Grain-Free vs Grain-Inclusive Dog Food: Which Is Better?

Grain-free vs grain-inclusive dog food: what’s actually different?

Grain-inclusive foods use cereal grains such as rice, barley, oats, wheat or corn. Grain-free foods leave those out, but not the carbohydrates. Tufts veterinary nutritionist Cailin Heinze has explained that some grain-free brands substitute similar amounts of highly refined starches, such as those from potatoes or tapioca, while others use peas, beans or lentils instead of grains.

The FDA saw the same swap when it began looking into canine heart disease reports in 2018: many of the foods were labeled grain-free and listed peas, lentils, other legume seeds (pulses) and/or potatoes among their first ten ingredients. The real difference between the two bags is less about grains and more about which starch replaces them, and how much.

Grain-free isn’t automatically low-carb, either. Heinze notes that the grain-free foods that are lower in carbohydrates “can be quite high in both fat and calories,” worth knowing if your dog is watching their weight. And grains aren’t empty filler: whole grains supply vitamins, minerals, essential fatty acids and fiber. Her verdict on the trend was blunt. Grain-free, she said, is “a marketing concept designed to sell pet food.”

Are grain allergies common in dogs?

Less common than the grain-free aisle suggests. A 2016 review in BMC Veterinary Research by Ralf Mueller, Thierry Olivry and Pascal Prélaud pulled together the published studies that identified the specific foods behind confirmed food allergies in 297 dogs.

Beef was the most frequently reported trigger, in 34% of those dogs, followed by dairy products (17%), chicken (15%) and wheat (13%). Soy turned up in 6%, lamb in 5%, and corn and egg in 4% each. Rice was reported in just 2% of dogs, and barley in a single dog. Some dogs reacted to more than one food, so the figures add up to more than 100%.

Wheat makes the top four, so grain allergies are real for some dogs. The authors also caution that the list may “merely reflect pet feeding habits in the preceding decades.” Still, it lines up with Heinze’s summary: “While food allergies in pets are uncommon, allergies to grains are even rarer.”

Confirming a food allergy takes strict dietary restriction until the signs clear, then food challenges, which the review recommends starting with beef and dairy. A grain-free bag from the pet store isn’t that test. If your dog itches or has ongoing stomach trouble, start with your vet and our guide to the best dog food for allergies.

What did the FDA find about grain-free food and heart disease?

In July 2018, the FDA announced it had begun investigating reports of dilated cardiomyopathy (DCM), a serious heart disease, in dogs eating certain pet foods, many of them labeled grain-free. FDA describes DCM as a recognized genetic condition, typically in large or giant breeds such as the Doberman Pinscher, Great Dane and Irish Wolfhound, yet many of the new reports involved breeds not previously known to be predisposed. If you feed a big dog, our best large breed dog food guide covers what to look for.

The June 27, 2019 update covered 524 DCM reports (515 involving dogs) received from January 2014 through April 2019. More than 90% of the products in those reports were labeled grain-free, 93% contained peas and/or lentils, and a far smaller share contained potatoes. FDA also published the brand names that appeared in ten or more reports.

FDA’s advice to owners is simple: work with your veterinarian before making diet changes, and contact a vet as soon as possible if your dog shows possible signs of heart disease.

Where the grain-free heart disease question stands now

FDA’s most recent public update is dated December 23, 2022. It said the agency “does not intend to release further public updates until there is meaningful new scientific information to share,” and that adverse event reports, by themselves, “do not supply sufficient data to establish a causal relationship” with the products reported.

Its question-and-answer page, last revised in August 2024, counts 1,382 reports of DCM in dogs through November 1, 2022, and notes reports have continued “at lower levels than experienced from 2018 through 2020.” FDA has received reports involving both grain-free and grain-containing diets, and it says it “has no definitive information indicating that the diets are inherently unsafe and need to be removed from the market.” That’s FDA’s position: it has not declared grain-free food unsafe or told owners to stop feeding it.

Diet-associated DCM appears to be associated with diets high in pulses (peas, lentils, chickpeas, beans).

Lisa M. Freeman, DVM, PhD, DACVIM (Nutrition), Tufts Petfoodology

Freeman, a board-certified veterinary nutritionist at Tufts, wrote that in a June 2026 update. She added that the concern “includes both grain-free and grain-inclusive diets since both can be high in pulses,” and that the disease “does not appear to be caused by a lack of grains.” More than 30 studies have been published, the specific cause is still under investigation, and the disease “can slowly improve if diet is changed (especially if caught early).”

Which dogs might still eat grain-free?

Some dogs do, with a veterinarian steering. PetMD’s vet-written guidance is that dogs “who are not allergic or intolerant to grains should be fed a commercially available diet that contains grains unless otherwise instructed by a veterinarian,” and that it’s important to make sure a dog truly needs a grain-free diet.

The clearest case is a dog whose elimination trial has pinned its reactions on a specific grain; wheat is the grain that shows up most often in the allergy research. PetMD also notes that dogs with food allergies may benefit from a limited-ingredient food, and some of those are grain-free. Even then, the goal is to avoid the ingredient your vet identifies, not every grain on the shelf.

If your dog already eats a grain-free food and is doing well, don’t switch in a panic. FDA asks owners to consult their veterinarian before changing a dog’s diet; that conversation can cover how heavily the food leans on pulses and what to move to if a change makes sense.

How to choose a dog food: a vet-backed checklist

Both the WSAVA Global Nutrition Committee and the Tufts nutrition team point owners past the marketing to questions about who makes the food and how. WSAVA notes that unregulated terms like “holistic” or “premium” are “of little practical value for nutritional assessment.” Check these instead:

• Complete for your dog’s life stage. The label should say whether the food is complete, and may say whether that was established by feeding trials or formulation. Foods labeled “for all life-stages” are formulated for reproduction and growth.
• A qualified nutritionist. Does the company employ a full-time nutritionist with a PhD in animal nutrition or board certification from the ACVN or ECVCN, and does someone with those qualifications formulate the food?
• Testing beyond the recipe. Tufts favors AAFCO feeding trials, or at least analysis of the finished product to confirm it meets AAFCO nutrient profiles.
• Quality control. Ask what quality-control steps the company uses and whether it owns its plants. WSAVA notes that “made by,” “made for” or “distributed by” on the label shows whether a third party manufactures it.
• Research. Does the company conduct nutrition research and publish it in peer-reviewed journals?
• Real numbers. A good manufacturer can give you calories per cup or can and the typical amount of any nutrient, not just guaranteed-analysis minimums and maximums.
• Where the pulses sit. Most diets in FDA’s DCM reports listed peas, lentils or other pulses high in their ingredients. If a food, grain-free or not, leans heavily on them, ask your vet.

If a company can’t or won’t answer, WSAVA says owners “should be cautious about feeding that brand,” and Tufts calls it a red flag. Your vet team is the tiebreaker. For brand-by-brand detail, see our Purina Pro Plan vs Royal Canin vs Hill’s comparison.

How to switch from grain-free to grain-inclusive food

Gradually. An abrupt change can cause vomiting, diarrhea and a drop in appetite, so the AKC recommends mixing the new food in over about a week:

• Day 1: 25% new food, 75% old food
• Day 3: 50% new, 50% old
• Day 5: 75% new, 25% old
• Day 7: 100% new food

Dogs with sensitive stomachs, food allergies or other digestive conditions may need longer, and if an upset stomach shows up partway through, slow down. If problems continue despite a gradual switch, call your vet. Our best dog food for sensitive stomachs guide covers gentler options.

Grain-free vs grain-inclusive at a glance

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