a preservative)” has to be in the list of ingredients on the label of the product. Therefore, if one of the sulfite preservatives is added by the manufacturer of an animal food product, the consumer should be alerted to the presence of the preservative when they look at the listing of the ingredients.

There are a few allowed exemptions from the requirement to declare an ingredient in the ingredients list on a product label when the product is made from two or more ingredients. These exemptions are very narrow and the pertinent regulation is Part 501.100(a)(3) in 21 CFR. These substances are the incidental additives. To be an incidental additive, the amount of the additive in the product must be at insignificant levels and the additive cannot have any technical or functional effect in the food. Thus, the only way a manufacturer would not have to declare a sulfite preservative in the ingredients list of a product would be if the sulfite preservative was present in the product by reason of having been incorporated into the product as part of another ingredient, in which the sulfite did have a preservative effect, but in the final or finished product the sulfite no longer has a preservative or other technical effect.

As indicated in the various regulations, sulfite preservatives should not be used in meats or food recognized as being a source of vitamin B1 (thiamine or thiamin). The reason is that sulfite preservatives are known to destroy vitamin B1 and vitamin B1 is an essential nutrient that participates in many biochemical pathways in the human and animal body. It is a water soluble vitamin, of which the body does not store significant reserves; therefore, regular dietary intake is very important. Because sulfite preservatives destroy thiamine, sulfite preservatives should not be used in pet foods that are marketed as being complete and balanced or that have thiamine (thiamine hydrochloride, thiamine mononitrate) in their list of ingredients.

We hope this response provides answers to your questions.


Though I haven’t found it (since receiving this response from FDA), I am confident I have seen the ingredient sodium bisulfite on many pet food labels. Should anyone out there find a pet food that includes this ingredient (or any of the others listed above) – please post a link to that pet food below in comments and I will send that to FDA with more questions.

Clinical signs of thiamine deficiency vary between dogs and cats, with more consistent and recognizable signs in cats. Early signs of thiamine deficiency include vomiting, diarrhea, loss of appetite and depression. As the condition progresses, signs may include impaired vision, a wobbly gait, head tilt or seizures. In some cases, affected animals develop a cardiac syndrome and die suddenly.


Wishing you and your pet(s) the best,

Susan Thixton
Pet Food Safety Advocate
Author Buyer Beware, Co-Author Dinner PAWsible
Association for Truth in Pet Food

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Clinical signs of thiamine deficiency vary between dogs and cats, with more consistent and recognisable signs in cats. Early signs of thiamine deficiency include vomiting, diarrhoea, loss of appetite and depression. As the condition progresses, signs may include impaired vision, a wobbly gait, head tilt or seizures. In some cases, affected animals develop a cardiac syndrome and die suddenly.

Read more at:

Clinical signs of thiamine deficiency vary between dogs and cats, with more consistent and recognisable signs in cats. Early signs of thiamine deficiency include vomiting, diarrhoea, loss of appetite and depression. As the condition progresses, signs may include impaired vision, a wobbly gait, head tilt or seizures. In some cases, affected animals develop a cardiac syndrome and die suddenly.

Read more at:

May 12, 2014

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21 COMMENTS ON THIS POST To “Science in Australia Concerning to Pet Owners in the US”

  1. Wolf says:

    does sodium bisulfate have a direct relationship to menadione sodium bisulfate (synthetic Vit K)? That is, of course, in all kinds of foods…

    • Susan Thixton says:

      No – my understanding is that it does not. Menadione is the synthetic vitamin K – sodium bisulfite is the preservative. Though it would be great if a vet or manufacturer could weigh in on this and provide a full understanding for all of us.

    • devonne johnson says:

      Ok I buy fussie cat and the label says it has SULPHATES not Sulphites…am I ok?

  2. Dori says:

    Both Alpo and Beneful contain menadione sodium bisulfite. I’m sure other low quality foods probably do also. I just came across those two for examples.

  3. Jessica says:

    Susan, if it turns out to be the same…
    All 3 flavors of the naturals and other crunchy treats I looked at have it. As well as some of the foods.
    Maybe that is how they get away with it? I noticed that these have ethoxyquin and they don’t have it.

  4. Marsha says:

    I do not find any of this in Earthborn Holistic Dog Food, Coastal Catch.
    Do they have to list it?

  5. Casey says:

    It’s my understanding that the AU pet foods affected were “meat minces” – ground raw meats intended for pets sold in the freezer section.

