Grain-Free vs Grain-Inclusive Dog Food: What the Science Says
The Verdict
Our Verdict
Grain-inclusive food is the safer default choice. The FDA investigation into grain-free diets and DCM is ongoing. Choose grain-free only if your dog has a confirmed grain allergy.
Key Takeaways
Grain-inclusive food is the safer default choice. The FDA investigation into grain-free diets and DCM is ongoing. Choose grain-free only if your dog has a confirmed grain allergy.
Purina Pro Plan Adult Chicken & Rice 4.6 #1 pick | Hill's Science Diet Adult 4.7 #2 pick | Royal Canin Medium Adult 4.7 #3 pick | Taste of the Wild High Prairie 4.6 #1 pick | Merrick Backcountry Raw Infused 4.3 #2 pick | Orijen Original 4.6 #3 pick | |
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| Price | ~$60Buy on Amazon | ~$65Buy on Amazon | ~$58Buy on Amazon | ~$55Buy on Amazon | ~$70Buy on Amazon | ~$90Buy on Amazon |
| Buyer sentiment | Pet Consumption Value for money Digestibility Healthy Infections Buyers praise pet consumption, value for money, digestibility and healthy. Some flag infections. Based on 1,378 user mentions | Taste Healthy Buyers praise taste and healthy. Mixed feedback on value for money. Based on 413 user mentions | Quality Healthiness Kibble Size Taste Buyers praise quality, healthiness, kibble size and taste. Mixed feedback on value for money and digestive effects. Based on 361 user mentions | Quality Ingredients Healthy Pet Preference Diarrhea Buyers praise quality, ingredients, healthy and pet preference. Mixed feedback on value for money and palatability. Some flag diarrhea. Based on 1,288 user mentions | Quality Ingredients Digestive Issues Value for money Raw Portion Buyers praise quality, ingredients and digestive issues. Mixed feedback on ease of use and frozen-dried. Some flag value for money and raw portion. Based on 140 user mentions | Quality Ingredients Healthiness Taste Value for money Digestion Odor Buyers praise quality, ingredients, healthiness and taste. Mixed feedback on digestibility. Some flag value for money and digestion. Based on 758 user mentions |
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* Prices are approximate and may vary. Please check the latest price on Amazon.
Grain vs Grain-Free: Label-Level Comparison
Side-by-side specs for three grain-inclusive kibbles and three grain-free kibbles.
| Product | Grain Status | First Ingredient | Protein (min) | Fat (min) | Fiber (max) | kcal / cup | AAFCO Stage |
|---|---|---|---|---|---|---|---|
| Purina Pro Plan Adult Chicken & Rice | Grain-inclusive | Chicken | 26% | 16% | 3% | — | Adult Maintenance |
| Hill's Science Diet Adult | Grain-inclusive | Chicken | 20% | 11.5% | 4% | 363 | Adult Maintenance |
| Royal Canin Medium Adult | Grain-inclusive | Brewer's rice | 23% | 12% | 3.4% | 340 | Adult Maintenance |
| Taste of the Wild High Prairie | Yes | Water buffalo | 32% | 18% | 4% | 422 | Adult Maintenance |
| Merrick Backcountry Raw Infused | Yes | Deboned beef | 35% | 17% | 3.5% | 394 | Adult Maintenance |
| Orijen Original | Yes | Chicken | 38% | 18% | 4% | 473 | All Life Stages |
Guaranteed analysis and ingredient data from manufacturer product pages as of April 2026.
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The grain-free dog food trend exploded in the 2010s, fueled by marketing that painted grains as fillers and allergens. Then the FDA stepped in with a bombshell investigation linking grain-free diets to dilated cardiomyopathyDCMDilated cardiomyopathy — a heart-muscle disease causing enlarged, weakened ventricles. The FDA's 2018-2022 investigation linked a rise in non-hereditary DCM cases to grain-free diets heavy in peas, lentils, and potatoes. Most cardiologists now recommend WSAVA-compliant diets unless a vet has diagnosed a true grain allergy. (DCM) — a potentially fatal heart condition. Suddenly, the "premium" choice looked dangerous.
The truth, as usual, is more nuanced than either side wants to admit. This research-based comparison breaks down what the science actually says, who should feed grain-free, and the best options in both categories.
The Short Answer
- Best grain-inclusive food: Purina Pro Plan Adult Chicken & Rice — vet-backed, feeding-trial validated
- Best grain-free food (when medically needed): Taste of the Wild High Prairie — quality proteins at a fair price
- Bottom line: Most dogs should eat grain-inclusive food unless a vet has diagnosed a grain allergy
The DCM Investigation: What You Need to Know
In 2018, the FDA began investigating reports of DCM in dogs eating grain-free diets — particularly formulas where legumes (peas, lentils, chickpeas) or potatoes replaced grains as the primary carbohydrate source. Here's what they found:
- Over 1,100 reports of DCM were submitted, with a disproportionate number involving grain-free kibblekibbleExtruded dry dog food — the most common format in the US. Made by mixing dry and wet ingredients, cooking under high pressure, and shaping into bite-sized pieces. Long shelf life, low moisture (~10%), and the cheapest cost-per-calorie option for most dogs.
