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The Hidden Danger in Your Pet’s Food Bowl

Known to cause acute toxic illness and cancer in animals and humans, and considered among the most carcinogenic substances on the planet. Cats and dogs are more sensitive to this than many other animals.

aflatoxin contamination in pet food


  • If you buy ultraprocessed pet food for your dog or cat, you’re actually buying animal feed by another name; it’s important to know the difference between feed and food, especially when it comes to contaminants like aflatoxins
  • Aflatoxin contamination has been the cause of many major disease outbreaks and pet food/feed recalls over the last 20+ years, and are known to cause acute toxic illness and cancer in both animals and humans
  • The five pet food/feed ingredients most like to be contaminated by aflatoxins: corn, peanuts, cottonseed meal, tree nuts, and oilseeds
  • Aflatoxicosis is chiefly a disease of the liver, causing gastrointestinal (GI) symptoms, reproductive issues, anemia, and jaundice
  • Additional “unavoidable” contaminants in pet food/feed: arsenic, mercury, PCBs, BPA, dioxins

The ultraprocessed pet food industry is actually in the business of selling feed, not food. It’s important to understand the difference between the two.

Susan Thixton of Truth About Pet Food points out that with the exception of dogs and cats, human-provided nourishment for almost every other species is called “feed,” e.g., horse feed, cattle feed, poultry feed, etc. But for some reason, when it comes to animal companions, it’s called “food.”

“Food is what humans eat, so perhaps the intent was — from the very beginning — to cause the consumer to think pet food is similar to human food — nothing like a cattle feed or poultry feed,” writes Thixton. “We want to provide our pets a safer, more quality ‘food’… right? Here begins the problem for the consumer.”1

Thixton explains that it wasn’t until the late 1950’s that the American Association of Feed Control Officials (AAFCO), the organization that develops pet food/animal feed ingredient definitions, regulations, and labeling requirements, established the Pet Food Committee. But despite setting up a separate regulatory group, AAFCO has always and continues to view pet food as simply a “specialty product” of animal feed — not different in any significant way.

For more information on the differences between feed and food, including the contaminants that are allowed in feed for animals (including pets), but not food for humans, check out Susan’s page linked above.

About Those Contaminants

Now that you’re aware that most ultraprocessed pet food is actually feed, let’s take a look at a recent headline in a pet food industry journal:

“How to deal with feed ingredients prone to aflatoxin contamination: Find out which animal feed ingredients are more prone to aflatoxin contamination, when the risk of contamination is higher and strategies to mitigate its effects on animals.”2

Aflatoxin contamination has been the reason behind a number of regional pet food recalls and several major disease outbreaks over the past 20+ years. Aflatoxins are naturally occurring mycotoxins produced by the Aspergillus flavus and Aspergillus parasiticus fungi and are the most extensively researched mycotoxins in the world.

Aflatoxins are known to cause acute toxic illness and cancer in animals and humans and are considered among the most carcinogenic substances on the planet. Cats and dogs are more sensitive to aflatoxins than many other animals.

Aflatoxins frequently contaminate agricultural crops before they are harvested. Conditions that promote pre-harvest contamination include high temperatures, prolonged periods of drought, and insect activity. Aflatoxins can also be a problem after harvesting if the crop stays wet for too long. And they can grow on stored crops if the moisture level is too high and mold develops.

The pet food industry journal article lists five animal feed ingredients that are susceptible to aflatoxin contamination:3

  1. Corn can be easily contaminated by mycotoxins and especially aflatoxins. The risk is even higher in warm and humid climates. Aflatoxins proliferate on corn when it is exposed to moisture and stored improperly.
  2. Peanuts are also highly susceptible to aflatoxin contamination, as they are often grown in conditions conducive to mold growth. Aflatoxins can accumulate on raw peanuts and peanut meal used in animal feed.
  3. Cottonseed meal can be contaminated with aflatoxins during the harvesting and storage processes. As a large part of cottonseeds are used in dairy nutrition, care should be taken to avoid their transfer to milk.
  4. Tree nuts (almonds, walnuts, and pistachios) are at risk of aflatoxin contamination, particularly if they come into contact with moisture. These are not fed to animals, but byproducts are infrequently found in animal feeds, often at high quantities (locally).
  5. Oilseeds such as sunflower, rapeseed and soybeans, can become contaminated with aflatoxins under the right conditions.

