Update on Grain-Free Diets for Pets

Sep 03, 2019

Update on Grain-Free Diets for Pets

New pet foods often mirror human dietary trends, and the recent surge in low-carbohydrate and gluten-free diets is no exception. Grain-free options fill pet store shelves, leaving many pet owners to question whether they should stick with a traditional food or try a new variety. Since it seems like more pet foods are made without grains than with them these days, you may be feeding your pet a grain-free diet without even realizing it. Unfortunately, recent evidence suggests that grain-free diets may do more harm than good to some pets. With so many different new diet choices, it can be difficult for pet owners to know what is best for their beloved companion, and we want to ensure you have the latest information to help you choose a diet that is well-suited for your pet’s lifestyle and long-term health.


What Are Grain-free Pet Diets?

Until recently, most dog and cat foods were manufactured with grains, such as corn or wheat, as their main carbohydrate source, but grain-free varieties are formulated with alternative carbohydrate sources, such as peas, lentils, or potatoes. Although swapping one carbohydrate source for another sounds harmless, newer diets are not backed by decades of research and proven health benefits that traditional ingredients provide. In addition, recent evidence suggests that grain-free diets may actually cause dilated cardiomyopathy (DCM), a life-threatening heart disease in dogs. 


What Is Dilated Cardiomyopathy in Dogs?

DCM causes a pet’s muscular heart walls to become weakened. The high pressure of blood flowing through the heart causes the walls to become thinner, and the heart chambers to become enlarged. Overall, the heart becomes dilated, and cannot contract as forcefully to pump sufficient blood volume, with subsequent progression to congestive heart failure and death. Historically, DCM diagnosis has been mainly limited to genetically predisposed dog breeds, such as Doberman pinschers, Great Danes, and Irish wolfhounds; however, a recent significant increase of DCM development in other dog breeds has raised suspicion that grain-free diets may be the cause. 

Heart Conditions Caused by Grain-free Diets

Assuming that a simple dietary change could cause a life-threatening heart disease may seem like a stretch, but dietary influence on heart disease development was demonstrated in the 1980’s, when cats fed a taurine-deficient diet were found to develop DCM. After this important finding, cat foods were  formulated with a specific amount of the essential amino acid, and feline DCM cases dramatically decreased. However, whether taurine plays a role in DCM development in dogs fed grain-free diets is unclear. Whereas cats must take taurine in through their diet, dogs can synthesize taurine from the amino acids methionine and cysteine, so a deficiency-related cause seems less likely. 


What Is Being Done to Determine Whether Grain-free Diets Cause DCM in Dogs?

In 2018, the Food and Drug Administration (FDA) announced a formal investigation into the potential link between grain-free pet foods and DCM development in dogs. Since DCM is not a reportable disease, the number of dogs diagnosed prior to the investigation is not available; however, evidence suggests that a significant increase has occurred in the last several years. Of the 560 recent canine DCM cases reported to the FDA, over 90% of the affected dogs were fed a grain-free diet, and in some cases, more than one pet in a household was diagnosed.


So far, a direct cause for increased canine DCM diagnosis has not been identified. The FDA has analyzed many of the diets fed to dogs who developed DCM, and they all contain adequate taurine, methionine, and cysteine levels. Protein, fat, moisture, fiber, and starch levels have also been measured, with no obvious abnormalities. The alternative carbohydrate sources added to grain-free pet foods—mainly peas and lentils—are being investigated as a possible cause, as are possible changes in ingredient sourcing or processing. The FDA investigation is ongoing, and grain-free foods will continue to be analyzed to determine whether they are a cause of DCM in dogs. 


If you have questions about your dog’s diet, or about grain-free diets and a possible link to DCM, speak with your family veterinarian. 


Veterinary Professionals