Federal health officials have identified 16 dog food brands that may be linked to a mysterious rise in canine heart disease, leading to warnings by veterinarians about popular “grain-free” diets.
The Food and Drug Administration in a report released Thursday called the increase “puzzling” after reviewing more than 500 recent cases of canine dilated cardiomyopathy, or DCM. In nearly all of the cases, the dog had been regularly eating a mostly grain-free product, it said.
The majority of those products came from the brands 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.
Most cases involved dry dog food formulations but raw, semimoist and wet foods were also included. Nearly all of the meals were grain-free and contained peas and/or lentils. Nearly half contained potatoes and/or sweet potatoes.
Golden retrievers were the most common breed affected, though the FDA cautioned that it had observed a reporting bias for the dog breed due to breed-specific social media groups and activities that raised awareness of the issue and urged owners and vets to submit reports to the FDA. Cases involving cats were also studied, though there were only 14 reported.
Though the cases have some strong similarities, exactly what is causing DCM among them remains unknown.
“Another puzzling aspect of the recent spike in DCM cases is that they have occurred just in the last few years. The FDA is working with the pet food industry to better understand whether changes in ingredients, ingredient sourcing, processing or formulation may have contributed to the development of DCM,” the FDA said.
The FDA launched an investigation into DCM’s potential ties to dog food in July 2018 following an uptick in reported DCM cases that included breeds that are not typically prone to the heart disease. Of the 560 DCM cases reported to the FDA, 119 of the dogs have died, it said.
Several of the brands have released statements defending their products and noting that the FDA’s investigation remains ongoing.
“To date, the FDA still has not found any science-based causes to link grain-free diets — including Taste of the Wild — to DCM. As they note, it is a complex issue with numerous factors to consider. We continue to monitor this issue closely and support ongoing research efforts,” Taste of the Wild said in a statement on Facebook.
Though the FDA is not urging the public to discontinue use of the brands, some veterinarians are calling the “grain-free” diet an unnecessary fad that should be reconsidered.
“The whole grain-free thing is a popular myth,” John de Jong, president of the American Veterinary Medical Association, told The New York Times. “If they look at the dogs’ relatives in the wild, like coyotes, wolves and hyenas, they live on their prey. Those animals they prey on are typically herbivores, so they are ingesting grains anyway.”
Dr. Lisa Freeman, a veterinary nutritionist and researcher with the Cummings School of Veterinary Medicine at Tufts University, has also called grain-free diets largely unnecessary. She further warned against small, boutique companies and products offering exotic ingredients.
“The fact is that food allergies are very uncommon, so there’s no benefit of feeding pet foods containing exotic ingredients,” she stated in a past blog post about the potential link between DCM and a dog’s nutrition. “And while grains have been accused on the internet of causing nearly every disease known to dogs, grains do not contribute to any health problems and are used in pet food as a nutritious source of protein, vitamins, and minerals.”
Freeman advised switching from a small pet food manufacturer ― which she said may be better at marketing than nutrition and quality control ― to one that meets extensive quality control and testing.
Freeman offers this online guide on how to select your dog’s food.
Dr. Bruce Kornreich, a veterinary cardiologist in the department of clinical sciences at the Veterinary College of Cornell University and associate director of the Cornell Feline Health Center, also urged this, telling NBC News that consumers should select a food that’s “produced by a company with a long-standing history.”