Diet-induced cardiac dysfunction and impaired cognitive performance in Beagles

Diet-induced dilated cardiomyopathy (DCM) in dogs has been linked to grain-free, pea-containing diets, possibly due to increased oligosaccharides. Since cross-sectional human studies indicate that heart failure is associated with decreased cerebral blood flow and cognitive decline, we explored whether a similar association could be detected in dogs. This study tested whether diet-induced cardiac impairment coincides with a lower index of cerebral blood flow and cognitive decline in dogs. Eight adult Beagles were fed four diets for 5 wk each. A commercial dental diet was fed prestudy as a husbandry diet, followed by three test diets fed in a randomized crossover design: a grain-based diet formulated with rice flour (GB), a grain-based diet with rice flour and 1% of the oligosaccharide raffinose (GB-O), and a grain-free diet containing pea flour (GF). Cardiac function and brain blood flow were assessed using ultrasound, and cognitive function using a sand maze test. Ejection fraction was lower, and left ventricular end-systolic volume was greater in dogs fed the GF and husbandry diets compared to the GB and GB-O diets. End-diastolic velocity and conductance index were greater in basilar cerebral arteries, whereas resistive index was lower in dogs fed GF and husbandry diets. Sand maze retrieval times were slower for GF and husbandry diet-fed dogs compared with the GB-O diet. Thus, reduced ejection fraction was associated with lower cerebral vascular tone and cognitive function in dogs fed GF and husbandry diets. This study is suggestive of a novel link between diet, cardiac function, and cognition in dogs.NEW & NOTEWORTHY This study is the first to investigate the heart-brain connection in dogs, revealing parallel emergence of subclinical cardiac dysfunction and reduced cognitive performance under certain dietary conditions in Beagles. Additionally, transcranial Doppler ultrasound identified a reduction in the index of cerebrovascular tone, potentially reflecting a compensatory response to early cardiac dysfunction. These findings provide a basis for further exploration of how diet, cardiac function and cognition may influence one another in dogs.