Grain-Free Diets and Heart Disease in Dogs

About a year ago the U.S. Food and Drug Administration (FDA) first released a statement alerting dog owners about a possible link in canines between dilated cardiomyopathy (DCM) and a diet containing peas, lentils, potatoes and other legumes as a main ingredient. These ingredients are commonly found in diets advertised as “grain-free”. The FDA suggested that high levels of peas, potatoes and lentils may cause low taurine levels in dogs, contributing to DCM.

Unless we take a deeper dive into canine nutrition and the impact of these specific ingredients, there is a tendency for pet parents to panic and experience anxiety about their dog’s diet. This is understandable because Canine DCM can be a devastating disease.

Today’s blog post will seek to provide fact-based information about canine DCM and the link to grain-free diets.

What is Canine Dilated Cardiomyopathy?

Canine dilated cardiomyopathy is a disease of the cardiac muscle that results in a decreased ability of the heart to pump blood through the vascular system of the body.

What Causes Canine Dilated Cardiomyopathy?

The cause of canine DCM is still under investigation by the FDA and other veterinary medical research facilities. It is likely that there are several factors that cause canine DCM, including dietary, metabolic and genetic factors. Millions of healthy dogs around the world eat grain-free diets their entire lives; this is the first time grain-free diets have been implicated as a possible cause of canine heart disease. At this time, a direct cause-and-effect relationship between canine DCM and grain-free diets has not been proven.

What are the Signs of Canine Dilated Cardiomyopathy?

The signs of canine DCM include:

• Lethargy, weakness, weight loss and/or collapse due to decreased oxygen throughout the body
• Coughing, increased respiratory rate and/or effort, abdominal distention due to congestion of blood in the lungs.

If your dog presents any of these symptoms, it is important that your dog be seen by your veterinarian right away.

What is Known About Canine Dilated Cardiomyopathy?

The FDA has released three statements about the potential link between grain-free diets and canine DCM.

• The first statement was issued July 12, 2018, alerting the public that it had begun investigating reports of canine DCM and a possible link to grain-free diets in dogs.
• The second statement was issued February 19, 2019. At that time 294 cases of canine DCM had been reported. These instances occurred between January 2014 and November 30, 2018.
• The third statement was issued June 27, 2019. By this time a total of 515 canine reports of DCM had been documented, occurring between January 2014 and April 30, 2019.

Here’s what we know:

1. It’s not just grain-free diets. However, there may be a link between

• boutique diets
• exotic ingredients (like alligator, duck, rabbit, venison, bison, ostrich, brushtail and kangaroo)
• grain-free diets.

2. Some dogs diagnosed with DCM do not have low taurine levels. One study found that over 90 percent of dogs with DCM were being fed diets listed as either “grain-free” or “zero grain.” However, another study found as many as 90 percent of dogs diagnosed with DCM did not have lowered taurine levels, even in dogs eating a grain-free diet. This suggests there’s something else playing a role.

3. Raw diets and homemade diets are not safe alternatives. Out of concern, some owners are switching from grain-free diets to a raw or home-cooked diet. However, dogs have been diagnosed who eat these types of diets too. Raw and home-cooked diets may pose other health problems. Home-cooked diets are not tested for safety and nutritional adequacy. If you feel strongly about feeding your dog raw or a home-cooked diet, I recommend you consult with a board-certified veterinary nutritionist. 

4. Current thoughts on Canine DCM. It appears there may be three groups of dogs that are being diagnosed with DCM. 1.) Dogs eating a grain-free, exotic or boutique diet that do NOT have low taurine levels. 2.) Dogs who are of predisposed breeds that are eating a normal diet. 3.) Dogs with a taurine deficiency that are eating a grain-free, exotic or boutique diet.

Note: It is important to recognize that the FDA does not have a measure of the frequency of this disease, especially because many pet owners do not elect to pay for expensive testing that could identify the disease. Generally, the occurrence of disease in dogs is not routinely tracked or reported.

