Aflatoxins: is corn the culprit?

Aflatoxins have been getting a lot of publicity lately with the recent recalls and deaths associated with contaminated pet food. But, what are aflatoxins? Is it really was simple as not using corn in the diet? I often hear alot of blame around corn, but surely there is more to it. If corn was such an issue, manufacturers wouldn’t use it – it would be a liability and no-one wants bad publicity of harming pets.

Are you worried about aflatoxins in your pet’s food? Let’s look into how contamination occurs and what consumers and manufacturers can do to prevent pets becoming ill.

What is it?

Aflatoxins are produced by certain toxigenic strains of Aspergillus flavus, Aspergillus parasiticus, and Aspergillus nominus. They are a form of mold/fungus that produce a type of toxin that are designed to exert toxic effects on animals and human beings, to avoid being eaten. The major aflatoxins are called B1, B2, G1 and G2 – Aflatoxin B1 is the most toxic, followed by aflatoxins G1, B2, and G2.

So how does it get into pet food?

Aspergillus sp. can grow on grains stored under high moisture/humidity (>14%), at warm temperatures (>20°C). Grains that are inadequately dried or stored can lead to extensive mold growth and aflatoxin production. The most commonly affected crops are corn, cottonseed, ground nuts, and tree nuts. However, it is not just restricted to grains; meat, milk and eggs can also contain aflatoxins, particularly if the production animal has ingested significant amounts or it has been contaminated during production. This is why it’s important to note that a grain or corn free diet WILL NOT prevent aflatoxin contamination considering meat, which is a key aspect of pet food, can also be affected.

There are two ways that aflatoxins get into food: Field contamination or storage contamination. Field contamination is the most common form; with the move away from pesticides on crops due to a rise in organic farming, insects interfere with and damage the crops allowing fungus to grow which leads to aflatoxin production. Therefore using an organic pet food is actually a risk for aflatoxin contamination. Improper storage is a big issue aswell; grains must be stored in dry, cool conditions and must be free from damage or insects in storage, to ensure the fungus does not grow.

Are there legal requirements for manufacturers? How do they test for it?

The aflatoxin control limit adopted in the US is 20 parts per billion for aflatoxin B1.

To test for contamination, it’s actually fairly difficult; if you take on a small sample of grain it may be fine, however there may be a portion in a damp and warm corner that is affected. Therefore you could potentially miss the contamination all together due to poor sample collection – you would need to take multiple samples, throughout the production and storage process, though it is still easy to miss contamination. The FDA does not require this form of testing be performed on aflatoxin, it’s unfortunately up to the manufacturer whether they undertake this or not. However, all corn and corn products are routinely tested for
aflatoxin contamination prior to their use in the man-
ufacture of commercial food formulated for dogs. How they do this, is they screen it for fluorescence by the use of a black light. This is done prior to its sale to manufacturers and again by the manufacturer themselves, before being unloaded from trucks. Any fluorescence and the entire shipment must be rejected. However, fluorescence screening is only a presumptive test for aflatoxins and is based on the natural bright greenish-
yellow fluorescence of kijic acid that is produced by the fungi, signifying fungal growth. This test cannot be used to determine the amount of toxin present in the batch. Following manufacturing of the pet food, more testing on the final product should be conducted to ensure the total amount of aflatoxin is under the limit (but again, this is not a legal requirement). If it is over the 20 parts per billion limit, the batch must be discarded. This doesn’t need to trigger a recall, particularly if the manufacturer has tested their final product and stopped it before it leaves the factory. Therefore, recalls as I’ve mentioned in the past, are not always a good indicator of a company being “low quality” as there may be numerous internal recalls before a product reaches shelves and consumers are notified.

What does aflatoxin do?

Susceptibility and symptoms vary with breed, species, age, dose, length of exposure and nutritional status. Animal species display differing degrees of susceptibility to aflatoxins, however, and it is now recognized that young animals are more susceptible.

In dogs and cats, the symptoms of acute aflatoxicoses include vomiting, depression, excessive drinking, excessive urination, weakness, anorexia, diarrhea, icterus, epistaxis, and petechiae (spotting) on mucous membranes. Liver issues such as hepatitis and enlarged livers, are also attributed to aflatoxin poisoning. Subacute aflatoxicosis (at 0.5–1 mg/kg of pet food over 2–3 weeks) can cause dogs and cats to become lethargic, anorexic, and jaundiced. Chronic exposure to aflatoxin (0.05– 0.3 mg aflatoxin/kg pet food over 6–8 weeks or longer) shows similar hepatic effects as above.

So, what should I feed?

I know the recent recalls are alarming, and the number of dogs affected is substantial however we don’t really know the cause yet to be able to comment on why or how this happened. I see clients jumping to their own conclusions and becoming increasingly concerned about their pet food containing corn, thinking this is the reason these pets are dying, and that corn shouldn’t be in pet food in the first place. Let me explain why this is completely false; corn is one of the richest sources of linoleic acid, protein and low sugar carbs. It is not a filler, nor is it indigestible – when used in its milled form (as in dry pet food) it is highly digestible, up to 97%. This is incredible, dense, bioavailable nutrition for your pet. As for corn being the culprit of aflatoxin poisoning; as we talked about above regarding the types of foods and ingredients that can be affected, there’s a huge range of ingredients that can be affected by mould, including meat which is in almost every pet food. In addition, corn is the only ingredient that is checked for aflatoxin multiple times – no other ingredient is, therefore corn is probably a safer ingredient where mould is concerned. Do not be manipulated by manufacturers claiming their grain free, wheat/oat/corn free or organic foods are safe from this type of contamination. The best way to ensure your pet’s safety is to use a manufacturer who has a long history of good quality control, testing and scientific formulating.

If you do suspect your pet may be ill as a result of aflatoxin poisoning; discuss this with your veterinarian, retain your pet’s food for testing and submitting a report, and change your pet’s diet. Majority of pets see a complete resolution of symptoms when changing to a different diet – and if aflatoxin isn’t the culprit from your pet’s symptoms, a change in diet may still be beneficial regardless.

Do you have any concerns about aflatoxin poisoning? Ask me in the comments below!

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

5 thoughts on “Aflatoxins: is corn the culprit?

  1. Fantastic read thank you!! What is your take on the belief that pets who eat traditional diets (containing corn/grains) are potentially building up toxins on an accumulative level from potentially low level aflatoxins over their lifetime from a diet that contains corn and grains, specifically? I’ve heard this statement being voiced on pseudoscience websites/pages. Thank you!

    • It absolutely can happen, but given aflatoxin is not limited to grain inclusive diets, it’s not exactly easy to pin it down to one diet and ‘prevent’ this from happening. It is recommended though, that if vets detect issues with the liver that they should consider a diet change first and retest liver values after a month. If the pet has been on the same diet for a long time, this is usually a good idea anyway to either switch to a prescription liver diet, or at least rule out the potential aflatoxin poisoning. But of course, liver values can change for billions of reasons and it’s unlikely for the diet to be the one and only reason for it.

      • Thank you for your response! Are grains such as corn more commonly affected by aflatoxins than meat and eggs for example? Or are they both as susceptible to potential aflatoxin poisoning?

      • They are both equally as susceptible, however grain is more commonly tested for it. So, it’s not more susceptible but it’s more likely to be found, therefore may appear to be more common…if that makes sense?