Understanding Dilated Cardiomyopathy in Dogs
Dilated Cardiomyopathy (DCM) is a disease of the heart muscle, which results in dilation of the heart chambers. This, in turn, decreases the ability of the heart to pump efficiently, leading to buildup of fluid in the chest and abdomen, known as congestive heart failure.
What Causes DCM?
The exact cause of DCM in dogs is not always clear, but there are several factors that can contribute to its development:
Genetics: Some dog breeds are genetically predisposed to DCM, including Doberman Pinschers, Boxers, Great Danes, and Cocker Spaniels. It is believed to have a hereditary component, and dogs with a family history of DCM are at higher risk.
Nutritional Deficiencies: In some cases, a deficiency in specific nutrients, such as taurine, can lead to the development of DCM. This is more common in certain breeds, like Golden Retrievers and American Cocker Spaniels.
Other Medical Conditions: DCM can also develop as a secondary condition to other diseases, such as thyroid problems or infectious diseases.
Nutrition and DCM
You may have seen the ongoing debate about whether pulses (peas, beans and lentils) in dog food can lead to dilated cardiomyopathy (DCM). In July 2018, the the United States Food and Drug Administration (FDA) announced it had begun investigating reports of canine dilated cardiomyopathy in dogs eating certain pet foods, many labeled as “grain-free.” Although pulses had been used in pet foods for many years with no evidence to indicate that they were inherently dangerous, they were implicated early on as they are often used in greater proportions in grain-free diets.
Further Investigation: 2018-2020
Since 2018, sixteen peer-reviewed research articles on DCM have been published. No cause-effect relationship between grain-free diets and DCM was identified in any of the studies conducted by the FDA. Independent researchers also began studying this to understand potential links between certain diets and DCM.
In June 2020, a review in the Journal of Animal Science compiled information on the research to date around incidence, symptoms, treatments and preventative measures, as well as potential causes of the disease. They concluded that DCM is the second most prevalent heart disease in dogs, affecting over 300,000 dogs in the United States at any given time, and that multiple dietary and environmental factors, in addition to genetics, can potentially lead to development of the disease.
As of July, 2020, more than 1100 dogs with DCM had been reported to the FDA. Based on the data collected and analyzed by that time, they published a Q&A that stated, “emerging science appears to indicate that non-hereditary forms of DCM occur in dogs as a complex medical condition that may be affected by multiple factors such as genetics, underlying medical conditions, and diet. Aspects of diet that may interact with genetics and underlying medical conditions may include nutritional makeup of the ingredients and how dogs digest them, ingredient sourcing, processing, formulation, and/or feeding practices.”
A retrospective study published in December 2020, reviewed the medical records from 71 dogs diagnosed with DCM. Researchers concluded that dogs with DCM eating nontraditional diets experienced improvement in cardiac function after switching to a grain-inclusive diet, as well as treatment with medication and supplements, but that additional research was needed to examine possible associations between diet and DCM.
Further Investigation: 2021-2022
In August 2021, a study looking into specific compounds found in grain-free diets vs grain inclusive diets, found that a series of chemical compounds could only be found in the former and that the source of those compounds was mainly peas. The authors stated that more research is needed to see if those compounds actually have an effect on DCM onset, but suggested that nutrient insufficiency may be the real culprit.
In December 2022, the FDA issued their fourth update on diet-associated dilated cardiomyopathy (DCM) in the form of frequently asked questions. At this time, they also announced that they will no longer be updating the public on the potential link between certain diets and canine dilated cardiomyopathy until there is meaningful new scientific information to share. In the latest update, another 255 dogs with DCM had been reported to the FDA, bringing the total number of dogs with DCM reported to the FDA to 1,382. It is unclear whether this lower rate of dogs reported is due to there being fewer cases, or rather just fewer veterinarians and pet owners reporting cases.
Regardless, in response to whether the diets associated with DCM have any commonalities, the FDA’s response was:
“Most of the diets associated with the reports of non-hereditary DCM have legume seed ingredients, also called “pulses” (e.g., peas, lentils, etc.), high in their ingredient lists (although soy is a legume, we did not see a signal associated with this ingredient). These include both “grain-free” and grain-containing formulations… The FDA does not know the specific connection between these diets and cases of non-hereditary DCM and is continuing to explore the role of genetics, underlying medical conditions, and/or other factors.”
Recent Research: Do Pulses Cause DCM?
A recently published study in The Journal of Nutrition has provided some clarity. Researchers from the University of Guelph conducted a study which investigated the effects of including whole pulse ingredients (e.g., lentils, chickpeas) in a dog's diet with chicken meal and pea starch. In this 20-week study, 28 healthy owned adult Siberian Huskies were fed a grain-free dog food containing up to 45% inclusion of whole dietary pulse ingredients. The dogs were randomly fed one of four types of diets with equivalent micronutrient supplementation and increasing levels of pulse ingredients (0%, 15%, 30% and 45%). The researchers tested whether this diet impacted the dog's cardiac function, fasted sulfur amino acid status, or overall health.
They assessed cardiac function using echocardiographic measurements and cardiac biomarkers (N-terminal pro-B-type natriuretic peptide and cardiac troponin I), and found that there were no differences between groups or across time. They also measured plasma sulfur amino acid concentrations as they may limit taurine synthesis, and evaluated body composition and hematological and biochemical indices- all of which were similar among treatments and over time.
Correlation Does Not Mean Causation
The conclusion? The researchers concluded that including up to 45% pulse ingredients in a dog's diet did not affect any of these measures, indicating that pulse ingredients can be included in a complete and balanced diet for dogs without any negative health effects.
Wild Earth’s Commitment to Heart Health
Although many can rest assured that peas may not be the direct cause of DCM in dogs, we have decided to exclude pulses from our diets. We have also added Taurine to our diets. The recommended amount of Taurine for dogs with heart disease is 0.1%. Both our Maintenance and Performance formulas contain 0.2% taurine. Lastly, we supplemented both of our diets with L-carnitine, another amino acid that plays a role in heart health.