    But from a labeling standpoint, if a manufacturer purchased meat that had already had sulphites added, would they have to list that on the label? I don’t think that they do because they (the manufacturer) didn’t add it in.

    • Dori says:

      You bring up a very interesting point. Also a frightening one because I think you’re absolutely correct in your thinking.

  6. Diane Allen says:

    Interesting. I don’t know much about Vitamins, so looked up Vit. B1. It is mostly found in whole grains and some leafy green vegetables. Since most commercial dog food (not MY choice!) contains only “fragments” of grains, perhaps the sulfite preservatives (yech) really don’t have much impact on the thiamine levels. All the more reason to feed homemade….

  7. Cindy says:

    Purina One contains menadione sodium bisulfite complex (source of Vitamin K activity) according to their website at

  8. Nic D says:

    SUSAN, I did a quick search. The following pet products contain “sodium metabisulfite”: Pro-Pet Premium Dog Biscuits (, Milk-Bone Original Biscuits (, Champion Breed Cat Food Shredded Turkey & Cheese Dinner in Gravy (, Beefeaters Sweet Potato Snacks for Dogs (, Pedogree Breathbuster Dog Treat ( I did not find much on any of the other listed sulphite preservatives.

  9. ellie says:

    It is very sad but most consumers have no idea of the possibility of a harmful substance possibly lurking in their pet food.

  10. Christine says:

    Thiamine in some canned cat foods may be too low.
    This is worrying because my family agrees with information on and only feel low carb foods. We don’t want any more urinary issues and must prevent our rescued diabetic cat from coming out of remission.

    “Researchers at the Cummings School of Veterinary Medicine at Tufts University noted that five U.S. Food and Drug Administration voluntary recalls of commercial cat foods due to low levels of thiamine have been made in the past five years. This prompted them to measure thiamine concentration in commercial canned cat foods and determine effects of flavor (fish vs. moonfish), texture (‘pate’ vs. ‘non-pate’), country of manufacture, and company size on thiamine concentration. An additional low thiamine level recall was made during the publication process, bringing the total number of recalls to six in the past five years. The researchers analyzed 90 non-therapeutic canned cat foods (one fish and one non-fish flavor) from 45 brands.

    Thiamine levels were below minimum requirement set by the Association of American Feed Control Officials in 12 of 90 (13.3%) foods and below minimum recommended allowance of the National Research Council in 14 of 90 (15.6%) foods. ‘Pate’ foods had significantly lower thiamine level than ‘non-pate’ foods, and smaller companies (less than $1,000,000 in retail sales) had significantly lower thiamine levels than larger companies (more than $2,000,000 retail in sales). Neither fish or non-fish flavor nor country of manufacture had a significant effect on thiamine level. Thiamine concentrations were found over a wide range in the foods evaluated. The researchers concluded that pet food companies should strive to measure and limit thiamine loss during processing and implement strict quality control practices. In addition, veterinarians should consider thiamine deficiency in cats presenting with acute neurologic dysfunction, especially with accompanying gastrointestinal signs. [GO]”

    Reported on the WINN Feline Foundation blog,

  11. Anna-Bella says:

    Dear Susan and fellow passionate dog lovers
    I live in Melbourne, Australia. I have already had some correspondence with Susan.
    Given this blog is related to “Australia”, I would like to know if anyone who subscribes to Susan’s information is from Australia, and if so, apart from what Susan advocates in her books, what Australian products do you feed your dogs?
    Susan – Not sure if appropriate to ask here, but I’m not sure if you’re familiar with VETS ALL NATURAL, an Australian line of products. Here is the website! Any advice would be wonderful!!
    Many thanks

  12. Linda Muir says:

    I have a female tortie cat who is 15. She has always been the size of a 4 month old kitten….(7 lbs or so)
    Before I discovered Susan Thixton, she ate all the so called good foods, which as I know now are junk. The ones you buy at the supermarket.

    She has had kidney disease for several years, and the only way she has survived and even thrived is by administering subcu fluids every day (God bless my husband) She will eat a few portions of cat food every day, but prefers plain cooked minced chicken. She has been on a diet of Fussie Cat, but not exclusively. I see the culprit might be: Menadione Sodium Bisulfite Complex. What do you think about that? Fussie Cat also contains Carrageenan.
    Maggie has a wobbly gait, is blind and deaf, and has her own space, away from the big kitties. She manages to use her litter box, drinks water, eats high end canned food, and must have a big heart. She is a survivor. But where did all her health problems come from?……….all those years when I was not informed nor did I do research, and did not know about Susan Thixton. Thank God, we haven’t lost her!

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