Keeping Mycotoxins Out of Pet Food

Keeping Mycotoxins Out of Pet Food

These naturally occurring toxins can cause serious health problems in pets. Here’s how to avoid them.

Brand Insights from Romer Labs.

Mycotoxins are a life-and-death issue for pet food manufacturers. When found too late, mycotoxins may not only lead to expensive recalls but can seriously endanger pet health. 

“Different mycotoxins can cause everything from eczema conditions to lethargy to reproductive effects, all the way to the death of the animal,” said Christy Swoboda, technical services director at Romer Labs, which offers diagnostic solutions for food and feed safety.

The mycotoxins that affect pet food are products of molds and fungi that grow on crops. They can form while the plant is growing or after harvest, during transportation and storage. Once a mycotoxin is present, it is extremely difficult to remove from the food it contaminates. Killing the mold or fungus does not remove the mycotoxin.

“Mycotoxins are chemicals. Once they've been formed by the molds, they don't go away,” said Randy Ford, chief scientific officer at Red Collar Pet Foods. “They cannot be killed and they're very heat stable. Pet food processes will not kill the mycotoxins.”

Mycotoxins to Watch For

Six classes of mycotoxins most frequently affect common pet food ingredients like wheat, rice, oats, barley, and corn: aflatoxin, DON (vomitoxin or deoxynivalenol), fumonisin, ochratoxin, type A tricothecenes (T-2 and HT-2) and zealarone. 

“But in reality, there are literally thousands of these mycotoxins,” said Ford. “As research continues and technology improves in regard to detection and what we know about these toxins, our ability to reduce risk is going to grow and grow.”

This year, the U.S. wheat harvest has been affected by ochratoxin and DON. “This was a better year for zearalenone, which has been a real challenge in the past few years,” Ford said. The corn crop was not in at the time of this interview, but Swoboda and Ford said hot, dry conditions in the Upper Midwest, South, and Southwest of the United States means producers and buyers should watch for aflatoxin.

Swoboda noted that predictions help determine what to keep an eye out for, but testing is necessary to determine if mycotoxins are present and at what level. “Just because environmental conditions are there doesn’t mean mycotoxins will develop,” Swoboda said. “A lot of it depends upon the environmental conditions of the individual plant at different stages of growth and what stressors are on the plant, such as insect damage.”

Mitigating Mycotoxins

“People ask me what the magic bullet is for mycotoxins in pet food,” said Ford. “The answer is easy—there is no magic bullet for mycotoxin mitigation. The only real mitigation for mycotoxin is to not buy contaminated grain.”

That solution sounds simple, but it requires vigilance and a well-developed mycotoxin mitigation program. Ford offers the following guidelines:

  • Pay attention to mycotoxin predictions each growing season. Predictions help you know what to look for.
  • Know your suppliers. Are they doing crop assessments? Are they pretesting grains before delivering them to you?
  • Establish a robust inbound testing program. Mycotoxins may develop during transportation and storage, so you cannot completely rely on earlier testing. 
  • Communicate with other businesses about mycotoxin issues. Food safety is an industry issue. Gather information from your partner businesses before purchasing grain, and share information with others. 
  • Verify testing methods. When testing inbound grains, use test kits that are validated with the commodities you use them on. 
  • Perform sample checks. Send periodic samples to a commercial testing lab to ensure the results in your factory lab are accurate.
  • Test finished product in a commercial lab. Finished product is extremely complex and can contain ingredients that may interfere with rapid test kit results. Liquid chromatography-tandem mass spectrometry (LC-MS), offered by commercial labs, is preferable.

The Role of Rapid Testing

To quickly screen grains for mycotoxin contamination, pet food manufacturers can use rapid test kits on inbound deliveries. These kits quantitate a level of mycotoxin and generally give results in 10 to 15 minutes.

However, rapid test kits are not a complete testing solution. While a variety of rapid test options are available for many types of grain, processed ingredients like corn gluten meal or beet pulp are more difficult to test accurately and precisely using rapid methods, Swoboda said.

Similarly, rapid tests are not recommended as a sole testing method for outbound finished product. “The finished products have such a complex matrix,” said Ford. “Some of the rapid kits are advertised to be pretty accurate, but you still need to do a reference method like LC-MS to really get rid of those interferences that a complex matrix would cause.”

Another challenge with rapid test kits is the need for hazardous solvents in preparing samples. “The trick with the rapid tests is that mycotoxins, except for DON, are very difficult to extract out of grain or pet food with water,” said Swoboda. “It is easier to extract them with a strong solvent like acetonitrile or methanol. But those are hazardous solvents, so the industry wants to go to a water-based extraction. That's been a struggle for test kit manufacturers.  It is still hard to find a test kit that is compatible with water extraction, but then is very precise and accurate on a quantitative basis.”

Despite these challenges, rapid testing has an important role to play in mycotoxin mitigation, particularly when speedy results are needed on incoming deliveries of raw ingredients. And rapid tests are likely to play an even bigger role as technology advances.

Sampling for Safe Levels

Whether you use a rapid test or send samples to a commercial lab, “a robust sampling plan is critical,” said Swoboda. “When we talk about error in analysis for mycotoxins, greater than 90 percent of the analytical error is related to how well a subsample was pulled, not related to the method you chose or the type of kit.”

Mycotoxins are not homogeneous within a lot of any grain, even when all the grain comes from one field, Swoboda explained. “Different bags of grain from the same farmer may have different mycotoxin levels, because mycotoxins do not appear uniformly throughout a crop.”

Whether testing grain from the field, a bulk delivery, or bags, “pulling lots of small subsets from lots of different areas is a must,” Swoboda said. “Appropriately homogenizing, grinding and subdividing samples is critical to getting the most accurate result for understanding what the true mycotoxin contamination of that lot is.”

Ford bolstered the point with this example: “For aflatoxin, we look for a level of 20 parts per billion or less. For reference, one part per billion is one second in 32 years. So that's what we're up against. We're looking for the needle in a haystack. So your sampling really has to be robust.”

The 20 parts per billion threshold for aflatoxin in pet food is an action level set by the U.S. Food and Drug Administration (FDA). Manufacturers who exceed that limit face legal action. 

The FDA provides guidance on safe levels for other mycotoxins, but these do not have the same legal standing as an action level. 

“Outside of aflatoxin, there's not that clear regulatory standard benchmark in the United States,” said Swoboda. “So the industry focuses more on scientific and academic data that determines adverse health effects from those toxins to guide what limits are acceptable. Different species can tolerate different mycotoxins at significantly different levels.”

Standards differ in the European Union and other parts of the world, so manufacturers must be aware of those limits when preparing pet food for export.

The number of mycotoxin varieties in an ingredient or finished product is another important factor. “There's a lot of work being done right now in academia and within the FDA about the synergism of different mycotoxins,” Ford said. “Your acceptable limit for a certain mycotoxin may be far less when combined with another toxin.”

Both Swoboda and Ford recommend the Mycotoxin Handbook from the U.S. Department of Agriculture (USDA) as the go-to resource for understanding contamination levels and proper sampling.


Randy Ford, Chief Scientific Officer, Red Collar Pet Foods,

Christy Swoboda, Technical Services Director, Romer Labs,

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