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,
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