# Grain-Free Dog Food and Heart Disease: What Owners Should Know Grain-free dog food has been linked to a heart condition called dilated cardiomyopathy (DCM) in dogs, especially in breeds that do not normally get it. The concern centers on diets high in peas, lentils, and potatoes, and on the fact that some affected dogs improved after switching foods. The FDA and veterinary cardiologists have not banned these diets, but they have asked owners to think carefully about what is in the bowl. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - The FDA reported in 2019 that grain-free, boutique, and exotic meat diets were linked to DCM in dogs, including breeds with no genetic risk for the disease [1]. - Many of these diets replace grains with potatoes, lentils, or peas, ingredients that can be low in the amino acids a dog needs to make taurine [1]. - Not every study agrees. Some controlled feeding trials found no drop in taurine and no clinical heart changes over 18 months in healthy dogs eating grain-free food [2]. - Diet-associated DCM is often reversible when the dog returns to a balanced diet that includes grains [1]. - If your dog eats grain-free food and shows coughing, fainting, or unusual tiredness, call your veterinarian now. ## Is a Grain-Free Diet Safe for Your Dog? The honest answer is that it depends on the diet and the dog. Grain-free food is not a poison, and millions of dogs have eaten it without obvious problems. But a real safety signal exists, and it deserves your attention. In June 2019 the FDA released a report describing a link between grain-free, boutique, and exotic meat diets and dilated cardiomyopathy in dogs [1]. DCM causes the four chambers of the heart to stretch, which changes normal blood flow through the heart and can progress to congestive heart failure [1]. What worried veterinarians was not just the disease itself. It was who was getting it. DCM has well-known genetic risk in large and giant breeds such as the Doberman Pinscher [1]. The FDA began receiving reports of DCM in dogs outside those usual risk groups, and the common thread was diet [1]. That does not mean every grain-free bag is dangerous. It means the pattern is strong enough that owners should not treat grain-free as automatically safer or healthier. If you want a broader look at how this debate developed, see [Grain-Free Dog Food: Should Owners Be Concerned?](/knowledge/veterinary-medicine/nutrition/grain-free-dog-food). ### What the Research Actually Shows The evidence is mixed, and that is the fairest way to describe it. A 2025 narrative review of peer-reviewed literature reported a strong link between diet and DCM, particularly with legumes. Dogs of various breeds fed non-traditional, grain-free, legume-rich diets showed larger left ventricular diameters, reduced systolic function, and more premature ventricular complexes than dogs on traditional, low-legume diets [3]. Many affected dogs improved clinically and functionally after dietary changes and treatment, which suggests this form of DCM can be reversible [3]. A 2022 study fed healthy adult Labrador Retrievers grain-free diets with high legume inclusion (20% split peas and 40% lentils) for 30 days. Compared with baseline, those dogs had progressive, significant decreases in red blood cell counts, hematocrit, and total hemoglobin, plus a rise in plasma inorganic phosphate [4]. The authors noted these responses shared features with dogs suspected of having DCM [4]. Other work points the other way. An 18-month randomized, double-blind study in 60 healthy adult dogs compared four foods: grain-free with potatoes and peas, grain-inclusive with peas and pea fiber, grain-inclusive without peas or potatoes, and grain-free with potatoes. Whole blood and plasma taurine stayed in the normal range and were not affected by diet, and no clinically significant changes appeared in cardiac troponin-I or NT-BNP. All dogs were considered clinically normal for DCM [2]. A 2020 study fed a commercial grain-free diet to eight Labrador Retrievers for 26 weeks. The diet did not decrease plasma amino acids or taurine status, though it did increase bile acid excretion [5]. One more wrinkle matters. A 2026 analysis from the Dog Aging