Do grain-free diets cause heart disease in dogs?

The theory that grain-free dog food causes heart disease in dogs is a popular topic due to the increased incidence of diet-associated cardiomyopathy in recent years. You may be surprised to learn the veterinary community is still working to understand how grain-free feeding and heart disease are connected, if at all. Read on to find answers to questions such as:

• How does dilated cardiomyopathy affect dogs?
• Do grain-free dog foods cause heart disease?
• How do I know if my dog has dilated cardiomyopathy?
• How are dogs with diet-associated cardiomyopathy treated?
• What type of food should I give my dog?

Grain-free diets and other non-traditional diets have become popular with pet owners in recent decades. With the increased popularity of these diets, more cases of diet-associated cardiomyopathy are being reported in dogs. The specific connection between certain diets and diet-associated cardiomyopathy is complicated and leads to more questions than answers. Ongoing scientific studies aim to discover more about the relationship between grain-free foods and the disease process.

Dilated cardiomyopathy (DCM) is a cardiac disease that affects heart muscle function by decreasing the heart’s ability to pump blood. In DCM, the heart’s chambers expand and the cardiac walls begin to thin, causing heartbeat abnormalities, changes to overall cardiac function, and congestive heart failure. Canine DCM occurs for a number of reasons, including genetics, poisoning, infections, and nutritional deficiencies. In the past few years, the idea that diet-associated dilated cardiomyopathy is caused by grain-free diets has become a popular target of debate and misinformation online. This is due to an increase in diet-associated cardiomyopathy in dogs coinciding with increased popularity of grain-free diets combined with lack of scientific information about why rates of occurrence are rising.

Some boutique, exotic, and grain-free dog foods, or BEG diets, are associated with the onset of cardiac disease in some dogs. This association is complicated and most likely the result of multiple factors that require exploration in future studies. Not all BEG diets cause diet-related DCM in dogs, and not all dogs with DCM eat grain-free pet foods. DCM is one of the most common heart diseases in dogs, so a dog with DCM that is eating a BEG diet may not have developed the condition from the food at all.

The United States Food and Drug Administration (FDA) released a statement in 2019 that they are investigating the relationship between a dog’s diet and DCM. They reported that dogs fed primarily with grain-free dry kibble have higher rates of cardiac abnormality. This correlation, however, does not mean grain-free food is the cause of heart disease. There are many other contributing variables. For example, dry dog food is the most popular type of food dog owners choose, so the FDA’s data may be skewed. In addition, the FDA suspects that cases of diet-related DCM are underreported and biased, which makes the data unreliable.

Misinformation abounds, and articles that clearly state grain-free diets cause dilated cardiomyopathy are easy to find. Some dog groups on social media, especially concerning Golden Retrievers, are more vocal about the issue than others. The bottom line is there are gaps in scientific and veterinary knowledge concerning diet-associated cardiomyopathy that require results from current research and future study before conclusions about causation can be established.

What ingredients are linked to diet-associated cardiomyopathy in dogs?

Most of the foods in reported cases of diet-associated DCM contain high levels of legumes, also called pulse ingredients, such as peas, garbanzo beans, and lentils as the primary source of carbohydrates. Not all of these diets are entirely grain-free or a BEG diet. Legumes as a dog food ingredient have been on the market for decades without noticeably affecting cardiac function. These ingredients weren’t added to dog food in high proportions until grain-free diets became popular with dog owners. High levels of pulse ingredients are often found in dog foods labeled as:

• Grain-free diets
• Exotic or non-traditional diets
• Boutique or specialty diets

The only way to know if your dog food contains pulse ingredients is by reading the ingredients list. Foods that contain legumes like peas, chickpeas, and lentils as the only source of carbohydrates are more likely to contain higher pulse levels.

As a separate note, dogs eating homemade diets are at a greater risk of developing diet-associated DCM due to any of a number of nutritional deficiencies. Always consult a veterinary nutritionist before switching your dog’s diet to a homemade or non-traditional diet to ensure they are receiving adequate nutrition.

