Grain-free pet food has been a huge trend in recent years. Marketing promises a "more natural" diet, but in 2018 the U.S. Food and Drug Administration (FDA) began investigating a possible link between grain-free diets and heart disease (DCM) in dogs. In this article we review what the science currently says — and what veterinarians recommend.
The FDA Investigation and Heart Disease
The FDA investigated hundreds of reports of dilated cardiomyopathy (DCM) — a heart disease in which the heart muscle weakens and the heart enlarges. What was concerning was that DCM also appeared in breeds not genetically predisposed to it, such as Golden Retrievers, Labradors and mixed breeds. Of the reported diets, over 90% were grain-free and 93% contained peas or lentils as main ingredients (FDA). However, the FDA has not established a causal link: according to the agency, the number of reports alone is not sufficient to prove a connection, and no new updates have been published since November 2022. The link between grain-free food and DCM therefore remains scientifically open — neither confirmed nor ruled out.
Does My Pet Need Grain-Free Food?
Probably not. The marketing claim that grains are merely "fillers" or a common cause of allergies is not supported by science. Dogs have evolved alongside humans for thousands of years and carry up to about 34 copies of the starch-digesting AMY2B gene (typically 4–34), while wolves usually have only 2 (Axelsson et al., Nature 2013). Thanks to this genetic adaptation, dogs digest cooked grains very efficiently. Grain allergy is also clearly less common than animal-protein allergy: the most common food allergens in dogs are beef (34%), dairy (17%) and chicken (15%), while wheat causes about 13%, corn 4% and rice 2% of cases (Mueller et al., 2016).
What About Cats?
Cats are carnivores and need plenty of animal protein. However, grain-free cat foods often replace grains with potatoes, peas or tapioca — meaning the carbohydrate content is practically the same or even higher. Studies show cats digest plant-based carbohydrates efficiently too: total starch digestibility is over 93%, ranging from about 94% to 99% depending on the ingredient (de-Oliveira et al., 2008). What matters most in cat food is adequate animal protein and taurine — not whether it is grain-free or not.
Veterinary Recommendation
Do not choose grain-free food without a medical reason. Avoid foods where peas, lentils or chickpeas are among the main ingredients. Choose food from established manufacturers that employ animal nutrition experts and conduct feeding trials (WSAVA recommendation). If you suspect a food allergy, contact your veterinarian — proper diagnosis is made through an elimination diet, not by randomly switching foods. If your pet currently eats grain-free food, discuss your options with your vet.
Sources
- U.S. Food and Drug Administration (FDA): Investigation into potential link between certain diets and canine dilated cardiomyopathy (DCM) — Questions & Answers. fda.gov
- Axelsson E. ym. (2013): The genomic signature of dog domestication reveals adaptation to a starch-rich diet. Nature 495:360–364. nature.com
- Mueller R.S., Olivry T., Prélaud P. (2016): Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats. BMC Veterinary Research 12:9. doi.org
- de-Oliveira L.D. ym. (2008): Effects of six carbohydrate sources on cat diet digestibility and postprandial glucose and insulin response. Journal of Animal Science 86(9):2237–2246. doi.org
- WSAVA Global Nutrition Committee: Guidelines on Selecting Pet Foods. wsava.org