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Is Grain-Free Dog Food Linked to Heart Disease?

The FDA just dropped a bombshell on the dog food industry.

By warning of a possible link between grain-free dog food and canine heart disease.

It is still under investigation, but the implications are self-evident.

The rise of grain-free dog food

types-of-grains-excluded-from-dog-foods

BARF. Prey-model. Grain-free. Homemade. Freeze-dried raw.

These are just a few of the types of natural dog food that have gained massive popularity ever since the massive pet food recall of 2007. With exotic meat often included, many natural dog foods have a nutrient-dense ingredient list that can satisfy even the most discerning pet parent’s eyes.

Though canine nutrition remains a hot topic of debate overall, most dog owners can agree on one thing: We want the most nutritious, delicious, and species-appropriate diet for our furry best friends. For this reason, more and more dog owners have turned to commercial grain-free dog foods, which represented $3.4 billion in sales, or 43% of the U.S. market share in 2017.

However, on July 12, 2018, the U.S. Food and Drug Administration’s Center for Veterinary Medicine announced that it is working with its Veterinary Laboratory Investigation and Response Network (Vet-LIRN) to investigate a possible association between grain-free diets and dilated cardiomyopathy (DCM), a common heart disease in dogs.

What exactly happened . . .

CVCA, a group of 19 veterinary cardiologists who filed the initial report with the FDA, noted that the canine patients who developed DCM had one common factor – they were all on a grain-free diet.

The same group of veterinarians also conducted a survey of 150 patients who were recently diagnosed with DCM, and most of them were on grain-free diets.

Other veterinary cardiologists have noticed the same phenomenon.

Veterinarians at Tufts University and North Carolina State University have also seen increased rates of DCM in dog breeds such as shih tzus and beagle/lab mixes. These dogs were also being fed a grain-free, high-protein diet.

What is dilated cardiomyopathy?

Dilated cardiomyopathy (DCM) is a heart disease characterized by the degeneration of the heart muscle, particularly the wall of the left ventricle. This results in weakened contractions and enlargement, or dilation, of the heart.

An enlarged heart cannot pump blood as efficiently and the heart valves may leak, resulting in fluid buildup in the lungs and abdomen.

Clinical signs of DCM can be difficult to detect early on, but here are some signs that could indicate heart disease:

  • decreased energy or exercise intolerance
  • weakness
  • fainting
  • increased breathing rate
  • excess panting for level of activity
  • cough.

Abnormal heart rhythm caused by DCM can also lead to sudden death.

What causes DCM in dogs?

In the late 1980s, researchers found that taurine deficiency in cats was associated with DCM. When the cats were fed a diet with sufficient taurine, the researchers at the University of California, Davis showed that diet-related DCM was reversible.

It also showed that taurine is an essential amino acid for cats, which means that it cannot be synthesized naturally by cats. Essential amino acids must be supplied in an organism’s diet.

As obligate carnivores, cats must have meat included in their diet to prevent serious eye and heart diseases. However, taurine deficiency does not appear to be the direct cause of DCM in most dogs.

In the FDA announcement, many of the affected dogs, except golden retrievers and cocker spaniels, had normal levels of taurine. Taurine is also not an essential amino acid for dogs, since their bodies have the ability to manufacture taurine from scratch.

Why is the FDA investigating grain-free diets?


While the underlying cause of dilated cardiomyopathy is not fully understood, large-and giant-breed dogs, such as Newfoundlands, Great Danes, Boxers, Doberman Pinschers, and Saint Bernards appear to have a genetic predisposition for the disease.

However, what makes this case even more confusing is that DCM has been seen more frequently in other breeds such as shih tzus, bulldogs, schnauzers, and whippets, which are not typically associated with DCM.

The only common factor in most of these dogs was their grain-free diet.

The diets of dogs reported in this case were heavy in sweet potatoes, potatoes, peas, lentils, or other legumes and their derivatives. These ingredients were often among the first listed, indicating that they were among the main ingredients.

And while taurine is not considered an essential amino acid for dogs, taurine deficiency-related DCM cannot be ruled out.

Golden retrievers have received the most focus for taurine deficiency-related DCM, and the Morris Animal Foundation Golden Retriever Lifetime Study is investigating the possibility that the breed is less efficient at manufacturing taurine.

Some veterinarians speculate that in dogs with diet-related DCM, legumes may interfere with their ability to synthesize taurine. With treatment, taurine supplements, and a change in their diet, some have reported recoveries.

Should you switch your dog’s diet?

Natural dog food companies say that a protein-rich, grain-free diet is much healthier option because dogs’ digestive systems cannot properly digest grains, and that grains are a common cause of allergies.

Some veterinarians argue that there is no evidence that grain-free diets are better for dogs’ health.

With an ingredient list full of exotic meats and legumes, they believe that dog owners simply fell for marketing tactics. These veterinarians also believe that smaller pet food companies also lack funding and ability to perform extensive testing and quality control on their products.

They also cite scientific evidence that dogs have evolved to be able to digest starch, further questioning pet food manufacturers’ claims of the benefits of grain-free food.

On the other hand, some veterinarians and raw food advocates say that the lack of grains is not the only thing causing DCM. Because grains are typically replaced with high levels of carbohydrates, they believe that starches are always inappropriate and harmful for dogs.

Note: Only you and your vet know what works for your dog, before switching to anything, get together and discuss a plan of action.

Final say on the FDA’s warning

Don’t panic. At this point in time, a direct cause-and-effect relationship has not been established.

Some dogs have recovered with a change in their diet, but without further investigation, it is much too early to say grain-free foods are harmful to dogs. Also, a sudden switch in your dog’s diet could cause digestive upset, so any changes should be done after consulting with your veterinarian.

If you are looking to switch your dog’s food, read the label on the package to ensure that the food meets the AAFCO nutrient profiles.

For dogs who are on grain-free food, look for signs of DCM listed above, such as weakness, fainting, or coughing. If you notice any of these symptoms, visit your veterinarian immediately. Your veterinarian will listen to your dog’s heart and may perform additional testing before making a formal diagnosis.

If your dog is diagnosed with DCM, file a consumer complaint with the FDA. Reporting your case may help with the investigation.

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About the Author

Hyo Song, MSc.

Hyo Song, MSc.

Hyo loves dogs, plain and simple! She holds a Bachelors of Science in Biology, and a Masters in Molecular Targets and Drug Discovery; as well as a degree in Music. Loves spending time with her beautiful 11-yr old Siberian Husky named Hero, has been featured in several scientific publications and is active in providing help to dogs in need.

Read More Posts By: Hyo Song, MSc.

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