It’s worth noting that aflatoxicosis is more common in dogs than cats because commercial dog food formulas more often contain corn products.

As of the end of January 2021, 110 pets in the U.S. had died and another 210 had been sickened from apparently lethal levels of aflatoxins in Sportmix brand dog or cat food produced by Midwestern Pet Foods based in Evansville, IN. The aflatoxin contamination is presumably confined to corn products in Midwestern’s Oklahoma plant.4 The contaminated foods may also have been shipped to 35 other nations around the globe.

Symptoms to Watch for and Pet Feed Ingredients to Avoid

Aflatoxicosis is chiefly a disease of the liver, causing gastrointestinal (GI) symptoms, reproductive issues, anemia, and jaundice. Certain types of aflatoxins are linked to cancer in animals.

If your dog or cat ingests food contaminated with aflatoxins, you can anticipate one or more of the following symptoms:

  • Severe, persistent vomiting
  • Sluggishness
  • Bloody diarrhea
  • Discolored urine
  • Lack of appetite
  • Jaundice, especially around the whites of the eyes, gum, and belly
  • Fever

If you think your pet has eaten potentially contaminated food, even if he’s showing no symptoms of illness, get him to your veterinarian or an emergency vet clinic as soon as possible. And bring the food with you.

I recommend that pets exposed to aflatoxins receive ozone therapy, hyperbaric oxygen treatments, intravenous (IV) vitamin C and oral glutathione, chlorella, and charcoal, all of which help to naturally detoxify the body and assist in cellular repair.

If you feed kibble to your pet (which I only recommend if you cannot afford a better quality food), be sure to study the ingredient list carefully and avoid brands containing grains or corn in any form, including corn gluten meal, whole grain corn, corn flour, etc.

Along with the increased risk of aflatoxin contamination, corn is a notoriously allergenic food that is difficult for many animals to digest. Also avoid formulas containing cereal grains like maize, sorghum, pearl millet, rice, and wheat.

Many inexpensive, low quality pet foods rely heavily on all these ingredients. Many treats also contain these ingredients, including organic “cookies” (made from organic whole wheat or rice), which are an under-represented potential source of toxicosis, in my opinion.

Inevitable, ‘Unavoidable’ Pet Food Contaminants

The ultraprocessed pet food industry admits that unwanted toxins inevitably make their way into dog, cat, and other pet foods, and “some level of contamination is unavoidable.” The list of “ingredients and substances” pet food manufacturers should try to avoid includes “arsenic, mercury, PCB, BPA, dioxin and aflatoxin.”5

Needless to say, among the many reasons to seriously consider switching from ultraprocessed diets to fresh food for furry family members, unwanted toxins are high up the list. We’ve examined aflatoxins — now let’s take a closer look at the remaining five inevitable and “unavoidable” contaminants.

  1. Arsenic — Arsenic is a heavy metal mineral. Inorganic arsenic is often found in products like herbicides, insecticides, wood preservatives, and some types of insulation. Organic arsenic is used in certain drugs to treat or prevent blood parasites, including heartworm.

    In some cases of poisoning in pets, an animal inadvertently ingests a product containing arsenic that is lying around. However more commonly, sublethal doses are consistently consumed, and toxicity occurs slowly, over a long period of time (such as when a dog or cat eats grass that is regularly treated with herbicides containing arsenic).

    The main source of arsenic exposure is from conventionally raised (nonorganic), factory farmed chickens. Arsenic is added to commercial chicken feed to inhibit mold and fungi in many countries, and it’s passed up the food chain.
  2. Mercury — Mercury is a naturally occurring substance, but it’s toxic, nonetheless. It’s released into the air and the oceans primarily though burning coal. Seafood is the most common route of exposure for both people and pets. Studies have revealed high levels of mercury in both dog and cat food.

