Dilated Cardiomyopathy (DCM) in Dogs: Updated Information & Nutrition Guidance

Image of a Great Dane dog lying on a grassy field

Updated: February 2024

This blog post will be updated if and when the FDA or other veterinary nutrition leaders release information tied to DCM and its potential causes. The investigation remains closed by the FDA and new academic research continues to affirm the safety of pulse-inclusive diets for dogs. 

Recent updates:

Dilated Cardiomyopathy (DCM) is a serious but rare disease of the heart muscle that can have life-threatening consequences. While the causes of DCM in dogs can vary, the pet nutrition industry has been focused on a possible connection between certain diets and the cardiac condition. However, the vast majority of DCM cases are genetic and tend to disproportionately affect large breeds and male dogs. 

We have been closely following the research into dietary factors and heart health since we started the company, and our formulations incorporate the recommendations of multiple veterinary nutritionists to reflect the current evidence. Genetics are the most common cause of DCM, and predisposed breeds like Doberman Pinschers can inherit the disease at high rates. Diet-related DCM is much rarer than genetic DCM and is typically associated with a deficiency in the amino acid (protein building block) taurine, which is a critical component of heart muscle. Diet-related DCM is typically diagnosed by low blood taurine levels, and can often be reversed through supplementation with taurine and/or a transition to a diet higher in taurine and/or methionine. 

In this blog post, we will delve into the common causes of DCM, the link to breed-specific genetics, and our evolving understanding of nutrition’s role (specifically grain-free diets). Lastly, we will explore the specific formulation decisions made by Petaluma’s veterinary team to address known diet-related issues and support heart health.

Understanding Dilated Cardiomyopathy

Dilated Cardiomyopathy is a heart condition characterized by the enlargement of the heart chambers, particularly the left ventricle, leading to a weakened and less efficient pumping mechanism. As a result, the heart struggles to circulate blood effectively, causing symptoms such as lethargy, coughing, and difficulty breathing. While DCM can occur in any breed, certain breeds are more predisposed to this condition. The genetic component of DCM is well-established, and it's commonly seen in large and giant breeds such as Doberman Pinschers, Great Danes, and Irish Wolfhounds. These breeds are often linked to a few genetic mutations associated with the production of cardiac muscle proteins.

In recent years there has been concern that there is a rise in DCM cases among breeds not traditionally associated with the condition, sparking concerns and investigations into potential dietary links. We will delve more deeply into this potential link later on in this blog post, but it is important to note that the majority of DCM cases are not diet-related, and by some estimates account for less than 1% of an already rare condition.  Environmental factors, diet, and other variables may contribute to the development of DCM, broadening the scope of understanding beyond breed-specific genetics.

A diagram of two hearts, one of which is enlarged due to DCM

Image source: https://www.amcny.org/pet_health_library/dilated-cardiomyopathy-dcm-in-dogs/

The FDA Investigates - and a Grain-Free Controversy is Sparked

In 2018, the U.S. Food and Drug Administration (FDA) launched an investigation into a potential association between certain diets, particularly those labeled as grain-free, and the occurrence of DCM in dogs. The FDA's concern stemmed from anecdotal reports from clinical veterinarians of a perceived rise in DCM cases in breeds like Golden Retrievers, Labrador Retrievers, and other popular breeds that were not typically predisposed to the condition.

In the last decade, the pet food industry has seen a surge in the popularity of grain-free diets for dogs. From 2010 to 2018, there was a massive shift towards grain-free formulas - which ballooned from <5% of sales in 2010 to ~50% of sales in 2018. Grain-free diets were typically the highest-priced premium kibble and were often marketed as a solution for dogs with allergies or sensitivities. Many pet owners sought out grain-free formulas to provide what they believed to be a more natural and healthy option as carbohydrates were (inappropriately) marketed as bad for dogs.

Taurine, an amino acid crucial for heart health, was identified as a potential factor, as some dogs on grain-free diets were found to have low blood taurine levels that likely contributed to the development of DCM. Taurine is not considered an essential amino acid for dogs - i.e. it can be made from other nutrients and does not need to be in the diet. Dogs (and humans) are able to make taurine from other amino acids, particularly the essential amino acid methionine. However, many veterinary nutritionists now consider taurine to be ‘conditionally essential’ because some dogs seem to have defective taurine synthesis pathways, meaning they are not able to efficiently convert methionine (and some other precursors) into taurine leaving them with insufficient taurine levels to maintain heart muscle and other important bodily functions. 

