Do dogs need grains, or is grain-free food better?

For our Nami, rice works without any problems, and so do oats. We once had problems with wheat – so we avoid it.

Healthy dogs don't need grain-free food. Over the course of domestication, most of them gained extra copies of a gene for starch digestion, and they digest cooked rice, oats or millet well. Grain-free only makes sense for a proven intolerance – and grain-free foods rich in pulses are even suspected of being linked to a heart disease.

“My dog is a carnivore, they don't need grain.” You hear this in dog forums about five times a day. It sounds logical, but it doesn't stand up scientifically – and in certain situations it's even dangerous. Let's take a sober look at it.

That's not meant polemically, it's genetics. In 2013, the journal Nature published a study from Uppsala University that compared the genomes of the domestic dog and the wolf. The result: on average, dogs have considerably more copies of the AMY2B gene, which produces amylase in the pancreas – exactly the enzyme that breaks down starch. Wolves usually have only two copies, whereas dogs mostly have considerably more – individual dogs up to about 30. This genetic adaptation took place over the roughly 15,000 to 20,000 years of domestication, alongside humans settling down and taking up farming.

In plain terms: dogs digest cooked starch from rice, oats, potatoes or millet very well. It isn't a stopgap, but part of their biology. Incidentally, certain primitive breeds such as the Husky or Akita have somewhat fewer AMY2B copies – which is also why Husky owners sometimes report more sensitive stomachs. But even Huskies digest starch better than any wolf.

Grain-free is a marketing trend that started in the US around 2010 and quickly arrived in Germany too. The logic behind it sounds simple: dog = wolf = carnivore = no grain. Manufacturers were happy to pick up the trend, because grain-free foods can be sold at higher prices.

What happens in most grain-free dry foods: instead of rice or maize, pulses go in – peas, lentils, chickpeas. Sometimes potato or sweet potato too. It sounds harmless, but it isn't in every case.

In July 2018, the US Food and Drug Administration issued a first warning: in dogs fed a grain-free diet – especially one with a high proportion of peas, lentils or potatoes – an increased number of cases of DCM had been observed. DCM, dilated cardiomyopathy, is a disease of the heart muscle in which the heart chambers enlarge and the muscle pumps more weakly.

Certain breeds such as the Doberman, Boxer or Irish Wolfhound are genetically predisposed to DCM; that has long been known. What made the FDA sit up: DCM suddenly appeared more often in breeds that aren't normally affected too – Golden Retrievers, mixed breeds, Labradors. The common denominator was often a grain-free diet with pulses as the main source of carbohydrates.

The FDA has published several updates since then. To this day, there's no final causal explanation – taurine may play a role, or perhaps a combination of several factors. But the warning remains in place, and both the FDA and many veterinary cardiologists recommend not using pulses as the main source of carbohydrates unless there's a medical reason.

The topic is also being discussed in veterinary medicine in Europe. Blanket panic isn't called for – but anyone who relies on pulse-rich, grain-free food without a medical reason is taking a risk with no recognisable benefit.

There are cases in which grain-free food is the right choice:

• For a diagnosed grain allergy, identified through an elimination diet with your vet. This is rarer than the advertising suggests. In an analysis of published cases, beef, dairy and chicken were the most common triggers; wheat came after them. How an elimination diet works is explained in our guide to dogs with allergies.
• For certain metabolic diseases, where the vet prescribes a low-carbohydrate diet.
• Acute stomach and gut episodes, on the other hand, don't call for grain-free food – quite the opposite: soft-cooked rice is the classic ingredient of a bland diet for dogs.

If your dog just seems “somehow sensitive”, grain-free is rarely the answer. The solution is more often: fewer varieties, clearer ingredient lists, a proper elimination diet.

Rice is the classic and is very well tolerated by most dogs. Brown rice contains more fibre, while white rice is gentler when there are stomach and gut problems. Important: cook it until it's nice and soft, so the starch is well broken down.

Oats, to be honest, are underrated. Oats contain beta-glucans, are filling and low in gluten, and provide valuable B vitamins. Rolled oats soaked in water or cooked into a porridge make a great base.

Millet is naturally gluten-free and is often very well tolerated. It provides iron and magnesium and is a good alternative to rice if you'd like to bring some variety into the menu.

Maize and wheat basically work too, but they're more often associated with allergies than rice and oats. If your dog has no problems, that's no drama. If they react sensitively, rice, oats and millet are the safer bets.

Besides rice, oats and millet, quinoa, buckwheat, spelt or couscous often end up in the bowl too. There are hardly any studies on these specific types in dogs. That's why we treat them like rice: without salt or seasoning, thoroughly cooked and soft.

• Quinoa: the outer seed coat contains saponins – bitter substances that should be removed before eating. This is most often done with water: in one study, three washes reduced the saponin content from around 1% to below 0.2%. So rinse quinoa thoroughly in a fine sieve under running water before cooking, and then cook it until soft.
• Buckwheat: botanically not a cereal but, like quinoa, a pseudocereal and gluten-free. Rinse briefly and cook until soft.
• Spelt: a type of wheat and therefore contains gluten. Whole grains take a long time to soften – spelt flakes or spelt semolina are easier and can be cooked into a porridge.
• Couscous and pasta: these are usually made from durum wheat semolina, so they're wheat too. Cook without salt, and leave out sauce and seasoning.

Gluten is only an issue for dogs with a proven intolerance – then every type of wheat counts, including spelt. With all the other types, it's best to alternate. Try anything new in a small amount first and keep an eye on your dog's stools, as with any change of food.

In a home-cooked meal, cooked carbohydrates make up about a fifth – how to divide up meat, vegetables, carbohydrates, oil and calcium is shown in the beginner's guide to home cooking. The carbohydrates can be rice, oats, potato or millet – it's best to alternate. Quinoa, buckwheat or spelt are also possible when cooked, as the A to Z list of foods shows. So grain isn't a filler, but a sensible component, as long as your dog doesn't have a genuine allergy.

The DoggoMeal app works out the right proportion of carbohydrates for you automatically, depending on your dog's weight, activity and individual intolerances. Rice, oats or potato after all? You choose, the app does the balancing. Get the app here – and that's the end of the marketing muddle.