Ultrastructural differences in the myocardium of cats with dilated cardiomyopathy eating high- versus low-pulse diets

In 2018, the FDA issued an alert about a potential link between dilated cardiomyopathy (DCM) in pet dogs and cats and diets high in pulses (peas, lentils, chickpeas, and beans). Given reported myocardial ultrastructural abnormalities in this disease, the objective was to compare myocardial mitochondria, autophagic structures, and other subcellular organelles in cats with DCM eating high- versus low-pulse diets. Left ventricular tissue from cats with DCM eating high- (n = 4) or low-pulse (n = 3) diets was evaluated using transmission electron microscopy. Myofibrils, mitochondria, T-tubules, nuclei, z-lines, autophagic structures, and intercalated discs were evaluated qualitatively. Diet groups were compared for qualitative findings, as well as mitochondrial number, area, and perimeter; sarcomere length; lipid droplet number and area, and mitochondrial stage in the perinuclear, interfibrillar, and subsarcolemmal regions. Cats with DCM eating high-pulse diets had more unknown vacuoles and fewer Stage B mitochondria, with more Stage BC mitochondria compared to cats with DCM eating low-pulse diets. These results suggest that cats with DCM eating high-pulse diets have mitochondria in more advanced stages of degeneration. The higher number of unknown vacuoles could represent more mitochondrial degeneration or increased autophagy. Further ultrastructural investigation is warranted to help identify the cause of this diet-associated disease.