Does Your Dog Need a Gluten-Free Diet?

We look at the science behind gluten digestion and sensitivity in dogs.

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Several years ago, I had a neighbor whose preschool daughter was suffering from a mysterious and frightening set of chronic symptoms. They’d been taking her to multiple specialists, whose tests continued to turn up little. Finally, an internist at the Mayo Clinic managed to put it together: Celiac disease, a pronounced inflammatory immune reaction to eating the gluten found in wheat, barley, and rye.

Back in those days, few of us had heard of this very real, very serious condition. Yet it didn’t take long for the term “gluten-free” to become popular lingo. It seemed that suddenly, nearly everyone felt the need to avoid gluten for “health reasons” — whether they actually suffered from Celiac disease or not. Soon after, similar conversations began cropping up within pet circles.

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Wheat harvest by Shutterstock.

Gluten-containing staple grains have been consumed by both humans and animals for literal centuries. So more than once, I’ve asked myself why they’ve come to be viewed with a level of suspicion bordering on animosity. How did wheat, for example — which seems to be most strongly associated with gluten in popular culture — earn a reputation as the felon of the food pyramid? And more importantly, do our pups really need to go gluten-free?

The answer, as with most issues, may not necessarily be a completely straightforward “yes” or “no.” There are several underlying dynamics at work, so let’s take a closer look.

The digestion connection

Just like the human body, the canine body is much like a factory in the way it processes incoming nutrients and eradicates waste materials. Based upon this analogy, the digestive tract functions as the Immunity Department. The brain and the gut conduct ongoing, back-and-forth correspondence via endocrine and neural pathways. A truly balanced gut contains beneficial bacteria strains that keep yeast and other potentially dubious microorganisms in check.

Unfortunately, multiple factors can throw gut bacteria out of balance. These factors include chronic stress, illness, certain medications, and environmental toxins. This can make it challenging for pet parents to isolate a single factor that may be contributing to immunity issues or digestive distress. Often, the problem can have its root in an accumulation of factors over time.

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Canine chow time by Shutterstock.

Modern harvesting practices

I live in the Midwest, surrounded by wide-ranging farmland and state-of-the-art harvesting equipment. Some of my longtime friends are farmers, and they’ve mentioned the ongoing challenge they face when harvesting grain crops like wheat. To optimize yield and quality, each tiny kernel must be ripened evenly. That’s hundreds of thousands of kernels! Further complicating matters, harvesters apparently cut more cleanly when they’re reaping moisture-free stalks.

This is why many farmers depend upon herbicides like Roundup, either before planting or in the weeks leading up to harvest. These agents are specifically formulated to help kernels dry out more evenly. This drying-out process — commonly called “dessication” — has been practiced for several decades, though it seems to have grown more prevalent in recent years. In fact, certain conventional farms have been reported to use these agents on crops like barley, rice, sugar cane, soy, and others.

The main ingredient that helps to facilitate dessication is something called “glyphosate.” People tend to disagree on the possible long-term effects of this compound. Some claim it’s perfectly safe; others, like journalist/author Marie-Monique Robin and MIT researcher Anthony Samsel, contend that consumption of glyphosate-treated foods may contribute to various digestive imbalances. There’s evidence to be examined on both sides of the issue … and not everyone agrees that the conclusions are entirely clear-cut.

Enzyme insights

Books by agricultural expert Andre Leu and others point to studies suggesting that glyphosate may potentially disrupt the action of certain detoxifying digestive enzymes. These enzymes typically help to regulate bile acid production; activate and process various key vitamins such as A and D3; and neutralize environmental toxins. What may be worth noting is that certified organic gluten-containing crops and grains don’t generally demonstrate the glyphosate residues of their conventionally-grown counterparts. This likely has something to do with the difference in cultivation practices. Organic cultivation omits the use of certain additives and optimization agents over the course of the growing season.

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Canines Crop Up Everywhere photo by Shutterstock.

Wolf vs. canine diet

Gluten opponents sometimes argue that wheat and other gluten-containing grains aren’t historically part of the traditional wolf diet. Could this prove that consumption triggers canine complications?

Well, it’s long been believed that our domesticated canine friends evolved directly from gray wolves — and thus share strikingly similar DNA patterns. Recent research, however, raises some intriguing points. Scientist John Novembre and Robert Wayne, a professor in UCLA’s Department of Ecology and Evolutionary Biology, suggest that the common ancestor of dogs and wolves hasn’t walked the earth for thousands of years. Based upon their research findings, this large, wolf-like creature actually lived between 9,000 and 34,000 years ago; and it likely went extinct during the late Pleistocene period (roughly 20,000 to 12,000 years ago).

Domesticated dogs, on the other hand, have been living among humans for more than 10,000 years — and without question, sharing human foods. So would it make sense to assume that dogs have evolved right along with their human companions? Might their bodies have adapted to process some of the same foods and grains we do?

Eric Axelsson actually put these questions to the test. As an evolutionary geneticist in the Department of Medical Biochemistry and Microbiology at Sweden’s Uppsala University, Axelsson compared corresponding DNA samples. He found that unlike wolves, dogs have actually developed starch-digesting genes. Domesticated canines exhibit up to 30 copies of these specific genes, whereas wolves have only two. In some cases, canines also have longer starch-digesting enzymes. According to Axelsson, these findings suggest a level of starch-digesting efficiency wolves simply don’t possess.

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Watchful wolf by Shutterstock.

Bottom-line conclusions

Remember, wheat is not the only whole grain that contains gluten. Conversely, be aware that various whole grains like quinoa, millet, buckwheat, teff, and amaranth are generally considered gluten-free.

So when it comes to gluten-containing grains, what’s the key takeaway? It wasn’t so many decades ago that families consumed an almost exclusively home-grown diet — in cultivation terms, the rough equivalent of today’s “organic” food designation. So it’s worth considering modern organic and/or non-GMO grains as an option that may help minimize sensitivity and maintain better gut balance.

It’s also worth noting that most dogs have apparently gained measurable starch-digesting capabilities over the centuries. Make no mistake: Canines will always require a healthy proportion of good-quality protein in their diets, but they’re not obligate carnivores like felines. So a balanced, species-specific diet that’s purity-focused and free of chemical additives is a sensible approach.

But it’s always smart to watch for possible food or ingredient sensitivities, and gluten is no exception. According to my vet, gluten-reactive signs might include diarrhea, vomiting, weight loss, excessive gas, poor appetite, extreme itchiness, and/or a ”corn-chippy” (i.e., yeasty) aroma on the skin. Of course, many of these symptoms can also be connected with a broad range of other ailments. After consulting with your own vet, it’s sometimes wise to try a food-elimination diet and see if that pinpoints a culprit. In the end, some pups may need to go completely gluten-free — while others may thrive with reasonable proportions of healthy grains and/or gluten in their diets.

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Marybeth Bittel

Marybeth lives in the Midwest with her wonderful husband, and her rescue dogs Grant and Maizy — all of them Heinz 57 mixed-breed types. A freelance writer and marketing consultant, she’s been rehabilitating severely abused rescues for over two decades. She’s currently working toward specialized certifications in animal nutrition counseling. Connect with her on LinkedIn or check out her family Instagram feed.

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