Cat and Dog Nutrition--the Thiamine Issue

Thamine (vitamin B1) deficiency in pet foods is an issue of clinical importance and in spite of proclaimed advances in the science of pet food nutrition and ingredient formulation, there have been five major pet food recalls since 2009 in the United States because of thiamine deficiency, several cats developing clinical signs of deficiency disease. Two recent articles published in the Journal of the American Veterinary Medical Association ( 1&2) highlight this issue which cannot be simply fixed by manufacturers adding more thiamine supplement to their products.

On March 10th 2013, Diamond Pet Foods posted that it is voluntarily recalling limited production codes of Premium Edge Finicky Adult Cat Formula dry cat food, Premium Edge Senior Cat Hairball Management Formula dry cat food, Premium Edge Kitten Formula dry cat food, Diamond Naturals Kitten Formula dry cat food and 4health All Life Stages Cat Formula dry cat food. Tests conducted by the company indicated the products might have a low level of thiamine. There have been other cat food recalls for canned as well as dry foods by other vigilant companies because of thiamine deficiency, but none to my knowledge with commercial raw meat-based cat foods. Thiamine is essential for cats in maintaining normal nervous system function.

Symptoms of thiamine deficiency displayed by an affected cat can be gastrointestinal or neurological in nature. Early signs of thiamine deficiency may include decreased appetite, salivation, vomiting and weight loss. In advanced cases, neurological signs can develop, which may include ventriflexion (bending towards the floor) of the neck, wobbly walking, falling, circling and seizures.

Veterinarian Elizabeth Katz (3) notes that “thiamine is a water soluble B vitamin important for helping the body to utilize carbohydrates as energy through a process called the TCA cycle. Thiamine is a necessary cofactor involved in this energy producing process…..Thiamine is naturally found in various food sources some of which include whole grains and vegetables, legumes, and brewer’s yeast. But, it is also present in muscle tissue of animals, particularly in the liver and heart. The mere presence of thiamine in a food may not correlate with its activity or bioavailability. Several factors may affect the bioavailability and/or activity of thiamine in processed foods. As much as 50% to 100% of the thiamine present in raw meat can be inactivated by one or more of the following processing methods: heat, high amounts of sulfur based food preservatives, i.e. sulfur dioxide, and certain thickening additives in canned foods which may alter the pH of the food…. Raw meat diets are not exposed to heat as canned and dry diets are, therefore the thiamine in these diets remains intact. These diets also do not use any of the additives or preservatives used in canned foods.”

Many seafood products contain thiaminase which destroys thiamine, cod and salmon being two exceptions. A high corn/grain diet calls for more thiamine. Thiamine is often prescribed for human patients with diabetes Type 2 and progressive kidney disease, these being common health issues in the cat population today being fed (as well as their mothers) on thiamine-compromising diets which may play a role in the genesis of feline diabetes and chronic renal failure. The major pet food companies continue to include corn and grain ingredients—primarily human food and beverage industry byproducts such as corn meal, corn gluten meal and brewer’s grains which are also included in the diets of factory farmed animals. A review article on the dietary hazards of corn and grain byproducts to farmed animals (4) raises several red flags for farmed animal health and by association, the health of cats and dogs whose diets include such co-products from the ethanol, high fructose and brewing industries. Notably, the high sulfur levels in corn byproduct can cause brain disease with polioencephalomalacia developing in calves fed high levels of corn gluten. Sulfur converts into sulfide which can alter the bacterial content in the ruminant’s digestive system increasing the numbers of those that produce thiaminase and destroy thiamine. Both corn gluten meal and brewer’s grains are high in sulfur and also phosphate, which these authors stress is a significant animal waste environmental management problem and a serious (aquatic) contamination concern. Do high phosphate levels contribute to kidney disease in cats and other species that benefit from prescribed phosphate binders?

An article published in Australia (5) reported: “Some pet food suppliers treat products with high levels of sulfur dioxide to preserve the meat and to disguise signs of putrification (sic). But vets are calling for tough rules to limit the amount of chemicals used because it is proven to cause thiamine deficiency and lead to neurological problems. Dr Anne Fawcett, companion animal veterinarian at the University of Sydney’s Faculty of Vet Science, treated a thiamine deficient cat fed exclusively on supermarket bought kangaroo meat packaged for pets. The food was tested and found to have concentrations of sulphur dioxide almost double that allowed for human consumption. Sulphur dioxide is a known cause of thiamine deficiency in humans and animals. “In this day and age, with the knowledge that pet food manufacturers have, this is an entirely preventable condition,” Dr Fawcett said.

Susan Thixton ( wrote to the FDA about this concern and posted their reply which included the following pertinent information:

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).

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.”

It is surely clear that the rotting, disease- condemned and contaminated meats that go in to many pet foods are treated with these preservatives that put animals at risk. Additional concerns that I have about the inclusion of corn in pet foods are based on the evidence that I have compiled about the health risks of genetically engineered/modified (GMO) corn and also GMO soy (see special report posted on, significant quantities of which continue to be included in many cat and dog foods and which (along with peas and pea fiber now also being put in to pet foods) are high in phytoestrogens. Such ingredients, which have no place in a carnivore-cat diet, also contain high levels of phytases. These bind and prevent the absorption of essential minerals, a concern compounded by evidence that such essential minerals, that play many vital roles in enzyme and neurologic function as well as skeletal and muscle and organ maintenance, are actually deficient in GMO crops.

The diet related health problems in cats and dogs today, as documented by myself and two other veterinarians ( Marion E. Smart a professor of animal nutrition and Elizabeth Hodgkins, former director of technical affairs with Hill’s Pet Nutrition) in NOT FIT FOR A DOG: THE TRUTH ABOUT MANUFACTURED CAT & DOG FOODS (6) cast a shadow across the veterinary profession that has been deeply influenced by the multinational pet food companies which are a subsidiary of the now global industrial agribusiness industry. This shadow affects all of us who depend upon this food-chain for our own sustenance, much of it being unethically subsidized by our government from our tax dollars which indirectly feed the coffers of an increasingly dysfunctional health care system, as I describe in my recent book HEALING ANIMALS & THE VISION OF ONE HEALTH (7). Our dogs and cats have become the modern-day canaries in the mine-shaft alerting us, in the health problems they manifest, to hazards in our shared environment which includes the food system in which they and most of us still participate outside of the expanding umbrella of organically certified whole foods. We should all get under that umbrella, and there are several pet food manufacturers now getting under it, which as a veterinarian I applaud.


  1. Jessica.E.Markovich et al (2013) Thiamine deficiency in dogs and cats, JAVMA Vol. 243: 649—666
  2. Jessica E. Markovich et al (2014) JAVMA Analysis of thiamine concentrations in commercial canned foods formulated for cats, Vol.244: 175-179
  3. Elizabeth Katz (2014) Thiamine in a Raw Meat Diet posted on
  4. K.D.Raush and R.L.Belyea, (2006) The Future of Coproducts from Corn Processing Applied Biochemistry & Biotechnology, 128: 47-86
  5. Editorial (2014) PETS are being poisoned by dangerous levels of preservatives in commercial pet food that can leave dogs and cats with brain damage, veterinarians have warned, posted on May 11th/14 at
  6. M.W.Fox et al ( 2009) Not Fit for a Dog: The Truth About Manufactured cat & Dog Foods. Fresno CA Quill Driver Books
  7. M.W.Fox ( 2011) Healing Animals & The Vision of One Health. CreatSpace/