    To limit your pet’s exposure to mercury, my advice is to be very choosy about the fish you feed, and I certainly don't recommend feeding an exclusive diet of fish protein to dogs or cats (unless you’re making your pet’s food and choosing low-contaminant seafood). However, fish are a rich source of omega-3 fatty acids, which are essential to your pet's well-being. If you supplement with fish, I suggest using sardines packed in water. Sardines don't live long enough to store toxins in their bodies, and they're a terrific source of omega-3s.

    If you choose not to feed any fish, I recommend you supplement your pet's diet with krill oil or another omega-3 fatty acid that’s been third-party validated as contaminant-free and sustainably sourced.
  3. PCBs (Polychlorinated Biphenyl) — Fish-flavored pet food has also been found to contain PCBs. Dr. Jean Hofve of Little Big Cat explains how this occurs:

    “New research suggests that cats are especially sensitive to PBDEs (which, among other things, are used as fire retardants in carpeting and furniture), chemicals found at higher levels in both canned and dry cat foods than dog foods; and more in dry than canned cat foods.

    Fish-based foods are even worse, because marine organisms produce PDBEs naturally and can bioaccumulate up the food chain to high levels in fish; this compounds the exposure cats get from fabrics and dust.

    Predatory fish at the top of the food chain, such as tuna and salmon, may contain very elevated levels of heavy metals (including mercury) as well as PCBs, pesticides, and other toxins.

    Tilefish (listed on pet food labels as 'ocean whitefish') are among the worst contaminated, along with king mackerel, shark, and swordfish.

    Recent research found high levels of PCBs in dry and canned pet foods. Scientists also found that cats retain PCB metabolites in their blood longer than dogs.”6

  4. BPA (Bisphenol A) — Bisphenol A is an industrial chemical found in a wide range of household products that affect everyone in the home, including hard plastic water and baby bottles, and plastic pet food and water bowls. It's also found in the epoxy resins used as coatings inside food and drink cans, including pet food containers.

    BPA has the ability to imitate the body's hormones, especially estrogen, in ways that are damaging to the health of both humans and animals. For most animals, including humans, exposure to BPA occurs primarily through diet. A 2017 study conducted by researchers at the University of Missouri concluded that even a short-term (two week) feeding of canned dog food results in a significant increase (three-fold) of BPA in dogs.

    To protect your whole family from BPA exposure, avoid canned foods and don't store food in No. 7 plastics (you can find a chart of plastic types here). You can provide ongoing BPA detoxification support by offering foods rich in Lactobacillus acidophilus (kefir and yogurt)7 and glutathione-rich foods (including culinary and medicinal mushrooms).8
  5. Dioxins — Dioxins are created during many industrial processes when chlorine or bromine are burned in the presence of carbon and oxygen. These environmental pollutants can disrupt the delicate signaling of both male and female sex hormones in the body.

    Unfortunately, dioxins are found in much of the U.S. food supply. Factory-produced meat, fish, milk, eggs, and butter are the products most likely to be contaminated, so offer your pets (and yourself) as much organic food as possible.

Does Your Pet Need a Detoxification Program?

The world is becoming more polluted every day, and while we can’t control all points of chemical exposure for our family members, we need to do what we can to reduce known risks.

Switching to nontoxic home and garden products, filtering the air and water in your home, and minimizing the chemicals you choose to put on and, in your pets, will cut down on tag-along contaminants.

The only way to know exactly what you are feeding your pet is to buy the ingredients yourself and prepare nutritionally complete meals at home (Meal Mix for Dogs makes this easy!). If you choose to support a pet food company, knowing if human-grade ingredients are used and what quality control steps are in place for contaminant testing will bring you peace of mind (or send you looking for another pet food company to support).

Your pet's ability to clear accumulated toxins is based on the overall functioning of detoxification pathways. If those pathways aren't working as they should, detoxification systems become stressed or completely overwhelmed. Fortunately, there are many ways you can assist your pet's detoxification mechanisms to help them function optimally: 10 Ways to Help Your Pet's Body Detoxify.

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