Is Grain-Free Dog Food Healthy? What the Evidence Says

By Tailwisp Editorial TeamUpdated October 17, 20263 min read

Grain-free dog food boomed because it seemed natural: dogs descend from wolves, so why feed them wheat? But the picture turned out to be more complicated. Here is what we know, what we do not and how to decide.

Why grain-free became popular

Marketing suggested that grains are fillers, cause allergies and are unnatural for dogs. Many grain-free foods replaced grains with potatoes, peas, lentils or chickpeas. These foods often had attractive ingredient lists and premium pricing, which helped them look healthy.

Dogs and grains

Dogs are not strict carnivores. During domestication, they evolved extra copies of genes for digesting starch. Cooked grains such as rice, oats and barley are digestible and supply energy, fibre and nutrients. See our guide to carbohydrates in dog food. A grain is not automatically a filler.

Are grain allergies common?

Food allergies in dogs are real but uncommon, and most are to proteins such as beef, dairy, chicken or wheat gluten rather than to grains in general. Itchy skin and ear problems have many causes, including environmental allergies and fleas. See our guide to food allergy vs intolerance. Switching to grain-free without a proper trial may not solve the problem.

The heart disease investigation

In 2018, veterinary cardiologists and regulators in the United States reported cases of dilated cardiomyopathy, a serious heart disease, in dogs eating certain diets, many of them grain-free and high in legumes such as peas and lentils. Some breeds not normally prone to the disease were affected. Investigations have looked at ingredients, taurine metabolism and other factors, but no single cause has been proven. Some dogs improved after changing diets and receiving treatment.

What this means:

• A link is suspected, but not proven.
• Not every grain-free diet is implicated.
• Risk to any single dog is likely low, but the concern is serious.
• Vets generally recommend diets from established manufacturers with strong nutrition expertise.

See our guide to congestive heart failure in dogs for signs to watch.

Who might need grain-free?

A small number of dogs with diagnosed grain allergies may need a grain-free diet. Most dogs with food allergies need an elimination diet to identify the real trigger, which might be a protein. Your vet can guide this. See our guide to feeding a dog with food allergies.

Ingredient swaps are not automatically better

Replacing grains with potatoes or legumes does not make a diet healthier. These ingredients are also starchy, and some are high in plant protein, which can change the overall nutrient profile. Judge the whole diet, not just one ingredient.

What to do if your dog eats grain-free

• Do not panic.
• Talk to your vet about the diet, your dog's breed and any heart concerns.
• Consider a transition to a diet that includes grains, if your vet agrees. See how to switch dog food safely.
• Watch for signs of heart disease: tiring easily, coughing, fainting, fast breathing or a swollen belly. Contact your vet promptly if you see them.

Choosing a food

Look for a food that is complete and balanced for your dog's life stage, from a company with qualified nutritionists, feeding trials and good quality control. Our kibble guide outlines the questions to ask.

Limited ingredient diets

Some owners choose limited-ingredient foods for sensitive dogs. These are different from grain-free foods, and their value depends on the protein and carbohydrate sources. See our guide to limited ingredient dog food.

The takeaway

Grain-free is not healthier for most dogs, and it has been linked with safety questions. Unless your vet has diagnosed a specific problem, a well-made diet with grains is a sound choice.

This article is general educational information, not veterinary advice. Every dog is different. If your dog is unwell, or you are unsure about a symptom, diet change or medication, contact your veterinarian.