Aflatoxin Poisoning In Dogs

cancer causing aflatoxins

In 2014, some testing of dry pet food revealed dangerous facts about the food your dog or cat may be eating.

The Consumer Council of Hong Kong published the results of testing performed on nearly 40 popular pet foods. The results were a shock to many pet owners. Three popular US food manufacturers, Purina, Hill’s and AvoDerm, all had foods that were found to contain cancer causing aflatoxins (aflatoxin B1). (The Hill’s food tested was cat food.)

Aflatoxin poisoning in dogs is a serious risk, so you need to know more about aflatoxins in dog food.

How Do Aflatoxins Get In Dog Food?

Grains such as corn, wheat, and rice, as well as nuts and legumes, are often contaminated with molds. This may be due to poor growing conditions and substandard or extended storage. Molds called aflatoxins can easily grow from the mold Aspergillus flavus … and these produce a very potent carcinogen. Aflatoxins are very stable and even the high temperature processing involved in kibble manufacturing won’t destroy them, leaving little protection for any dog eating that food.

Purina confirmed this in a statement to the South China Morning Post. They stated that cancer causing aflatoxins were an “unavoidable natural contaminant.” AvoDerm stated that they have since removed the corn from its formula as they believed it was the source of the aflatoxins.

Corn has become a major source of aflatoxin. Droughts in the US Midwest in recent years have caused a record amount of mold-infested crops amounting to nearly $75 million in insurance claims. In response to this surplus of corn that wasn’t safe for human consumption, the FDA increased the allowable amount of aflatoxin permitted in animal feed.

History Of Aflatoxin Dog Food Recalls

The pet food industry is no stranger to dog food recalls due to these molds. The earliest documented aflatoxin outbreak was in 1974 when hundreds of stray dogs in India died after eating aflatoxin-contaminated corn. In 1998, 55 dogs died of contaminated corn and in December 2005, over 100 dogs were killed from aflatoxin-contaminated pet food in the US. According to Cornell University, about two-thirds of dogs who ate the tainted foods died.

More recently, in September 2020, Sunshine Mills recalled some pet foods after a sample was found to contain an unsafe level of aflatoxins. And in December 2020, the FDA issued warnings about potentially fatal levels of aflatoxins in several foods made by Midwestern Pet Foods, Inc. These foods were recalled but caused at least 28 deaths and 8 illnesses in dogs.

Aflatoxin Tests

After the 2005 poisonings, Cornell University’s College of Veterinary Medicine adapted new screening tests to measure aflatoxin poisoning. Vets around the country can send blood and liver samples for testing. Cornell will also test foods for contamination, and conducts post-mortems to look for evidence of toxicity.

Testing in the US also shows that apart from the dog food recalls due to high levels of aflatoxins, nearly every pet food on the market contains aflatoxins or other mold-related mycotoxins. The animal health and nutrition company Alltech analyzed 965 pet food samples and found 98% of them were contaminated with one or more mycotoxins, while 93% contained two or more mycotoxins.

Even grain-free pet foods still contain a high carbohydrate content from legumes. This means there is still potential for mold spores to contaminate the kibble during storage … especially if it’s exposed to a moist environment. This can even happen in your home if your kibble is stored in a moist basement or an open container.

Symptoms Of Aflatoxin Poisoning In Dogs

Aflatoxins mainly affect the liver. Dogs who eat 0.5 to 1 mg aflatoxin per kg of body weight can die within days. Smaller amounts of aflatoxins, like those found in most pet food samples, can cause sub-acute symptoms including…

  • Weight loss
  • Lethargy
  • Vomiting
  • Diarrhea
  • Jaundice (yellow eyes, gums or skin)
  • Unexplained bruising or bleeding
  • Diarrhea

Aflatoxin poisoning in dogs can cause death, so if you see some of these symptoms in your dog, get to your vet right away.

Aflatoxins are also carcinogenic. They bind with DNA and cause cell mutations. Newberne and Wogan (1968) were able to produce malignant tumors in rats with less than 1 mg of aflatoxin per kg of feed.

Because eating small amounts of aflatoxins over time will cause cumulative liver damage or cancerous tumors, food may not be recognized as the cause. This means aflatoxin poisoning is likely under-reported.

RELATED: Read more about how mold exposure can affect your dog …

Other Toxins In Pet Foods

The Consumer Council study also found some other alarming trends. Three of the US brands tested (Purina, Iams and Solid Gold) also contained melamine or cyanuric acid. These are the substances that poisoned thousands of pets in 2007.

On top of that, processed pet foods also contain other toxic ingredients including heterocyclic amines, acrylamides, and most recently discovered in dry, cooked pet foods, PBDEs (polybrominated diphenyl ethers) – a chemical used as a flame retardant.

RELATED: Learn more about these toxic ingredients in kibble …

Trevor Smith, a mycotoxin researcher at the University of Guelph, says …

“A shift in pet food ingredients is on. Instead of worrying about bacteria spoilage or disease contamination, like we have in the past, we now have to focus on removing mycotoxins.”

Aflatoxin poisoning in dogs can be deadly. It’s safest to avoid any food containing corn, especially as mold infested corns are added to animal feeds. However it’s important to also remember that melamine and other harmful substances will still be in many processed foods, so feeding fresh, whole foods is still the best way to protect your pet from cancer and other diseases that processed pet foods can cause.


Aquino, Simone & Correa, Benedito. (2011). Aflatoxins in Pet Foods: A Risk to Special Consumers. 10.5772/25171.

Kumar P, Mahato DK, Kamle M, Mohanta TK, Kang SG. Aflatoxins: A Global Concern for Food Safety, Human Health and Their Management. Front Microbiol. 2017;7:2170. Published 2017 Jan 17.

Susan S Lang. Dogs keep dying: Too many owners remain unaware of toxic dog food. Cornell Chronicle. January 6 2006

PM Newborn, GN Wogan. Sequential Morphologic Changes in Aflatoxin B1 Carcinogenesis In The Rat. Cancer Research. April 1968.

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