Distribution of coronary arteries and histopathological analysis of three-toed sloth (Bradypus variegatus) heart

Abstract

The three-toed sloth (Bradypus variegatus) has been a victim of disorderly human interventions, leading to an increase in accidents and diseases for the species. This study aimed to provide a description of the coronary arteries and to highlight the histopathological findings in the sloth’s heart. This information should be beneficial for medical clinics dealing with these species. Eighteen B. variegatus specimens were dissected after natural death. Fifteen of them, comprising five adult males, nine adult females, and one juvenile, were fixed with formaldehyde and preserved in saline solution. In two males and one female, red-coloured latex was injected through the left common carotid artery to make the coronary arteries more visible. In the female, blue-coloured latex was also injected through the right external jugular vein to aid in arterial identification. The chests were opened to evaluate and extract the heart for a detailed description of the coronary arteries. For histopathological analysis, histological slides were prepared from four hearts collected from four animals (three adults and one juvenile). Arterial analyses revealed that sloths possess two coronary arteries: one on the right and one on the left side, each of which supplies blood to their respective surfaces. The heart is composed of the endocardium, myocardium, and epicardium, similar to mammals in general. However, necrosis of endocardial tissue and cardiac muscle fibres, as well as myxomatous degeneration of valves and thrombi in vascular lumens, were observed. These necrotic events, more extensive in nature, are related to infarctions, while the more subtle ones may be associated with stressful situations experienced by the individuals.