Genetic Factors

Initially, the breeds recognized as predisposed to dilated cardiomyopathy included:

• Doberman Pinscher
• Great Dane
• Boxer
• Cocker Spaniel.

Dietary carnitine deficiency may play a role in some cases of Boxer DCM, and taurine responsive DCM has been identified in Cocker Spaniels.

The most recent FDA update includes many more breeds than were originally thought to be at risk. Dilated cardiomyopathy is recognized as a genetic condition in dogs, typically large or giant breeds.

Golden retrievers are especially at risk due to their genetic tendency for taurine deficiency.

Breeds with 5 or more reports of DCM include:

• Golden retriever
• Labrador retriever
• Great Dane
• Pit Bull
• German Shepherd
• Doberman Pinscher
• Australian Shepherd
• Boxer
• Mastiff
• German Short-haired Pointer
• Shetland Sheepdog
• Weimaraner
• American Bulldog
• American Cocker Spaniel
• Standard Poodle
• Bulldog
• Shih Tzu
• Irish Wolfhound

In addition, mixed and unknown breeds have received more than 5 reports. There are many more breeds that have received 2-4 reports. There have been a higher proportion of males reported than females, consistent with what is generally seen with genetic conditions.

Dietary Implications in Grain-Free Diets

The issue as it relates to grain-free diets and a link to canine DCM is complicated. There are many factors to take into consideration. Here are a few:

• Taurine

Taurine is a unique amino acid because it is a free amino acid in the body. While it’s function is not completely known, it is known to contribute to heart health as well as activating bile acids in the liver, enabling canines to break down fats. Dogs can make taurine using two other amino acids, methionine and cysteine. For this reason, taurine is not required if enough methionine and cysteine are present in a dog’s diet. The methionine content in pulses (peas, lentils, potatoes and other legumes) is lower compared to animal-based proteins, but this can easily be remedied by supplementing ingredients rich in this amino acid.

• Protein

Not all protein used in dog’s diets is nutritionally equal. Taurine, and its precursors, methionine and cysteine, are naturally found in animal-based proteins. Therefore, if the diet is based on high-quality animal-based proteins sufficient amounts of taurine will be present. However, if low-quality animal-based proteins are used (i.e. low levels of one or more essential amino acids), the diet may not include enough methionine and cysteine for the dog to produce enough taurine. Methionine, lysine and taurine are often supplemented in dog food to ensure they contain sufficient amounts of these essential amino acids.

• Fiber

The amount and type of fiber in a dog’s diet may also affect the ability of the animal to process and manufacture taurine. More research is needed to understand the impact of fiber – too much or too little – and a possible link to canine DCM.

• Cooking

Another factor to consider is how cooking affects protein and amino acids in dog food. Different types of dog food (i.e. kibble, canned food, etc.) requires cooking at different temperatures. If a food is cooked at a temperature that is too high, it will destroy the amino acids. On the flip side, raw foods that are not cooked may contain factors that can affect the absorption of certain nutrients. For these reasons, it is imperative that dog food manufacturers take into account the impact of cooking on the food they produce.

Dog Foods in Question

The FDA is concerned about dog food that contains a high proportion of peas, lentils, other legume seeds and/or potatoes in various forms, typically labeled as “grain-free”. The most reports were for dry dog food but raw, semi-moist and wet foods were also represented.

The brands with the highest frequency of DCM cases include:

• Acana (67 cases)
• Zignature (64 cases)
• Taste of the Wild (53 cases)
• 4Health (32 cases)
• Earthborn Holistic (32 cases)
• Blue Buffalo (31 cases)
• Nature’s Domain (29 cases)
• Fromm (24 cases)
• Merrick (16 cases)
• California Natural (15 cases)
• Natural Balance (15 cases)
• Orijen (12 cases)
• Nature’s Variety (11 cases)
• NutriSource (10 cases)
• Nutro (10 cases)
• Rachael Ray Nutrish (10 cases)

What Can We Conclude About the Link Between Grain-Free Diets and Canine Dilated Cardiomyopathy?