Project found that owner-reported grain-free diet status was often misclassified when checked against actual ingredients, and grain-free diets were not predictive of new owner-reported cardiac diagnoses over two years [6]. In plain terms, some of the earlier diet data may have been less reliable than it looked. ## Why Grain-Free Diets Might Affect the Heart The leading theory involves taurine. Taurine is an amino acid a dog's body can produce on its own, and it plays a role in normal heart muscle function. Grain-free foods often use tubers like potatoes or legumes like lentils and peas instead of grains, and these ingredients have low levels of certain amino acids the dog's body needs to make taurine [1]. Over the long term, taurine deficiency can progress to DCM [1]. That said, taurine is not the whole story. A 2025 review noted that emerging hypotheses extend beyond simple nutritional inadequacy, and that the mechanisms remain unclear [3]. Some dogs with diet-associated DCM had low taurine levels, and some did not [5]. Researchers are still working out what else may be involved. There is also a newer finding worth knowing. A 2026 study in Beagles fed four diets for five weeks each found lower ejection fraction and greater left ventricular end-systolic volume in dogs eating a grain-free diet containing pea flour compared with a grain-based rice flour diet [7]. The same study looked at brain blood flow and cognitive performance, which is a reminder that diet can affect more than one body system [7]. ## Which Dogs Are at Risk? Any dog eating a grain-free, boutique, or exotic meat diet could be at risk, but some groups stand out. - Breeds with known genetic DCM risk, such as the Doberman Pinscher, are already vulnerable, and diet may add to that risk [1]. - Dogs outside the usual genetic risk groups have developed DCM while eating these diets, which is what triggered the FDA reports [1]. - Dogs eating diets high in legumes, especially peas and lentils, show more concerning heart changes in some studies [4][3]. - Dogs on these diets for months to years are the ones most likely to show cumulative effects, since taurine deficiency develops over the long term [1]. If your dog falls into one of these groups, that is a reason to talk to your veterinarian, not a reason to panic. ## What Are the Real Risks of Grain-Free Food? The main risk is heart disease, specifically diet-associated DCM [1][3]. This is not a minor concern. DCM can lead to congestive heart failure [1]. A second risk is nutritional imbalance. A 2025 review of commercially available grain-free pet foods found significant variability in nutritional composition, and grain-free formulations typically have higher protein and fat levels [8]. Higher fat and protein are not automatically bad, but they change the nutritional picture, and they may not suit every dog. A third issue is that grain-free does not mean allergy-free. Many owners switch to grain-free because they believe grains cause skin or food allergies. Grains do not increase your pet's risk of skin or food allergies [1]. If your dog has true food allergies, the culprit is usually a protein, and your veterinarian can help you identify it. The review also noted that grain-free diets may offer some potential benefits, including improved blood sugar control, reduced mycotoxin exposure, and better palatability [8]. Those are real points in their favor. They just have to be weighed against the cardiac risk [8]. | Diet Type | Safe? | Notes | |---|---|---| | Grain-free with high peas and lentils | Use with caution | Linked to heart changes in some studies [4][3] | | Grain-free with potatoes only | Uncertain | No taurine drop or clinical DCM seen in one 18-month trial [2] | | Grain-inclusive with peas and pea fiber | Generally considered lower risk | No clinical DCM seen in the same trial [2] | | Grain-inclusive without peas or potatoes | Generally considered lower risk | No clinical DCM seen in the same trial [2] | | Boutique or exotic meat diets | Use with caution | Included in the FDA link to DCM [1] | ## How to Choose a Heart-Safe Diet Start with the manufacturer. Look for a company that employs board-certified veterinary nutritionists and does