Grain-free Diets and DCM

Are grain-free and gluten-free diets a suitable option for dogs and cats?

Grain-free and gluten-free diets can be appropriate for dogs and cats when formulated to meet complete and balanced nutritional requirements according to FEDIAF or AAFCO guidelines. The nutritional quality of a diet should be assessed based on formulation adequacy, amino acid balance, digestibility, ingredient quality, and feeding validation rather than the simple presence or absence of grains.

Gluten is a group of storage proteins naturally occurring in cereals such as wheat, barley, and rye. Compared to animal-origin proteins, gluten proteins generally have substantially lower digestibility and lower biological value for carnivorous species. Nevertheless, cereal-derived ingredients are widely used in extruded pet foods because of their technological functionality, including heat stability, binding properties, starch contribution, expansion during extrusion, and relatively low raw material cost.

Although healthy dogs and cats may tolerate gluten-containing ingredients without clinical issues, gluten and certain cereal components may contribute to adverse food reactions in susceptible individuals. Reported gluten-related disorders in companion animals include food hypersensitivity reactions, gluten-sensitive enteropathy, inflammatory bowel disease-like syndromes, and chronic enteropathies.^1,2

From a nutritional perspective, grains are not physiologically required for dogs or cats, provided the diet delivers appropriate levels of digestible protein, fat, carbohydrates, fiber, essential amino acids, fatty acids, vitamins, and minerals. Modern grain-free formulations commonly utilize alternative carbohydrate sources such as peas, lentils, chickpeas, potatoes, or tapioca together with higher inclusion of animal-origin ingredients. Legumes provide several nutritional benefits, including a relatively high content of protein and dietary fiber, a higher amylose-to-amylopectin ratio, and a lower glycemic index compared with cereals such as wheat, rice, and corn, as well as potatoes. Studies have shown that legume-containing diets may reduce postprandial glycemic and insulin responses, which may support metabolic health.^3,4 When properly formulated and quality controlled, grain-free and gluten-free diets can support normal health, digestion, and long-term nutritional adequacy in both dogs and cats.

Do current studies support a link between grain-free diets and DCM?

In 2018, the U.S. Food and Drug Administration (FDA) announced an investigation into reports of canine dilated cardiomyopathy (DCM) potentially associated with certain pet foods, including some grain-free diets containing high proportions of legumes such as peas, lentils, chickpeas, beans, and/or potatoes. Many reported cases involved breeds not classically predisposed to hereditary DCM, leading to increased scientific and media attention regarding possible dietary involvement.

However, the FDA case reports were observational in nature and did not establish causality. Importantly, cases of diet-associated DCM were reported in dogs consuming both grain-free and grain-inclusive diets. To date, no specific dietary ingredient or formulation characteristic has been conclusively identified as the direct cause of DCM⁵.

In 2020, a board-invited review published in the Journal of Animal Science evaluated the available evidence regarding diet-associated DCM. The authors concluded that existing studies contained important methodological limitations, including retrospective design, inconsistent diagnostic criteria, lack of suitable controls, incomplete dietary histories, and multiple confounding factors. The review concluded that available evidence was insufficient to establish a causal relationship between grain-free diets and DCM⁶.

The same year, the FDA participated in a scientific forum hosted by Kansas State University involving veterinary cardiologists, nutritionists, researchers, and industry experts to discuss current hypotheses surrounding non-hereditary DCM. Proposed mechanisms included taurine metabolism, sulfur amino acid availability, altered bile acid metabolism, carnitine dysregulation, ingredient interactions, and microbiome-related effects. No consensus causal mechanism specific to grain-free diets was identified.

More recent prospective feeding studies further challenge the hypothesis that properly formulated grain-free diets inherently impair cardiac health.

In a 2023 University of Guelph study, healthy adult Siberian Huskies were fed complete and balanced diets containing up to 45% peas and pea-derived ingredients for 20 weeks. Researchers observed no clinically relevant changes in echocardiographic measurements, cardiac biomarkers, sulfur amino acid status, or overall health parameters compared with grain-inclusive controls⁷.

Similarly, an 18-month prospective study published in 2025 demonstrated that dogs fed nutritionally complete grain-free and grain-inclusive diets with differing carbohydrate sources maintained normal cardiac function and taurine status throughout the study⁸.

Overall, current evidence does not support grain-free status alone as a proven risk factor for DCM. Current scientific understanding increasingly suggests that nutritional adequacy, amino acid balance, digestibility, ingredient quality, and manufacturer quality control are more relevant factors than the simple inclusion or exclusion of grains.

