Grain-free diets threatening dogs’ health

By Dr. Beth Leermakers

Grain-free dog food has been considered the gold standard for canine nutrition. Recently, however, grain-free diets have been linked to dilated cardiomyopathy (DCM), a serious and often fatal heart condition in dogs. Is a grain-free diet causing this serious medical condition? The Food and Drug Administration (FDA) is investigating whether diet and other factors are increasing pets’ risk of developing DCM. Cats can also develop DCM. 

DCM is characterized by an enlarged heart and thinning of the heart muscle that weaken the heart’s ability to pump blood. The disease tends to be progressive, eventually leading to heart failure. In the past, DCM has occurred primarily in middle-aged and older dogs, particularly large and giant breeds such as Dobermans, Great Danes and Irish Wolfhounds. The past few years, however, DCM has been occurring more frequently in dogs, affecting a wide variety of breeds. This suggests that genetics isn’t responsible for causing this disease.

The FDA has joined forces with diagnostic laboratories, veterinary cardiologists and nutritionists to study canine DCM cases. The FDA asked veterinarians to report any occurrences of DCM in dogs. At least 560 dogs with DCM have been reported. The FDA is studying these dogs’ blood tests, diagnostic findings (e.g., symptoms and ECG measurements), diet, and other factors, trying to determine what’s causing the disease.

The dogs with DCM range in age from puppies to adults and represent a wide variety of breeds. DCM has been reported most commonly in Golden Retrievers, Labrador Retrievers and mixed breeds. When the FDA examined the sick dogs’ diets, they discovered that more than 90 percent were eating a “grain-free” or “zero grain” diet. In these diets, peas or lentils replaced grains as the main ingredients. A smaller number of the grain-free diets contained potatoes or sweet potatoes as a major ingredient. Other components of the diet — protein source, carbohydrates, and starches — were not associated with DCM. According to the FDA, dogs with DCM had diets that were high in certain ingredients such as peas, chick peas, lentils and/or potatoes, which are typically found in grain-free diets. Some of the sick dogs were eating food that contained these ingredients but wasn’t grain-free. 

The investigators also examined whether low taurine (an amino acid that can’t be produced by the body and must be obtained from the diet) may be linked to DCM. The results were inconclusive. Just under 50 percent of the tested dogs had low taurine levels, while the others had normal levels. Studies have shown that Golden Retrievers may be genetically predisposed to taurine deficiency, which can lead to DCM. 

So far, the FDA’s strongest finding is that almost all of the DCM dogs were being fed a grain-free diet. Fortunately, nearly all the dogs recovered after they received heart medication and taurine supplements and switched to a diet that included grains. 

The FDA is still studying DCM in dogs. On their FAQ page, they state, “At this time, we are not advising dietary changes based solely on the information we have gathered so far.” If you’re concerned about your dog’s diet, or if your dog shows any symptoms of heart disease (coughing, breathing difficulties, weakness or collapse), consult your veterinarian.