its own feeding trials. That is widely accepted veterinary guidance, and it matters more than any single ingredient on the label. Look at the ingredient list with legumes in mind. If peas, lentils, chickpeas, or other pulses appear high on the list, or if several of them appear, that is a diet to discuss with your veterinarian [3]. Consider grains again. The good news about diet-associated DCM is that it is reversible by returning your pet to a balanced diet with grains such as corn [1]. That does not mean every dog needs corn. It means grains are not the enemy, and a grain-inclusive diet is a reasonable option for most dogs. If your dog has another condition, diet choices get more complicated. Dogs with kidney disease need specific nutrient targets, which you can read about in [Dog Kidney Disease Diet](/knowledge/veterinary-medicine/nutrition/dog-kidney-disease-diet). Dogs with diabetes have their own needs, covered in [Safe Foods For Diabetic Dogs](/knowledge/veterinary-medicine/toxicology-and-food-safety/safe-foods-for-diabetic-dogs). ### Should You Switch Foods Right Now? Do not make a sudden switch based on a headline. Talk to your veterinarian first, especially if your dog is doing well. If you and your veterinarian decide to change diets, transition gradually over about a week to avoid stomach upset. If your dog has a confirmed or suspected heart problem, the conversation is more urgent. Ask whether a diet change is part of the plan, and ask whether taurine supplementation is appropriate. Your veterinarian will calculate any dose based on your dog's weight and health. ## What to Do If You Are Worried If your dog is eating grain-free food and seems completely normal, schedule a routine visit. Bring the food label or a photo of it. Your veterinarian can review the diet, check your dog's heart with a stethoscope, and decide whether further testing is needed. If your dog has symptoms, act faster. Coughing, especially at night, labored breathing, fainting or collapse, a distended belly, or unusual weakness and exercise intolerance are reasons to call your veterinarian the same day. These can be signs of heart disease, and early action matters. For a detailed list of warning signs, see [Dog Heart Disease: Recognizing the Early Signs and Knowing When to Act](/knowledge/veterinary-medicine/senior-and-chronic-care/dog-heart-disease-early-signs). If your dog collapses, struggles to breathe, or cannot stand, treat it as an emergency and go to the nearest veterinary emergency hospital now. For diet-related questions about a specific food, your veterinarian is the right first call. If you are concerned your dog ate something toxic, contact the ASPCA Animal Poison Control Center at (888) 426-4435 or the Pet Poison Helpline at (855) 764-7661. There may be a consultation fee. ## Limitations and When to Contact a Veterinarian The research on grain-free diets and DCM is still evolving. Some studies show a link, and some do not [6][2][3]. That uncertainty is exactly why your dog's individual situation needs a veterinarian's eyes. No article can tell you whether your specific dog's specific food is safe. Contact your veterinarian the same day if your dog has a new cough, seems winded on normal walks, tires more easily than usual, or has fainted. These can be early signs of heart disease. Go to an emergency hospital immediately if your dog collapses, breathes with obvious effort while resting, has a blue or gray tint to the gums, or cannot be roused. Schedule a routine visit if your dog eats grain-free food and has no symptoms. Ask about diet review, a heart listen, and whether taurine testing or an echocardiogram makes sense for your dog's breed and age. ## Frequently Asked Questions ### Does grain-free food cause heart disease in dogs? It can contribute to a form of heart disease called diet-associated DCM in some dogs, but it does not cause it in every dog. The FDA reported a link between grain-free, boutique, and exotic meat diets and DCM, including in breeds without genetic risk [1]. Some controlled studies found no cardiac changes in healthy dogs eating grain-free food, so the response appears to vary by dog and by diet [2]. ### Which ingredients in grain-free food