Epidemiological and pathological aspects of cardiomyopathies in cats in southern Brazil

Abstract

Cardiomyopathies are considered one of the most important causes of heart failure in cats and are subdivided into three main morphological types: hypertrophic (HCM), dilated (DCM), and restrictive (RCM). This study aimed to determine the frequency and types of cardiomyopathies in cats diagnosed in southern Brazil, with an emphasis on their epidemiological and pathological aspects. Necropsy reports filed in a veterinary pathology laboratory were reviewed, and cats diagnosed with cardiomyopathy were selected for the study. Animal identification data, history and clinical signs, and gross lesions, were reviewed and compiled. During the study period, 1.594 cat necropsies were performed, of which 72 (4.5%) comprised a diagnosis of cardiomyopathy. HCM was the most frequent followed by CMR and CMD, representing 77.8%, 12.5% and 9.7%, respectively. Age ranged from three months to 18 years, with a median age of seven years. In relation to sex, 62.5% were males and 37.5% females. In 76.4% of the cases, it affected cats without a breed defined. Restrictive mixed dyspnea and hydrothorax were the main signs or findings of the clinical examination. Sudden death and acute paresis of the pelvic limbs due to aortic thromboembolism have also been described. In HCM, myocardial thickening was observed, with a reduction in the ventricular chamber. Hypertrophy, disarray, and fibrosis of the myofibers were the main histological findings. In RCM, whitish and thickened endocardium was seen in most cases. DCM was characterized by dilated cardiac chambers, and microscopic examination revealed no significant findings. The main extra cardiac lesions revealed pulmonary edema and congestion, hydrothorax and chronic passive congestion of the liver. Cardiomyopathies are important causes of death in cats and should be included in the differential diagnosis of patients with cardio respiratory clinical signs and in cases related to sudden death and acute paresis of the pelvic limbs.