Overall, it is important to remember that “correlation does not equal causation”. Not all grain-free diets are nutritionally equal, and it is likely misguided to point fingers at single ingredients or the grain-free aspect of the food as the cause of heart disease in dogs.

Clearly, this is a complicated issue that involves genetics, protein quality, fiber and other factors, some of which may not have been identified.

While FDA and other veterinary medical researchers continue to uncover evidence-based facts and compile a comprehensive report it is recommended that you seek the advice of your veterinarian before making any changes to your dog’s diet.

If you have been feeding your dog a grain-free, exotic or boutique diet and are concerned about DCM, you may want to ask your vet about testing, which would involve an exam and possibly additional tests like an x-ray, blood test, electrocardiogram or ultrasound of the heart.

If your dog has been eating a grain-free diet and is diagnosed with DCM, please don’t feel guilty. Trying to decide what is really the best dog food is confusing and difficult. Hopefully, this issue will shed a light on the complexities of safe and nutritious dog food and the importance of nutritional expertise and quality control.

Is your dog on a grain-free diet? What are your thoughts about the possible link between a grain-free diet and canine DCM? Please comment below…

 

Sources:

Medicine, Center for Veterinary. “Potential Connection Between Diet and Cases of Canine Heart Disease.” U.S. Food and Drug Administration, FDA, 12 July 2018, https://www.fda.gov/animal-veterinary/cvm-updates/fda-investigating-potential-connection-between-diet-and-cases-canine-heart-disease.

Medicine, Center for Veterinary. “FDA Investigation Update: Potential Link Between Diet & Canine DCM.” U.S. Food and Drug Administration, FDA, 19 Feb. 2019, https://www.fda.gov/animal-veterinary/cvm-updates/fda-provides-update-investigation-potential-connection-between-certain-diets-and-cases-canine-heart.

Medicine, Center for Veterinary. “FDA Investigates Potential Link Between Diet & Heart Disease in Dogs.” U.S. Food and Drug Administration, FDA, 27 June 2019, https://www.fda.gov/animal-veterinary/news-events/fda-investigation-potential-link-between-certain-diets-and-canine-dilated-cardiomyopathy#diet.

“Canine Dilated Cardiomyopathy (DCM).” Cornell University College of Veterinary Medicine, 6 Feb. 2018, https://www.vet.cornell.edu/hospitals/companion-animal-hospital/cardiology/canine-dilated-cardiomyopathy-dcm.

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National Research Council. Nutrient Requirements of Dogs and Cats. 2006. Washington, D.C.: The National Academies Press.

Boye, J., Zare, F., and A. Pletch. Pulse proteins: Processing, characterization, functional properties and applications in food and feed. Food Res. Int., 2010. 43(2): 414-431.

Torres, C. L., et al., Taurine status in normal dogs fed a commercial diet associated with taurine deficiency and dilated cardiomyopathy. J. Anim. Physiol. Anim. Nutr. 2003. 87(9-10): 359-372.

Thompson, A. Ingredients: Where Pet Food Starts. Top. Companion Anim. Med. 2008. 23(3): 127-132.

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Stratton-Phelps, M., et al., Dietary Rice Bran Decreases Plasma and Whole-Blood Taurine in Cats. J. Nutr. 2002. 132(6): 1745-1747.

Adin, D., et al., Echocardiographic phenotype of canine dilated cardiomyopathy differs based on diet type. Vet. Card. 2019. 21: 1-9.

Kaplan, J.L., et al., Taurine deficiency and dilated cardiomyopathy in golden retrievers fed commercial diets. PLOS ONE, 2018. 13(12): e0209112.

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Freeman, Lisa M., and Dacvn. “It’s Not Just Grain-Free: An Update on Diet-Associated Dilated Cardiomyopathy.” Clinical Nutrition Service at Cummings School, 28 Aug. 2019, https://vetnutrition.tufts.edu/2018/11/dcm-update/.