Grains of truth: Are fad diets harming pets?

The recent increase of a life-threatening heart condition among dogs—and the suspicion that it may be related to grain-free diets—has led pet owners to question what to feed their animals. The recent increase of a life-threatening heart condition among dogs—and the suspicion that it may be related to grain-free diets—has led pet owners to question what to feed their animals.

Pet owners face a perplexing variety of food choices for their animals. From national staples to obscure boutique brands, there are dozens of options, each trying to earn your loyalty. Pet diets, like those of humans, are subject to trends and fads with little nutritional basis. In recent years, the burgeoning market of grain-free foods has been particularly baffling. Their bags proudly declare the absence of ingredients like corn, rice, and wheat. Repeatedly faced with that messaging, it’s easy to see how consumers would come to believe these grains were worth avoiding.

For most dogs there is absolutely no benefit to eating a grain-free diet. There are exceptions for specific allergies, but dogs can develop allergies to nearly anything they eat, so it’s senseless that grains have been uniquely targeted. Simply put, it’s a fad perpetuated by savvy marketing. That kind of misdirection and manipulation annoys me—keeping pets healthy is my job, after all—but I’ve generally regarded these diets as harmless even if they were unnecessary.

Unfortunately, this may no longer be true. In recent years, a pattern of heart disease associated with these diets has emerged. Specifically, dogs are developing a life-threatening condition called dilated cardiomyopathy, where the chambers of the heart stretch out and lose their ability to contract effectively. The ailment is not necessarily rare in dogs, particularly among large and giant breeds, but the increased prevalence of DCM in dogs not historically prone to it prompted the FDA to investigate. It later issued a statement saying no definite link between grain-free diets and DCM has been found, but that the inquiry would continue.

It is unclear how these diets might be causing DCM, and it sadly isn’t limited to grain-free fare. Boutique brands whose offerings contain unusual or exotic ingredients (lentils, chickpeas, and certain meats, vegetables, and fruits) have been implicated. It is currently unknown whether these foods may be nutritionally deficient, incorporate some toxic ingredient, or are demonstrating another mechanism entirely.

It’s an established fact that cats are subject to DCM if their diets lack the amino acid taurine. Some dog breeds (like golden retrievers) show a similar tendency, and the initial suspicion was that their diets might be taurine deficient. If so, supplementation would have been a simple fix. But it is now clear this isn’t the case. The condition is being observed in many breeds, and testing has shown that their taurine levels are fine. So, we have a better sense of what the problem isn’t, but not what it is.

All of this has led to a great deal of confusion among pet owners and veterinarians alike, but the current consensus is that dogs should be fed a well-established, nationally recognizable brand unless there is a clear medical reason not to do so. So far, these foods haven’t been associated with DCM and are presumed safe.

I know how tin-eared this advice can sound, and I can see the skepticism on my clients’ faces when I offer it. They deliberately avoided large corporate brands and made their choices intending to offer their pets the best food, only to learn they may have accomplished the opposite. I hope that ongoing research will provide more nuance, but right now there are too many gaps in our knowledge, and sticking to mainstream brands is the only recommendation I can make for my patients in good conscience.

I find many pet owners are concerned about the prospect of returning to a diet that includes grains. Amidst all the confusion, the only consolation I can offer is that regardless of what any label suggests, there was never anything wrong with grains to begin with.

Dr. Mike Fietz is a small-animal veterinarian at Georgetown Veterinary Hospital. He has lived in Charlottesville since 2003, the same year he received his veterinary degree from Cornell University.