Unconventional dog foods suspected in heart disease

Investigators scrutinize grain-free kibble with exotic proteins

September 4, 2018 (published)
By Edie Lau

Labrador Retrievers — Pippin (left) and Fuji (right)
Photo by Lloyd Taplin
Pippin (left) and Fuji were active dogs until last year, when both were diagnosed with the same heart condition, dilated cardiomyopathy. Fuji, then 9, and Pippin, 4, had been on grain-free diets owing to allergies. Whether diet is a factor in cases like theirs is a focus of urgent research. Fuji is taking several heart medications now; Pippin died last September.

Fuji seemed her usual fun-loving doggy self the day Lloyd Taplin took the Labrador retriever outside their home in Ohio for a game of fetch. But very quickly, Taplin realized something wasn't right.

"I threw the ball once, she brought it back and just melted in a puddle at my feet," Taplin recounted.

Up to that point, Fuji had been active and healthy, apart from having skin allergies. After collapsing in the driveway, Fuji, then age 9, was able to get up woozily. Taplin rushed the dog to an emergency veterinary hospital, where she was diagnosed with a serious heart condition called dilated cardiomyopathy, or DCM.

DCM isn't rare in dogs but typically, it's seen in particular breeds, usually large ones. Doberman pinschers. Great Danes. Newfoundlands. Boxers. Irish wolfhounds. Cocker spaniels (an exception to the size rule-of-thumb). Labrador retrievers aren't on the usual-suspect list.

It turns out that Fuji's case is among a recent spate of canine DCM diagnoses not explained by heritage. Instead, the common thread is diet: Affected dogs have been on narrow diets of commercial dry foods that are grain-free and/or contain exotic meat proteins and/or a limited mix of ingredients, particularly potatoes, or legumes such as lentils or peas.

Fuji ate a kibble consisting primarily of kangaroo and lentils. A second Lab in the same household, 4-year-old Pippin, also had allergies and ate the same food. In July 2017, seven months after Fuji's diagnosis, Pippin started coughing. Her veterinarian detected a heart murmur and recommended she see a cardiologist.

Taplin scheduled Pippin at the same time that Fuji was due for a follow-up visit, two months later. In retrospect, Taplin said, "We were really stupid." While Pippin seemed OK in July, still able to run, by August, she was coughing badly. Taplin and her husband took the dog to the cardiologist then, but it was too late. Pippin died in September.

Veterinary cardiologists and nutritionists researching the relationship between diet and dilated cardiomyopathy in dogs recommend that veterinarians with suspected cases take these steps:

Hundreds of reports

As of Aug. 24, the U.S. Food and Drug Administration had received reports of about 200 cases of dogs with heart disease potentially related to diet. Of those, 140 have diagnoses of DCM, according to Dr. Martine Hartogensis, deputy director of the FDA Center for Veterinary Medicine Office of Surveillance and Compliance.

The FDA posted an alert about the suspected association between food and the heart condition on July 12, after being notified by veterinary cardiologists that something was amiss.

The agency checked its log of pet food complaints. "Sure enough, we had about 25 to 30 cases in our database," Hartogensis said in a telephone interview.

In its public notification, the agency elaborated: "Diet in cases reported to the FDA frequently list potatoes or multiple legumes such as peas, lentils, other 'pulses' (seeds of legumes), and their protein, starch and fiber derivatives early in their ingredient list, indicating that they are the main ingredients. Early reports from the veterinary cardiology community indicate that the dogs consistently ate these foods as their primary source of nutrition for time periods ranging from months to years. High levels of legumes or potatoes appear to be more common in diets labeled as 'grain-free,' but it is not yet known how these ingredients are linked to cases of DCM."

DCM is a disease resulting in an enlarged, weakened heart that is unable to pump blood efficiently. Often progressing over time, the condition can cause fluid buildup or sudden death. Dogs with DCM may tire quickly, cough, and have a labored and increased rate of breathing. More dramatic clinical signs are episodes of sudden weakness, fainting or collapse.

Although the link between DCM and diet was — and continues to be — undefined, Hartogensis said it was compelling enough that the FDA believed alerting the veterinary community at large and the general public was warranted.

"Veterinary cardiologists were very concerned," she said. "They said, 'Please do something. We've seen enough of these cases that we think something is going on, and we want people to be aware of it.' " She added, "Lentils, potatoes, these kinds of ingredients have exploded in the market."