While grain-free diets may not inherently lack taurine, the specific formulations and ingredients used can impact its absorption and utilization by the dog's body. Grains are relatively high in methionine, the precursor protein for taurine, while pulses are relatively low in methionine, so there was a legitimate concern that foods that removed large amounts of grains and replaced them with large amounts of pulses could be leading to taurine deficiencies and DCM, particularly when a dietary change and supplementation of taurine caused the DCM signs to disappear. 

The controversy surrounding grain-free diets and their potential link to DCM sparked a heated debate within the veterinary and pet nutrition communities. The initial theory was that pet food brands added significant amounts of pulses (peas, chickpeas, lentils) as well as potatoes as a replacement for the grains that had been removed to make marketing claims. Removing grains was largely a marketing exercise without a reasonable nutritional basis, and one learning from this health scare is that they are not just "filler ingredients." Pulses have a different nutritional profile than grains, including the amino acids that constitute their protein, and also contain more anti-nutritional factors (compounds that bind to certain nutrients and prevent digestion) in their raw, uncooked form (i.e. one reason we don't eat raw chickpeas or beans). Pulses are also typically more expensive than grains, and some brands seem to have also reduced the amount of animal protein in the food to accommodate the increased cost of pulse-based ingredients. This resulted in some formulas deriving over 60% of protein from peas, which will have a less balanced amino acid profile than foods that use a mix of proteins from different food groups (including grains).

Case closed - now what?

The FDA collected data from veterinarians, pet owners, and the pet food industry to analyze and identify potential factors contributing to the increased incidence of DCM. Non-hereditary DCM remained rare - less than 1,000 cases were reported to the FDA over 4 years after their call for submissions despite estimates of genetic DCM incidence rate suggesting over 1,000,000 U.S. dogs would ‘naturally’ have the disease. The validity of the original trigger for the investigation - i.e. that DCM cases were significantly increasing in dogs that could not be explained by genetics and may be related to insufficient nutrition - is still highly debated and was likely vastly overstated. The inability to determine if DCM is actually becoming more common, let alone if that is driven by diet, is a huge problem. The veterinary care industry is hampered by a lack of good population-level health data, mainly because pets rarely have insurance and the standardized diagnosis codes used to bill insurance in human healthcare are typically how human health trends are analyzed. After multiple years of data collection, studies are suggesting that the DCM diagnoses have not increased in the last two decades even as grain-free and legume-rich diets grew to 50% of the market.

Crucially, studies have not been able to replicate high-pulse diets causing DCM, potentially because the experimental diets are almost always balanced - i.e. are formulated by nutritionists so that they have all essential nutrients including methionine, even with high pulses. It is possible (and likely) that some of the commercial diets implicated in the FDA’s announcement may have been nutritionally incomplete, as random testing of commercial diets with all types of ingredient lists often finds that diets don’t meet the nutritional guidelines that they claim. That said, the nutritional deficiencies found in dog food are typically marginal and most people will experience more significant nutritional gaps in their daily diets that are rarely planned. 

The FDA announced they were closing their investigation in 2022 without establishing any link between diet (and particularly pulses) and heart disease. The language of the FDA’s statement seems intentionally ambiguous, as they are not confirming or nullifying the initial hypothesis about a dietary cause of DCM. There have been a large number of studies attempting to determine a link between pulse ingredients and the development of DCM, and none have found evidence to suggest that the inclusion of pulse ingredients harmed the heart muscle. This includes studies that concluded 1) actual cases of DCM have not increased with the increase of grain-free and pulse-inclusive foods, 2) randomly assigning diets with various levels of pulse ingredients did not result in heart muscle changes (largest studies here and here), and 3) randomly assigning a vegan diet with pulse ingredients did not result in changes in heart muscle function or heart biomarkers.

In response to the emerging evidence and concerns surrounding grain-free diets and DCM, veterinary organizations and experts began reevaluating their nutritional recommendations for dogs. While not all grain-free diets were implicated, the focus shifted towards more balanced diets, irrespective of the presence or absence of grains. Pet owners were advised to consult with veterinarians to choose diets that meet the specific nutritional needs of their dogs, considering factors such as breed, age, and health status. The emphasis on the overall diet composition, including diverse protein sources and essential nutrients like taurine, became the standard advice for reducing the risk of a plausible but unsubstantiated theory.

