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Causes Tumors, Major Organ Damage and Premature Death — Is Your Pet at Risk?

According to a survey of 1,500 US dog owners, 65% of those surveyed prefer excluding these ingredients from their pet's food.

gmos in pet food


  • Despite pet food industry insistence that genetically modified ingredients in dog and cat food are harmless, pet parents aren’t onboard
  • Consumers don’t trust the science behind GM foods and tend to ignore assurances by “experts” who insist it’s safe to eat products made with GM ingredients
  • Studies of rats fed GM corn showed significant damage to multiple organs after just 90 days
  • To protect your pet from GM ingredients, avoid all prepared foods containing corn and soy products, since these are the crops most likely to originate from GM seeds

According to Richard Butterwick, Global Nutrition Advisor for Mars Petcare, based at the WALTHAM Petcare Science Institute in the UK, GMO ingredients in dog and cat food don’t hurt pets.1 We’ll call this opinion vs. fact, which will become clear further along in this article.

Fortunately, according to the journal, a growing number of pet owners object to genetically modified organisms (GMOs) in dog and cat food. This is good news, because the so-called “science” on this subject has tried hard to convince us GM ingredients are entirely harmless in both human and pet food. Here’s a brief disturbing description of the GMOs used in U.S. crops:

“In the United States, GMO crops processed into food include yellow corn, soybeans and cotton, in the form of cottonseed oil.
Companies such as Monsanto and DuPont engineer these plants to contain a pesticide derived from the Bacillus thuringensis bacteria, to resist applications of herbicides (particularly glyphosate, known by the brand name Round-Up) and to have other characteristics.”2

Put another way, these are unnatural, human-engineered plants that are “born” containing pesticides and with the ability to withstand heavy exposure to glyphosate (Round-Up), a known cancer-causing agent.

Consumers No Longer Trust the Advice of Food Scientists

Do we really want to eat chemically “enhanced” food or offer it to furry family members?

Apparently not, according to a NUTRO™ survey of 1,500 U.S. dog owners. Two thirds (65%) of those surveyed prefer non-GMO ingredients in their pet’s food.3 Consumers believe natural farming techniques are better for the environment and prefer pet food ingredients with minimal or no synthetic pesticides, herbicides, and fertilizers.

It seems that when scientists sing the praises of GMOs, more and more people are tuning them out. “Many consumers no longer trust science or scientists,” says Debbie Phillips-Donaldson of, “at least not when it comes to their own food or pet food.”4

In response to scientists’ claims that GMO products are safe, consumer watchdog groups argue that substances such as trans-fats, BPA, red dye no. 2, and leaded gasoline were also once considered safe. In addition, there’s the argument that much of the research done on GMOs and glyphosate has been funded by entities with something to gain.

For an example of how scientists have manipulated the facts about GMOs to suit their own purposes, I recommend reading The UK’s Royal Society: a Case Study in How the Health Risks of GMOs Have Been Systematically Misrepresented.

GM Corn Destroyed the Health of Study Animals

A 2009 study showed that genetically modified corn causes significant kidney and liver disease in rats after only a 90-day feeding trial, and has a negative effect on other organs as well, including the heart and spleen.5

A 2012 lifetime study of rats fed a diet containing GM corn shows they not only died earlier than rats on a standard diet, but developed mammary tumors and severe kidney and liver damage as well. Half the male rats and 70% of females died prematurely, compared with 30% of males and 20% of females in the control group.6

The lead researcher of the 2012 study, Gilles-Eric Seralini of the University of Caen, believes his results, which involve the full lifespan of rats, give a more comprehensive and realistic view of the risks of GM corn than 90-day feeding trials. A rat at three months is still a young adult. (Interestingly, this study was retracted two years after publication, which is in my opinion a testament to the power of Big Agriculture to influence the “science.” Consumers are smart to be distrustful.)

In a 2016 study, rats fed GM corn for 90 days suffered serious damage to the surface mucous membranes of the jejunum, which is part of the small intestine.7 The damage included the villi, which are the finger-like structures in the intestine that absorb dietary nutrients.

The villi were misshapen and flattened, with some cells joined together. The mucosal glands (called crypts) were abnormal and blood vessels were congested. Inflammation was present around the damaged areas. The cells of the intestinal lining were abnormal in structure as well.

What Every Pet Parent Should Know About GMOs

If you're wondering how genetically modified ingredients affect your dog or cat, unfortunately, we still don't have a lot of specifics. However, in a 2009 report on GM foods, the authors write:

“Animal toxicity studies with certain GM foods have shown that they may toxically affect several organs and systems. The review of these studies should not be conducted separately for each GM food, but according to the effects exerted on certain organs it may help us create a better picture of the possible health effects on human beings.
The results of most studies with GM foods indicate that they may cause some common toxic effects such as hepatic, pancreatic, renal, or reproductive effects and may alter the hematological, biochemical, and immunologic parameters.
Small amounts of ingested DNA may not be broken down under digestive processes and there is a possibility that this DNA may either enter the bloodstream or be excreted, especially in individuals with abnormal digestion as a result of chronic gastrointestinal disease or with immunodeficiency.”8

Veterinarian Dr. Michael W. Fox has compiled an extensive list of the potential risks of genetically modified foods, including:

  • The toxic insecticidal agent Bacillus thuringiensis is present in most GM crops in the U.S. that wind up in animal feed and pet food.
  • The herbicides glufosinate and glyphosate are applied to millions of acres of genetically modified crops across the U.S. and other countries. These poisons are absorbed by the crops — which are engineered to be herbicide resistant — while decimating everything else growing in the area and much of the aquatic life in nearby bodies of water.

    These herbicides cause kidney damage in animals, endocrine disruption and birth defects in frogs and are lethal to many amphibians. Glyphosate has also been linked to miscarriages, premature births, and Non-Hodgkin's lymphoma in humans.
  • Nutritionists and other health experts increasingly are connecting the rise in human allergies, including skin conditions and inflammatory GI disorders to broader consumption of GM foods and food additives — in particular, GM soy products containing novel proteins.

    Dr. Fox suspects the high number of skin and food allergies, and other allergies associated with GI disorders are caused or aggravated by these novel proteins and other contaminants in genetically modified crops.
  • Independent animal feeding safety studies show adverse or unexplained effects of GM foods, including inflammation and abnormal cell growth in the GI tract, as well as in the liver, kidney, testicles, heart, pancreas and brain.
  • GM crops have proven to be unstable and prone to unplanned mutations — which means we don't really know whether the food being grown from these plants is safe or nutritious.

Fox's advice to pet parents is to buy only food with USDA Organic certification. He also advises to avoid all prepared foods, including cooking oils that contain corn and soy products, since these are the products most likely to originate from GM crops.

In addition, I recommend omitting grains entirely from your carnivorous pet's diet. Corn and soy are not biologically appropriate ingredients in dog and cat food, even if they are conventionally grown. Both are linked to a wide variety of health problems in companion animals, including allergies, skin disorders, oral disease, inflammatory bowel disease and cystitis, and many grains are sprayed with glyphosate after harvesting as a desiccating agent.9

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