Canine dilated cardiomyopathy has multiple symptoms. Clinical signs of dogs with diet-associated DCM include:

• Lethargy
• Weakness
• Weight loss
• Coughing
• Difficulty breathing
• Exercise intolerance
• Abdominal distension
• Collapse
• Sudden death

Dogs with diet-associated DCM may not show every symptom on this list, and many of these clinical signs could be caused by other diseases. It is important to get a definitive diagnosis from a veterinarian to ensure proper veterinary care and prevent heart failure or sudden death. Clinical outcomes of DCM vary from dog to dog, especially when it is caused by diet.

Diagnosing a dog with dilated cardiomyopathy involves an echocardiogram, or ultrasound of the heart, to see the abnormally thin and dilated heart chamber walls. A veterinarian may refer your pet to a board-certified cardiologist for these tests. “Determining if DCM in a canine patient is related to diet is more difficult,” explains Dr. Jo Myers, a Vetster veterinarian. “Dogs with DCM typically undergo a full workup to look for genetic, toxic, or infectious causes. Learning more about the dog’s dietary history is also helpful, but there’s no specific test to show the diet is what caused heart disease. The outcome for dogs with diet-related DCM are good if their diet is changed and the condition is caught early. Other forms of DCM are more difficult to treat.”

Veterinary care for diet-associated DCM includes:

• Changing the diet
• Dietary supplementation
• Exercise restriction
• Heart medications

Dilated cardiomyopathy can progress to congestive heart failure and death. Sometimes sudden death is the only symptom. Once DCM shows severe symptoms or progresses to heart failure, the outcome is usually poor. Consulting a veterinary cardiologist for treatment may be beneficial.

There is no single “best” type of diet for dogs. Most dogs do just fine on any of a number of commercially available diets.  Just check to see that it has a nutritional adequacy statement, or AAFCO statement, on the label,” adds Dr. Myers. Foods with an AAFCO statement contain all of the essential nutrients a dog needs, including essential amino acids, carbohydrates, and protein. With a nutritionally complete diet, dietary supplements are not needed. Unless otherwise instructed by a veterinarian, avoiding diets with high levels of pulse ingredients may be best until more is known about the connection between DCM and diet. Keep in mind that grains are healthy for dogs and there was never a scientific basis for the popularity of grain-free diets in the first place. Grain allergies do exist, but are rare in dogs.

If you have questions about what diet is best for your dog, or if your dog is experiencing symptoms of DCM, you can consult an online vet today.

Are grain-free foods good for dogs?

Grain-free canine diets are not necessarily any better or worse than foods that contain grain. Grain is a perfectly satisfactory ingredient for use in dog foods. However, many dogs who developed dilated cardiomyopathy were eating grain-free diets containing high levels of legumes on their ingredient lists.

What is the healthiest dog food?

There is no such thing as the “healthiest” dog food. Any commercially available food that has a nutritional adequacy statement is nutritionally complete for dogs, making dozens of available foods perfectly healthy for dogs. Many boutique, exotic, or grain-free foods (BEG diets) do not have this statement. The choice of brand, flavor, or choosing between wet and dry foods is up to the owner and a dog’s preferences.

What ingredients in grain-free pet foods cause heart disease?

Researchers are still unsure exactly what factors and ingredients in a dog’s diet lead to DCM, and studies are ongoing. The underlying cause is most likely due to multiple factors, including an individual dog’s genetics. We do know that many of the reported cases of diet-associated cardiomyopathy occurred in dogs eating foods with large proportions of lentils, peas, chickpeas, and other legumes.

These ingredients have been safely included in dog foods for decades, but were used in larger amounts when grain-free foods became popular. The timing of this popularity coincided with increased incidence and reports of canine cardiomyopathy. It is important to note that any commercially produced dog food can have high levels of these ingredients. Dogs can develop DCM no matter what kind of diet they’re on, and not all cases of DCM are dietary in origin. Not all dogs who eat grain-free or other BEG diets develop cardiomyopathy, and dogs can develop DCM while eating grain-inclusive foods.

What should I do if my dog has cardiac disease from their food?

If your dog is showing symptoms of cardiac disease, consult a veterinarian. If they suspect your dog’s diet is a factor, a change in diet will be recommended. Canine DCM may also be treated with heart medications and exercise restriction. A veterinarian or veterinary cardiologist will also aid in the treatment of heart disease after a definitive diagnosis and ruling out symptoms from concurrent diseases.