Why GMOs are bad for your dog

Have you realized your dog’s health may be at risk from genetically modified ingredients (GMOs)? Here’s what you need to know.

Like the proverbial canary down the mine shaft, dogs have become our sentinels. They alert us to health hazards in the home environments we share, and in the products and by-products of the food industry that feeds us. Now, they’re making us more aware of the health risks associated with GMOs.

In the mid-1990s, I began to suspect diet might be playing a role in a cluster of health problems not seen nearly as often as when dogs were being fed conventional corn and soy. Since that time, I’ve formed the professional opinion that there’s sufficient proof from evidence-based medicine that dietary ingredients derived from GM crops are not safe for companion animals, and by extension, for human consumers either.

More than coincidence

More and more genetically engineered corn and soy were being used in pet foods and fed to farmed animals by the mid-90s. At the same time, as a nationally syndicated veterinary newspaper columnist, I began to receive more letters from people whose dogs were suffering from this cluster of health problems. In the 40 years I’ve been writing that column, I’ve benefited from a wide-angled and historical perspective that I would never have realized by running a conventional veterinary clinic. The thousands of letters I receive from across the US keep me informed about new and emerging health problems, and veterinary responses to the same.

People often wrote to report failed treatments and harmful side effects to prescribed remedies (e.g. steroids), as well as problems with various manufactured prescription diets after their attending veterinarians diagnosed their animals with allergies, asthma, atopic dermatitis and other skin problems, irritable bowel syndrome, leaky gut syndrome, infl ammatory bowel disease, colitis, recurrent diarrhea, vomiting and indigestion, along with abnormalities in liver, pancreatic and immune system functions.

Evidence of harm

In the creation of GM crops like corn and soybean, novel proteins are created that can cause allergies and assault the immune system. This in turn creates illness, especially in the offspring of mothers fed such foods, and to young animals fed diets containing GM ingredients. The genetic modifi cation of such food crops can also lower their nutrient content, elevate potential toxins, and create novel RNA variations. The latter are not destroyed by digestion, and so-called micro RNA has been found in mammalian tissues where they can exert influences on gene expression and therefore affect health across generations. These kinds of problems are in part due to the inherent genetic instability of GM plants that can result in spontaneous and unpredictable mutations.

“The results of most of the rather few studies conducted with GM foods indicate that they may cause hepatic, pancreatic, renal and reproductive effects and may alter hematological, biochemical and immunologic parameters, the significance of which remains unknown,” state Dona and Arvanitoyannis in their detailed 2009 review of animal safety studies of GM foods. Altered DNA from GM foods can be incorporated by gut bacteria and may alter their behavior and ecology in the digestive tract. Likewise, the bacterial incorporation of genetic material from antibiotic resistance genes used to identify some varieties of GM food crops could have serious health implications.

Where does this leave us?

To help protect your dog, look for pet foods that are free of GM corn and soy, and/or that are organically certified. Pet food manufacturers that use USDA Certifi ed Organic ingredients, and especially those that use no corn, soy, canola, cotton by-products (oil and cake) or sugar beet, which could be genetically engineered, or imported rice (which can be contaminated with GM rice) can legitimately claim “No GMO Ingredients” on their packaging. You can find a list of hidden GMO ingredients, as well as tips for avoiding GMOs, at NonGMOShoppingGuide.com. Many websites also provide recipes for home-prepared diets for companion animals – for example, drfoxvet.net or dogcathomeprepareddiet.com.

This is an important issue. I have communicated my concerns to several responsible pet food manufacturers who are not unaware of what Hippocrates advised: to let our food be our medicine and our medicine our food. You can do the same. Enlightened consumer action is an integral part of the long overdue revolution in agriculture to promote more ecologically sound, sustainable and humane farming practices, a healthier environment – and more healthful, wholesome and affordable food for you and your canine companion.


Dr. Michael W. Fox (drfoxvet.com) writes the nationally syndicated newspaper column "Animal Doctor" and has also authored the best-selling books Understanding Your Cat and Supercat: How to Raise the Perfect Feline Companion.