(Aug. 5, 2025) — In this chapter about pet diets, I’d like to explore whether grain-free diets are actually better for our pets – or is it just clever marketing?

Since the rise of the grain-free trend 12-15 years ago, we’ve seen an unexpected and potentially serious consequence emerge in some dogs.

Certain ingredients – specifically a group of crops known as pulse legumes – have been quietly replacing grains in many pet foods over the last two decades. These include peas, lentils, chickpeas and similar ingredients that have been increasingly used as carbohydrate sources rather than traditional grains such as rice, barley and oats etc., particularly in diets marketed as grain-free.

This shift began mostly in smaller, “boutique” pet food companies that were also experimenting with novel proteins. These diets often excluded traditional grains in favor of pulse legumes, sweet potatoes and potatoes. Interestingly, this change coincided with a drop in global demand for pulse legume crops, especially from India, prompting the pulse industry to seek new markets – pet food being among them.

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“Grain-free” became a buzzword, and soon these formulations made their way into big-name brands, including those sold at Costco and other mainstream retailers.

But around 2017, veterinarians started noticing something concerning. Dogs – many of them non-typical breeds for heart disease – were being diagnosed with dilated cardiomyopathy (DCM). This is a serious condition in which the heart becomes enlarged and weakened, reducing its ability to pump blood effectively.

While certain large breed dogs like Dobermans and Great Danes have a known genetic predisposition, what was alarming here was the number of atypical breeds being affected. A common thread was that many were eating grain-free diets rich in legumes and potatoes.

This trend became so concerning that in July 2018, the Food & Drug Administration (FDA) issued a public alert, acknowledging a possible link between certain grain-free diets and the possible development of nutritionally mediated DCM. The government asked veterinarians to begin reporting cases, including information on diets.

By June 2019, an update showed that most reported cases involved diets from just a handful of companies. Acana, Zignature and Taste of the Wild topped the list, though 13 additional brands were also implicated. Since that time, studies trying to identify the cause have been conflicting.

It’s important to note that this is a complex issue, and no single ingredient or brand has been definitively proven to cause DCM. But evidence continues to mount suggesting that diets high in pulse legumes and potatoes – particularly when they dominate the ingredient list – may somehow interfere with nutrient absorption or metabolism in ways that impact heart function.

What we do know is this: In many dogs diagnosed with DCM and fed diets highly concentrated in pulse legumes and/or potatoes or sweet potatoes, when their diets were changed to a more traditional diet, many dogs showed dramatic improvement or even full reversal of their heart condition. In veterinary medicine, that kind of turnaround is rare and gives us strong clues that diet may be playing a causative role.
So, what should pet owners do?

First, don’t panic if your dog is eating a grain-free diet. But do take a moment to read the ingredient list. If legumes or potatoes are listed in the first five ingredients, consider speaking to your veterinarian about switching to a more traditional diet, particularly one with the Association of American Feed Control Officials (AAFCO) feeding trial data and formulation oversight by board-certified veterinary nutritionists.

Second, remember that grains are not inherently bad for dogs. In fact, whole grains such as brown rice, barley, and oats provide valuable nutrients and fiber. The notion that grains are harmful is a marketing message, not a medical one.

The FDA continues to investigate this issue and has not issued recalls. But they have maintained communication with veterinary cardiologists and nutritionists across the country. The present recommendation is to exercise caution with diets that contain exotic ingredients or that were formulated without veterinary nutritionist oversight.

As always, if you have concerns about your pet’s diet or heart health, talk to your veterinarian. And if you’re curious about formulating a homemade or specialized diet, consult through your vet with a board-certified veterinary nutritionist who can ensure it meets your dog’s specific needs.

Email questions and comments for Micki McCabe Walls to drmccabevet@gmail.com