What is DCM?

Dilated cardiomyopathy (DCM) is a myocardial disease characterized by reduced cardiac contractility and dilation of one or both ventricles. The disease is most commonly diagnosed in medium and large breed dogs, including Dobermans, Great Danes, Boxers, Irish Wolfhounds, and Cocker Spaniels, although it may occasionally occur in small dogs and cats.

DCM is considered a multifactorial disease with potential genetic, metabolic, infectious, and nutritional contributors. In many patients, the exact etiology remains unidentified. The disease is typically progressive and may lead to congestive heart failure, arrhythmias, syncope, exercise intolerance, or sudden cardiac death. Clinical onset most commonly occurs between 4 and 10 years of age, with males generally affected more frequently than females.

References:

[1] Ralf S. Mueller, Thierry Olivry and Pascal Prélaud. Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats. BMC Veterinary Research, 2016 Jan 12;12:9. https://doi.org/10.1186/s12917-015-0633-8

[2] R. M. Batt, M. W. Carter and L. McLean. Morphological and biochemical studies of a naturally occurring enteropathy in the Irish Setter dog: a comparison with coeliac disease in man. Research in Veterinary Science, 1984 Dec;37(3):339-346. https://doi.org/10.1016/S0034-5288(18)31973-1

[3] J. L. Adolphe, M. D. Drew, T. I. Silver, J. Fouhse, H. Childs and L. P. Weber. Effect of an extruded pea or rice diet on postprandial insulin and cardiovascular responses in dogs. Journal of Animal Physiology and Animal Nutrition, 2015 Aug;99(4):767-76. https://doi.org/10.1111/jpn.12275Digital Object Identifier (DOI)

[4] A. C. Carciofi, F. S. Takakura, L. D. de-Oliveira, E. Teshima, J. T. Jeremias, M. A. Brunetto and F. Prada. Effects of six carbohydrate sources on dog diet digestibility and post-prandial glucose and insulin response. Journal of Animal Physiology and Animal Nutrition,2008 Jun;92(3):326-36. https://doi.org/10.1111/j.1439-0396.2007.00794.x

[5] FDA Investigation into Potential Link between Certain Diets and Canine Dilated Cardiomyopathy, December 23, 2022:

FDA does not intend to release further public updates until there is meaningful new scientific information to share. A count of reports of DCM in dogs submitted to FDA as of November 1, 2022, has been added to Questions & Answers: FDA’s Work on Potential Causes of Non-Hereditary DCM in Dogs. FDA has followed up on a subset of these reports, but is unable to investigate every report to verify or confirm the reported

information. While adverse event numbers can be a potential signal of an issue with an FDA regulated product, by themselves, they do not supply sufficient data to establish a causal relationship with reported product(s). FDA continues to encourage research and collaboration by academia, veterinarians, and industry. https://www.fda.gov/animal-veterinary/outbreaks-and-advisories/fda-investigation-potential-link-between-certain-diets-and-canine-dilated-cardiomyopathy

[6] Sydney R. McCauley, Stephanie D. Clark, Bradley W. Quest, Renee M. Streeter,1 and Eva M. Oxford. Review of canine dilated cardiomyopathy in the wake of diet-associated concerns. Journal of Animal Science, 2020, 1–20. https://doi.org/10.1093/jas/skaa155

[7] Pawanpreet Singh, Sydney Banton, Shari Raheb, James R. Templeman, Jennifer Saunders-Blades, Darcia Kostiuk, Janelle Kelly, Christopher PF. Marinangeli, Adronie Verbrugghe, Shoshana Verton-Shaw, Anna K. Shoveller. The Pulse of It: Dietary Inclusion of Up to 45% Whole Pulse Ingredients with Chicken Meal and Pea Starch in a Complete and Balanced Diet Does Not Affect Cardiac Function, Fasted Sulfur Amino Acid Status, or Other Gross Measures of Health in Adult Dogs. The Journal of Nutrition 153 (2023) 1461–1475. https://doi.org/10.1016/j.tjnut.2023.03.027

[8] Elizabeth M. Morris,1, Cheryl A. Stiers, Leslie B. Hancock, and Kathy L. Gross. Different carbohydrate sources in dog foods supported overall health and cardiac function: an 18-mo prospective study in healthy adult dogs. Journal of Animal Science, 2025, 103. https://doi.org/10.1093/jas/skaf225