Canine dilated cardiomyopathy (DCM) is a disease of a dog’s heart muscle that results in an enlarged heart, leading to a decreased ability of the heart to generate pressure to pump blood through the vascular system (1,2).
Certain breeds, like the Doberman Pinscher, the Great Dane, the Boxer, and the Cocker Spaniel, are genetically predisposed to this disease, suggesting that there is a hereditary component, however, the definitive cause of DCM has not been identified and it’s thought to involve a multitude of factors (3).
The controversy surrounding DCM and its link to diet is mainly due to the multiple announcements made by the FDA in recent years. Starting in 2018, the FDA hypothesized, based on a few reported cases, that there was a potential link between grain-free diets and DCM (4). In these diets, grain ingredients such as corn, wheat and rice have been largely substituted with legumes, (e.g. peas, lentils) and/or potatoes. Over the course of the next 2+ years, the FDA collected more data and information on a total of 1100 DCM cases, and presented its final report to date (September 2020) where they state that DCM is in fact a multifactorial issue with many potential variables including, but not limited to, genetics, breed, age, weight, underlying medical conditions, metabolism and nutrition, among others. No cause-effect relationship between grain-free diets and DCM has been identified in any of the studies conducted by the FDA (5).
Independent researchers have also been studying this to understand any potential links. 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 actually 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 (6). They compared this prevalence to the total cases submitted to the FDA, and suggested that the sample size was too small to be representative (only 0.05-0.1% of the US dog population).
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 (7).
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 (8).
All current information suggests that if a link in fact exists between diet and DCM, it may be due to nutritional deficiencies in the diet or to bioavailability of certain nutrients vs. a high content of pulse ingredients. As Dr. Steven Solomon, director of the FDA’s Center for Veterinary Medicine, stated in his remarks during the FDA’s forum on DCM “It is important to note that pulse ingredients have been used in pet food for a long time, and we have no evidence to indicate that they are inherently dangerous”. He further recommends that any changes to the pet’s diet be done in consultation with your veterinarian and based on your dog’s health and medical history (9).
By Abril Estrada