Grain-Free Diets Possibly Linked to Heart Disease in Dogs

Laurie Anne Walden, DVM

You may have read recent news reports about a possible association between grain-free diets and heart disease in dogs. Here’s what we know about this issue so far.
 
In July 2018, the US Food and Drug Administration (FDA) notified the public that they were investigating reports of dilated cardiomyopathy in dogs eating diets whose main ingredients were legumes (such as beans, peas, and lentils) or tubers (potatoes and sweet potatoes). These ingredients are common in diets labeled “grain free.”
 
Dilated cardiomyopathy is a disease of the heart muscle. In this disease, the heart chambers enlarge and the chamber walls become thinner and weaker. Patients may develop a murmur and an irregular heartbeat. If untreated, the condition leads to heart failure and death. Symptoms, which often don’t appear until the patient is in heart failure, include decreased energy, coughing, and episodes of collapse.
 
The causes of dilated cardiomyopathy are not fully known, but several factors have been implicated. The disease is thought to have a genetic link; it’s familial in Dobermans, boxers, and other large breeds. In cats and sometimes in dogs, it is also associated with dietary deficiency of the amino acid taurine.
 
Taurine is not considered an essential dietary nutrient for dogs. Normally dogs (unlike cats) can synthesize taurine from other nutrients in their diets. But some dogs, notably golden retrievers and Cocker spaniels, do develop taurine deficiency that leads to dilated cardiomyopathy. The dogs with dilated cardiomyopathy in the recent reports were of various breeds, not just the breeds considered typical for dilated cardiomyopathy.
 
Some of the dogs with dilated cardiomyopathy who were eating grain-free diets had normal blood taurine levels, so simply adding taurine to the diet might not solve the problem. Dr Lisa Freeman, a veterinary nutritionist at Tufts University, has suggested that changes in how the body processes taurine could lead to a functional taurine deficiency even if levels of taurine in the diet and the blood are normal. A high proportion of legumes in the diet could affect the way a dog’s body metabolizes amino acids (by altering gut bacteria, for instance).

Other explanations of how grain-free diets could be connected to dilated cardiomyopathy have been proposed, although most are still speculative. Taurine deficiency could potentially result from increased excretion of taurine in feces. A diet with legumes and tubers as main ingredients could be deficient in nutrients dogs need to make taurine. Other ingredients, like exotic protein sources, could also be associated with dilated cardiomyopathy, according to Dr Freeman.
 
At this point, the potential link between grain-free diets and dilated cardiomyopathy is not clear. The FDA is continuing to investigate, and cardiologists from several veterinary schools (including the University of California, Davis) are collecting more data.
 
What you should do
So far there is no evidence that legumes and potatoes in dog food cause a problem if they are not main ingredients—that is, if the food is a conventional diet that also happens to include these ingredients. If you’re currently feeding your dog a grain-free diet or one containing exotic ingredients (like kangaroo), talk to your veterinarian about the possible risks. Also ask your veterinarian if your dog really needs to eat that diet. For the vast majority of dogs, a grain-free diet has no benefit over a conventional diet.
 
Consult your veterinarian if your dog is showing symptoms of heart disease. If your dog has dilated cardiomyopathy, your veterinarian can test her blood taurine levels. Veterinarians and pet owners can report suspected cases of diet-associated dilated cardiomyopathy to the FDA through the online Safety Reporting Portal or by calling their state’s FDA Consumer Complaint Coordinator.

Photo by John Price on Unsplash

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