The Great Grainspiracy

What’s wrong with feeding grains?

Grain free diets have been increasing in popularity over the last decade, but is there a reason we should not feed grains to our dogs and are grain free diets healthy?

grain free diet

What are grains?

Grains, sometimes called cereals, are the edible seeds of grasses belonging to a family called Poaceae. They include: Rice, Oats, Wheat, Barley, Maize (also known as corn), Rye, Sorghum and Millet (of which there are several species).

Pseudo-grains are the edible seeds from other plant families. They are nutritionally similar to grains and can be used as alternatives to true grains: Amaranth, Quinoa, Buckwheat.

Are grain free diets more natural for dogs?

If you are feeding your dog a grain free dried dog food, then the manufacturer will have to replace the grain with another carbohydrate. There are a few reasons for this. Firstly, dry diets need at least a small amount of carbohydrate in them to form the structure of the kibble, secondly meat/fish is expensive and most (but not all) carbohydrate sources are cheaper than meat. Thirdly, if the diet was majority meat or fish it may end up being far too high in fat and calories and too low in fibre. We already have an obesity crisis in the UK with nearly 50% of all dogs being classed as overweight. Therefore, grains are usually replaced with potato, sweet potato, or legumes. Is eating a potato more natural for a dog than eating rice?

Have dogs evolved to eat grains?

The theory behind many ancestral diets for dogs is that they have not evolved since their days living as wolves. However, dogs evolved from wolves 1000’s of years ago (the exact date is argued amongst scientists with estimates between 10,000 to 30,000 years ago). When we look at them, we can see they have evolved, a good starting place is comparing the chihuahua with the wolf. Dogs have floppy ears, smaller heads, and paws than wolves and through selective breeding humans have caused further changes in their physical features (not always to the benefit of their health). So, if their physical appearance has drastically changed, why would their digestive system not have evolved too?

Dogs have different genes than wolves when it comes to digesting starch (carbohydrate). Dogs have more copies of a gene called AMY2B. This gene is for amylase, the enzyme responsible for digesting starch. Wolves have 2 copies and dogs have between 4 to 30 copies. Interestingly, different breeds of dogs have different numbers of this gene, so there could be some dogs able to digest starch better than others. The same study showed that this gene is 28 times more active in the dog’s pancreas than in wolves. There also changes in the gene MGAM responsible for helping conversion of maltose into glucose. Dogs and wolves have the same number of copies of this gene but there are mutations in the dog genes leading to a 2 fold increase in the maltose to glucose turnover in dogs and 12 times more enzyme activity in the dogs pancreas. There are also differences between dogs and wolves regarding the gene SGLT1, which is used for the transport of glucose (Arendt et al, 2014).

This genetic evidence is supported by feeding trials. In one such study researchers measured the weight and consistency of faeces from dogs fed on oat groats, rice, wheat, barley, and corn to determine digestibility. They also looked at blood sugar levels after eating. It showed that dogs are highly efficient at digesting grains with rice being the most easily digested, followed by oats (Kempe et al, 2004).

Do grains cause allergies in dogs?

Despite there being a lot of talk around this subject, the science does not support the theory that a huge number of dogs are allergic to grains. In fact, only 5% of skin conditions and only 20% of skin and digestive problems in dogs and cats are a result of an adverse reaction to food (Olivry and Mueller, 2017 and 2018). Furthermore, some of these adverse food reactions (AFRs) are food intolerances not allergies. For more info click here.

A 2016 review (Mueller et al, 2016) of several studies on skin disease as a result of an adverse food reaction showed that the most common AFRs in dogs are to beef, wheat, dairy, chicken and lamb.

Prior to this, another review showed that most common food allergens in dogs were beef, cow’s milk and wheat (Hand et al, 2010).

Apart from wheat, grain allergies are not commonly associated with food allergies in cats and dogs.

Are grain free diets healthier than diets containing grains?

This really depends on the balance of the entire food. Healthy nutrition cannot be determined from one ingredient alone. Other considerations include (but are not limited to) fibre type and level, fat content, quality of protein and balance of minerals.

However, in the last year or two there have been some concerns about grain free diets. After over 500 reports between 2014 and 2019, the FDA (US Food and Drug Administration) and several veterinary teams have started investigating a potential link between grain free diets and heart disease, more specifically Dilated Cardiomyopathy (DCM). Veterinary cardiologists are reporting an increase in DCM, not only in breeds that DCM commonly affects (Boxers, Dobermans, Great Danes, Cocker Spaniels) but also in smaller breeds where it is not common. When the affected dogs are changed off the grain free diets, they improve. However, it is unclear if it is the absence of grains that is the issue or the use of large amounts of potatoes, lentils, peas, chickpeas instead. These diets also seem to have novel sources of protein (such as kangaroo) and the addition of less common fruits and vegetables, some even have small amounts of grains. Research is on-going with this.

I want to feed a gluten free diet, can I still feed grains?

Some dogs may react adversely to the gluten. For example, owners of Border Terriers with Canine Epileptoid Cramping Syndrome, also known as Spike’s Disease seem to be particularly sensitive to gluten (Lowrie, 2015) and a wheat-gluten enteropathy has been identified in Irish Setters, as well as being suspected in other breeds.

The good news is that rice, maize (corn), sorghum and millet are all gluten free grains. Interestingly, although oats contain gluten, many human coeliacs (people that have an autoimmune reaction to gluten) can tolerate oats and the same seems to be true for some dogs. Another option would be dog foods containing pseudo-grains, as these are naturally gluten free.

And Finally

Having said all this, there are some superb grain free diets out there and if your dog has an adverse food reaction and you cannot pinpoint what’s causing it, a grain free diet with a single source of protein can be a great place to start. The point of this blog is to get us out of the mindset that grains are all bad, after all vets have been recommending a highly digestible meal of cooked chicken and rice for upset dog tummies for years.


References & Further Reading

Arendt, Maja et al. “Amylase activity is associated with AMY2B copy numbers in dog: implications for dog domestication, diet and diabetes.” Animal genetics vol. 45,5 (2014): 716-22.

Axelsson, E., Ratnakumar, A., Arendt, M. et al. The genomic signature of dog domestication reveals adaptation to a starch-rich diet. Nature 495, 360–364 (2013).

Kempe, Riitta & Saastamoinen, Markku & Hyyppä, Seppo & Smeds, Kurt. (2004). Composition, digestibility and nutritive value of cereals for dogs. Agricultural and Food Science. 13. 5-17.

Lowrie M et al (2015). The clinical and serological effect of a gluten-free diet in border terriers with canine epileptoid cramping syndrome, Journal of Veterinary Internal Medicine 29(6): 1,564-1,568.

Mueller RS, Olivry T. Critically appraised topic on adverse food reactions of companion animals (6): prevalence of noncutaneous manifestations of adverse food reactions in dogs and cats. BMC Vet Res. 2018;14(1):341.

Mueller RS, Olivry T and Prélaud P (2016). Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats, BMC Vet Res 12: 9.

Olivry, T., & Mueller, R. S. (2017). Critically appraised topic on adverse food reactions of companion animals (3): prevalence of cutaneous adverse food reactions in dogs and cats. BMC veterinary research, 13(1), 51.

Watson, T (2011) Breaking it down – measuring food quality and digestibility. Vet Times. 28 February 2011.



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