Dilated Cardiomyopathy in Dogs Fed Nontraditional vs Traditional Diets

In 2018, the FDA issued an alert for a possible connection between cardiac disease (ie, dilated cardiomyopathy [DCM]) and diet because of increased cases of DCM in canine breeds not typically predisposed to primary DCM.¹ Attention was initially focused primarily on grain-free diets; however, nontraditional diets include both grain-free and grain-inclusive diets rich in pulses (eg, peas, lentils, chickpeas) or potatoes/sweet potatoes. Most studies investigating the association between diet and DCM have been retrospective.^2-4

This prospective study* compared characteristics of dogs with DCM fed nontraditional (n = 51) and traditional (n = 9) diets and evaluated the effect of diet change on echocardiographic measurements and cardiac biomarkers over a 9-month period. Dogs in both groups received standard medical treatment at the discretion of their primary clinician. In addition, a group of dogs with subclinical cardiac abnormalities (ie, echocardiographic changes not meeting the definition of DCM) previously fed nontraditional diets were monitored for serial echocardiographic and cardiac biomarker changes after diet change. 

In dogs with DCM previously fed nontraditional diets and transitioned to a traditional diet, echocardiographic findings demonstrated a significant increase in fractional shortening (an indicator of systolic function) during the study period. Dogs with subclinical cardiac abnormalities also showed improvement in echocardiographic findings following diet change; these dogs were fed a nontraditional diet for a shorter duration than dogs with DCM, indicating initial echocardiographic abnormalities likely represented an earlier form of diet-associated DCM.

Taurine deficiency has been considered a cause of diet-associated DCM; however, taurine levels did not differ between diet groups in this study, and no dogs had low plasma or whole blood taurine concentrations.  

Survival times did not significantly differ between diet groups. Dogs with DCM originally fed nontraditional diets had a median survival time of 611 days, compared with 161 days in dogs with DCM originally fed traditional diets. This finding contrasts with previous retrospective studies that showed diet change was associated with longer survival times in dogs with DCM originally fed nontraditional diets.^2,3 The relatively low number of dogs in the traditional diet group was a limitation of this study.

Key pearls to put into practice:

Nontraditional diets associated with DCM can include both grain-free and grain-inclusive diets with pulses or potatoes/sweet potatoes in the top 10 ingredients. Obtaining patient diet history, including ingredient lists, is key for identifying at-risk dogs.

Transition from a nontraditional to a traditional diet can result in significantly improved echocardiographic findings in dogs with DCM.

Subclinical cardiac abnormalities have been identified in dogs fed nontraditional diets for shorter duration than in dogs with overt DCM, likely representing an earlier form of diet-associated DCM. Pet owners should be educated about risks of nontraditional diets as well as potential cardiac benefits of switching to a traditional diet.