More than you Ever Wanted to Know about Mycotoxins

Mycotoxins are molds, deadly molds, prone to grow on many common pet food ingredients.  While many pet owners are familiar with aflatoxin contamination (causing pet food recalls in the past), a 2007 scientific report seems to suggest numerous mycotoxins even at low levels over time can cause serious health consequences to our pets.

From the International Journal of Food Microbiology, Drs. Herman J. Boermans and Maxwell C.K. Leung published the report “Mycotoxins and the pet food industry:  Toxicological evidence and risk assessment” in 2007.  This report gives Pet Owners a wealth of information on the risks associated with many common pet food ingredients, plus it more than proves the point that strict mycotoxin testing must be required and followed by pet food.

One of the biggest issues of concern discussed, is that existing studies of mycotoxin contamination in pet food overlook the day to day consumption of small amounts of mycotoxins;  resulting in “chronic diseases such as liver and kidney fibrosis, infections resulting from immonosuppression and cancer.”  While practicing veterinarians are familiar with severe mycotoxin contamination symptoms in pets, Drs. Boermans and Leung suggest chronic diseases are “often overlooked” as caused from long term consumption of lesser amounts of mycotoxins.

The following are excerpts…

“These available reports of acute mycotoxicosis, however, cannot provide the whole picture of the mycotoxin problem associated with pet foods since only a small number of food poisoning cases are published. Veterinarians, furthermore, often overlooked mycotoxins as the cause of chronic diseases such as liver and kidney fibrosis, infections resulting from immunosuppression and cancer.  These findings suggest that mycotoxin contamination in pet food poses a serious health threat to pet species.”

“Aflatoxins are commonly found in corn, peanuts, cottonseed, milk, and tree nuts.  After ingestion, aflatoxins are absorbed and carried to the liver via the circulatory system.  They are then converted by the liver into toxic reactive epoxides which bind covalently to intracellular macromolecules such as DNA, RNA and protein enzymes, resulting in damage to liver cells.”

“In addition to their hepatotoxic properties, aflatoxins are also carcinogenic. The binding of DNA causes genotoxicity and mutation in cells. The chronic carcinogenic dose of aflatoxins is much lower than the acute dose. Since aflatoxins are both acute and chronic hepatotoxins and carcinogens, the actual number of dogs affected by aflatoxins would be far more than the total number reported in acute poisoning cases.”

“Ochratoxins are a group of potent renal mycotoxins that widely contaminate the agricultural commodities, such as corn, wheat, oats and dried beans, in temperate regions. There are four ochratoxin homologues — A, B, C and D. Ochratoxin A (OTA) is the most prevalent and, together with ochratoxin C, most toxic. Initial symptoms of ochratoxicosis observed in all species include anorexia, polydipsia, polyuria and dehydration, and are associated with renal damage.”

“Upon absorption, ochratoxins enter the circulatory system, bind tightly to serum proteins and accumulate in the kidneys, where they disrupt protein synthesis and other pathways in proximal tubular cells. This results in the degeneration of the proximal tubules and interstitial fibroses. OTA is also known to bind with DNA molecules and induce renal tumors in animal models, although its carcinogenic mechanism remains controversial.  Dogs show a high susceptibility to OTA.”

“Trichothecenes are a family of Fusarium mycotoxins commonly found in corn, wheat, barley, as well as oats worldwide. Trichothecenes are potent irritants and inhibitors of protein and DNA synthesis which interferes with cellular metabolic activities, ultimately leading to cell death. Rapidly dividing cells are particularly sensitive with the gastrointestinal and immune systems primarily affected in exposed animals. Typical clinical signs of trichothecene toxicosis include loss of appetite, vomiting, diarrhea, gastrointestinal hemorrhage, ataxia, and immune suppression.”

“Feed refusal and vomiting, the most notable behavioral effects of trichothecenes, are possibly related to their influences on brain regional neurochemistry and feed intake regulation  The vulnerability of gastrointestinal and immune systems to trichothecene toxicity accounts for the symptoms of gastrointestinal distress, bloody diarrhea and immune suppression in trichothecene poisoning.”

“Multiple mycotoxin exposure is common in the natural situation.  The toxicity of a particular mycotoxin, therefore, depends on not only its own concentration but also the presence of other mycotoxins.  Thus mycotoxins of relatively low toxicity may pose significant risks if exposure is great, frequent, and long.  Although the exposure of pet animals to mycotoxins in grain-based pet food is generally low, it is unavoidable and occurs throughout the entire lifespan of the animal.”

“Considering that the intrinsic toxicological properties of a chemical cannot be altered, regulatory agencies consider exposure mitigation the only meaningful opportunity for risk reduction (NRC, 1993). Government regulations of mycotoxin contamination, however, are often compromised by the analytical detection limits, regional prevalence, as well as trade relationships amongst different countries instead of fulfilling the scientific approach of risk assessment and safety determination (Leung et al., 2006).  Scientifically based regulations for the acceptable limit of mycotoxins in pet food would be beneficial. Strict regulations, however, would create greater competition with the human food chain resulting in increased pet food costs and decreased industry profits. It is also possible that the avoidance of severe regulations will promote mycotoxin outbreaks. Pet food amelioration is often considered a practical solution for mycotoxin contamination. Food processing techniques such as sieving, washing, pearling, ozonation, and acid-based mold inhibition can reduce the mycotoxin content of cereal grains (Leung et al., 2006). Dietary supplementation with large neutral amino acids, antioxidants, and omega-3 polyunsaturated fatty acids as well as inclusion of mycotoxin-sequestering agents and detoxifying microbes may ameliorate the harmful effects of mycotoxins in contaminated pet food. Amelioration of pet food, however, should be used as an additional safety factor but not to replace the sound application of risk and safety determination. The public has recently begun a shift to organic pet foods. The public perception is that organic foods are safer due to the lack of pesticide residues. In the case of mycotoxins, however, the avoidance of insecticides and fungicides may result in increased crop pest damage, fungal growth and mycotoxin production.”

“Mycotoxin contamination in pet food poses a serious health threat to pets. The health problems of pets are of a highly emotional concern and pet food safety is the responsibility of the pet food industry. Risk and safety determination is needed and must address many issues including sensitivity of toxic endpoints, multiple mycotoxin exposure, and pet food amelioration.”

To read the full paper, visit http://www.sciencedirect.com/science/article/pii/S0168160507003935

My interpretation of this paper would be to suggest to pet owners to avoid pet foods/treats containing grains common to mycotoxin contamination.  The ingredients most frequently mentioned were corn and wheat; to a lesser extent (mentioned in the paper) were barley and oats.  Because we (Pet Owners) don’t know the testing methods each pet food manufacturer follows on mycotoxin testing or what allowable levels they accept in ingredients (or the long term effect of day to day minute mycotoxin consumption), avoiding these ingredients seems to be our only recourse.  The paper also suggested the addition of antioxidants (berries are a great source) and omega-3 polyunsaturated fatty acids (fish oil a great source – should be purified grade) to the diet helped to protect the pet from mycotoxin exposure.  (Add berries and fish oil to your pets food just in case.)

Wishing you and your pet(s) the best,

Susan Thixton
Pet Food Safety Advocate
Author, Buyer Beware
Co-Author Dinner PAWsible
TruthaboutPetFood.com
PetsumerReport.com

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