Dilated cardiomyopathy is thought to be the second most common acquired heart disease in dogs. Historically, it is considered either an idiopathic condition or associated with taurine deficiency. In recent years, certain diets have been linked to the development of DCM in dogs. The particular group of diets implicated has been termed “BEG diets”: This acronym is used to describe diets that are considered either a Boutique food, have Exotic ingredients, or be Grain-free. The goal of this article is to increase awareness of diet associated cardiomyopathy among veterinarians, and review what is currently known about the possible association between certain diets and DCM in dogs.
Diet-associated DCM first came to light in cats in the late 1980s and in dogs in the mid-1990s. These first cases were typically associated with taurine deficiency. Recently, an increasing number of DCM cases involving dogs appear to have been related to diet and other possible deficiencies. The extent of this problem and exact association with diet is still not clear. Veterinary cardiologists have been reporting possible diet-associated DCM cases to the FDA for over 8 years now and have prompted the FDA to produce statements regarding this emerging problem.
The first published report from the US FDA in 2018 alerted pet owners and veterinarians about reports of DCM in dogs eating pet foods containing peas, lentils, other legume seeds, or potatoes as main ingredients. In February 2019, an FDA update was issued, and in June 2019, a third FDA report was issued. These reports are available on the FDA website. Greater than 93% of dogs with DCM reported to the FDA in the past 8 years have been found to have been fed BEG diets. The FDA lists the most implicated brands of dog foods that have been documented. To date, the FDA continues to work with veterinary cardiologists to investigate this issue.
Taurine deficiency DCM was historically prevalent in cats and certain dog breeds, predominantly Golden Retrievers and Cocker Spaniels. This condition has been rare since the advent of taurine supplementation in diets. Alongside the increase in popularity of BEG diets, there has been a marked increase in DCM cases. Many of these dogs are fed BEG diets containing foodstuffs such as kangaroo, duck, buffalo, salmon, lamb, bison, venison, lentils, peas, fava beans, or chickpeas as major ingredients. Some of the affected dogs had low plasma or whole blood taurine concentrations and improved with taurine supplementation and a diet change. Some dogs that did not have low plasma or whole blood taurine concentrations also improved with a diet change and taurine supplementation.
Currently, we believe that there are still dogs with DCM completely unrelated to diet (eg, breed-specific DCM), but increased incidence of diet-associated DCM. The potential dietary factors are being heavily researched. There appears to be a link between BEG diets and DCM related to the grain-free nature of these diets (ie, use of ingredients such as lentils, chickpeas, or potatoes to replace grains), other common ingredients in BEG diets (eg, exotic meats, flaxseed, fruits, or probiotics), possible nutritional imbalances during metabolism of these diets.
The pet food industry is regulated by the Association of American Feed Control Officials (AAFCO). Pet foods must contain all required nutrients in the right amounts and right proportions. Nutrient standards (minimums and, for some nutrients, maximums) are established by the AAFCO. However, the effects of processing the ingredients, and the nutrient bioavailability should be considered. The AAFCO recommends extensive testing on an ongoing basis to ensure quality control. Inclusion of exotic ingredients, such as kangaroo, alligator, peas, and lentils, adds more complexity because they likely have different nutritional profiles and different digestibility than typical ingredients and have the potential to affect the metabolism of other nutrients. Currently, the pet food companies that consistently follow the guidelines established by AAFCO are called the Big Five: Purina, Iams, Science Diet, Royal Canin and Eukanuba.
Based on cases documented so far, it appears that dogs with DCM that have been eating grain-free diets have more advanced cardiomyopathic changes than dogs with DCM that have been eating grain-based diets. It also appears that the many dogs clinically and echocardiographically improved after a diet change. Taurine supplementation was prescribed for many of these dogs despite the lack of apparent deficiency, and it is unclear what role taurine may play in recovery for some dogs. Possible causes other than taurine deficiency that are being investigated include deficiencies of other nutrients, reduced bioavailability of certain nutrients, different -nutrient interactions, and the inadvertent inclusion of toxic ingredients. BEG diets could possibly be more likely to have deficiencies of nutrients other than taurine, that have been associated with cardiomyopathies in humans. Deficiencies could occur if diets do not contain appropriate amounts of all dietary nutrients. This may be a concern for diets based on exotic ingredients, whose nutritional properties are not well studied.
For dogs in which possible diet-associated DCM is diagnosed, the current FDA recommendation is that the owner changes the diet to one made by a well-established manufacturer that contains standard ingredients (eg, chicken, beef, rice, corn, and wheat). In dogs with a taurine deficiency, taurine supplementation is critical. In dogs with taurine concentrations within reference limits, it is unclear whether taurine supplementation is needed, and some patients have recovered with only a diet change. However, taurine supplementation may still have some benefits owing to other effects of taurine (eg, antioxidant and positive inotropic effects). Changing to a raw or home-prepared diet is not encouraged as these diets may not be sufficient to improve cardiac abnormalities and may increase the risk for other nutritional deficiencies or infectious diseases. Consultation with a board-certified veterinary nutritionist is recommended. It is encouraging that some recovery of cardiac function has been observed in many dogs following a change in diet, with or without taurine supplementation.
Follow-up echocardiography should be performed within 6 months. It appears that some improvements are typically evident in this time span. In some dogs with more advanced disease, it may take even longer for improvements to be apparent echocardiographically. It appears that dogs that are diagnosed early in the stage of their nutritional deficiency have a faster recovery and better long-term prognosis. For cats: If cats diagnosed with DCM are eating a BEG, vegetarian, vegan, or home-prepared diet, the same protocol is recommended.
Nutritional deficiency or diet associated dilated cardiomyopathy, has become an emerging problem in veterinary medicine in the past 5 to 10 years. Pet food marketing has increasingly become a driving factor in choosing a pet food, and owners are not always making healthy, science-based decisions for their pets due to heavy marketing of BEG diets. The recent cases of diet-associated DCM are highly concerning and warrant further research and proactive management in the veterinary community. Importantly, although there appears to be an association between DCM and feeding BEG, vegetarian, vegan, or home-prepared diets in dogs. To date, a cause-and-effect relationship has not been proven, and other dietary factors may be equally or more important. There is ongoing research with the FDA and many veterinary cardiologists and academic institutions, regarding the etiology of this emerging category of DCM. For veterinarians: regular assessment of diet history in all patients can help to identify diet-related cardiac diseases as early as possible. Early detection of a potential cardiomyopathy can aid in prevention of worsening disease. It appears that documenting and addressing possible diet associated DCM cases as early as possible in the course of the disease markedly improves the patient’s chance for complete or nearly complete recovery of cardiac function. In conclusion, identifying at risk animals and ensuring well balanced diets is the best method of prevention for veterinarians. Ongoing research and reporting cases to the FDA will likely help work to identify the primary cause and, potentially, best treatment for diet-associated DCM in dogs.