- Breeds not typically prone to DCM (Golden Retrievers, Labs, mixed breeds) were developing the condition
- The suspected mechanism involves taurine deficiency — legume-heavy diets may interfere with taurine synthesis or absorption
- The FDA has not concluded that grain-free diets definitively cause DCM, but the correlation is strong enough that most veterinary cardiologists now recommend grain-inclusive diets
The investigation remains open. No recalls have been issued. But the veterinary consensus has shifted decisively toward grain-inclusive feeding for most dogs.
When Grain-Free Actually Makes Sense
Grain-free food is medically appropriate in one specific scenario: your dog has a confirmed grain allergy diagnosed through a veterinary elimination diet. True grain allergies are rare — most food allergies in dogs are triggered by proteins (chicken, beef, dairy), not grains. Based on veterinary dermatology research, fewer than 1% of dogs have genuine grain allergies.
If your dog has itchy skin, hot spots, or digestive issues, don't assume grains are the problem. Work with your vet to identify the actual trigger through a proper elimination diet before switching to grain-free.
Head-to-Head Comparison
| Grain-Inclusive | Grain-Free | |
|---|---|---|
| DCM risk | Low (standard) | Potentially elevated |
| Veterinary consensus | Recommended for most dogs | Only for confirmed grain allergies |
| Typical price (30 lbs) | $55–$65 | $60–$75 |
| Common carb sources | Rice, barley, oats | Peas, potatoes, lentils |
| Digestibility | High (grains are easily digested) | High (legumes are digestible) |
| Taurine levels | Normal | May be reduced |
| AAFCO validation | Most brands use feeding trials | More brands rely on formulation only |
Best Grain-Inclusive Dog Foods
#1 Purina Pro Plan Adult Chicken & Rice (~$60/30 lbs)
The most vet-recommended dog food on the market. Real chicken first ingredient, 26% protein, live probiotics, and validated through actual feeding trials — not just lab analysis. This is the default recommendation from veterinary nutritionists for a reason.
#2 Hill's Science Diet Adult (~$65/30 lbs)
Clinically validated nutrition with a focus on digestibility. Excellent for dogs with sensitive stomachs. Higher price reflects the research infrastructure behind every formula.
#3 Royal Canin Medium Adult (~$58/30 lbs)
Size-specific kibble geometry, highly palatable, and backed by decades of veterinary science. The go-to for picky eaters who reject other premium brands.
Best Grain-Free Dog Foods (When Vet-Recommended)
#1 Taste of the Wild High Prairie (~$55/28 lbs)
Roasted bison and venison as primary proteins make this ideal for dogs with common chicken or beef sensitivities. Sweet potato and pea carbohydrate sources provide sustained energy. The novel proteins are the real draw here.
#2 Merrick Backcountry Raw Infused (~$70/22 lbs)
Freeze-driedfreeze-driedFood preserved by removing water through sublimation (frozen → vacuum → vapor) rather than heat. Retains nutrient profile better than kibble extrusion. Lightweight, shelf-stable, and rehydrates with water. Common format for high-end raw-style dog foods. raw pieces mixed with grain-free kibble. Higher protein content and more animal-sourced ingredients than most grain-free options. The raw infusion adds palatability that picky dogs appreciate.
#3 Orijen Original (~$90/25 lbs)
The premium grain-free option with 85% animal ingredients and 38% protein. Multiple named protein sources (chicken, turkey, fish, eggs). If your vet recommends grain-free and budget isn't a constraint, Orijen delivers the most nutritionally dense formula available.
What About "Ancient Grains" Formulas?
Several brands now market "ancient grains" formulas featuring quinoa, millet, sorghum, and chia seeds. These are grain-inclusive (which is good from a DCM perspective) and provide some nutritional variety. However, there's no evidence that ancient grains are superior to standard grains like rice, barley, or oats for dogs. It's marketing differentiation, not nutritional innovation. Standard grains are perfectly healthy for dogs.
How to Read the Label
Whether choosing grain-inclusive or grain-free, look for:
- Named protein as the first ingredient — "chicken" not "poultry by-products"
- AAFCO nutritional adequacy statement — "complete and balanced" validated through feeding trials
- No ingredient splitting — watch for brands listing the same ingredient multiple ways ("peas, pea protein, pea fiber") to push protein sources up the list
- Omega-3 fatty acids from fish oil — supports skin, coat, and joint health
Frequently Asked Questions
Are grains bad for dogs? No. Dogs are omnivores that have evolved to digest grains efficiently. Grains like rice, barley, and oats are excellent carbohydrate sources that provide energy, fiber, and essential nutrients. The "grains are fillers" narrative is marketing, not science.
