A new report from the Food and Drug Administration makes navigating the pet food aisle more complicated for dog owners. As The New York Times reports, the FDA has linked 16 popular dog food brands to canine heart disease—many of which bill themselves as healthier options.

The FDA traced adverse cardiovascular symptoms in dogs to many grain-free pet foods that replace ingredients like wheat and corn with peas, lentils, legume seeds, or potatoes. The brands included in the study—listed in descending order of most related heart disease cases—included Acana, Zignature, Taste of the Wild, 4Health, Earthborn Holistic, Blue Buffalo, Nature’s Domain, Fromm, Merrick, California Natural, Natural Balance, Orijen, Nature’s Variety, NutriSource, Nutro and Rachael Ray Nutrish.

Products from these brands are often marketed as "wholesome," "high-protein," and "all-natural" alternatives to conventional dog food. But the new report from the FDA shows that a grain-free diet can be potentially harmful to a dog's health. Between January 1, 2014 and April 30, 2019, the FDA received 560 reports of canine dilated cardiomyopathy, a condition that's typically seen in larger dog breeds and can lead to heart failure. Of those cases, 119 of them were fatal. Canine dilated cardiomyopathy is believed to be partly genetic, but according to the administration, many of the dogs they studied were not genetically predisposed towards the condition. The likely culprit behind their diagnoses was diet.

"We understand the concern that pet owners have about these reports: the illnesses can be severe, even fatal, and many cases report eating 'grain-free' labeled pet food," the FDA stated in the report. "The FDA is using a range of science-based investigative tools as it strives to learn more about this emergence of DCM [dilated cardiomyopathy] and its potential link to certain diets or ingredients."

Makers of grain-free pet food claim that kibble made from corn and wheat doesn't reflect the diet of dogs' wild ancestors, and is therefore bad for them. Canine heath experts say this is a myth: Wild canids like wolves ingest grains in the stomachs of the herbivores they hunt. What's more, grains contain vitamins, minerals, and fiber that dogs can benefit from.

Regardless of a dog's diet, pet owners should be aware of the symptoms of canine dilated cardiomyopathy. A dog that exhibits decreased energy, coughing, difficulty breathing, and episodes of collapse should be taken to the vet as soon as possible.

[h/t The New York Times]