are the concern? Legumes are the main focus, especially peas and lentils, along with potatoes used in place of grains [1][3]. These ingredients can be low in the amino acids a dog needs to make taurine [1]. A 2025 review found the strongest link with legume-rich diets [3]. ### Can diet-associated DCM be reversed? Often, yes. Many affected dogs improved clinically and functionally after dietary changes and treatment [3]. Returning a dog to a balanced diet with grains such as corn has been reported to reverse this type of DCM [1]. Your veterinarian will guide the timing and any additional treatment. ### Should I switch my dog off grain-free food? Talk to your veterinarian before changing diets, especially if your dog is healthy and doing well. If you do switch, transition slowly over about a week to prevent digestive upset. If your dog has heart symptoms, call your veterinarian right away instead of waiting. ### Are grains bad for dogs? No. Grains do not increase your pet's risk of skin or food allergies [1]. Many grain-free diets are marketed as hypoallergenic, but true food allergies usually involve a protein source. A grain-inclusive diet is a reasonable choice for most dogs and is often recommended when diet-associated heart concerns are on the table [1]. ## Related Articles - [Grain-Free Dog Food: Should Owners Be Concerned?](/knowledge/veterinary-medicine/nutrition/grain-free-dog-food) - [Grain-Free Diet for Dogs: DCM Link FDA Warning and Safe Alternatives](/knowledge/veterinary-medicine/nutrition/grain-free-diet-for-dogs-dcm-link-fda-warning-and-safe-alternatives) - [Dog Heart Disease: Recognizing the Early Signs and Knowing When to Act](/knowledge/veterinary-medicine/senior-and-chronic-care/dog-heart-disease-early-signs) - [Dog Kidney Disease Diet](/knowledge/veterinary-medicine/nutrition/dog-kidney-disease-diet) - [Safe Foods For Diabetic Dogs](/knowledge/veterinary-medicine/toxicology-and-food-safety/safe-foods-for-diabetic-dogs) - [Diet Dog Food](/knowledge/veterinary-medicine/nutrition/diet-dog-food) ## References 1. [Grain Free Diets For Pets](https://www.petpoisonhelpline.com/uncategorized/grain-free-diets/). Pet Poison Helpline. 2. [Different carbohydrate sources in dog foods supported overall health and cardiac function: an 18-mo prospective study in healthy adult dogs](https://pubmed.ncbi.nlm.nih.gov/40642821/). Journal of animal science, 2025. 3. [Role of Diet as a Predisposing Factor for Dilated Cardiomyopathy in Dogs: A Narrative Review](https://pubmed.ncbi.nlm.nih.gov/41295744/). Veterinary sciences, 2025. 4. [Responses in randomised groups of healthy, adult Labrador retrievers fed grain-free diets with high legume inclusion for 30 days display commonalities with dogs with suspected dilated cardiomyopathy](https://pubmed.ncbi.nlm.nih.gov/35484585/). BMC veterinary research, 2022. 5. [A commercial grain-free diet does not decrease plasma amino acids and taurine status but increases bile acid excretion when fed to Labrador Retrievers](https://pubmed.ncbi.nlm.nih.gov/32832860/). Translational animal science, 2020. 6. [Multiple Modelling Methods Suggest That Grain-Free Diets Are Not Predictive of New Owner-Reported Cardiac Diagnoses Over Two Years in the Dog Aging Project, Despite Owner Misclassification of Diet](https://pubmed.ncbi.nlm.nih.gov/42749338/). Veterinary medicine and science, 2026. 7. [Diet-induced cardiac dysfunction and impaired cognitive performance in Beagles](https://pubmed.ncbi.nlm.nih.gov/41817417/). American journal of physiology. Regulatory, integrative and comparative physiology, 2026. 8. [Grain-Free Diets for Dogs and Cats: An Updated Review Focusing on Nutritional Effects and Health Considerations](https://pubmed.ncbi.nlm.nih.gov/40723483/). Animals : an open access journal from MDPI, 2025. ## Further Reading - [ASPCA Animal Poison Control Center](https://www.aspca.org/pet-care/animal-poison-control) - [ASPCA: People Foods to Avoid Feeding Your Pets](https://www.aspca.org/pet-care/aspca-poison-control/people-foods-avoid-feeding-your-pets) - [U.S. Food and Drug Administration: Potentially Dangerous Items for Your Pet](https://www.fda.gov/animal-veterinary/animal-health-literacy/potentially-dangerous-items-your-pet)