My dog seems fine on grain-free food. Should I switch? Discuss with your vet. If your dog has no diagnosed grain allergy, most veterinary cardiologists recommend transitioning to a grain-inclusive diet as a precaution. The transition should be gradual over 7–10 days.
Does grain-free food cost more? Typically yes — $5–$15 more per bag. The premium is not justified for dogs without grain allergies, since grain-inclusive foods from the same brands offer comparable or superior nutrition.
The Bottom Line
For most dogs, grain-inclusive food is the safer, more evidence-backed choice. The DCM investigation hasn't produced a definitive causal link, but the correlation is strong enough that the veterinary consensus is clear: feed grains unless your dog has a diagnosed reason not to.
If you're currently feeding grain-free and want to switch, transition slowly over 7–10 days. And regardless of which category you choose, prioritize foods validated through feeding trials from brands with veterinary research teams — Purina Pro Plan, Hill's Science Diet, and Royal Canin remain the gold standard.
🏆 Bottom Line: Given the FDA's ongoing investigation into grain-free diets and DCM, most veterinary nutritionists now recommend grain-inclusive diets from established manufacturers with feeding trial data. Unless your dog has a diagnosed grain allergy (rare), there's no evidence that grain-free offers nutritional benefits.
Related Reading
- Best Dog Food 2026 — Our complete rankings across all categories
- Raw vs Kibble — What the science says about feeding formats
- Best Dog Health Supplements — What's actually worth adding to your dog's diet
Sources
- FDA — "FDA Investigation into Potential Link between Certain Diets and Canine Dilated Cardiomyopathy." FDA.gov, updated 2022.
- Freeman LM et al. — "Diet-associated dilated cardiomyopathy in dogs." JAVMA, 2018.
- Tufts University Cummings Veterinary Medical Center — "The Grain-Free Dog Food Controversy: What We Know." 2022.
- American Veterinary Medical Association (AVMA) — Grain-free diet position statement and DCM update. avma.org.
- Torres-Henderson C, Bunkers J, Contreras ET — "Use of Purina Cardiac Index to Assess Body Composition in Cats." Topics in Companion Animal Medicine, 2017.
Frequently Asked Questions
- Is grain-free dog food actually healthier than grain-inclusive?
- Research suggests grain-free diets are not inherently healthier for most dogs. AKC notes that grains rarely cause allergies in dogs and that dogs evolved the ability to digest starch. Grain-free is justified only when a veterinarian diagnoses a specific grain sensitivity.
- What is the FDA investigation into grain-free diets and heart disease?
- The FDA received more than 1,100 reports between 2014 and 2020 of diet-associated dilated cardiomyopathy (DCM) in dogs, with 90% of single-diet cases involving grain-free foods high in peas, lentils, or potatoes. Veterinary guidelines indicate the cause is still being investigated.
- Are pulses like peas and lentils the real concern?
- Tufts Cummings School cardiologists describe the pattern as 'BEG diets' — boutique companies, exotic ingredients, or grain-free — noting that pulses (peas, lentils, chickpeas) appearing high in the ingredient deck correlate most strongly with diet-associated DCM. Traditional grains like rice have not shown this association.
- When does grain-free make sense?
- Veterinary guidelines indicate grain-free is appropriate when an elimination trial confirms a grain allergy or intolerance, which is uncommon. Otherwise, a grain-inclusive diet substantiated by AAFCO feeding trials is typically the lower-risk default.
- How do I read a label to compare the two?
- AAFCO specifies four required guaranteed-analysis entries: minimum crude protein, minimum crude fat, maximum crude fiber, and maximum moisture. Compare those four numbers and the nutritional adequacy statement (life stage plus substantiation method) before weighing grain status.
Research Sources
- Role of Diet as a Predisposing Factor for Dilated Cardiomyopathy in Dogs: A Narrative Review — NCBI / National Library of Medicine, 2025
- Diet-associated dilated cardiomyopathy: The cause is not yet known but it hasn't gone away — Tufts University Cummings School Petfoodology, 2023
- It's Not Just Grain-Free: An Update on Diet-Associated Dilated Cardiomyopathy — Tufts University Cummings School Petfoodology, 2018
- Can Dogs Eat Wheat And Other Grains? — American Kennel Club, 2024
- Dilated Cardiomyopathy in Dogs: Closer to Solving the Mystery? — American Kennel Club, 2024
- Reading Labels — AAFCO
Hilly Shore Labs
Founder & EditorDog owner for 5+ years, product researcher, and founder of PawBench. Every recommendation is based on hands-on experience with Maggie — my Australian Labradoodle — plus cross-referencing veterinary research from the AKC, AVMA, and peer-reviewed studies.
All product reviews are independently researched. Our recommendations are based on published veterinary guidelines, manufacturer specifications, and verified customer feedback. See our methodology.