VIN News Service photo
Pet foods labeled as grain-free have become ubiquitous.

Grain-free is all the rage

Grain-free and "limited ingredient" pet foods are so popular that in stores such as Petco, one of the largest pet retailers in the country, such formulations dominate the central aisles. Traditional recipes containing grains such as corn and wheat are relegated to the outer realm.

"A significant portion of consumer demand is for grain-free, and that's reflected in both our online and in-store assortments," Dr. Whitney Miller, Petco's director of veterinary medicine, said by email.

According to a blog post, "Pet food ingredients: What's hot and getting hotter?" grain-free pet foods claimed 43 percent of the pet specialty market in 2017, with $3.4 billion in sales. (The pet specialty channel comprises mainly pet stores. It doesn't include mass-market, online or grocery channels.)

Pet-food makers say the rise of grain-free varieties during the past 10 years is fueled by pet owners' desire to style their pets' eating habits after their own. "Many people today have become increasingly interested in their own diet, following trends such as lower-carb diets, and their food and nutrition philosophies carry over when selecting food for their four-legged family members," Dana Brooks, president and CEO of the trade group Pet Food Institute, said by email.

Past food-associated diseases

Asked whether any pet food makers who invest heavily in grain-free formulations are considering shifting to more conventional blends, in light of the health concerns, Brooks replied: "It is important to note that the FDA has not recommended any recalls or advised any dietary change for healthy pets — their investigation is in its early stages .... PFI members also are investigating any possible links [between diet and DCM in dogs not predisposed to the condition] and are carefully reviewing their formulations to assess and ensure nutritional adequacy."

To date, news about the potential problem with grain-free diets hasn't altered consumer buying patterns, according to Miller at Petco. "We've seen no measurable change in demand since the FDA alert in July," she said.

Confounding factors

Because multiple brands are involved in suspect cases, researchers and the FDA are reluctant to publicly name names. Furthermore, evidence doesn't suggest that any particular ingredient needs to be completely avoided. The issue is proportion, not presence. "Those ingredients [such as potatoes and peas] have been in pet foods for years, 30, 40 years," Hartogensis said. "It's the amount that has changed."

At first, the culprit generally appeared to be grain-free formulations, but understanding of the problem is evolving rapidly. Researchers say now that identifying the problem as grain-free diets is at once too narrow and too broad.

Trying to more accurately characterize the issue, Dr. Lisa Freeman, a veterinary nutritionist at Tufts University, coined the term "BEG" diet, for boutique, exotic and/or grain-free. "I think all of those are suspect at this point," Freeman said.

Exotic diets have unusual meats such as kangaroo, alligator, bison, venison and the like.

"We don't know much about the nutritional value of those protein sources like we do chicken and beef," observed Dr. Darcy Adin, a veterinary cardiologist who is part of a team at North Carolina State University working on the puzzle. "So that's one potential cause."

At the same time, grain-free formulations aren't all implicated. "It doesn't seem to be that all grain-free diets are represented in these [affected] dogs," Adin said. Another confounding factor, she said, is the fact that "the majority of foods on the shelves are grain-free."

It could be, Adin said, that affected dogs have a predisposition to developing heart disease on particular diets.

A further possibility is that a high content of legumes such as lentils and peas somehow reduces bioavailability of other nutrients, or causes an interaction among nutrients that leads to disease, she said.

The complicated role of taurine

One nutrient deficiency most associated with DCM is that of taurine, a sulfur-containing amino acid found abundantly in meat. Veterinarians discovered 30 years ago that the majority of cats with DCM were taurine-deficient as a result of eating any of several brands and formulations of commercial cat foods. Giving the cats taurine supplements cured the disease. Changing the formulation of cat foods to include more taurine largely eliminated the disease. Today, DCM in domestic cats is rare.

(Among reports the FDA has received of potentially diet-related DCM in pets are three reports involving seven cats. The agency said the causes in those cases, logged in 2015 and 2016, were undetermined.)

In dogs, the role of taurine in DCM is unclear. Unlike cats, dogs can synthesize taurine from methionine and cysteine, common sulfur-containing amino acids found in lots of foods. Consequently, no industry standards exist for taurine supplementation in dog foods.

Researchers attempting to discern the role of taurine in the development of typical cases of DCM found that "the vast majority of dogs with DCM had normal taurine levels," according to a Morris Animal Foundation article.

However, a few breeds have been found to be susceptible to developing DCM related to taurine deficiency: cocker spaniels, Newfoundlands and golden retrievers.

