Review of canine dilated cardiomyopathy in the wake of diet-associated concerns

Abstract

Dilated cardiomyopathy (DCM) has been in the literature and news because of the recent opinion-based journal articles and public releases by regulatory agencies. DCM is commonly associated with a genetic predisposition in certain dog breeds and can also occur secondary to other diseases and nutritional deficiencies. Recent communications in veterinary journals have discussed a potential relationship between grain-free and/or novel protein diets to DCM, citing a subjective increase in DCM in dog breeds that are not known to have a genetic predisposition for the disease. This literature review describes clinical presentations of DCM, common sequelae, treatment and preventative measures, histopathologic features, and a discussion of the varied etiological origins of the disease. In addition, current literature limitations are addressed, in order to ascertain multiple variables leading to the development of DCM. Future studies are needed to evaluate one variable at a time and to minimize confounding variables and speculation. Furthermore, to prevent sampling bias with the current FDA reports, the veterinary community should be asked to provide information for all cases of DCM in dogs. This should include cases during the same time period, regardless of the practitioner's proposed etiology, due to no definitive association between diets with specific characteristics, such as, but not limited to, grain-free diets and those containing legumes, novel protein diets, and those produced by small manufacturers to DCM in dogs. In summary, in order to determine if certain ingredients, categories of diets, or manufacturing processes are related to an increased risk of DCM, further studies investigating these variables are necessary.

Keywords: carnitine; deficiency; diet; dilated cardiomyopathy; dog; taurine.

Figure 1.

Known and potential etiologies associated with DCM.

Figure 2.

Recommended veterinarian guidelines for managing diet concerns for pets with and without clinical signs of cardiac disease.

Figure 3.

Percentage of dog cases reported in the FDA report that are breeds predisposed (dark gray) to DCM, non-predisposed (white) to DCM, and mixed or unknown breeds (light gray). Dogs considered predisposed to DCM include Great Danes, Doberman Pinschers, Boxers, Golden Retrievers, Cocker Spaniels, German Shepherds, and Bulldogs. FDA (2019a).

Figure 4.

Dogs in FDA report diagnosed via echocardiogram that have known underlying medical conditions (gray) and dogs that had no known medical issues (white). Known underlying medical conditions include chronic valve disease, hypothyroidism, and tick-borne diseases. FDA (2019a).

Figure 5.

Top six U.S. manufacturers (gray) and other U.S. manufacturers (white) named in the FDA report concerning DCM in dogs. FDA (2019a).