Abstract
A 2-year-3-month-old neutered male domestic shorthair cat was presented for cardiological evaluation at the University of Agricultural Sciences and Veterinary Medicine in Cluj-Napoca, Romania, with a history of dyspnea, open-mouth breathing, cyanosis, and exercise intolerance. Physical examination identified a grade 4/6 systolic murmur, cyanosis, and mild dyspnea, with no abdominal abnormalities. Echocardiography revealed right ventricular hypertrophy, severe right atrial dilation, a thickened tricuspid valve, and a large nonrestrictive ventricular septal defect with a left-to-right shunt, consistent with persistent truncus arteriosus (PTA), confirmed postmortem. During necropsy, in addition to the clinically confirmed diagnoses, bilateral myxomatous degeneration of the A-V valves, and associated anomalies such as an atrial diverticulum and splenopancreatic fusion were observed and confirmed histologically. This case emphasizes the clinical and morphological complexity of congenital heart defects in felines, highlighting the importance of advanced diagnostic and histopathological techniques for accurate diagnosis and characterization.