Petaluma’s approach

Petaluma launched its first formula in 2021, well after the FDA investigation was opened. We worked alongside veterinary nutrition experts to craft formulas that would incorporate guidance from the investigation as it unfolded. We brought a heightened awareness to our formulation process and marketing to proactively address concerns that may arise from clinical veterinarians and pet parents. In general, our philosophy is to focus on ingredients with a long and successful track record in pet food, and transparently share data about our formulas so customers can feed Petaluma confidently. 

#1: It’s all about balance - moderate inclusion of legumes & diversified protein sources

The DCM investigation into grain-free diets was particularly focused on the substitution of grains for legumes, which can result in some significant changes in the types of proteins in the food. However, legumes have been included in more balanced grain-inclusive formulas for decades with no ill effects.

While chickpeas are the first ingredient in Petaluma’s diets, they represent less than 15% of our formulas as we've formulated with multiple ingredient groups as protein sources. Pulses (chickpea and pea protein) represent less than 25% of our diet and less than 30% of our protein, which is not considered a high-legume diet in the context of the DCM investigation (including in a recent experimental study that did not find an association of legume content at any level with heart deficits).  Peanuts are also legumes but not pulses and are closer in nutritional profile to soybeans, which also are not included in the investigation. 

#2: Healthy whole grains play an important role

We include over 20% organic whole grains in our formula (organic oats and organic barley), which are complementary proteins to legumes. We use pre-cooked, steamed chickpea flour that is then baked in our food, and these heat treatment steps have been shown to remove essentially all of the anti-nutrient factors that could inhibit the digestion of proteins. While the initial FDA investigation mentioned potatoes, the FDA no longer considers potatoes as potentially linked to DCM cases and removed them from their investigation. 

#3: Proper supplementation provides extra assurance for heart health

On the guidance of veterinary nutrition experts, we supplement our food with the amino acids taurine, methionine, and l-carnitine, as all three have a role in heart muscle function and the supplemental version is highly digestible. Supplementing taurine has become a standard recommendation for commercial dog food diets (regardless of protein source). In addition, our food contains supplemental sources of choline, which have both been shown to contribute to the maintenance of healthy blood taurine levels and heart muscle strength.

#4: Veterinary nutrition experts formulate and validate Petaluma’s diets

We know the importance of working alongside experts in the veterinary nutrition field to stay up-to-date on the latest science and make formulation adjustments as appropriate. We have some more in-depth commentary from our veterinarian formulator, Dr. Blake Hawley, here for further reading. 

Petaluma has conducted in-depth nutritional analyses to demonstrate the full nutritional profile (including taurine and methionine), partnered with a university laboratory for digestibility testing to validate that protein is being absorbed at a high rate, and also conducted an at-home feeding trial with companion dogs. In our product reviews, there is anecdotal evidence from customers who saw diet-related DCM symptoms reverse and heart muscle improve after switching from other diets to Petaluma. 

In Closing

DCM remains a very rare condition outside of the known genetic cases, and the cardiology clinic data suggest that cases have not increased. In general dog owners who are willing to spend more on veterinary care (such as getting an echocardiogram to diagnose DCM) are also more likely to spend more on nutrition, so the higher proportion of diagnosed cases in which dogs were eating "grain-free" diets, which historically had more premium kibble, is not surprising. There is ongoing research on this topic, but the FDA has largely backpedaled from its initial announcement because the assertion of both an increase in DCM incidence and a correlation with grain-free/pulse-ruch diets has not been supported by subsequent evidence. 

We believe that eliminating an entire category of nutritious ingredients (pulses) due to an ambiguous and unsubstantiated threat is not a responsible step, particularly when the way we got here was by removing another category of ingredients (grains) for marketing-led, non-nutritional reasons. The FDA investigation highlighted the need for a cautious approach to pet nutrition, emphasizing the importance of balanced and complete diets. As our knowledge evolves, pet owners must stay informed and work closely with veterinarians to make informed decisions about their dogs' diets, ensuring the optimal health and the well-being of their beloved companions.

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