Among recent cases of DCM in atypical breeds, changing the diet and adding taurine has improved or reversed the heart disease in many instances. That's true even for dogs who didn't present with low taurine levels, said Adin, who offered an example of seven patients she and her colleagues followed. After the dogs were changed to a grain-based diet and given taurine supplements, they showed significant improvement in three to nine months, she reported. (Whether the improvement came about because of the added taurine, the different diet, or both is an open question.)

While taurine might be a factor in some cases of DCM, Freeman cautioned against assuming it is true of all cases. "There are dogs with taurine deficiency, both typical and atypical breeds, but there are also dogs, both typical and atypical breeds, that do not have taurine deficiency," she said.

"Then, there are the typical breeds of dogs with DCM that has nothing to do with diet but is the result of their genetic predisposition," she said.

At the same time, DCM in individual members of those typical breeds could, in fact, be diet-related. "We saw a doberman [a typical breed] last week that had taurine deficiency," Freeman said. "His condition is improving with diet change and taurine supplementation."

Which food to give?

Millie, a 3-year-old Boston terrier
Photo courtesy of Brynn McGlinchey
Millie, a 3-year-old Boston terrier in Connecticut, was diagnosed in July with dilated cardiomyopathy. She ate a grain-free kibble composed largely of lentils and venison for most of her life. Whether her heart condition is related to the diet is uncertain.

Tracy McGlinchey, a pet owner in Connecticut, has been reading up on dietary factors in DCM since her 3-year-old Boston terrier, Millie, was diagnosed in July. The first sign that something wasn't right surfaced the weekend after the Independence Day holiday, when Millie developed a random dry cough. "Think: cat with furball," McGlinchey said. "Nothing terrible. You half ignore it."

On Monday, McGlinchey's 16-year-old daughter noticed Millie breathing fast and shallow. They took the dog to the veterinarian. An X-ray revealed an enlarged heart. An immediate trip to the emergency hospital for an echocardiogram showed DCM.

Millie is prone to allergies, and McGlinchey believes potatoes are the cause, so she's always steered clear of foods containing potato. Millie seemed to do well on a kibble composed of venison, lentils, peas and chickpeas. When the brand was discontinued, McGlinchey switched Millie to a boutique blend the first four ingredients of which are anchovy meal, peas, fava beans and sunflower oil.

Now that Millie has heart disease, McGlinchey is diving deep into ingredient labels, and trying one diet after another. Millie likes them all, but McGlinchey hasn't found one that she loves.

"Finding grained foods is challenging," she said. "Everything is grain-free. And if it doesn't have grains, then there's a lot of potatoes. And the peas. It's crazy."

She's been searching in pet stores rather than grocery stores, which are more likely to stock traditional brands, because buying pet food at the supermarket is "almost embarrassing," McGlinchey said, half laughing at herself. "Like buying your kids a soda."

She understands that the grain-free movement is fed by marketing. She said, "Who says dogs shouldn't have grains?"

Freeman, the Tufts University veterinary nutritionist, said grains are perfectly fine ingredients. "Grains do not contribute to any health problems, and are used in pet food as a nutritious source of protein, vitamins and minerals," she said.

While many pet owners may feed grain-free and/or limited-ingredient formulations in an attempt to control allergies, the pet might not actually be allergic to a food or foods, according to Freeman. It might be allergic to pollen, molds and/or dust mites instead, she said.

Even if a dog with skin or gastrointestinal problems gets better on a different diet, that doesn't mean that the improvement is attributable to a change in ingredients. Changing the diet brings changes in fat level, fiber level, fiber type and digestibility, too, Freeman noted. "While owners commonly think it's the ingredients that helped, many other factors also changed that are more likely to have caused the improvement," she said.

Millie's case has caused her veterinarian, Dr. Neil Marrinan, to change his ways when it comes to talking about diet with dog owners. Earlier in his career, he would advise them to feed a variety of foods, regularly changing brands and ingredients. After awhile, although his opinion remained firm, he stopped offering it. "People [have] ... a preconceived idea of what they want to feed their dog, and [they] come to the doctor for validation," he said. "Unless I heard something that seemed out of the ordinary, I would avoid commentary."

No more. "It got out of hand, these narrow-cast diets," Marrinan said. "It's cause for us to say, 'This is not good.' "

He's back to speaking up now. His advice: "I recommend varying the diet to include grains, with meat as the first ingredient."

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